What is the difference between xmalloc and malloc?

Question

What is the difference between xmalloc() and malloc() for memory allocation?
Is there any pro of using xmalloc()?

Answer 1

xmalloc is part of libiberty

https://gcc.gnu.org/onlinedocs/libiberty/index.html which is a GNU utils library.

malloc is ANSI C.

xmalloc is often included in-source in many important GNU projects, including GCC and Binutils, both of which use it a lot. But it is also possible to build it as a dynamic library to use in your programs. E.g. Ubuntu has the libiberty-dev package.

xmalloc is documented at: https://gcc.gnu.org/onlinedocs/libiberty/Functions.html and on GCC 5.2.0 it is implemented on libiberty/xmalloc.c

PTR
xmalloc (size_t size)
{
  PTR newmem;

  if (size == 0)
    size = 1;
  newmem = malloc (size);
  if (!newmem)
    xmalloc_failed (size);

  return (newmem);
}

void
xmalloc_failed (size_t size)
{
#ifdef HAVE_SBRK
  extern char **environ;
  size_t allocated;

  if (first_break != NULL)
    allocated = (char *) sbrk (0) - first_break;
  else
    allocated = (char *) sbrk (0) - (char *) &environ;
  fprintf (stderr,
       "\n%s%sout of memory allocating %lu bytes after a total of %lu bytes\n",
       name, *name ? ": " : "",
       (unsigned long) size, (unsigned long) allocated);
#else /* HAVE_SBRK */
  fprintf (stderr,
       "\n%s%sout of memory allocating %lu bytes\n",
       name, *name ? ": " : "",
       (unsigned long) size);
#endif /* HAVE_SBRK */
  xexit (1);
}

/* This variable is set by xatexit if it is called.  This way, xmalloc
   doesn't drag xatexit into the link.  */
void (*_xexit_cleanup) (void);

void
xexit (int code)
{
  if (_xexit_cleanup != NULL)
    (*_xexit_cleanup) ();
  exit (code);
}

Which as others mentioned, is pretty straightforward:

• try malloc
• if it fails
  • print error messages
  • call exit