# GNU libiberty

## Table of Contents

- Introduction
- 1 Using
- 2 Overview
  - 2.1 Supplemental Functions
  - 2.2 Replacement Functions
    - 2.2.1 Memory Allocation
    - 2.2.2 Exit Handlers
    - 2.2.3 Error Reporting
  - 2.3 Extensions
- 3 Obstacks
  - 3.1 Creating Obstacks
  - 3.2 Preparing for Using Obstacks
  - 3.3 Allocation in an Obstack
  - 3.4 Freeing Objects in an Obstack
  - 3.5 Obstack Functions and Macros
  - 3.6 Growing Objects
  - 3.7 Extra Fast Growing Objects
  - 3.8 Status of an Obstack
  - 3.9 Alignment of Data in Obstacks
  - 3.10 Obstack Chunks
  - 3.11 Summary of Obstack Functions
- 4 Function, Variable, and Macro Listing.
- Appendix A Licenses
  - A.1 GNU LESSER GENERAL PUBLIC LICENSE
    - A.1.1 Preamble
    - A.1.2 How to Apply These Terms to Your New Libraries
  - A.2 BSD
- Index

Next: Using

## Introduction

The `libiberty` library is a collection of subroutines used by various GNU programs. It is available under the Library General Public License; for more information, see Library Copying.

This edition accompanies GCC 3, September 2001.

Next: Overview, Previous: Top, Up: Top

## 1 Using

To date, `libiberty` is generally not installed on its own. It has evolved over years but does not have its own version number nor release schedule.

Possibly the easiest way to use `libiberty` in your projects is to drop the `libiberty` code into your project's sources, and to build the library along with your own sources; the library would then be linked in at the end. This prevents any possible version mismatches with other copies of libiberty elsewhere on the system.

Passing --enable-install-libiberty to the configure script when building `libiberty` causes the header files and archive library to be installed when `make install` is run. This option also takes an (optional) argument to specify the installation location, in the same manner as --prefix.

For your own projects, an approach which offers stability and flexibility is to include `libiberty` with your code, but allow the end user to optionally choose to use a previously-installed version instead. In this way the user may choose (for example) to install `libiberty` as part of GCC, and use that version for all software built with that compiler. (This approach has proven useful with software using the GNU `readline` library.)

Making use of `libiberty` code usually requires that you include one or more header files from the `libiberty` distribution. (They will be named as necessary in the function descriptions.) At link time, you will need to add -liberty to your link command invocation.

Next: Functions, Previous: Using, Up: Top

## 2 Overview

Functions contained in `libiberty` can be divided into three general categories.

Next: Replacement Functions, Up: Overview

### 2.1 Supplemental Functions

Certain operating systems do not provide functions which have since become standardized, or at least common. For example, the Single Unix Specification Version 2 requires that the `basename` function be provided, but an OS which predates that specification might not have this function. This should not prevent well-written code from running on such a system.

Similarly, some functions exist only among a particular “flavor” or “family” of operating systems. As an example, the `bzero` function is often not present on systems outside the BSD-derived family of systems.

Many such functions are provided in `libiberty`. They are quickly listed here with little description, as systems which lack them become less and less common. Each function foo is implemented in foo.c but not declared in any `libiberty` header file; more comments and caveats for each function's implementation are often available in the source file. Generally, the function can simply be declared as `extern`.

Next: Extensions, Previous: Supplemental Functions, Up: Overview

### 2.2 Replacement Functions

Some functions have extremely limited implementations on different platforms. Other functions are tedious to use correctly; for example, proper use of `malloc` calls for the return value to be checked and appropriate action taken if memory has been exhausted. A group of “replacement functions” is available in `libiberty` to address these issues for some of the most commonly used subroutines.

All of these functions are declared in the libiberty.h header file. Many of the implementations will use preprocessor macros set by GNU Autoconf, if you decide to make use of that program. Some of these functions may call one another.

Next: Exit Handlers, Up: Replacement Functions

#### 2.2.1 Memory Allocation

The functions beginning with the letter x are wrappers around standard functions; the functions provided by the system environment are called and their results checked before the results are passed back to client code. If the standard functions fail, these wrappers will terminate the program. Thus, these versions can be used with impunity.

Next: Error Reporting, Previous: Memory Allocation, Up: Replacement Functions

#### 2.2.2 Exit Handlers

The existence and implementation of the `atexit` routine varies amongst the flavors of Unix. `libiberty` provides an unvarying dependable implementation via `xatexit` and `xexit`.

Previous: Exit Handlers, Up: Replacement Functions

#### 2.2.3 Error Reporting

These are a set of routines to facilitate programming with the system `errno` interface. The `libiberty` source file strerror.c contains a good deal of documentation for these functions.

Previous: Replacement Functions, Up: Overview

### 2.3 Extensions

`libiberty` includes additional functionality above and beyond standard functions, which has proven generically useful in GNU programs, such as obstacks and regex. These functions are often copied from other projects as they gain popularity, and are included here to provide a central location from which to use, maintain, and distribute them.

Next: Licenses, Previous: Functions, Up: Top

## 3 Obstacks

An obstack is a pool of memory containing a stack of objects. You can create any number of separate obstacks, and then allocate objects in specified obstacks. Within each obstack, the last object allocated must always be the first one freed, but distinct obstacks are independent of each other.

Aside from this one constraint of order of freeing, obstacks are totally general: an obstack can contain any number of objects of any size. They are implemented with macros, so allocation is usually very fast as long as the objects are usually small. And the only space overhead per object is the padding needed to start each object on a suitable boundary.

Next: Preparing for Obstacks, Up: Obstacks

### 3.1 Creating Obstacks

The utilities for manipulating obstacks are declared in the header file obstack.h.

— Data Type: struct obstack

> An obstack is represented by a data structure of type `struct obstack`. This structure has a small fixed size; it records the status of the obstack and how to find the space in which objects are allocated. It does not contain any of the objects themselves. You should not try to access the contents of the structure directly; use only the functions described in this chapter.

You can declare variables of type `struct obstack` and use them as obstacks, or you can allocate obstacks dynamically like any other kind of object. Dynamic allocation of obstacks allows your program to have a variable number of different stacks. (You can even allocate an obstack structure in another obstack, but this is rarely useful.)

All the functions that work with obstacks require you to specify which obstack to use. You do this with a pointer of type `struct obstack *`. In the following, we often say “an obstack” when strictly speaking the object at hand is such a pointer.

The objects in the obstack are packed into large blocks called chunks. The `struct obstack` structure points to a chain of the chunks currently in use.

The obstack library obtains a new chunk whenever you allocate an object that won't fit in the previous chunk. Since the obstack library manages chunks automatically, you don't need to pay much attention to them, but you do need to supply a function which the obstack library should use to get a chunk. Usually you supply a function which uses `malloc` directly or indirectly. You must also supply a function to free a chunk. These matters are described in the following section.

Next: Allocation in an Obstack, Previous: Creating Obstacks, Up: Obstacks

### 3.2 Preparing for Using Obstacks

Each source file in which you plan to use the obstack functions must include the header file obstack.h, like this:

         #include <obstack.h>

Also, if the source file uses the macro `obstack_init`, it must declare or define two functions or macros that will be called by the obstack library. One, `obstack_chunk_alloc`, is used to allocate the chunks of memory into which objects are packed. The other, `obstack_chunk_free`, is used to return chunks when the objects in them are freed. These macros should appear before any use of obstacks in the source file.

Usually these are defined to use `malloc` via the intermediary `xmalloc` (see Unconstrained Allocation (The GNU C Library Reference Manual)). This is done with the following pair of macro definitions:

         #define obstack_chunk_alloc xmalloc
         #define obstack_chunk_free free

Though the memory you get using obstacks really comes from `malloc`, using obstacks is faster because `malloc` is called less often, for larger blocks of memory. See Obstack Chunks, for full details.

