diff options
Diffstat (limited to 'manual')
| -rw-r--r-- | manual/memory.texi | 16 | ||||
| -rw-r--r-- | manual/tunables.texi | 4 |
2 files changed, 16 insertions, 4 deletions
diff --git a/manual/memory.texi b/manual/memory.texi index 31ee36b..93305f2 100644 --- a/manual/memory.texi +++ b/manual/memory.texi @@ -1256,8 +1256,9 @@ environment variable @env{MALLOC_ARENA_MAX} to the desired value. @cindex consistency checking, of heap You can ask @code{malloc} to check the consistency of dynamic memory by -using the @code{mcheck} function. This function is a GNU extension, -declared in @file{mcheck.h}. +using the @code{mcheck} function and preloading the malloc debug library +@file{libc_malloc_debug.so} using the @var{LD_PRELOAD} environment variable. +This function is a GNU extension, declared in @file{mcheck.h}. @pindex mcheck.h @deftypefun int mcheck (void (*@var{abortfn}) (enum mcheck_status @var{status})) @@ -1368,7 +1369,10 @@ non-zero value less than 4, a special (less efficient) implementation is used which is designed to be tolerant against simple errors, such as double calls of @code{free} with the same argument, or overruns of a single byte (off-by-one bugs). Not all such errors can be protected -against, however, and memory leaks can result. +against, however, and memory leaks can result. Like in the case of +@code{mcheck}, one would need to preload the @file{libc_malloc_debug.so} +library to enable @code{MALLOC_CHECK_} functionality. Without this +preloaded library, setting @code{MALLOC_CHECK_} will have no effect. Any detected heap corruption results in immediate termination of the process. @@ -1747,6 +1751,12 @@ penalties for the program if the debugging mode is not enabled. @c fprintf dup (on newly-created stream) @aculock @c __cxa_atexit (once) dup @asulock @aculock @acsmem @c free dup @ascuheap @acsmem +The @code{mtrace} function provides a way to trace memory allocation +events in the program that calls it. It is disabled by default in the +library and can be enabled by preloading the debugging library +@file{libc_malloc_debug.so} using the @code{LD_PRELOAD} environment +variable. + When the @code{mtrace} function is called it looks for an environment variable named @code{MALLOC_TRACE}. This variable is supposed to contain a valid file name. The user must have write access. If the diff --git a/manual/tunables.texi b/manual/tunables.texi index ebdb562..e264e91 100644 --- a/manual/tunables.texi +++ b/manual/tunables.texi @@ -113,7 +113,9 @@ following tunables in the @code{malloc} namespace: @deftp Tunable glibc.malloc.check This tunable supersedes the @env{MALLOC_CHECK_} environment variable and is -identical in features. +identical in features. This tunable has no effect by default and needs the +debug library @file{libc_malloc_debug.so} to be preloaded using the +@code{LD_PRELOAD} environment variable. Setting this tunable to a non-zero value less than 4 enables a special (less efficient) memory allocator for the @code{malloc} family of functions that is |