diff options
Diffstat (limited to 'lib/libc')
| -rw-r--r-- | lib/libc/stdlib/malloc.3 | 21 | ||||
| -rw-r--r-- | lib/libc/stdlib/malloc.c | 14 |
2 files changed, 27 insertions, 8 deletions
diff --git a/lib/libc/stdlib/malloc.3 b/lib/libc/stdlib/malloc.3 index 9782588..479ab00 100644 --- a/lib/libc/stdlib/malloc.3 +++ b/lib/libc/stdlib/malloc.3 @@ -34,7 +34,7 @@ .\" SUCH DAMAGE. .\" .\" @(#)malloc.3 8.1 (Berkeley) 6/4/93 -.\" $Id: malloc.3,v 1.9 1997/03/22 23:48:12 mpp Exp $ +.\" $Id: malloc.3,v 1.10 1997/05/30 20:39:32 phk Exp $ .\" .Dd August 27, 1996 .Dt MALLOC 3 @@ -149,6 +149,11 @@ This can substantially aid in compacting memory. ``utrace'' generate entries for ktrace(1) for all operations. Consult the source for this one. +.It V +``sysV'' operations that attempt to allocate zero bytes will +return a null pointer. Be aware of the conflict if you also +have ``X'' set. + .It X ``xmalloc'' rather than return failure, @@ -217,7 +222,7 @@ Here is a brief description of the error messages and what they mean: .Pp ``(ES): mumble mumble mumble'': malloc have been compiled with -DEXTRA_SANITY and something looks -fishy in there. Consult sources and or wizards. +fishy in there. Consult sources and/or wizards. .Pp ``allocation failed'' if the ``A'' option is specified it is an error for @@ -272,6 +277,13 @@ would be possible to add a sigblock() around this package, but it would have a performance penalty that is not acceptable as the default. .Pp +``out of memory'' +The ``X'' flag is active and an allocation of memory failed. +.Pp +``open of /dev/zero'' +On certain architectures /dev/zero is used as a source of +anonymous pages for the page directory, opening failed. +.Pp ``unknown char in MALLOC_OPTIONS'' we found something we didn't understand. .Sh SEE ALSO @@ -286,6 +298,9 @@ The .Fn malloc function conforms to .St -ansiC . +.Sh BUGS +It can be argued that returning a null pointer when asked to +allocate zero bytes is a silly response to a silly question. .Sh HISTORY The present implementation of malloc started out as a filesystem on a drum attached to a 20bit binary challenged computer built with discrete germanium @@ -293,7 +308,7 @@ transistors, and it has since graduated to handle primary storage rather than secondary. .Pp The main difference from other malloc implementations are believed to be that -the free pages are not accessed until allocated. +the free pages are not accessed unless allocated. Most malloc implementations will store a data structure containing a, possibly double-, linked list in the free chunks of memory, used to tie all the free memory together. diff --git a/lib/libc/stdlib/malloc.c b/lib/libc/stdlib/malloc.c index 0327517..446f55d 100644 --- a/lib/libc/stdlib/malloc.c +++ b/lib/libc/stdlib/malloc.c @@ -6,7 +6,7 @@ * this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp * ---------------------------------------------------------------------------- * - * $Id: malloc.c,v 1.23 1997/05/30 20:39:32 phk Exp $ + * $Id: malloc.c,v 1.24 1997/06/04 12:55:49 jb Exp $ * */ @@ -216,6 +216,9 @@ static int malloc_hint; /* xmalloc behaviour ? */ static int malloc_xmalloc; +/* sysv behaviour for malloc(0) ? */ +static int malloc_sysv; + /* zero fill ? */ static int malloc_zero; @@ -488,6 +491,8 @@ malloc_init () case 'J': malloc_junk = 1; break; case 'u': malloc_utrace = 0; break; case 'U': malloc_utrace = 1; break; + case 'v': malloc_sysv = 0; break; + case 'V': malloc_sysv = 1; break; case 'x': malloc_xmalloc = 0; break; case 'X': malloc_xmalloc = 1; break; case 'z': malloc_zero = 0; break; @@ -774,7 +779,9 @@ imalloc(size_t size) if (suicide) abort(); - if ((size + malloc_pagesize) < size) /* Check for overflow */ + if (malloc_sysv && !size) + result = 0; + else if ((size + malloc_pagesize) < size) /* Check for overflow */ result = 0; else if (size <= malloc_maxsize) result = malloc_bytes(size); @@ -1179,9 +1186,6 @@ realloc(void *ptr, size_t size) } if (!ptr) { r = imalloc(size); - } else if (ptr && !size) { - ifree(ptr); - r = 0; } else { r = irealloc(ptr, size); } |