At run time, before the program can use a `struct obstack` object as an obstack, it must initialize the obstack by calling `obstack_init`.

— Function: int obstack_init (struct obstack *obstack-ptr)

> Initialize obstack obstack-ptr for allocation of objects. This function calls the obstack's `obstack_chunk_alloc` function. If allocation of memory fails, the function pointed to by `obstack_alloc_failed_handler` is called. The `obstack_init` function always returns 1 (Compatibility notice: Former versions of obstack returned 0 if allocation failed).

Here are two examples of how to allocate the space for an obstack and initialize it. First, an obstack that is a static variable:

         static struct obstack myobstack;
         ...
         obstack_init (&myobstack);

Second, an obstack that is itself dynamically allocated:

         struct obstack *myobstack_ptr
           = (struct obstack *) xmalloc (sizeof (struct obstack));

         obstack_init (myobstack_ptr);

— Variable: obstack_alloc_failed_handler

> The value of this variable is a pointer to a function that `obstack` uses when `obstack_chunk_alloc` fails to allocate memory. The default action is to print a message and abort. You should supply a function that either calls `exit` (see Program Termination (The GNU C Library Reference Manual)) or `longjmp` (see Non-Local Exits (The GNU C Library Reference Manual)) and doesn't return.

>               void my_obstack_alloc_failed (void)
>               ...
>               obstack_alloc_failed_handler = &my_obstack_alloc_failed;

Next: Freeing Obstack Objects, Previous: Preparing for Obstacks, Up: Obstacks

### 3.3 Allocation in an Obstack

The most direct way to allocate an object in an obstack is with `obstack_alloc`, which is invoked almost like `malloc`.

— Function: void * obstack_alloc (struct obstack *obstack-ptr, int size)

> This allocates an uninitialized block of size bytes in an obstack and returns its address. Here obstack-ptr specifies which obstack to allocate the block in; it is the address of the `struct obstack` object which represents the obstack. Each obstack function or macro requires you to specify an obstack-ptr as the first argument.

> This function calls the obstack's `obstack_chunk_alloc` function if it needs to allocate a new chunk of memory; it calls `obstack_alloc_failed_handler` if allocation of memory by `obstack_chunk_alloc` failed.

For example, here is a function that allocates a copy of a string str in a specific obstack, which is in the variable `string_obstack`:

         struct obstack string_obstack;

         char *
         copystring (char *string)
         {
           size_t len = strlen (string) + 1;
           char *s = (char *) obstack_alloc (&string_obstack, len);
           memcpy (s, string, len);
           return s;
         }

To allocate a block with specified contents, use the function `obstack_copy`, declared like this:

— Function: void * obstack_copy (struct obstack *obstack-ptr, void *address, int size)

> This allocates a block and initializes it by copying size bytes of data starting at address. It calls `obstack_alloc_failed_handler` if allocation of memory by `obstack_chunk_alloc` failed.

— Function: void * obstack_copy0 (struct obstack *obstack-ptr, void *address, int size)

> Like `obstack_copy`, but appends an extra byte containing a null character. This extra byte is not counted in the argument size.

The `obstack_copy0` function is convenient for copying a sequence of characters into an obstack as a null-terminated string. Here is an example of its use:

         char *
         obstack_savestring (char *addr, int size)
         {
           return obstack_copy0 (&myobstack, addr, size);
         }

Contrast this with the previous example of `savestring` using `malloc` (see Basic Allocation (The GNU C Library Reference Manual)).

Next: Obstack Functions, Previous: Allocation in an Obstack, Up: Obstacks

### 3.4 Freeing Objects in an Obstack

To free an object allocated in an obstack, use the function `obstack_free`. Since the obstack is a stack of objects, freeing one object automatically frees all other objects allocated more recently in the same obstack.

— Function: void obstack_free (struct obstack *obstack-ptr, void *object)

> If object is a null pointer, everything allocated in the obstack is freed. Otherwise, object must be the address of an object allocated in the obstack. Then object is freed, along with everything allocated in obstack since object.

Note that if object is a null pointer, the result is an uninitialized obstack. To free all memory in an obstack but leave it valid for further allocation, call `obstack_free` with the address of the first object allocated on the obstack:

         obstack_free (obstack_ptr, first_object_allocated_ptr);

Recall that the objects in an obstack are grouped into chunks. When all the objects in a chunk become free, the obstack library automatically frees the chunk (see Preparing for Obstacks). Then other obstacks, or non-obstack allocation, can reuse the space of the chunk.

Next: Growing Objects, Previous: Freeing Obstack Objects, Up: Obstacks

### 3.5 Obstack Functions and Macros

The interfaces for using obstacks may be defined either as functions or as macros, depending on the compiler. The obstack facility works with all C compilers, including both ISO C and traditional C, but there are precautions you must take if you plan to use compilers other than GNU C.

If you are using an old-fashioned non-ISO C compiler, all the obstack “functions” are actually defined only as macros. You can call these macros like functions, but you cannot use them in any other way (for example, you cannot take their address).

Calling the macros requires a special precaution: namely, the first operand (the obstack pointer) may not contain any side effects, because it may be computed more than once. For example, if you write this:

         obstack_alloc (get_obstack (), 4);

you will find that `get_obstack` may be called several times. If you use `*obstack_list_ptr++` as the obstack pointer argument, you will get very strange results since the incrementation may occur several times.

In ISO C, each function has both a macro definition and a function definition. The function definition is used if you take the address of the function without calling it. An ordinary call uses the macro definition by default, but you can request the function definition instead by writing the function name in parentheses, as shown here:

         char *x;
         void *(*funcp) ();
         /* Use the macro.  */
         x = (char *) obstack_alloc (obptr, size);
         /* Call the function.  */
         x = (char *) (obstack_alloc) (obptr, size);
         /* Take the address of the function.  */
         funcp = obstack_alloc;

This is the same situation that exists in ISO C for the standard library functions. See Macro Definitions (The GNU C Library Reference Manual).

Warning: When you do use the macros, you must observe the precaution of avoiding side effects in the first operand, even in ISO C.

If you use the GNU C compiler, this precaution is not necessary, because various language extensions in GNU C permit defining the macros so as to compute each argument only once.

Next: Extra Fast Growing, Previous: Obstack Functions, Up: Obstacks

### 3.6 Growing Objects

Because memory in obstack chunks is used sequentially, it is possible to build up an object step by step, adding one or more bytes at a time to the end of the object. With this technique, you do not need to know how much data you will put in the object until you come to the end of it. We call this the technique of growing objects. The special functions for adding data to the growing object are described in this section.

You don't need to do anything special when you start to grow an object. Using one of the functions to add data to the object automatically starts it. However, it is necessary to say explicitly when the object is finished. This is done with the function `obstack_finish`.

The actual address of the object thus built up is not known until the object is finished. Until then, it always remains possible that you will add so much data that the object must be copied into a new chunk.

While the obstack is in use for a growing object, you cannot use it for ordinary allocation of another object. If you try to do so, the space already added to the growing object will become part of the other object.

— Function: void obstack_blank (struct obstack *obstack-ptr, int size)

> The most basic function for adding to a growing object is `obstack_blank`, which adds space without initializing it.

— Function: void obstack_grow (struct obstack *obstack-ptr, void *data, int size)

> To add a block of initialized space, use `obstack_grow`, which is the growing-object analogue of `obstack_copy`. It adds size bytes of data to the growing object, copying the contents from data.

— Function: void obstack_grow0 (struct obstack *obstack-ptr, void *data, int size)

> This is the growing-object analogue of `obstack_copy0`. It adds size bytes copied from data, followed by an additional null character.

