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criu/test/libfault/libfault.c
Radostin Stoyanov 1da29f27f6 zdtm: add support for LD_PRELOAD tests
This commit adds a `--preload-libfault` option to ZDTM's run command.
This option runs CRIU with LD_PRELOAD to intercept libc functions
such as pread(). This method allows to simulate special cases,
for example, when a successful call to pread() transfers fewer
bytes than requested.

Signed-off-by: Radostin Stoyanov <rstoyanov@fedoraproject.org>
2024-09-11 16:02:11 -07:00

32 lines
830 B
C

#define _GNU_SOURCE
#include <unistd.h>
#include <dlfcn.h>
#include <errno.h>
ssize_t (*original_pread)(int fd, void *buf, size_t count, off_t offset) = NULL;
/**
* This function is a wrapper around pread() that is used for testing CRIU's
* handling of cases where pread() returns less data than requested.
*
* pmc_fill() in criu/pagemap.c is a good example of where this can happen.
*/
ssize_t pread64(int fd, void *buf, size_t count, off_t offset)
{
if (!original_pread) {
original_pread = dlsym(RTLD_NEXT, "pread");
if (!original_pread) {
errno = EIO;
return -1;
}
}
/* The following aims to simulate the case when pread() returns less
* data than requested. We need to ensure that CRIU handles such cases. */
if (count > 2048) {
count -= 1024;
}
return original_pread(fd, buf, count, offset);
}