Return to malloc.3 CVS log

Up to [Power 6/32 Unix Tahoe 4.2BSD] / cci / usr / src / man / man3

Annotation of cci/usr/src/man/man3/malloc.3, revision 1.1.1.1

1.1       root        1: .TH MALLOC 3  "19 January 1983"
                      2: .UC 4
                      3: .SH NAME
                      4: malloc, free, realloc, calloc, alloca \- memory allocator
                      5: .SH SYNOPSIS
                      6: .nf
                      7: .B char *malloc(size)
                      8: .B unsigned size;
                      9: .PP
                     10: .B free(ptr)
                     11: .B char *ptr;
                     12: .PP
                     13: .B char *realloc(ptr, size)
                     14: .B char *ptr;
                     15: .B unsigned size;
                     16: .PP
                     17: .B char *calloc(nelem, elsize)
                     18: .B unsigned nelem, elsize;
                     19: .PP
                     20: .B char *alloca(size)
                     21: .B int size;
                     22: .fi
                     23: .SH DESCRIPTION
                     24: .I Malloc
                     25: and
                     26: .I free
                     27: provide a simple general-purpose memory allocation package.
                     28: .I Malloc
                     29: returns a pointer to a block of at least
                     30: .I size
                     31: bytes beginning on a word boundary.
                     32: .PP
                     33: The argument to
                     34: .I free
                     35: is a pointer to a block previously allocated by
                     36: .IR malloc ;
                     37: this space is made available for further allocation,
                     38: but its contents are left undisturbed.
                     39: .PP
                     40: Needless to say, grave disorder will result if the space assigned by
                     41: .I malloc
                     42: is overrun or if some random number is handed to
                     43: .IR free .
                     44: .PP
                     45: .I Malloc
                     46: maintains multiple lists of free blocks according to size,
                     47: allocating space from the appropriate list.
                     48: It calls
                     49: .I sbrk
                     50: (see
                     51: .IR brk (2))
                     52: to get more memory from the system when there is no
                     53: suitable space already free.
                     54: .PP
                     55: .I Realloc
                     56: changes the size of the block pointed to by
                     57: .I ptr
                     58: to
                     59: .I size
                     60: bytes and returns a pointer to the (possibly moved) block.
                     61: The contents will be unchanged up to the lesser of the new and old sizes.
                     62: .PP
                     63: In order to be compatible with older versions,
                     64: .I realloc
                     65: also works if
                     66: .I ptr
                     67: points to a block freed since the last call of
                     68: .I malloc, realloc
                     69: or
                     70: .IR calloc ;
                     71: sequences of
                     72: .I free, malloc
                     73: and
                     74: .I realloc
                     75: were previously used to attempt storage compaction.
                     76: This procedure is no longer recommended.
                     77: .PP
                     78: .I Calloc
                     79: allocates space for an array of
                     80: .I nelem
                     81: elements of size
                     82: .I elsize.
                     83: The space is initialized to zeros.
                     84: .PP
                     85: .I Alloca
                     86: allocates 
                     87: .I size
                     88: bytes of space in the stack frame of the caller.
                     89: This temporary space is automatically freed on
                     90: return.
                     91: .PP
                     92: Each of the allocation routines returns a pointer
                     93: to space suitably aligned (after possible pointer coercion)
                     94: for storage of any type of object.
                     95: .SH DIAGNOSTICS
                     96: .I Malloc, realloc
                     97: and
                     98: .I calloc
                     99: return a null pointer (0) if there is no available memory or if the arena
                    100: has been detectably corrupted by storing outside the bounds of a block.
                    101: .I Malloc
                    102: may be recompiled to check the arena very stringently on every transaction;
                    103: those sites with a source code license may check the source code to see
                    104: how this can be done.
                    105: .SH BUGS
                    106: When
                    107: .I realloc
                    108: returns 0, the block pointed to by
                    109: .I ptr
                    110: may be destroyed.
                    111: .PP
                    112: .I Alloca
                    113: is machine dependent; it's use is discouraged.

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.