memswap(3pub) [debian man page]

MEMSWAP(3pub)						       C Programmer's Manual						     MEMSWAP(3pub)

NAME

       memswap - swap the contents of two memory blocks

SYNOPSIS

       #include <publib.h>
       void memswap(void *block1, void *block2, size_t n);

DESCRIPTION

       memswap	will  swap  the  contents  of  the  two blocks pointed by its first two arguments.  The last argument gives the size of the memory
       blocks.

EXAMPLE

       To swap two structs, one might do the following.

	    struct tm tm1, tm2;

	    memswap(&tm1, &tm2, sizeof(struct tm));

BUGS

       Using memswap to swap small portions of memory is inefficient.  It is not worth it to use it to swap variables of any of the  basic  types,
       for instance.  Use inline code for such cases.  However, for large portions of memory, e.g., arrays, it is convenient.

       memswap	can't  swap variables whose address can't be taken.  This excludes variables with the register specifier and bitfields in structs.
       But then, there is no way to write a function (or macro) that can handle any kind of arguments.	Life is hard.

SEE ALSO

       publib(3)

AUTHOR

       Lars Wirzenius (lars.wirzenius@helsinki.fi)

Publib							       C Programmer's Manual						     MEMSWAP(3pub)

XMALLOC(3pub)						       C Programmer's Manual						     XMALLOC(3pub)

NAME

       xmalloc, xrealloc, xfree, xstrdup, xmemdup, memdup - memory allocation functions for Publib

SYNOPSIS

       #include <publib.h>

       void *xmalloc(size_t bytes);
       void *xrealloc(void *ptr, size_t bytes);
       void xfree(void *ptr);
       char *xstrdup(const char *string);
       void *memdup(const void *mem, size_t bytes);
       void *xmemdup(const void *mem, size_t bytes);

DESCRIPTION

       These  functions are utility functions for memory allocation from the publib library.  xmalloc, xrealloc, and xfree are error checking ver-
       sions of the standard library routines malloc, realloc, and free, respectively.	They are guaranteed to never return unless  there  was	no
       problem:  if, for example, xmalloc is unable to allocate the requested amount of memory, it prints an error message and terminates the pro-
       gram.  Hence, the caller does not need to check for a NULL return value, and the code that calls these functions is simpler due to the lack
       of error checks.

       Similarly,  xstrdup  is an error checking version of the common (though not standard) strdup routine, which creates a duplicate of a string
       by allocating memory for the copy with malloc.  (For systems that lack strdup, publib provides one in its portability module; it is  always
       declared in <publib.h>.)

       memdup  is  similar to strdup, it creates a copy of an arbitrary memory area (the arguments are a pointer to the beginning of the area, and
       its size) by allocating memory for the copy with malloc.  xmemdup is its error checking version.

NOTE

       xmalloc and xrealloc treat a request to allocate a block of 0 bytes as an error.  xrealloc will allow its first argument to be NULL.

SEE ALSO

       publib(3), malloc(3), strdup(3)

AUTHOR

       Lars Wirzenius (lars.wirzenius@helsinki.fi)

Publib							       C Programmer's Manual						     XMALLOC(3pub)