проверка согласованности кучи (heap consistency checking)
Имя (Name)
mcheck, mcheck_check_all, mcheck_pedantic, mprobe - heap
consistency checking
Синопсис (Synopsis)
#include <mcheck.h>
int mcheck(void (*abortfunc)(enum mcheck_status mstatus));
int mcheck_pedantic(void (*abortfunc)(enum mcheck_status mstatus));
void mcheck_check_all(void);
enum mcheck_status mprobe(void *ptr);
Описание (Description)
The mcheck() function installs a set of debugging hooks for the
malloc(3) family of memory-allocation functions. These hooks
cause certain consistency checks to be performed on the state of
the heap. The checks can detect application errors such as
freeing a block of memory more than once or corrupting the
bookkeeping data structures that immediately precede a block of
allocated memory.
To be effective, the mcheck() function must be called before the
first call to malloc(3) or a related function. In cases where
this is difficult to ensure, linking the program with -lmcheck
inserts an implicit call to mcheck() (with a NULL argument)
before the first call to a memory-allocation function.
The mcheck_pedantic() function is similar to mcheck(), but
performs checks on all allocated blocks whenever one of the
memory-allocation functions is called. This can be very slow!
The mcheck_check_all() function causes an immediate check on all
allocated blocks. This call is effective only if mcheck() is
called beforehand.
If the system detects an inconsistency in the heap, the caller-
supplied function pointed to by abortfunc is invoked with a
single argument, mstatus, that indicates what type of
inconsistency was detected. If abortfunc is NULL, a default
function prints an error message on stderr and calls abort(3).
The mprobe() function performs a consistency check on the block
of allocated memory pointed to by ptr. The mcheck() function
should be called beforehand (otherwise mprobe() returns
MCHECK_DISABLED).
The following list describes the values returned by mprobe() or
passed as the mstatus argument when abortfunc is invoked:
MCHECK_DISABLED (mprobe() only)
mcheck() was not called before the first memory allocation
function was called. Consistency checking is not
possible.
MCHECK_OK (mprobe() only)
No inconsistency detected.
MCHECK_HEAD
Memory preceding an allocated block was clobbered.
MCHECK_TAIL
Memory following an allocated block was clobbered.
MCHECK_FREE
A block of memory was freed twice.
Возвращаемое значение (Return value)
mcheck() and mcheck_pedantic() return 0 on success, or -1 on
error.
Версии (Versions)
The mcheck_pedantic() and mcheck_check_all() functions are
available since glibc 2.2. The mcheck() and mprobe() functions
are present since at least glibc 2.0
Атрибуты (Attributes)
For an explanation of the terms used in this section, see
attributes(7).
┌───────────────────────────┬───────────────┬────────────────────┐
│Interface │ Attribute │ Value │
├───────────────────────────┼───────────────┼────────────────────┤
│mcheck(), │ Thread safety │ MT-Unsafe │
│mcheck_pedantic(), │ │ race:mcheck │
│mcheck_check_all(), │ │ const:malloc_hooks │
│mprobe() │ │ │
└───────────────────────────┴───────────────┴────────────────────┘
Стандарты (Conforming to)
These functions are GNU extensions.
Примечание (Note)
Linking a program with -lmcheck and using the MALLOC_CHECK_
environment variable (described in mallopt(3)) cause the same
kinds of errors to be detected. But, using MALLOC_CHECK_ does
not require the application to be relinked.
Примеры (Examples)
The program below calls mcheck() with a NULL argument and then
frees the same block of memory twice. The following shell
session demonstrates what happens when running the program:
$ ./a.out
About to free
About to free a second time
block freed twice
Aborted (core dumped)
Program source
#include <stdlib.h>
#include <stdio.h>
#include <mcheck.h>
int
main(int argc, char *argv[])
{
char *p;
if (mcheck(NULL) != 0) {
fprintf(stderr, "mcheck() failed\n");
exit(EXIT_FAILURE);
}
p = malloc(1000);
fprintf(stderr, "About to free\n");
free(p);
fprintf(stderr, "\nAbout to free a second time\n");
free(p);
exit(EXIT_SUCCESS);
}
Смотри также (See also)
malloc(3), mallopt(3), mtrace(3)
