1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
|
/*
* Copyright 2004 The WebRTC Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "webrtc/base/posix.h"
#include <sys/wait.h>
#include <errno.h>
#include <unistd.h>
#if defined(WEBRTC_LINUX) && !defined(WEBRTC_ANDROID)
#include "webrtc/base/linuxfdwalk.h"
#endif
#include "webrtc/base/logging.h"
namespace rtc {
#if defined(WEBRTC_LINUX) && !defined(WEBRTC_ANDROID)
static void closefds(void *close_errors, int fd) {
if (fd <= 2) {
// We leave stdin/out/err open to the browser's terminal, if any.
return;
}
if (close(fd) < 0) {
*static_cast<bool *>(close_errors) = true;
}
}
#endif
enum {
EXIT_FLAG_CHDIR_ERRORS = 1 << 0,
#if defined(WEBRTC_LINUX) && !defined(WEBRTC_ANDROID)
EXIT_FLAG_FDWALK_ERRORS = 1 << 1,
EXIT_FLAG_CLOSE_ERRORS = 1 << 2,
#endif
EXIT_FLAG_SECOND_FORK_FAILED = 1 << 3,
};
bool RunAsDaemon(const char *file, const char *const argv[]) {
// Fork intermediate child to daemonize.
pid_t pid = fork();
if (pid < 0) {
LOG_ERR(LS_ERROR) << "fork()";
return false;
} else if (!pid) {
// Child.
// We try to close all fds and change directory to /, but if that fails we
// keep going because it's not critical.
int exit_code = 0;
if (chdir("/") < 0) {
exit_code |= EXIT_FLAG_CHDIR_ERRORS;
}
#if defined(WEBRTC_LINUX) && !defined(WEBRTC_ANDROID)
bool close_errors = false;
if (fdwalk(&closefds, &close_errors) < 0) {
exit_code |= EXIT_FLAG_FDWALK_ERRORS;
}
if (close_errors) {
exit_code |= EXIT_FLAG_CLOSE_ERRORS;
}
#endif
// Fork again to become a daemon.
pid = fork();
// It is important that everything here use _exit() and not exit(), because
// exit() would call the destructors of all global variables in the whole
// process, which is both unnecessary and unsafe.
if (pid < 0) {
exit_code |= EXIT_FLAG_SECOND_FORK_FAILED;
_exit(exit_code); // if second fork failed
} else if (!pid) {
// Child.
// Successfully daemonized. Run command.
// WEBRTC_POSIX requires the args to be typed as non-const for historical
// reasons, but it mandates that the actual implementation be const, so
// the cast is safe.
execvp(file, const_cast<char *const *>(argv));
_exit(255); // if execvp failed
}
// Parent.
// Successfully spawned process, but report any problems to the parent where
// we can log them.
_exit(exit_code);
}
// Parent. Reap intermediate child.
int status;
pid_t child = waitpid(pid, &status, 0);
if (child < 0) {
LOG_ERR(LS_ERROR) << "Error in waitpid()";
return false;
}
if (child != pid) {
// Should never happen (see man page).
LOG(LS_ERROR) << "waitpid() chose wrong child???";
return false;
}
if (!WIFEXITED(status)) {
LOG(LS_ERROR) << "Intermediate child killed uncleanly"; // Probably crashed
return false;
}
int exit_code = WEXITSTATUS(status);
if (exit_code & EXIT_FLAG_CHDIR_ERRORS) {
LOG(LS_WARNING) << "Child reported probles calling chdir()";
}
#if defined(WEBRTC_LINUX) && !defined(WEBRTC_ANDROID)
if (exit_code & EXIT_FLAG_FDWALK_ERRORS) {
LOG(LS_WARNING) << "Child reported problems calling fdwalk()";
}
if (exit_code & EXIT_FLAG_CLOSE_ERRORS) {
LOG(LS_WARNING) << "Child reported problems calling close()";
}
#endif
if (exit_code & EXIT_FLAG_SECOND_FORK_FAILED) {
LOG(LS_ERROR) << "Failed to daemonize";
// This means the command was not launched, so failure.
return false;
}
return true;
}
} // namespace rtc
|
