1 /*
2 * Copyright 2004 The WebRTC Project Authors. All rights reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
11 #include <sys/types.h>
12 #include <dirent.h>
13 #include <errno.h>
14 #include <stdlib.h>
15 #include <string.h>
16
17 #include "webrtc/base/linuxfdwalk.h"
18
19 // Parses a file descriptor number in base 10, requiring the strict format used
20 // in /proc/*/fd. Returns the value, or -1 if not a valid string.
parse_fd(const char * s)21 static int parse_fd(const char *s) {
22 if (!*s) {
23 // Empty string is invalid.
24 return -1;
25 }
26 int val = 0;
27 do {
28 if (*s < '0' || *s > '9') {
29 // Non-numeric characters anywhere are invalid.
30 return -1;
31 }
32 int digit = *s++ - '0';
33 val = val * 10 + digit;
34 } while (*s);
35 return val;
36 }
37
fdwalk(void (* func)(void *,int),void * opaque)38 int fdwalk(void (*func)(void *, int), void *opaque) {
39 DIR *dir = opendir("/proc/self/fd");
40 if (!dir) {
41 return -1;
42 }
43 int opendirfd = dirfd(dir);
44 int parse_errors = 0;
45 struct dirent *ent;
46 // Have to clear errno to distinguish readdir() completion from failure.
47 while (errno = 0, (ent = readdir(dir)) != NULL) {
48 if (strcmp(ent->d_name, ".") == 0 ||
49 strcmp(ent->d_name, "..") == 0) {
50 continue;
51 }
52 // We avoid atoi or strtol because those are part of libc and they involve
53 // locale stuff, which is probably not safe from a post-fork context in a
54 // multi-threaded app.
55 int fd = parse_fd(ent->d_name);
56 if (fd < 0) {
57 parse_errors = 1;
58 continue;
59 }
60 if (fd != opendirfd) {
61 (*func)(opaque, fd);
62 }
63 }
64 int saved_errno = errno;
65 if (closedir(dir) < 0) {
66 if (!saved_errno) {
67 // Return the closedir error.
68 return -1;
69 }
70 // Else ignore it because we have a more relevant error to return.
71 }
72 if (saved_errno) {
73 errno = saved_errno;
74 return -1;
75 } else if (parse_errors) {
76 errno = EBADF;
77 return -1;
78 } else {
79 return 0;
80 }
81 }
82