MALLOC(3C)                                             MALLOC(3C)



     NAME
          malloc, free, realloc, calloc - memory allocator

     SYNOPSIS
          char *malloc(size)
          unsigned size;

          free(ptr)
          char *ptr;

          char *realloc(ptr, size)
          char *ptr;
          unsigned size;

          char *calloc(nelem, elsize)
          unsigned nelem, elsize;

     DESCRIPTION
          Malloc and free provide a general-purpose memory allocation
          package.  Malloc returns a pointer to a block of at least
          size bytes beginning on a word boundary.

          The argument to free is a pointer to a block previously
          allocated by malloc; this space is made available for
          further allocation, but its contents are left undisturbed.

          Needless to say, grave disorder will result if the space
          assigned by malloc is overrun or if some random number is
          handed to free.

          Malloc maintains multiple lists of free blocks according to
          size, allocating space from the appropriate list.  It calls
          sbrk (see brk(2)) to get more memory from the system when
          there is no suitable space already free.

          Realloc changes the size of the block pointed to by ptr to
          size bytes and returns a pointer to the (possibly moved)
          block.  The contents will be unchanged up to the lesser of
          the new and old sizes.

          In order to be compatible with older versions, realloc also
          works if ptr points to a block freed since the last call of
          malloc, realloc or calloc; sequences of free, malloc and
          realloc were previously used to attempt storage compaction.
          This procedure is no longer recommended.

          Calloc allocates space for an array of nelem elements of
          size elsize. The space is initialized to zeros.

          Each of the allocation routines returns a pointer to space
          suitably aligned (after possible pointer coercion) for
          storage of any type of object.  If the space is of pagesize



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     MALLOC(3C)                                             MALLOC(3C)



          or larger, the memory returned will be page-aligned.

     SEE ALSO
          brk(2)

     DIAGNOSTICS
          Malloc, realloc and calloc return a null pointer (0) if
          there is no available memory or if the arena has been
          detectably corrupted by storing outside the bounds of a
          block.  Malloc may be recompiled to check the arena very
          stringently on every transaction; those sites with a source
          code license may check the source code to see how this can
          be done.

     BUGS
          When realloc returns 0, the block pointed to by ptr may be
          destroyed.

          The current implementation of malloc does not always fail
          gracefully when system memory limits are approached.  It may
          fail to allocate memory when larger free blocks could be
          broken up, or when limits are exceeded because the size is
          rounded up.  It is optimized for sizes that are powers of
          two.

     ORIGIN
          MIPS Computer Systems




























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