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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-15 19:41:07 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-15 19:41:07 +0000
commit3af6d22bb3850ab2bac67287e3a3d3b0e32868e5 (patch)
tree3ee7a3ec64525911fa865bb984c86d997d855527 /man3/malloc.3
parentAdding debian version 6.05.01-1. (diff)
downloadmanpages-3af6d22bb3850ab2bac67287e3a3d3b0e32868e5.tar.xz
manpages-3af6d22bb3850ab2bac67287e3a3d3b0e32868e5.zip
Merging upstream version 6.7.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r--man3/malloc.347
1 files changed, 23 insertions, 24 deletions
diff --git a/man3/malloc.3 b/man3/malloc.3
index eee0b30..0ef2cc9 100644
--- a/man3/malloc.3
+++ b/man3/malloc.3
@@ -12,7 +12,7 @@
.\" FIXME . Review http://austingroupbugs.net/view.php?id=374
.\" to see what changes are required on this page.
.\"
-.TH malloc 3 2023-07-20 "Linux man-pages 6.05.01"
+.TH malloc 3 2023-10-31 "Linux man-pages 6.7"
.SH NAME
malloc, free, calloc, realloc, reallocarray \- allocate and free dynamic memory
.SH LIBRARY
@@ -21,19 +21,19 @@ Standard C library
.SH SYNOPSIS
.nf
.B #include <stdlib.h>
-.PP
+.P
.BI "void *malloc(size_t " size );
.BI "void free(void *_Nullable " ptr );
.BI "void *calloc(size_t " nmemb ", size_t " size );
.BI "void *realloc(void *_Nullable " ptr ", size_t " size );
.BI "void *reallocarray(void *_Nullable " ptr ", size_t " nmemb ", size_t " size );
.fi
-.PP
+.P
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
-.PP
+.P
.BR reallocarray ():
.nf
Since glibc 2.29:
@@ -87,7 +87,7 @@ is 0, then
.BR calloc ()
returns a unique pointer value that can later be successfully passed to
.BR free ().
-.PP
+.P
If the multiplication of
.I nmemb
and
@@ -99,7 +99,7 @@ By contrast,
an integer overflow would not be detected in the following call to
.BR malloc (),
with the result that an incorrectly sized block of memory would be allocated:
-.PP
+.P
.in +4n
.EX
malloc(nmemb * size);
@@ -119,14 +119,14 @@ up to the minimum of the old and new sizes.
If the new size is larger than the old size, the added memory will
.I not
be initialized.
-.PP
+.P
If
.I ptr
is NULL, then the call is equivalent to
.IR malloc(size) ,
for all values of
.IR size .
-.PP
+.P
If
.I size
is equal to zero,
@@ -135,7 +135,7 @@ and
is not NULL, then the call is equivalent to
.I free(ptr)
(but see "Nonportable behavior" for portability issues).
-.PP
+.P
Unless
.I ptr
is NULL, it must have been returned by an earlier call to
@@ -156,13 +156,13 @@ elements, each of which is
.I size
bytes.
It is equivalent to the call
-.PP
+.P
.in +4n
.EX
realloc(ptr, nmemb * size);
.EE
.in
-.PP
+.P
However, unlike that
.BR realloc ()
call,
@@ -187,12 +187,12 @@ Attempting to allocate more than
.B PTRDIFF_MAX
bytes is considered an error, as an object that large
could cause later pointer subtraction to overflow.
-.PP
+.P
The
.BR free ()
function returns no value, and preserves
.IR errno .
-.PP
+.P
The
.BR realloc ()
and
@@ -247,7 +247,6 @@ T{
.BR realloc ()
T} Thread safety MT-Safe
.TE
-.sp 1
.SH STANDARDS
.TP
.BR malloc ()
@@ -275,12 +274,12 @@ POSIX.1-2001, C89.
.BR reallocarray ()
glibc 2.26.
OpenBSD 5.6, FreeBSD 11.0.
-.PP
+.P
.BR malloc ()
and related functions rejected sizes greater than
.B PTRDIFF_MAX
starting in glibc 2.30.
-.PP
+.P
.BR free ()
preserved
.I errno
@@ -301,7 +300,7 @@ in
.BR proc (5),
and the Linux kernel source file
.IR Documentation/vm/overcommit\-accounting.rst .
-.PP
+.P
Normally,
.BR malloc ()
allocates memory from the heap, and adjusts the size of the heap
@@ -324,7 +323,7 @@ were unaffected by the
resource limit;
since Linux 4.7, this limit is also enforced for allocations performed using
.BR mmap (2).
-.PP
+.P
To avoid corruption in multithreaded applications,
mutexes are used internally to protect the memory-management
data structures employed by these functions.
@@ -342,7 +341,7 @@ by the system
or
.BR mmap (2)),
and managed with its own mutexes.
-.PP
+.P
If your program uses a private memory allocator,
it should do so by replacing
.BR malloc (),
@@ -364,11 +363,11 @@ fail without having a valid reason in
.IR errno .
Private memory allocators may also need to replace other glibc functions;
see "Replacing malloc" in the glibc manual for details.
-.PP
+.P
Crashes in memory allocators
are almost always related to heap corruption, such as overflowing
an allocated chunk or freeing the same pointer twice.
-.PP
+.P
The
.BR malloc ()
implementation is tunable via environment variables; see
@@ -383,14 +382,14 @@ other implementations may return NULL without setting
and portable POSIX programs should tolerate such behavior.
See
.BR realloc (3p).
-.PP
+.P
POSIX requires memory allocators
to set
.I errno
upon failure.
However, the C standard does not require this, and applications
portable to non-POSIX platforms should not assume this.
-.PP
+.P
Portable programs should not use private memory allocators,
as POSIX and the C standard do not allow replacement of
.BR malloc (),
@@ -455,7 +454,7 @@ my_mallocarray(size_t nmemb, size_t size)
.BR mcheck (3),
.BR mtrace (3),
.BR posix_memalign (3)
-.PP
+.P
For details of the GNU C library implementation, see
.UR https://sourceware.org/glibc/wiki/MallocInternals
.UE .