— Function: void obstack_1grow (struct obstack *obstack-ptr, char c)

> To add one character at a time, use the function `obstack_1grow`. It adds a single byte containing c to the growing object.

— Function: void obstack_ptr_grow (struct obstack *obstack-ptr, void *data)

> Adding the value of a pointer one can use the function `obstack_ptr_grow`. It adds `sizeof (void *)` bytes containing the value of data.

— Function: void obstack_int_grow (struct obstack *obstack-ptr, int data)

> A single value of type `int` can be added by using the `obstack_int_grow` function. It adds `sizeof (int)` bytes to the growing object and initializes them with the value of data.

— Function: void * obstack_finish (struct obstack *obstack-ptr)

> When you are finished growing the object, use the function `obstack_finish` to close it off and return its final address.

> Once you have finished the object, the obstack is available for ordinary allocation or for growing another object.

> This function can return a null pointer under the same conditions as `obstack_alloc` (see Allocation in an Obstack).

When you build an object by growing it, you will probably need to know afterward how long it became. You need not keep track of this as you grow the object, because you can find out the length from the obstack just before finishing the object with the function `obstack_object_size`, declared as follows:

— Function: int obstack_object_size (struct obstack *obstack-ptr)

> This function returns the current size of the growing object, in bytes. Remember to call this function before finishing the object. After it is finished, `obstack_object_size` will return zero.

If you have started growing an object and wish to cancel it, you should finish it and then free it, like this:

         obstack_free (obstack_ptr, obstack_finish (obstack_ptr));

This has no effect if no object was growing.

You can use `obstack_blank` with a negative size argument to make the current object smaller. Just don't try to shrink it beyond zero length—there's no telling what will happen if you do that.

Next: Status of an Obstack, Previous: Growing Objects, Up: Obstacks

### 3.7 Extra Fast Growing Objects

The usual functions for growing objects incur overhead for checking whether there is room for the new growth in the current chunk. If you are frequently constructing objects in small steps of growth, this overhead can be significant.

You can reduce the overhead by using special “fast growth” functions that grow the object without checking. In order to have a robust program, you must do the checking yourself. If you do this checking in the simplest way each time you are about to add data to the object, you have not saved anything, because that is what the ordinary growth functions do. But if you can arrange to check less often, or check more efficiently, then you make the program faster.

The function `obstack_room` returns the amount of room available in the current chunk. It is declared as follows:

— Function: int obstack_room (struct obstack *obstack-ptr)

> This returns the number of bytes that can be added safely to the current growing object (or to an object about to be started) in obstack obstack using the fast growth functions.

While you know there is room, you can use these fast growth functions for adding data to a growing object:

— Function: void obstack_1grow_fast (struct obstack *obstack-ptr, char c)

> The function `obstack_1grow_fast` adds one byte containing the character c to the growing object in obstack obstack-ptr.

— Function: void obstack_ptr_grow_fast (struct obstack *obstack-ptr, void *data)

> The function `obstack_ptr_grow_fast` adds `sizeof (void *)` bytes containing the value of data to the growing object in obstack obstack-ptr.

— Function: void obstack_int_grow_fast (struct obstack *obstack-ptr, int data)

> The function `obstack_int_grow_fast` adds `sizeof (int)` bytes containing the value of data to the growing object in obstack obstack-ptr.

— Function: void obstack_blank_fast (struct obstack *obstack-ptr, int size)

> The function `obstack_blank_fast` adds size bytes to the growing object in obstack obstack-ptr without initializing them.

When you check for space using `obstack_room` and there is not enough room for what you want to add, the fast growth functions are not safe. In this case, simply use the corresponding ordinary growth function instead. Very soon this will copy the object to a new chunk; then there will be lots of room available again.

So, each time you use an ordinary growth function, check afterward for sufficient space using `obstack_room`. Once the object is copied to a new chunk, there will be plenty of space again, so the program will start using the fast growth functions again.

Here is an example:

         void
         add_string (struct obstack *obstack, const char *ptr, int len)
         {
           while (len > 0)
             {
               int room = obstack_room (obstack);
               if (room == 0)
                 {
                   /* Not enough room. Add one character slowly,
                      which may copy to a new chunk and make room.  */
                   obstack_1grow (obstack, *ptr++);
                   len--;
                 }
               else
                 {
                   if (room > len)
                     room = len;
                   /* Add fast as much as we have room for. */
                   len -= room;
                   while (room-- > 0)
                     obstack_1grow_fast (obstack, *ptr++);
                 }
             }
         }

Next: Obstacks Data Alignment, Previous: Extra Fast Growing, Up: Obstacks

### 3.8 Status of an Obstack

Here are functions that provide information on the current status of allocation in an obstack. You can use them to learn about an object while still growing it.

— Function: void * obstack_base (struct obstack *obstack-ptr)

> This function returns the tentative address of the beginning of the currently growing object in obstack-ptr. If you finish the object immediately, it will have that address. If you make it larger first, it may outgrow the current chunk—then its address will change!

> If no object is growing, this value says where the next object you allocate will start (once again assuming it fits in the current chunk).

— Function: void * obstack_next_free (struct obstack *obstack-ptr)

> This function returns the address of the first free byte in the current chunk of obstack obstack-ptr. This is the end of the currently growing object. If no object is growing, `obstack_next_free` returns the same value as `obstack_base`.

— Function: int obstack_object_size (struct obstack *obstack-ptr)

> This function returns the size in bytes of the currently growing object. This is equivalent to

>               obstack_next_free (obstack-ptr) - obstack_base (obstack-ptr)

Next: Obstack Chunks, Previous: Status of an Obstack, Up: Obstacks

### 3.9 Alignment of Data in Obstacks

Each obstack has an alignment boundary; each object allocated in the obstack automatically starts on an address that is a multiple of the specified boundary. By default, this boundary is 4 bytes.

To access an obstack's alignment boundary, use the macro `obstack_alignment_mask`, whose function prototype looks like this:

— Macro: int obstack_alignment_mask (struct obstack *obstack-ptr)

> The value is a bit mask; a bit that is 1 indicates that the corresponding bit in the address of an object should be 0. The mask value should be one less than a power of 2; the effect is that all object addresses are multiples of that power of 2. The default value of the mask is 3, so that addresses are multiples of 4. A mask value of 0 means an object can start on any multiple of 1 (that is, no alignment is required).

> The expansion of the macro `obstack_alignment_mask` is an lvalue, so you can alter the mask by assignment. For example, this statement:

>               obstack_alignment_mask (obstack_ptr) = 0;

> has the effect of turning off alignment processing in the specified obstack.

Note that a change in alignment mask does not take effect until after the next time an object is allocated or finished in the obstack. If you are not growing an object, you can make the new alignment mask take effect immediately by calling `obstack_finish`. This will finish a zero-length object and then do proper alignment for the next object.

Next: Summary of Obstacks, Previous: Obstacks Data Alignment, Up: Obstacks

### 3.10 Obstack Chunks

Obstacks work by allocating space for themselves in large chunks, and then parceling out space in the chunks to satisfy your requests. Chunks are normally 4096 bytes long unless you specify a different chunk size. The chunk size includes 8 bytes of overhead that are not actually used for storing objects. Regardless of the specified size, longer chunks will be allocated when necessary for long objects.

The obstack library allocates chunks by calling the function `obstack_chunk_alloc`, which you must define. When a chunk is no longer needed because you have freed all the objects in it, the obstack library frees the chunk by calling `obstack_chunk_free`, which you must also define.

