Mercurial > hg
annotate contrib/chg/procutil.c @ 31230:cc37b5a06e32
chg: forward user-defined signals
SIGUSR1 and SIGUSR2 are reserved for user-defined behaviors. They may be
redefined by an hg extension [1], but cannot be easily redefined for chg.
Since the default behavior (kill) is not that useful for chg, let's forward
them to hg, hoping it got redefined there and could be more useful.
[1] https://bitbucket.org/facebook/hg-experimental/commits/e7c883a465
author | Jun Wu <quark@fb.com> |
---|---|
date | Wed, 08 Mar 2017 13:46:26 -0800 |
parents | 68c94f286e25 |
children | ac5527021097 |
rev | line source |
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28060 | 1 /* |
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2 * Utilities about process handling - signal and subprocess (ex. pager) |
28060 | 3 * |
4 * Copyright (c) 2011 Yuya Nishihara <yuya@tcha.org> | |
5 * | |
6 * This software may be used and distributed according to the terms of the | |
7 * GNU General Public License version 2 or any later version. | |
8 */ | |
9 | |
30693 | 10 #include <assert.h> |
11 #include <errno.h> | |
12 #include <signal.h> | |
13 #include <stdio.h> | |
14 #include <string.h> | |
15 #include <sys/wait.h> | |
16 #include <unistd.h> | |
17 | |
18 #include "procutil.h" | |
19 #include "util.h" | |
20 | |
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21 static pid_t pagerpid = 0; |
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22 static pid_t peerpgid = 0; |
28060 | 23 static pid_t peerpid = 0; |
24 | |
25 static void forwardsignal(int sig) | |
26 { | |
27 assert(peerpid > 0); | |
28 if (kill(peerpid, sig) < 0) | |
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29 abortmsgerrno("cannot kill %d", peerpid); |
28060 | 30 debugmsg("forward signal %d", sig); |
31 } | |
32 | |
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33 static void forwardsignaltogroup(int sig) |
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34 { |
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35 /* prefer kill(-pgid, sig), fallback to pid if pgid is invalid */ |
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36 pid_t killpid = peerpgid > 1 ? -peerpgid : peerpid; |
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37 if (kill(killpid, sig) < 0) |
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38 abortmsgerrno("cannot kill %d", killpid); |
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39 debugmsg("forward signal %d to %d", sig, killpid); |
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40 } |
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41 |
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42 static void handlestopsignal(int sig) |
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43 { |
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44 sigset_t unblockset, oldset; |
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45 struct sigaction sa, oldsa; |
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46 if (sigemptyset(&unblockset) < 0) |
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47 goto error; |
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48 if (sigaddset(&unblockset, sig) < 0) |
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49 goto error; |
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50 memset(&sa, 0, sizeof(sa)); |
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51 sa.sa_handler = SIG_DFL; |
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52 sa.sa_flags = SA_RESTART; |
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53 if (sigemptyset(&sa.sa_mask) < 0) |
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54 goto error; |
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55 |
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56 forwardsignal(sig); |
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57 if (raise(sig) < 0) /* resend to self */ |
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58 goto error; |
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59 if (sigaction(sig, &sa, &oldsa) < 0) |
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60 goto error; |
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61 if (sigprocmask(SIG_UNBLOCK, &unblockset, &oldset) < 0) |
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62 goto error; |
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63 /* resent signal will be handled before sigprocmask() returns */ |
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64 if (sigprocmask(SIG_SETMASK, &oldset, NULL) < 0) |
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65 goto error; |
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66 if (sigaction(sig, &oldsa, NULL) < 0) |
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67 goto error; |
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68 return; |
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69 |
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70 error: |
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71 abortmsgerrno("failed to handle stop signal"); |
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72 } |
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73 |
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74 static void handlechildsignal(int sig UNUSED_) |
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75 { |
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76 if (peerpid == 0 || pagerpid == 0) |
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77 return; |
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78 /* if pager exits, notify the server with SIGPIPE immediately. |
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79 * otherwise the server won't get SIGPIPE if it does not write |
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80 * anything. (issue5278) */ |
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81 if (waitpid(pagerpid, NULL, WNOHANG) == pagerpid) |
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82 kill(peerpid, SIGPIPE); |
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83 } |
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84 |
30693 | 85 void setupsignalhandler(pid_t pid, pid_t pgid) |
28060 | 86 { |
87 if (pid <= 0) | |
88 return; | |
89 peerpid = pid; | |
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90 peerpgid = (pgid <= 1 ? 0 : pgid); |
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91 |
28060 | 92 struct sigaction sa; |
93 memset(&sa, 0, sizeof(sa)); | |
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94 |
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95 /* deadly signals meant to be sent to a process group: |
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96 * - SIGHUP: usually generated by the kernel, when termination of a |
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97 * process causes that process group to become orphaned |
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98 * - SIGINT: usually generated by the terminal */ |
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99 sa.sa_handler = forwardsignaltogroup; |
28060 | 100 sa.sa_flags = SA_RESTART; |
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101 if (sigemptyset(&sa.sa_mask) < 0) |
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102 goto error; |
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103 if (sigaction(SIGHUP, &sa, NULL) < 0) |
