diff options
Diffstat (limited to 'man3/malloc_usable_size.3')
| -rw-r--r-- | man3/malloc_usable_size.3 | 43 |
1 files changed, 19 insertions, 24 deletions
diff --git a/man3/malloc_usable_size.3 b/man3/malloc_usable_size.3 index 11598a471..91d22d8dd 100644 --- a/man3/malloc_usable_size.3 +++ b/man3/malloc_usable_size.3 @@ -3,7 +3,7 @@ .\" .\" SPDX-License-Identifier: Linux-man-pages-copyleft .\" -.TH malloc_usable_size 3 2022-12-15 "Linux man-pages 6.03" +.TH malloc_usable_size 3 2023-07-20 "Linux man-pages 6.05.01" .SH NAME malloc_usable_size \- obtain size of block of memory allocated from heap .SH LIBRARY @@ -13,20 +13,17 @@ Standard C library .nf .B #include <malloc.h> .PP -.BI "size_t malloc_usable_size(void *" ptr ); +.BI "size_t malloc_usable_size(void *_Nullable " ptr ); .fi .SH DESCRIPTION -The -.BR malloc_usable_size () -function returns the number of usable bytes in the block pointed to by -.IR ptr , -a pointer to a block of memory allocated by +This function can be used for +diagnostics or statistics about allocations from .BR malloc (3) or a related function. .SH RETURN VALUE .BR malloc_usable_size () -returns the number of usable bytes in -the block of allocated memory pointed to by +returns a value no less than +the size of the block of allocated memory pointed to by .IR ptr . If .I ptr @@ -34,33 +31,31 @@ is NULL, 0 is returned. .SH ATTRIBUTES For an explanation of the terms used in this section, see .BR attributes (7). -.ad l -.nh .TS allbox; lbx lb lb l l l. Interface Attribute Value T{ +.na +.nh .BR malloc_usable_size () T} Thread safety MT-Safe .TE -.hy -.ad .sp 1 .SH STANDARDS -This function is a GNU extension. -.SH NOTES +GNU. +.SH CAVEATS The value returned by .BR malloc_usable_size () -may be greater than the requested size of the allocation because -of alignment and minimum size constraints. -Although the excess bytes can be overwritten by the application -without ill effects, -this is not good programming practice: -the number of excess bytes in an allocation depends on -the underlying implementation. -.PP -The main use of this function is for debugging and introspection. +may be greater than the requested size of the allocation +because of various internal implementation details, +none of which the programmer should rely on. +This function is intended to only be used +for diagnostics and statistics; +writing to the excess memory without first calling +.BR realloc (3) +to resize the allocation is not supported. +The returned value is only valid at the time of the call. .SH SEE ALSO .BR malloc (3) |