These two must be defined (as macros) or declared (as functions) in each source file that uses `obstack_init` (see Creating Obstacks). Most often they are defined as macros like this:

         #define obstack_chunk_alloc malloc
         #define obstack_chunk_free free

Note that these are simple macros (no arguments). Macro definitions with arguments will not work! It is necessary that `obstack_chunk_alloc` or `obstack_chunk_free`, alone, expand into a function name if it is not itself a function name.

If you allocate chunks with `malloc`, the chunk size should be a power of 2. The default chunk size, 4096, was chosen because it is long enough to satisfy many typical requests on the obstack yet short enough not to waste too much memory in the portion of the last chunk not yet used.

— Macro: int obstack_chunk_size (struct obstack *obstack-ptr)

> This returns the chunk size of the given obstack.

Since this macro expands to an lvalue, you can specify a new chunk size by assigning it a new value. Doing so does not affect the chunks already allocated, but will change the size of chunks allocated for that particular obstack in the future. It is unlikely to be useful to make the chunk size smaller, but making it larger might improve efficiency if you are allocating many objects whose size is comparable to the chunk size. Here is how to do so cleanly:

         if (obstack_chunk_size (obstack_ptr) < new-chunk-size)
           obstack_chunk_size (obstack_ptr) = new-chunk-size;

Previous: Obstack Chunks, Up: Obstacks

### 3.11 Summary of Obstack Functions

Here is a summary of all the functions associated with obstacks. Each takes the address of an obstack (`struct obstack *`) as its first argument.

`void obstack_init (struct obstack *`obstack-ptr`)`
  Initialize use of an obstack. See Creating Obstacks.
`void *obstack_alloc (struct obstack *`obstack-ptr`, int` size`)`
  Allocate an object of size uninitialized bytes. See Allocation in an Obstack.
`void *obstack_copy (struct obstack *`obstack-ptr`, void *`address`, int` size`)`
  Allocate an object of size bytes, with contents copied from address. See Allocation in an Obstack.
`void *obstack_copy0 (struct obstack *`obstack-ptr`, void *`address`, int` size`)`
  Allocate an object of size+1 bytes, with size of them copied from address, followed by a null character at the end. See Allocation in an Obstack.
`void obstack_free (struct obstack *`obstack-ptr`, void *`object`)`
  Free object (and everything allocated in the specified obstack more recently than object). See Freeing Obstack Objects.
`void obstack_blank (struct obstack *`obstack-ptr`, int` size`)`
  Add size uninitialized bytes to a growing object. See Growing Objects.
`void obstack_grow (struct obstack *`obstack-ptr`, void *`address`, int` size`)`
  Add size bytes, copied from address, to a growing object. See Growing Objects.
`void obstack_grow0 (struct obstack *`obstack-ptr`, void *`address`, int` size`)`
  Add size bytes, copied from address, to a growing object, and then add another byte containing a null character. See Growing Objects.
`void obstack_1grow (struct obstack *`obstack-ptr`, char` data-char`)`
  Add one byte containing data-char to a growing object. See Growing Objects.
`void *obstack_finish (struct obstack *`obstack-ptr`)`
  Finalize the object that is growing and return its permanent address. See Growing Objects.
`int obstack_object_size (struct obstack *`obstack-ptr`)`
  Get the current size of the currently growing object. See Growing Objects.
`void obstack_blank_fast (struct obstack *`obstack-ptr`, int` size`)`
  Add size uninitialized bytes to a growing object without checking that there is enough room. See Extra Fast Growing.
`void obstack_1grow_fast (struct obstack *`obstack-ptr`, char` data-char`)`
  Add one byte containing data-char to a growing object without checking that there is enough room. See Extra Fast Growing.
`int obstack_room (struct obstack *`obstack-ptr`)`
  Get the amount of room now available for growing the current object. See Extra Fast Growing.
`int obstack_alignment_mask (struct obstack *`obstack-ptr`)`
  The mask used for aligning the beginning of an object. This is an lvalue. See Obstacks Data Alignment.
`int obstack_chunk_size (struct obstack *`obstack-ptr`)`
  The size for allocating chunks. This is an lvalue. See Obstack Chunks.
`void *obstack_base (struct obstack *`obstack-ptr`)`
  Tentative starting address of the currently growing object. See Status of an Obstack.
`void *obstack_next_free (struct obstack *`obstack-ptr`)`
  Address just after the end of the currently growing object. See Status of an Obstack.

Next: Obstacks, Previous: Overview, Up: Top

## 4 Function, Variable, and Macro Listing.

— Replacement: void* alloca (size_t size)

> This function allocates memory which will be automatically reclaimed after the procedure exits. The `libiberty` implementation does not free the memory immediately but will do so eventually during subsequent calls to this function. Memory is allocated using `xmalloc` under normal circumstances.

> The header file alloca-conf.h can be used in conjunction with the GNU Autoconf test `AC_FUNC_ALLOCA` to test for and properly make available this function. The `AC_FUNC_ALLOCA` test requires that client code use a block of preprocessor code to be safe (see the Autoconf manual for more); this header incorporates that logic and more, including the possibility of a GCC built-in function.

— Extension: int asprintf (char **resptr, const char *format, ...)

> Like `sprintf`, but instead of passing a pointer to a buffer, you pass a pointer to a pointer. This function will compute the size of the buffer needed, allocate memory with `malloc`, and store a pointer to the allocated memory in `*`resptr. The value returned is the same as `sprintf` would return. If memory could not be allocated, zero is returned and `NULL` is stored in `*`resptr.

— Supplemental: int atexit (void (*f)())

> Causes function f to be called at exit. Returns 0.

— Supplemental: char* basename (const char *name)

> Returns a pointer to the last component of pathname name. Behavior is undefined if the pathname ends in a directory separator.

— Supplemental: int bcmp (char *x, char *y, int count)

> Compares the first count bytes of two areas of memory. Returns zero if they are the same, nonzero otherwise. Returns zero if count is zero. A nonzero result only indicates a difference, it does not indicate any sorting order (say, by having a positive result mean x sorts before y).

— Supplemental: void bcopy (char *in, char *out, int length)

> Copies length bytes from memory region in to region out. The use of `bcopy` is deprecated in new programs.

— Supplemental: void* bsearch (const void *key, const void *base, size_t nmemb, size_t size, int (*compar)(const void *, const void *))

> Performs a search over an array of nmemb elements pointed to by base for a member that matches the object pointed to by key. The size of each member is specified by size. The array contents should be sorted in ascending order according to the compar comparison function. This routine should take two arguments pointing to the key and to an array member, in that order, and should return an integer less than, equal to, or greater than zero if the key object is respectively less than, matching, or greater than the array member.

— Extension: char** buildargv (char *sp)

> Given a pointer to a string, parse the string extracting fields separated by whitespace and optionally enclosed within either single or double quotes (which are stripped off), and build a vector of pointers to copies of the string for each field. The input string remains unchanged. The last element of the vector is followed by a `NULL` element.

> All of the memory for the pointer array and copies of the string is obtained from `malloc`. All of the memory can be returned to the system with the single function call `freeargv`, which takes the returned result of `buildargv`, as it's argument.

> Returns a pointer to the argument vector if successful. Returns `NULL` if sp is `NULL` or if there is insufficient memory to complete building the argument vector.

> If the input is a null string (as opposed to a `NULL` pointer), then buildarg returns an argument vector that has one arg, a null string.

— Supplemental: void bzero (char *mem, int count)

> Zeros count bytes starting at mem. Use of this function is deprecated in favor of `memset`.

— Supplemental: void* calloc (size_t nelem, size_t elsize)

> Uses `malloc` to allocate storage for nelem objects of elsize bytes each, then zeros the memory.

— Extension: char* choose_temp_base (void)

> Return a prefix for temporary file names or `NULL` if unable to find one. The current directory is chosen if all else fails so the program is exited if a temporary directory can't be found (`mktemp` fails). The buffer for the result is obtained with `xmalloc`.

