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#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);
}
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