diff options
Diffstat (limited to 'lib/libc/stdlib/malloc.3')
| -rw-r--r-- | lib/libc/stdlib/malloc.3 | 102 |
1 files changed, 51 insertions, 51 deletions
diff --git a/lib/libc/stdlib/malloc.3 b/lib/libc/stdlib/malloc.3 index b29509d..495fc22 100644 --- a/lib/libc/stdlib/malloc.3 +++ b/lib/libc/stdlib/malloc.3 @@ -143,8 +143,9 @@ function returns the usable size of the allocation pointed to by .Fa ptr . The return value may be larger than the size that was requested during allocation. +The .Fn malloc_usable_size -is not a mechanism for in-place +function is not a mechanism for in-place .Fn realloc ; rather it is provided solely as a tool for introspection purposes. Any discrepancy between the requested allocation size and the size reported by @@ -177,7 +178,7 @@ The process will call .Xr abort 3 in these cases. .It H -Use +Use .Xr madvise 2 when pages within a chunk are no longer in use, but the chunk as a whole cannot yet be deallocated. @@ -263,7 +264,7 @@ Each byte of new memory allocated by .Fn realloc or .Fn reallocf -will be initialized to 0x0. +will be initialized to 0. Note that this initialization only happens once for each byte, so .Fn realloc and @@ -279,48 +280,6 @@ and options are intended for testing and debugging. An application which changes its behavior when these options are used is flawed. -.Sh RETURN VALUES -The -.Fn malloc -and -.Fn calloc -functions return a pointer to the allocated memory if successful; otherwise -a -.Dv NULL -pointer is returned and -.Va errno -is set to -.Er ENOMEM . -.Pp -The -.Fn realloc -and -.Fn reallocf -functions return a pointer, possibly identical to -.Fa ptr , -to the allocated memory -if successful; otherwise a -.Dv NULL -pointer is returned, and -.Va errno -is set to -.Er ENOMEM -if the error was the result of an allocation failure. -The -.Fn realloc -function always leaves the original buffer intact -when an error occurs, whereas -.Fn reallocf -deallocates it in this case. -.Pp -The -.Fn free -function returns no value. -.Pp -The -.Fn malloc_usable_size -function returns the usable size of the allocation pointed to by -.Fa ptr . .Sh IMPLEMENTATION NOTES This allocator uses multiple arenas in order to reduce lock contention for threaded programs on multi-processor systems. @@ -353,7 +312,7 @@ Allocation requests that are larger than the maximum quantum-multiple size class, but no larger than one half of a page, are rounded up to the nearest power of two. Allocation requests that are larger than half of a page, but no larger than half -of a chunk (see the +of a chunk (see the .Dq K option), are rounded up to the nearest run size. Allocation requests that are larger than half of a chunk are rounded up to the @@ -402,7 +361,8 @@ which focus on detecting and pinpointing problems by trading performance for extra sanity checks and detailed diagnostics. .Sh DIAGNOSTIC MESSAGES If any of the memory allocation/deallocation functions detect an error or -warning condition, a message will be printed to file descriptor STDERR_FILENO. +warning condition, a message will be printed to file descriptor +.Dv STDERR_FILENO . Errors will result in the process dumping core. If the .Dq A @@ -418,10 +378,50 @@ file descriptor is not suitable for this. Please note that doing anything which tries to allocate memory in this function is likely to result in a crash or deadlock. .Pp -All messages are prefixed by: -.Bl -diag -.It <progname>: (malloc) -.El +All messages are prefixed by +.Dq Ao Ar progname Ac Ns Li : (malloc) . +.Sh RETURN VALUES +The +.Fn malloc +and +.Fn calloc +functions return a pointer to the allocated memory if successful; otherwise +a +.Dv NULL +pointer is returned and +.Va errno +is set to +.Er ENOMEM . +.Pp +The +.Fn realloc +and +.Fn reallocf +functions return a pointer, possibly identical to +.Fa ptr , +to the allocated memory +if successful; otherwise a +.Dv NULL +pointer is returned, and +.Va errno +is set to +.Er ENOMEM +if the error was the result of an allocation failure. +The +.Fn realloc +function always leaves the original buffer intact +when an error occurs, whereas +.Fn reallocf +deallocates it in this case. +.Pp +The +.Fn free +function returns no value. +.Pp +The +.Fn malloc_usable_size +function returns the usable size of the allocation pointed to by +.Fa ptr . .Sh ENVIRONMENT The following environment variables affect the execution of the allocation functions: |