> This function is provided for backwards compatability only. Its use is not recommended.

— Replacement: char* choose_tmpdir ()

> Returns a pointer to a directory path suitable for creating temporary files in.

— Supplemental: long clock (void)

> Returns an approximation of the CPU time used by the process as a `clock_t`; divide this number by CLOCKS_PER_SEC to get the number of seconds used.

— Extension: char* concat (const char *s1, const char *s2, ..., `NULL`)

> Concatenate zero or more of strings and return the result in freshly `xmalloc`ed memory. Returns `NULL` if insufficient memory is available. The argument list is terminated by the first `NULL` pointer encountered. Pointers to empty strings are ignored.

— Extension: char** dupargv (char **vector)

> Duplicate an argument vector. Simply scans through vector, duplicating each argument until the terminating `NULL` is found. Returns a pointer to the argument vector if successful. Returns `NULL` if there is insufficient memory to complete building the argument vector.

— Extension: int errno_max (void)

> Returns the maximum `errno` value for which a corresponding symbolic name or message is available. Note that in the case where we use the `sys_errlist` supplied by the system, it is possible for there to be more symbolic names than messages, or vice versa. In fact, the manual page for `perror(3C)` explicitly warns that one should check the size of the table (`sys_nerr`) before indexing it, since new error codes may be added to the system before they are added to the table. Thus `sys_nerr` might be smaller than value implied by the largest `errno` value defined in `<errno.h>`.

> We return the maximum value that can be used to obtain a meaningful symbolic name or message.

— Extension: int fdmatch (int fd1, int fd2)

> Check to see if two open file descriptors refer to the same file. This is useful, for example, when we have an open file descriptor for an unnamed file, and the name of a file that we believe to correspond to that fd. This can happen when we are exec'd with an already open file (`stdout` for example) or from the SVR4 /proc calls that return open file descriptors for mapped address spaces. All we have to do is open the file by name and check the two file descriptors for a match, which is done by comparing major and minor device numbers and inode numbers.

— Supplemental: int ffs (int valu)

> Find the first (least significant) bit set in valu. Bits are numbered from right to left, starting with bit 1 (corresponding to the value 1). If valu is zero, zero is returned.

— Replacement: int fnmatch (const char *pattern, const char *string, int flags)

> Matches string against pattern, returning zero if it matches, `FNM_NOMATCH` if not. pattern may contain the wildcards `?` to match any one character, `*` to match any zero or more characters, or a set of alternate characters in square brackets, like [a-gt8], which match one character (`a` through `g`, or `t`, or `8`, in this example) if that one character is in the set. A set may be inverted (i.e., match anything except what's in the set) by giving `^` or `!` as the first character in the set. To include those characters in the set, list them as anything other than the first character of the set. To include a dash in the set, list it last in the set. A backslash character makes the following character not special, so for example you could match against a literal asterisk with \*. To match a literal backslash, use \\.

> `flags` controls various aspects of the matching process, and is a boolean OR of zero or more of the following values (defined in `<fnmatch.h>`):

> `FNM_PATHNAME`
> `FNM_FILE_NAME`
>   string is assumed to be a path name. No wildcard will ever match `/`.
> `FNM_NOESCAPE`
>   Do not interpret backslashes as quoting the following special character.
> `FNM_PERIOD`
>   A leading period (at the beginning of string, or if `FNM_PATHNAME` after a slash) is not matched by `*` or `?` but must be matched explicitly.
> `FNM_LEADING_DIR`
>   Means that string also matches pattern if some initial part of string matches, and is followed by `/` and zero or more characters. For example, foo* would match either foobar or foobar/grill.
> `FNM_CASEFOLD`
>   Ignores case when performing the comparison.

— Extension: void freeargv (char **vector)

> Free an argument vector that was built using `buildargv`. Simply scans through vector, freeing the memory for each argument until the terminating `NULL` is found, and then frees vector itself.

— Replacement: long get_run_time (void)

> Returns the time used so far, in microseconds. If possible, this is the time used by this process, else it is the elapsed time since the process started.

— Supplemental: char* getcwd (char *pathname, int len)

> Copy the absolute pathname for the current working directory into pathname, which is assumed to point to a buffer of at least len bytes, and return a pointer to the buffer. If the current directory's path doesn't fit in len characters, the result is `NULL` and `errno` is set. If pathname is a null pointer, `getcwd` will obtain len bytes of space using `malloc`.

— Supplemental: int getpagesize (void)

> Returns the number of bytes in a page of memory. This is the granularity of many of the system memory management routines. No guarantee is made as to whether or not it is the same as the basic memory management hardware page size.

— Supplemental: char* getpwd (void)

> Returns the current working directory. This implementation caches the result on the assumption that the process will not call `chdir` between calls to `getpwd`.

— Extension: void hex_init (void)

> Initializes the array mapping the current character set to corresponding hex values. This function must be called before any call to `hex_p` or `hex_value`. If you fail to call it, a default ASCII-based table will normally be used on ASCII systems.

— Extension: int hex_p (int c)

> Evaluates to non-zero if the given character is a valid hex character, or zero if it is not. Note that the value you pass will be cast to `unsigned char` within the macro.

— Extension: int hex_value (int c)

> Returns the numeric equivalent of the given character when interpreted as a hexidecimal digit. The result is undefined if you pass an invalid hex digit. Note that the value you pass will be cast to `unsigned char` within the macro.

— Supplemental: char* index (char *s, int c)

> Returns a pointer to the first occurrence of the character c in the string s, or `NULL` if not found. The use of `index` is deprecated in new programs in favor of `strchr`.

— Supplemental: void insque (struct qelem *elem, struct qelem *pred)
— Supplemental: void remque (struct qelem *elem)

> Routines to manipulate queues built from doubly linked lists. The `insque` routine inserts elem in the queue immediately after pred. The `remque` routine removes elem from its containing queue. These routines expect to be passed pointers to structures which have as their first members a forward pointer and a back pointer, like this prototype (although no prototype is provided):

>               struct qelem {
>                 struct qelem *q_forw;
>                 struct qelem *q_back;
>                 char q_data[];
>               };

— Replacement: const char* lbasename (const char *name)

> Given a pointer to a string containing a typical pathname (/usr/src/cmd/ls/ls.c for example), returns a pointer to the last component of the pathname (ls.c in this case). The returned pointer is guaranteed to lie within the original string. This latter fact is not true of many vendor C libraries, which return special strings or modify the passed strings for particular input.

> In particular, the empty string returns the same empty string, and a path ending in `/` returns the empty string after it.

— Extension: const char* make_relative_prefix (const char *progname, const char *bin_prefix, const char *prefix)

> Given three strings progname, bin_prefix, prefix, return a string that gets to prefix starting with the directory portion of progname and a relative pathname of the difference between bin_prefix and prefix.

> For example, if bin_prefix is `/alpha/beta/gamma/gcc/delta`, prefix is `/alpha/beta/gamma/omega/`, and progname is `/red/green/blue/gcc`, then this function will return `/red/green/blue/../../omega/`.

> The return value is normally allocated via `malloc`. If no relative prefix can be found, return `NULL`.

— Replacement: const char* lrealpath (const char *name)

> Given a pointer to a string containing a pathname, returns a canonical version of the filename. Symlinks will be resolved, and “.” and “..” components will be simplified. The returned value will be allocated using `malloc`, or `NULL` will be returned on a memory allocation error.

— Extension: const char* make_relative_prefix (const char *progname, const char *bin_prefix, const char *prefix)

> Given three paths progname, bin_prefix, prefix, return the path that is in the same position relative to progname's directory as prefix is relative to bin_prefix. That is, a string starting with the directory portion of progname, followed by a relative pathname of the difference between bin_prefix and prefix.

