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git.proxmox.com Git - ceph.git/blob - ceph/src/common/Preforker.h
1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
2 // vim: ts=8 sw=2 smarttab
3 #ifndef CEPH_COMMON_PREFORKER_H
4 #define CEPH_COMMON_PREFORKER_H
6 #include <sys/socket.h>
11 #include "include/assert.h"
12 #include "common/safe_io.h"
13 #include "common/errno.h"
16 * pre-fork fork/daemonize helper class
18 * Hide the details of letting a process fork early, do a bunch of
19 * initialization work that may spam stdout or exit with an error, and
20 * then daemonize. The exit() method will either exit directly (if we
21 * haven't forked) or pass a message to the parent with the error if
27 int fd
[2]; // parent's, child's
35 int prefork(std::string
&err
) {
37 int r
= ::socketpair(AF_UNIX
, SOCK_STREAM
, 0, fd
);
38 std::ostringstream oss
;
40 oss
<< "[" << getpid() << "]: unable to create socketpair: " << cpp_strerror(errno
);
50 oss
<< "[" << getpid() << "]: unable to fork: " << cpp_strerror(errno
);
62 int get_signal_fd() const {
63 return forked
? fd
[1] : 0;
74 int parent_wait(std::string
&err_msg
) {
78 std::ostringstream oss
;
79 int err
= safe_read_exact(fd
[0], &r
, sizeof(r
));
80 if (err
== 0 && r
== -1) {
87 oss
<< "[" << getpid() << "]: " << cpp_strerror(err
);
89 // wait for child to exit
91 err
= waitpid(childpid
, &status
, 0);
93 oss
<< "[" << getpid() << "]" << " waitpid error: " << cpp_strerror(err
);
94 } else if (WIFSIGNALED(status
)) {
95 oss
<< "[" << getpid() << "]" << " exited with a signal";
96 } else if (!WIFEXITED(status
)) {
97 oss
<< "[" << getpid() << "]" << " did not exit normally";
99 err
= WEXITSTATUS(status
);
101 oss
<< "[" << getpid() << "]" << " returned exit_status " << cpp_strerror(err
);
108 int signal_exit(int r
) {
110 /* If we get an error here, it's too late to do anything reasonable about it. */
111 (void)safe_write(fd
[1], &r
, sizeof(r
));
124 int r2
= ::write(fd
[1], &r
, sizeof(r
));
125 r
+= r2
; // make the compiler shut up about the unused return code from ::write(2).