malloc(3) - Plan 9 from User Space

From adc93f6097615f16d57e8a24a256302f2144ec4e Mon Sep 17 00:00:00 2001 From: rsc Date: Fri, 14 Jan 2005 17:37:50 +0000 Subject: cut out the html - they're going to cause diffing problems. --- man/man3/malloc.html | 181 --------------------------------------------------- 1 file changed, 181 deletions(-) delete mode 100644 man/man3/malloc.html (limited to 'man/man3/malloc.html') diff --git a/man/man3/malloc.html b/man/man3/malloc.html deleted file mode 100644 index 9c30c293..00000000 --- a/man/man3/malloc.html +++ /dev/null @@ -1,181 +0,0 @@ - -malloc(3) - Plan 9 from User Space - - - - -

MALLOC(3) MALLOC(3) -

-
-

NAME
- -
- - malloc, mallocz, free, realloc, calloc, setmalloctag, setrealloctag, - getmalloctag, getrealloctag – memory allocator
- -
-

SYNOPSIS
- -
- - #include <u.h> - #include <libc.h> - - - void* malloc(ulong size) - - - void* mallocz(ulong size, int clr) - - - void free(void *ptr) - - - void* realloc(void *ptr, ulong size) - - - void* calloc(ulong nelem, ulong elsize) - - - void setmalloctag(void *ptr, ulong tag) - - - ulong getmalloctag(void *ptr) - - - void setrealloctag(void *ptr, ulong tag) - - - ulong getrealloctag(void *ptr) - -
-

DESCRIPTION
- -
- - Malloc and free provide a simple memory allocation package. Malloc - returns a pointer to a new block of at least size bytes. The block - is suitably aligned for storage of any type of object. No two - active pointers from malloc will have the same value. The call - malloc(0) returns a valid pointer rather than null. -
- - The argument to free is a pointer to a block previously allocated - by malloc; this space is made available for further allocation. - It is legal to free a null pointer; the effect is a no-op. The - contents of the space returned by malloc are undefined. Mallocz - behaves as malloc, except that if clr is non-zero, the memory - returned will be zeroed. -
- - 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. Realloc takes on special meanings when one or both arguments - are zero:
- realloc(0, size) - -
- - means malloc(size); returns a pointer to the newly-allocated memory
- -
- realloc(ptr, 0) - -
- - means free(ptr); returns null
- -
- realloc(0, 0) - -
- - no-op; returns null -
- - -
- Calloc allocates space for an array of nelem elements of size - elsize. The space is initialized to zeros. Free frees such a block. - -
- - The memory allocator on Plan 9 maintains two word-sized fields - associated with each block, the “malloc tag” and the “realloc - tag”. By convention, the malloc tag is the PC that allocated the - block, and the realloc tag the PC that last reallocated the block. - These may be set or examined with setmalloctag, getmalloctag, - setrealloctag, and getrealloctag. When allocating blocks directly - with malloc and realloc, these tags will be set properly. If a - custom allocator wrapper is used, the allocator wrapper can set - the tags itself (usually by passing the result of getcallerpc(3) - to setmalloctag) to provide more useful information about the - source - of allocation.
- -
-

SOURCE
- -
- - /usr/local/plan9/src/lib9/malloc.c - /usr/local/plan9/src/lib9/malloctag.c - -
-

SEE ALSO
- -
- - trump (in acid(1)), getcallerpc(3)
- -
-

DIAGNOSTICS
- -
- - Malloc, realloc and calloc return 0 if there is no available memory. - Errstr is likely to be set. If the allocated blocks have no malloc - or realloc tags, getmalloctag and getrealloctag return ~0. -
- - The trump library for acid can be used to obtain traces of malloc - execution; see acid(1).
- -
-

BUGS
- -
- - The different specification of calloc is bizarre. -
- - 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 malloc and free detect such - corruption, they abort. -
- - To avoid name conflicts with the system versions of these functions, - malloc, realloc, calloc, and free are preprocessor macros defined - as p9malloc, p9realloc, p9calloc, and p9free; see intro(3).
- -
- -

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