> If progname does not contain any directory separators, `make_relative_prefix` will search PATH to find a program named progname. Also, if progname is a symbolic link, the symbolic link will be resolved.

> For example, if bin_prefix is `/alpha/beta/gamma/gcc/delta`, prefix is `/alpha/beta/gamma/omega/`, and progname is `/red/green/blue/gcc`, then this function will return `/red/green/blue/../../omega/`.

> The return value is normally allocated via `malloc`. If no relative prefix can be found, return `NULL`.

— Replacement: char* make_temp_file (const char *suffix)

> Return a temporary file name (as a string) or `NULL` if unable to create one. suffix is a suffix to append to the file name. The string is `malloc`ed, and the temporary file has been created.

— Supplemental: void* memchr (const void *s, int c, size_t n)

> This function searches memory starting at `*`s for the character c. The search only ends with the first occurrence of c, or after length characters; in particular, a null character does not terminate the search. If the character c is found within length characters of `*`s, a pointer to the character is returned. If c is not found, then `NULL` is returned.

— Supplemental: int memcmp (const void *x, const void *y, size_t count)

> Compares the first count bytes of two areas of memory. Returns zero if they are the same, a value less than zero if x is lexically less than y, or a value greater than zero if x is lexically greater than y. Note that lexical order is determined as if comparing unsigned char arrays.

— Supplemental: void* memcpy (void *out, const void *in, size_t length)

> Copies length bytes from memory region in to region out. Returns a pointer to out.

— Supplemental: void* memmove (void *from, const void *to, size_t count)

> Copies count bytes from memory area from to memory area to, returning a pointer to to.

— Supplemental: void* memset (void *s, int c, size_t count)

> Sets the first count bytes of s to the constant byte c, returning a pointer to s.

— Replacement: int mkstemps (char *template, int suffix_len)

> Generate a unique temporary file name from template. template has the form:

>                  path/ccXXXXXXsuffix

> suffix_len tells us how long suffix is (it can be zero length). The last six characters of template before suffix must be XXXXXX; they are replaced with a string that makes the filename unique. Returns a file descriptor open on the file for reading and writing.

— Extension: int pexecute (const char *program, char * const *argv, const char *this_pname, const char *temp_base, char **errmsg_fmt, char **errmsg_arg, int flags)

> Executes a program.

> program and argv are the arguments to `execv`/`execvp`.

> this_pname is name of the calling program (i.e., `argv[0]`).

> temp_base is the path name, sans suffix, of a temporary file to use if needed. This is currently only needed for MS-DOS ports that don't use `go32` (do any still exist?). Ports that don't need it can pass `NULL`.

> (flags`& PEXECUTE_SEARCH`) is non-zero if PATH should be searched (??? It's not clear that GCC passes this flag correctly). (flags`& PEXECUTE_FIRST`) is nonzero for the first process in chain. (flags`& PEXECUTE_FIRST`) is nonzero for the last process in chain. The first/last flags could be simplified to only mark the last of a chain of processes but that requires the caller to always mark the last one (and not give up early if some error occurs). It's more robust to require the caller to mark both ends of the chain.

> The result is the pid on systems like Unix where we `fork`/`exec` and on systems like WIN32 and OS/2 where we use `spawn`. It is up to the caller to wait for the child.

> The result is the `WEXITSTATUS` on systems like MS-DOS where we `spawn` and wait for the child here.

> Upon failure, errmsg_fmt and errmsg_arg are set to the text of the error message with an optional argument (if not needed, errmsg_arg is set to `NULL`), and −1 is returned. `errno` is available to the caller to use.

— Supplemental: void psignal (unsigned signo, char *message)

> Print message to the standard error, followed by a colon, followed by the description of the signal specified by signo, followed by a newline.

— Supplemental: int putenv (const char *string)

> Uses `setenv` or `unsetenv` to put string into the environment or remove it. If string is of the form name=value the string is added; if no = is present the name is unset/removed.

— Extension: int pwait (int pid, int *status, int flags)

> Waits for a program started by `pexecute` to finish.

> pid is the process id of the task to wait for. status is the `status' argument to wait. flags is currently unused (allows future enhancement without breaking upward compatibility). Pass 0 for now.

> The result is the pid of the child reaped, or -1 for failure (`errno` says why).

> On systems that don't support waiting for a particular child, pid is ignored. On systems like MS-DOS that don't really multitask `pwait` is just a mechanism to provide a consistent interface for the caller.

— Supplement: long int random (void)
— Supplement: void srandom (unsigned int seed)
— Supplement: void* initstate (unsigned int seed, void *arg_state, unsigned long n)
— Supplement: void* setstate (void *arg_state)

> Random number functions. `random` returns a random number in the range 0 to `LONG_MAX`. `srandom` initializes the random number generator to some starting point determined by seed (else, the values returned by `random` are always the same for each run of the program). `initstate` and `setstate` allow fine-grained control over the state of the random number generator.

— Extension: char* reconcat (char *optr, const char *s1, ..., `NULL`)

> Same as `concat`, except that if optr is not `NULL` it is freed after the string is created. This is intended to be useful when you're extending an existing string or building up a string in a loop:

>                 str = reconcat (str, "pre-", str, NULL);

— Supplemental: int rename (const char *old, const char *new)

> Renames a file from old to new. If new already exists, it is removed.

— Supplemental: char* rindex (const char *s, int c)

> Returns a pointer to the last occurrence of the character c in the string s, or `NULL` if not found. The use of `rindex` is deprecated in new programs in favor of `strrchr`.

— Supplemental: int setenv (const char *name, const char *value, int overwrite)
— Supplemental: void unsetenv (const char *name)

> `setenv` adds name to the environment with value value. If the name was already present in the environment, the new value will be stored only if overwrite is nonzero. The companion `unsetenv` function removes name from the environment. This implementation is not safe for multithreaded code.

— Extension: int signo_max (void)

> Returns the maximum signal value for which a corresponding symbolic name or message is available. Note that in the case where we use the `sys_siglist` supplied by the system, it is possible for there to be more symbolic names than messages, or vice versa. In fact, the manual page for `psignal(3b)` explicitly warns that one should check the size of the table (`NSIG`) before indexing it, since new signal codes may be added to the system before they are added to the table. Thus `NSIG` might be smaller than value implied by the largest signo value defined in `<signal.h>`.

> We return the maximum value that can be used to obtain a meaningful symbolic name or message.

— Supplemental: int sigsetmask (int set)

> Sets the signal mask to the one provided in set and returns the old mask (which, for libiberty's implementation, will always be the value `1`).

— Extension: char* spaces (int count)

> Returns a pointer to a memory region filled with the specified number of spaces and null terminated. The returned pointer is valid until at least the next call.

— Supplemental: int strcasecmp (const char *s1, const char *s2)

> A case-insensitive `strcmp`.

— Supplemental: char* strchr (const char *s, int c)

> Returns a pointer to the first occurrence of the character c in the string s, or `NULL` if not found. If c is itself the null character, the results are undefined.

— Supplemental: char* strdup (const char *s)

> Returns a pointer to a copy of s in memory obtained from `malloc`, or `NULL` if insufficient memory was available.

— Replacement: const char* strerrno (int errnum)

> Given an error number returned from a system call (typically returned in `errno`), returns a pointer to a string containing the symbolic name of that error number, as found in `<errno.h>`.

> If the supplied error number is within the valid range of indices for symbolic names, but no name is available for the particular error number, then returns the string Error num, where num is the error number.

> If the supplied error number is not within the range of valid indices, then returns `NULL`.