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104 goto error; |
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105 if (sigaction(SIGINT, &sa, NULL) < 0) |
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106 goto error; |
28060 | 107 |
108 /* terminate frontend by double SIGTERM in case of server freeze */ | |
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109 sa.sa_handler = forwardsignal; |
28060 | 110 sa.sa_flags |= SA_RESETHAND; |
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111 if (sigaction(SIGTERM, &sa, NULL) < 0) |
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112 goto error; |
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113 |
28980 | 114 /* notify the worker about window resize events */ |
115 sa.sa_flags = SA_RESTART; | |
116 if (sigaction(SIGWINCH, &sa, NULL) < 0) | |
117 goto error; | |
31230 | 118 /* forward user-defined signals */ |
119 if (sigaction(SIGUSR1, &sa, NULL) < 0) | |
120 goto error; | |
121 if (sigaction(SIGUSR2, &sa, NULL) < 0) | |
122 goto error; | |
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123 /* propagate job control requests to worker */ |
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124 sa.sa_handler = forwardsignal; |
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125 sa.sa_flags = SA_RESTART; |
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126 if (sigaction(SIGCONT, &sa, NULL) < 0) |
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127 goto error; |
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128 sa.sa_handler = handlestopsignal; |
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129 sa.sa_flags = SA_RESTART; |
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130 if (sigaction(SIGTSTP, &sa, NULL) < 0) |
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131 goto error; |
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132 /* get notified when pager exits */ |
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133 sa.sa_handler = handlechildsignal; |
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134 sa.sa_flags = SA_RESTART; |
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135 if (sigaction(SIGCHLD, &sa, NULL) < 0) |
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136 goto error; |
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137 |
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138 return; |
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139 |
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140 error: |
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141 abortmsgerrno("failed to set up signal handlers"); |
28060 | 142 } |
143 | |
30693 | 144 void restoresignalhandler(void) |
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145 { |
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146 struct sigaction sa; |
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147 memset(&sa, 0, sizeof(sa)); |
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148 sa.sa_handler = SIG_DFL; |
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149 sa.sa_flags = SA_RESTART; |
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150 if (sigemptyset(&sa.sa_mask) < 0) |
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151 goto error; |
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152 |
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153 if (sigaction(SIGHUP, &sa, NULL) < 0) |
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154 goto error; |
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155 if (sigaction(SIGTERM, &sa, NULL) < 0) |
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156 goto error; |
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157 if (sigaction(SIGWINCH, &sa, NULL) < 0) |
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158 goto error; |
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159 if (sigaction(SIGCONT, &sa, NULL) < 0) |
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160 goto error; |
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161 if (sigaction(SIGTSTP, &sa, NULL) < 0) |
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162 goto error; |
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163 if (sigaction(SIGCHLD, &sa, NULL) < 0) |
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164 goto error; |
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165 |
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166 /* ignore Ctrl+C while shutting down to make pager exits cleanly */ |
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167 sa.sa_handler = SIG_IGN; |
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168 if (sigaction(SIGINT, &sa, NULL) < 0) |
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169 goto error; |
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170 |
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171 peerpid = 0; |
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172 return; |
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173 |
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174 error: |
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175 abortmsgerrno("failed to restore signal handlers"); |
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176 } |
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177 |
29344 | 178 /* This implementation is based on hgext/pager.py (post 369741ef7253) |
179 * Return 0 if pager is not started, or pid of the pager */ | |
30693 | 180 pid_t setuppager(const char *pagercmd) |
28060 | 181 { |
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182 assert(pagerpid == 0); |
28060 | 183 if (!pagercmd) |
29344 | 184 return 0; |
28060 | 185 |
186 int pipefds[2]; | |
187 if (pipe(pipefds) < 0) | |
29344 | 188 return 0; |
28060 | 189 pid_t pid = fork(); |
190 if (pid < 0) | |
191 goto error; | |
29344 | 192 if (pid > 0) { |
28060 | 193 close(pipefds[0]); |
194 if (dup2(pipefds[1], fileno(stdout)) < 0) | |
195 goto error; | |
196 if (isatty(fileno(stderr))) { | |
197 if (dup2(pipefds[1], fileno(stderr)) < 0) | |
198 goto error; | |
199 } | |
200 close(pipefds[1]); | |
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201 pagerpid = pid; |
29344 | 202 return pid; |
28060 | 203 } else { |
204 dup2(pipefds[0], fileno(stdin)); | |
205 close(pipefds[0]); | |
206 close(pipefds[1]); | |
207 | |
208 int r = execlp("/bin/sh", "/bin/sh", "-c", pagercmd, NULL); | |
209 if (r < 0) { | |
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210 abortmsgerrno("cannot start pager '%s'", pagercmd); |
28060 | 211 } |
29344 | 212 return 0; |
28060 | 213 } |
214 | |
215 error: | |
216 close(pipefds[0]); | |
217 close(pipefds[1]); | |
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218 abortmsgerrno("failed to prepare pager"); |
29344 | 219 return 0; |
220 } | |
221 | |
30693 | 222 void waitpager(void) |
29344 | 223 { |
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224 if (pagerpid == 0) |
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225 return; |
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226 |
29344 | 227 /* close output streams to notify the pager its input ends */ |
228 fclose(stdout); | |
229 fclose(stderr); | |
230 while (1) { | |
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231 pid_t ret = waitpid(pagerpid, NULL, 0); |
29344 | 232 if (ret == -1 && errno == EINTR) |
233 continue; | |
234 break; | |
235 } | |
28060 | 236 } |