.TH MALLOC 2.SH NAMEmalloc, free, realloc, calloc \- memory allocator.SH SYNOPSIS.B #include <u.h>.br.B #include <libc.h>.PP.ta \w'\fLvoid* 'u.Bvoid* malloc(long size).PP.Bvoid free(void *ptr).PP.Bvoid* realloc(void *ptr, long size).PP.Bvoid* calloc(long nelem, long elsize).SH DESCRIPTION.I Mallocand.I freeprovide a simple memory allocation package..I Mallocreturns a pointer to a new block of at least.I sizebytes.The block is suitably aligned for storage of any type of object.No two active pointers from.I mallocwill have the same value..PPThe argument to.I freeis a pointer to a block previously allocated by.IR malloc ;this space is made available for further allocation.It is legal to free a null pointer; the effect is a no-op..PP.I Reallocchanges the size of the block pointed to by.I ptrto.I sizebytes and returns a pointer to the (possibly moved)block.The contents will be unchanged up to thelesser of the new and old sizes.The call.B "realloc(0, size)means the same as.LR malloc(size) ..PP.I Callocallocates space foran array of.I nelemelements of size.IR elsize .The space is initialized to zeros..I Freefrees such a block..SS AlefExcept for.IR calloc ,these routines are available from Alef; they use the same arena as.BR alloc ..I Mallocand.I reallocexecute a.B checkwhen they fail, rather than return.BR nil .Memory returned by.I mallocis cleared..I Reallocdoes not guarantee new memory is cleared unless.I ptris.BR nil ..SH SOURCE.B /sys/src/libc/port/malloc.c.SH SEE ALSO.IR brk (2).SH DIAGNOSTICS.I Malloc, reallocand.I callocreturn 0 if there is no available memory..I Errstris likely to be set..SH BUGSThe different specification of.I callocis bizarre..PPUser errors can corrupt the storage arena.The most common gaffes are (1) freeing an already freed block,(2) storing beyond the bounds of an allocated block, and (3)freeing data that was not obtained from the allocator.When.I mallocand.I freedetect such corruption, they abort.
.TH MALLOC 2
.SH NAME
malloc, free, realloc, calloc \- memory allocator
.SH SYNOPSIS
.B #include <u.h>
.br
.B #include <libc.h>
.PP
.ta \w'\fLvoid* 'u
.B
void* malloc(long size)
.PP
.B
void free(void *ptr)
.PP
.B
void* realloc(void *ptr, long size)
.PP
.B
void* calloc(long nelem, long elsize)
.SH DESCRIPTION
.I Malloc
and
.I free
provide a simple memory allocation package.
.I Malloc
returns a pointer to a new block of at least
.I size
bytes.
The block is suitably aligned for storage of any type of object.
No two active pointers from
.I malloc
will have the same value.
.PP
The argument to
.I free
is a pointer to a block previously allocated by
.IR malloc ;
this space is made available for further allocation.
It is legal to free a null pointer; the effect is a no-op.
.PP
.I Realloc
changes the size of the block pointed to by
.I ptr
to
.I 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.
The call
.B "realloc(0, size)
means the same as
.LR malloc(size) .
.PP
.I Calloc
allocates space for
an array of
.I nelem
elements of size
.IR elsize .
The space is initialized to zeros.
.I Free
frees such a block.
.SS Alef
Except for
.IR calloc ,
these routines are available from Alef; they use the same arena as
.BR alloc .
.I Malloc
and
.I realloc
execute a
.B check
when they fail, rather than return
.BR nil .
Memory returned by
.I malloc
is cleared.
.I Realloc
does not guarantee new memory is cleared unless
.I ptr
is
.BR nil .
.SH SOURCE
.B /sys/src/libc/port/malloc.c
.SH SEE ALSO
.IR brk (2)
.SH DIAGNOSTICS
.I Malloc, realloc
and
.I calloc
return 0 if there is no available memory.
.I Errstr
is likely to be set.
.SH BUGS
The different specification of
.I calloc
is bizarre.
.PP
User errors can corrupt the storage arena.
The most common gaffes are (1) freeing an already freed block,
(2) storing beyond the bounds of an allocated block, and (3)
freeing data that was not obtained from the allocator.
When
.I malloc
and
.I free
detect such corruption, they abort.