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#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <unistd.h>
#include <string.h>
char *path_of(int fd) {
ssize_t len;
char proc[PATH_MAX], real[PATH_MAX];
snprintf(proc, sizeof(proc), "/proc/self/fd/%d", fd);
len = readlink(proc, real, sizeof(real));
real[len] = '\0';
return strdup(real);
}
/*
* Test that recusing up the tree with openat(fd, "../") handles slashes
* correctly and doesn't end up opening the same directory instead of going up a
* level.
*/
int main () {
int fd, dir_fd;
struct stat st;
ino_t ino;
char *path;
fd = openat(AT_FDCWD, ".", O_DIRECTORY, 0);
fstat(fd, &st);
ino = st.st_ino;
while (1) {
path = path_of(fd);
//puts(path);
dir_fd = openat(fd, "../", O_DIRECTORY, 0);
fstat(dir_fd, &st);
if (st.st_ino == ino) {
if (strcmp(path, "/") == 0) {
//puts("Reached top of tree");
return 0;
} else {
//puts("Recursion failed!");
return 1;
}
}
free (path);
ino = st.st_ino;
fd = dir_fd;
}
return 0;
}
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