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/* This demonstrates races: kernel may actually open other file then
* you read at strace output. Create /tmp/delme with 10K of zeros and
* 666 mode, then run this under strace. If you see open successfull
* open of /etc/shadow, you know you've seen a race.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int main(int argc, char *argv[])
{
char *c;
int fd;
fd = open("/tmp/delme", O_RDWR);
c = mmap(0, 4096, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
*c = 0;
if (fork()) {
while (1) {
strcpy(c, "/etc/passwd");
strcpy(c, "/etc/shadow");
}
} else {
while (1)
if ((fd = open(c, 0)) != -1)
close(fd);
}
return 0;
}
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