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#include <stddef.h>
#include <stdio.h>
#include <string.h>
#include <dirent.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/stat.h>
int find_fd_seccomp_notifier(const char *path)
{
char entry[2 * PATH_MAX + 1];
char buf[PATH_MAX + 1];
struct dirent *dp;
ssize_t nbytes;
struct stat sb;
DIR *dirp;
if ((dirp = opendir(path)) == NULL) {
fprintf(stderr, "failed reading fds from proc: %s \n", path);
return -1;
}
while ((dp = readdir(dirp)) != NULL) {
snprintf(entry, sizeof(entry), "%s/%s", path, dp->d_name);
if (lstat(entry, &sb) == -1) {
perror("lstat");
}
/* Skip the entry if it isn't a symbolic link */
if (!S_ISLNK(sb.st_mode))
continue;
nbytes = readlink(entry, buf, PATH_MAX);
if (nbytes == -1) {
perror("readlink");
}
if (nbytes == PATH_MAX) {
perror("buffer overflow");
continue;
}
/*
* From man proc: For file descriptors that have no
* corresponding inode (e.g., file descriptors produced by
* bpf(2)..), the entry will be a symbolic link with contents
* of the form:
* anon_inode:<file-type>
*/
if (strstr(buf, "anon_inode:seccomp notify") != NULL)
return atoi(dp->d_name);
}
fprintf(stderr, "seccomp notifier not found in %s\n", path);
return -1;
}
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