> The contents of the location pointed to are only guaranteed to be valid until the next call to `strerrno`.

— Supplemental: char* strerror (int errnoval)

> Maps an `errno` number to an error message string, the contents of which are implementation defined. On systems which have the external variables `sys_nerr` and `sys_errlist`, these strings will be the same as the ones used by `perror`.

> If the supplied error number is within the valid range of indices for the `sys_errlist`, but no message is available for the particular error number, then returns the string Error num, where num is the error number.

> If the supplied error number is not a valid index into `sys_errlist`, returns `NULL`.

> The returned string is only guaranteed to be valid only until the next call to `strerror`.

— Supplemental: int strncasecmp (const char *s1, const char *s2)

> A case-insensitive `strncmp`.

— Supplemental: int strncmp (const char *s1, const char *s2, size_t n)

> Compares the first n bytes of two strings, returning a value as `strcmp`.

— Supplemental: char* strrchr (const char *s, int c)

> Returns a pointer to the last occurrence of the character c in the string s, or `NULL` if not found. If c is itself the null character, the results are undefined.

— Supplemental: const char * strsignal (int signo)

> Maps an signal number to an signal message string, the contents of which are implementation defined. On systems which have the external variable `sys_siglist`, these strings will be the same as the ones used by `psignal()`.

> If the supplied signal number is within the valid range of indices for the `sys_siglist`, but no message is available for the particular signal number, then returns the string Signal num, where num is the signal number.

> If the supplied signal number is not a valid index into `sys_siglist`, returns `NULL`.

> The returned string is only guaranteed to be valid only until the next call to `strsignal`.

— Extension: const char* strsigno (int signo)

> Given an signal number, returns a pointer to a string containing the symbolic name of that signal number, as found in `<signal.h>`.

> If the supplied signal number is within the valid range of indices for symbolic names, but no name is available for the particular signal number, then returns the string Signal num, where num is the signal number.

> If the supplied signal number is not within the range of valid indices, then returns `NULL`.

> The contents of the location pointed to are only guaranteed to be valid until the next call to `strsigno`.

— Supplemental: char* strstr (const char *string, const char *sub)

> This function searches for the substring sub in the string string, not including the terminating null characters. A pointer to the first occurrence of sub is returned, or `NULL` if the substring is absent. If sub points to a string with zero length, the function returns string.

— Supplemental: double strtod (const char *string, char **endptr)

> This ISO C function converts the initial portion of string to a `double`. If endptr is not `NULL`, a pointer to the character after the last character used in the conversion is stored in the location referenced by endptr. If no conversion is performed, zero is returned and the value of string is stored in the location referenced by endptr.

— Extension: int strtoerrno (const char *name)

> Given the symbolic name of a error number (e.g., `EACCES`), map it to an errno value. If no translation is found, returns 0.

— Supplemental: long int strtol (const char *string, char **endptr, int base)
— Supplemental: unsigned long int strtoul (const char *string, char **endptr, int base)

> The `strtol` function converts the string in string to a long integer value according to the given base, which must be between 2 and 36 inclusive, or be the special value 0. If base is 0, `strtol` will look for the prefixes `0` and `0x` to indicate bases 8 and 16, respectively, else default to base 10. When the base is 16 (either explicitly or implicitly), a prefix of `0x` is allowed. The handling of endptr is as that of `strtod` above. The `strtoul` function is the same, except that the converted value is unsigned.

— Extension: int strtosigno (const char *name)

> Given the symbolic name of a signal, map it to a signal number. If no translation is found, returns 0.

— Supplemental: char* tmpnam (char *s)

> This function attempts to create a name for a temporary file, which will be a valid file name yet not exist when `tmpnam` checks for it. s must point to a buffer of at least `L_tmpnam` bytes, or be `NULL`. Use of this function creates a security risk, and it must not be used in new projects. Use `mkstemp` instead.

— Extension: int vasprintf (char **resptr, const char *format, va_list args)

> Like `vsprintf`, but instead of passing a pointer to a buffer, you pass a pointer to a pointer. This function will compute the size of the buffer needed, allocate memory with `malloc`, and store a pointer to the allocated memory in `*`resptr. The value returned is the same as `vsprintf` would return. If memory could not be allocated, zero is returned and `NULL` is stored in `*`resptr.

— Supplemental: int vfork (void)

> Emulates `vfork` by calling `fork` and returning its value.

— Supplemental: int vprintf (const char *format, va_list ap)
— Supplemental: int vfprintf (FILE *stream, const char *format, va_list ap)
— Supplemental: int vsprintf (char *str, const char *format, va_list ap)

> These functions are the same as `printf`, `fprintf`, and `sprintf`, respectively, except that they are called with a `va_list` instead of a variable number of arguments. Note that they do not call `va_end`; this is the application's responsibility. In `libiberty` they are implemented in terms of the nonstandard but common function `_doprnt`.

— Supplemental: int waitpid (int pid, int *status, int)

> This is a wrapper around the `wait` function. Any “special” values of pid depend on your implementation of `wait`, as does the return value. The third argument is unused in `libiberty`.

— Function: int xatexit (void (*fn) (void))

> Behaves as the standard `atexit` function, but with no limit on the number of registered functions. Returns 0 on success, or −1 on failure. If you use `xatexit` to register functions, you must use `xexit` to terminate your program.

— Replacement: void* xcalloc (size_t nelem, size_t elsize)

> Allocate memory without fail, and set it to zero. This routine functions like `calloc`, but will behave the same as `xmalloc` if memory cannot be found.

— Replacement: void xexit (int code)

> Terminates the program. If any functions have been registered with the `xatexit` replacement function, they will be called first. Termination is handled via the system's normal `exit` call.

— Replacement: void* xmalloc (size_t)

> Allocate memory without fail. If `malloc` fails, this will print a message to `stderr` (using the name set by `xmalloc_set_program_name`, if any) and then call `xexit`. Note that it is therefore safe for a program to contain `#define malloc xmalloc` in its source.

— Replacement: void xmalloc_failed (size_t)

> This function is not meant to be called by client code, and is listed here for completeness only. If any of the allocation routines fail, this function will be called to print an error message and terminate execution.

— Replacement: void xmalloc_set_program_name (const char *name)

> You can use this to set the name of the program used by `xmalloc_failed` when printing a failure message.

— Replacement: void* xmemdup (void *input, size_t copy_size, size_t alloc_size)

> Duplicates a region of memory without fail. First, alloc_size bytes are allocated, then copy_size bytes from input are copied into it, and the new memory is returned. If fewer bytes are copied than were allocated, the remaining memory is zeroed.

— Replacement: void* xrealloc (void *ptr, size_t size)

> Reallocate memory without fail. This routine functions like `realloc`, but will behave the same as `xmalloc` if memory cannot be found.

— Replacement: char* xstrdup (const char *s)

> Duplicates a character string without fail, using `xmalloc` to obtain memory.

— Replacement: char* xstrerror (int errnum)

> Behaves exactly like the standard `strerror` function, but will never return a `NULL` pointer.

Next: Index, Previous: Obstacks, Up: Top

## Appendix A Licenses

Next: BSD, Up: Licenses

### A.1 GNU LESSER GENERAL PUBLIC LICENSE

Version 2.1, February 1999

         Copyright © 1991, 1999 Free Software Foundation, Inc.
         59 Temple Place – Suite 330, Boston, MA 02111-1307, USA

         Everyone is permitted to copy and distribute verbatim copies
         of this license document, but changing it is not allowed.

         [This is the first released version of the Lesser GPL.  It also counts
         as the successor of the GNU Library Public License, version 2, hence the
         version number 2.1.]

#### A.1.1 Preamble

The licenses for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public Licenses are intended to guarantee your freedom to share and change free software—to make sure the software is free for all its users.

