1/*
2 * libjingle
3 * Copyright 2004--2009, Google Inc.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 *  1. Redistributions of source code must retain the above copyright notice,
9 *     this list of conditions and the following disclaimer.
10 *  2. Redistributions in binary form must reproduce the above copyright notice,
11 *     this list of conditions and the following disclaimer in the documentation
12 *     and/or other materials provided with the distribution.
13 *  3. The name of the author may not be used to endorse or promote products
14 *     derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
17 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
18 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
19 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
22 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
23 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
24 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
25 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28#include <sys/types.h>
29#include <dirent.h>
30#include <errno.h>
31#include <stdlib.h>
32#include <string.h>
33
34#include "talk/base/linuxfdwalk.h"
35
36// Parses a file descriptor number in base 10, requiring the strict format used
37// in /proc/*/fd. Returns the value, or -1 if not a valid string.
38static int parse_fd(const char *s) {
39  if (!*s) {
40    // Empty string is invalid.
41    return -1;
42  }
43  int val = 0;
44  do {
45    if (*s < '0' || *s > '9') {
46      // Non-numeric characters anywhere are invalid.
47      return -1;
48    }
49    int digit = *s++ - '0';
50    val = val * 10 + digit;
51  } while (*s);
52  return val;
53}
54
55int fdwalk(void (*func)(void *, int), void *opaque) {
56  DIR *dir = opendir("/proc/self/fd");
57  if (!dir) {
58    return -1;
59  }
60  int opendirfd = dirfd(dir);
61  int parse_errors = 0;
62  struct dirent *ent;
63  // Have to clear errno to distinguish readdir() completion from failure.
64  while (errno = 0, (ent = readdir(dir)) != NULL) {
65    if (strcmp(ent->d_name, ".") == 0 ||
66        strcmp(ent->d_name, "..") == 0) {
67      continue;
68    }
69    // We avoid atoi or strtol because those are part of libc and they involve
70    // locale stuff, which is probably not safe from a post-fork context in a
71    // multi-threaded app.
72    int fd = parse_fd(ent->d_name);
73    if (fd < 0) {
74      parse_errors = 1;
75      continue;
76    }
77    if (fd != opendirfd) {
78      (*func)(opaque, fd);
79    }
80  }
81  int saved_errno = errno;
82  if (closedir(dir) < 0) {
83    if (!saved_errno) {
84      // Return the closedir error.
85      return -1;
86    }
87    // Else ignore it because we have a more relevant error to return.
88  }
89  if (saved_errno) {
90    errno = saved_errno;
91    return -1;
92  } else if (parse_errors) {
93    errno = EBADF;
94    return -1;
95  } else {
96    return 0;
97  }
98}
99