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When we speak of free software, we are referring to freedom of use, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish); that you receive source code or can get it if you want it; that you can change the software and use pieces of it in new free programs; and that you are informed that you can do these things.

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We protect your rights with a two-step method: (1) we copyright the library, and (2) we offer you this license, which gives you legal permission to copy, distribute and/or modify the library.

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Most GNU software, including some libraries, is covered by the ordinary GNU General Public License. This license, the GNU Lesser General Public License, applies to certain designated libraries, and is quite different from the ordinary General Public License. We use this license for certain libraries in order to permit linking those libraries into non-free programs.

When a program is linked with a library, whether statically or using a shared library, the combination of the two is legally speaking a combined work, a derivative of the original library. The ordinary General Public License therefore permits such linking only if the entire combination fits its criteria of freedom. The Lesser General Public License permits more lax criteria for linking other code with the library.

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16. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE LIBRARY AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE LIBRARY (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE LIBRARY TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

#### A.1.2 How to Apply These Terms to Your New Libraries

If you develop a new library, and you want it to be of the greatest possible use to the public, we recommend making it free software that everyone can redistribute and change. You can do so by permitting redistribution under these terms (or, alternatively, under the terms of the ordinary General Public License).

To apply these terms, attach the following notices to the library. It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.

         one line to give the library's name and an idea of what it does.
         Copyright (C) year  name of author

         This library is free software; you can redistribute it and/or modify it
         under the terms of the GNU Lesser General Public License as published by
         the Free Software Foundation; either version 2.1 of the License, or (at
         your option) any later version.

         This library is distributed in the hope that it will be useful, but
         WITHOUT ANY WARRANTY; without even the implied warranty of
         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
         Lesser General Public License for more details.

         You should have received a copy of the GNU Lesser General Public
         License along with this library; if not, write to the Free Software
         Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307,
         USA.

Also add information on how to contact you by electronic and paper mail.

You should also get your employer (if you work as a programmer) or your school, if any, to sign a “copyright disclaimer” for the library, if necessary. Here is a sample; alter the names:

         Yoyodyne, Inc., hereby disclaims all copyright interest in the library
         `Frob' (a library for tweaking knobs) written by James Random Hacker.

         signature of Ty Coon, 1 April 1990
         Ty Coon, President of Vice

That's all there is to it!

Previous: Library Copying, Up: Licenses

### A.2 BSD

Copyright © 1990 Regents of the University of California. All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
3. [rescinded 22 July 1999]
4. Neither the name of the University nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS “AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Previous: Licenses, Up: Top

## Index

- alignment (in obstacks): Obstacks Data Alignment
- `alloca`: Functions
- allocation (obstacks): Allocation in an Obstack
- `asprintf`: Functions
- `atexit`: Functions
- `basename`: Functions
- `bcmp`: Functions
- `bcopy`: Functions
- `bsearch`: Functions
- `buildargv`: Functions
- `bzero`: Functions
- `calloc`: Functions
- changing the size of a block (obstacks): Growing Objects
- `choose_temp_base`: Functions
- `choose_tmpdir`: Functions
- chunks: Obstack Chunks
- `clock`: Functions
- `concat`: Functions
- `dupargv`: Functions
- efficiency and obstacks: Extra Fast Growing
- efficiency of chunks: Obstack Chunks
- `errno_max`: Functions
- error reporting: Error Reporting
- exit handlers: Exit Handlers
- extensions: Extensions
- `fdmatch`: Functions
- `ffs`: Functions
- `fnmatch`: Functions
- `freeargv`: Functions
- freeing (obstacks): Freeing Obstack Objects
- functions, extension: Extensions
- functions, missing: Supplemental Functions
- functions, replacement: Replacement Functions
- functions, supplemental: Supplemental Functions
- `get_run_time`: Functions
- `getcwd`: Functions
- `getpagesize`: Functions
- `getpwd`: Functions
- growing objects (in obstacks): Growing Objects
- `hex_init`: Functions
- `hex_p`: Functions
- `hex_value`: Functions
- how to use: Using
- `index`: Functions
- `initstate`: Functions
- `insque`: Functions
- `lbasename`: Functions
- LGPL, Lesser General Public License: Library Copying
- libiberty usage: Using
- `lrealpath`: Functions
- macros: Obstack Functions
- `make_relative_prefix`: Functions
- `make_temp_file`: Functions
- `memchr`: Functions
- `memcmp`: Functions
- `memcpy`: Functions
- `memmove`: Functions
- memory allocation: Memory Allocation
- `memset`: Functions
- `mkstemps`: Functions
- obstack status: Status of an Obstack
- `obstack.h`: Creating Obstacks
- `obstack_1grow`: Growing Objects
- `obstack_1grow_fast`: Extra Fast Growing
- `obstack_alignment_mask`: Obstacks Data Alignment
- `obstack_alloc`: Allocation in an Obstack
- `obstack_alloc_failed_handler`: Preparing for Obstacks
- `obstack_base`: Status of an Obstack
- `obstack_blank`: Growing Objects
- `obstack_blank_fast`: Extra Fast Growing
- `obstack_chunk_alloc`: Preparing for Obstacks
- `obstack_chunk_free`: Preparing for Obstacks
- `obstack_chunk_size`: Obstack Chunks
- `obstack_copy`: Allocation in an Obstack
- `obstack_copy0`: Allocation in an Obstack
- `obstack_finish`: Growing Objects
- `obstack_free`: Freeing Obstack Objects
- `obstack_grow`: Growing Objects
- `obstack_grow0`: Growing Objects
- `obstack_init`: Preparing for Obstacks
- `obstack_int_grow`: Growing Objects
- `obstack_int_grow_fast`: Extra Fast Growing
- `obstack_next_free`: Status of an Obstack
- `obstack_object_size`: Status of an Obstack
- `obstack_object_size`: Growing Objects
- `obstack_ptr_grow`: Growing Objects
- `obstack_ptr_grow_fast`: Extra Fast Growing
- `obstack_room`: Extra Fast Growing
- obstacks: Obstacks
- `pexecute`: Functions
- `psignal`: Functions
- `putenv`: Functions
- `pwait`: Functions
- `random`: Functions
- `reconcat`: Functions
- `remque`: Functions
- `rename`: Functions
- replacement functions: Replacement Functions
- `rindex`: Functions
- `setenv`: Functions
- `setstate`: Functions
- shrinking objects: Growing Objects
- `signo_max`: Functions
- `sigsetmask`: Functions
- `spaces`: Functions
- `srandom`: Functions
- status of obstack: Status of an Obstack
- `strcasecmp`: Functions
- `strchr`: Functions
- `strdup`: Functions
- `strerrno`: Functions
- `strerror`: Functions
- `strncasecmp`: Functions
- `strncmp`: Functions
- `strrchr`: Functions
- `strsignal`: Functions
- `strsigno`: Functions
- `strstr`: Functions
- `strtod`: Functions
- `strtoerrno`: Functions
- `strtol`: Functions
- `strtosigno`: Functions
- `strtoul`: Functions
- supplemental functions: Supplemental Functions
- `tmpnam`: Functions
- `unsetenv`: Functions
- using libiberty: Using
- `vasprintf`: Functions
- `vfork`: Functions
- `vfprintf`: Functions
- `vprintf`: Functions
- `vsprintf`: Functions
- `waitpid`: Functions
- `xatexit`: Functions
- `xcalloc`: Functions
- `xexit`: Functions
- `xmalloc`: Functions
- `xmalloc_failed`: Functions
- `xmalloc_set_program_name`: Functions
- `xmemdup`: Functions
- `xrealloc`: Functions
- `xstrdup`: Functions
- `xstrerror`: Functions