Commit | Line | Data |
---|---|---|
c215a4bc IJ |
1 | /* |
2 | * This file is part of secnet. | |
3 | * See README for full list of copyright holders. | |
4 | * | |
5 | * secnet is free software; you can redistribute it and/or modify it | |
6 | * under the terms of the GNU General Public License as published by | |
7 | * the Free Software Foundation; either version d of the License, or | |
8 | * (at your option) any later version. | |
9 | * | |
10 | * secnet is distributed in the hope that it will be useful, but | |
11 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | * General Public License for more details. | |
14 | * | |
15 | * You should have received a copy of the GNU General Public License | |
16 | * version 3 along with secnet; if not, see | |
17 | * https://www.gnu.org/licenses/gpl.html. | |
18 | */ | |
19 | ||
baab3a63 | 20 | #define _GNU_SOURCE |
7138d0c5 SE |
21 | #include "secnet.h" |
22 | #include <unistd.h> | |
23 | #include <fcntl.h> | |
24 | #include <errno.h> | |
25 | #include <sys/wait.h> | |
baab3a63 | 26 | #include <string.h> |
7138d0c5 SE |
27 | #include "process.h" |
28 | ||
29 | /* Process handling - subprocesses, signals, etc. */ | |
30 | ||
31 | static bool_t signal_handling=False; | |
32 | static sigset_t emptyset, fullset; | |
33 | static sigset_t registered,pending; | |
34 | ||
35 | struct child { | |
36 | pid_t pid; | |
fe5e9cc4 | 37 | cstring_t desc; |
7138d0c5 SE |
38 | process_callback_fn *cb; |
39 | void *cst; | |
40 | bool_t finished; | |
41 | struct child *next; | |
42 | }; | |
43 | ||
44 | static struct child *children=NULL; | |
45 | ||
46 | struct signotify { | |
47 | int signum; | |
48 | signal_notify_fn *notify; | |
49 | void *cst; | |
50 | struct signotify *next; | |
51 | }; | |
52 | ||
53 | static struct signotify *sigs=NULL; | |
54 | ||
55 | static int spw,spr; /* file descriptors for signal notification pipe */ | |
56 | ||
7138d0c5 SE |
57 | /* Long-lived subprocesses can only be started once we've started |
58 | signal processing so that we can catch SIGCHLD for them and report | |
59 | their exit status using the callback function. We block SIGCHLD | |
60 | until signal processing has begun. */ | |
042a8da9 | 61 | pid_t makesubproc(process_entry_fn *entry, process_callback_fn *cb, |
fe5e9cc4 | 62 | void *est, void *cst, cstring_t desc) |
7138d0c5 SE |
63 | { |
64 | struct child *c; | |
7138d0c5 SE |
65 | pid_t p; |
66 | ||
b7886fd4 | 67 | NEW(c); |
7138d0c5 SE |
68 | c->desc=desc; |
69 | c->cb=cb; | |
70 | c->cst=cst; | |
71 | ||
72 | if (!signal_handling) { | |
4f5e39ec | 73 | fatal("makesubproc called before signal handling started"); |
7138d0c5 SE |
74 | } |
75 | p=fork(); | |
76 | if (p==0) { | |
77 | /* Child process */ | |
5e7a5e2d | 78 | afterfork(); |
7138d0c5 SE |
79 | entry(est); |
80 | abort(); | |
81 | } else if (p==-1) { | |
82 | fatal_perror("makesubproc (%s): fork",desc); | |
83 | } | |
84 | c->pid=p; | |
85 | c->finished=False; | |
86 | c->next=children; | |
87 | children=c; | |
042a8da9 | 88 | return p; |
7138d0c5 SE |
89 | } |
90 | ||
91 | static signal_notify_fn sigchld_handler; | |
92 | static void sigchld_handler(void *st, int signum) | |
93 | { | |
94 | struct child *i,*n,**p; | |
95 | struct work { | |
96 | pid_t pid; | |
97 | process_callback_fn *cb; | |
98 | void *cst; | |
99 | int status; | |
100 | struct work *next; | |
101 | }; | |
102 | struct work *w=NULL, *nw; | |
103 | pid_t rv; | |
104 | int status; | |
105 | ||
106 | for (i=children; i; i=i->next) { | |
107 | rv=waitpid(i->pid,&status,WNOHANG); | |
108 | if (rv==-1) { | |
109 | fatal_perror("sigchld_handler: waitpid"); | |
110 | } | |
111 | if (rv==i->pid) { | |
112 | i->finished=True; | |
113 | ||
b7886fd4 | 114 | NEW(nw); |
7138d0c5 SE |
115 | nw->pid=i->pid; |
116 | nw->cb=i->cb; | |
117 | nw->cst=i->cst; | |
118 | nw->status=status; | |
119 | nw->next=w; | |
120 | w=nw; | |
121 | } | |
122 | } | |
123 | ||
124 | /* Remove all the finished tasks from the list of children */ | |
125 | for (i=children, p=&children; i; i=n) { | |
126 | n=i->next; | |
127 | if (i->finished) { | |
128 | free(i); | |
129 | *p=n; | |
130 | } else { | |
131 | p=&i->next; | |
132 | } | |
133 | } | |
134 | ||
135 | /* Notify as appropriate, then free the list */ | |
136 | while (w) { | |
137 | w->cb(w->cst,w->pid,w->status); | |
138 | nw=w; | |
139 | w=w->next; | |
140 | free(nw); | |
141 | } | |
142 | } | |
143 | ||
fe5e9cc4 | 144 | int sys_cmd(const char *path, const char *arg, ...) |
7138d0c5 SE |
145 | { |
146 | va_list ap; | |
baab3a63 | 147 | int rv, rc; |
7138d0c5 SE |
148 | pid_t c; |
149 | ||
7138d0c5 SE |
150 | c=fork(); |
151 | if (c) { | |
152 | /* Parent -> wait for child */ | |
baab3a63 RK |
153 | do { |
154 | rc = waitpid(c,&rv,0); | |
155 | } while(rc < 0 && errno == EINTR); | |
156 | if (rc < 0) | |
157 | fatal_perror("sys_cmd: waitpid for %s", path); | |
158 | if (rc != c) /* OS has gone mad */ | |
159 | fatal("sys_cmd: waitpid for %s returned wrong process ID!", | |
160 | path); | |
161 | if (rv) { | |
4ac7fd3f IJ |
162 | /* If the command failed report its exit status */ |
163 | lg_exitstatus(0,"sys_cmd",0,M_ERR,rv,path); | |
baab3a63 | 164 | } |
7138d0c5 SE |
165 | } else if (c==0) { |
166 | char *args[100]; | |
167 | int i; | |
168 | /* Child -> exec command */ | |
fe5e9cc4 SE |
169 | /* Really we ought to strcpy() the arguments into the args array, |
170 | since the arguments are const char *. Since we'll exit anyway | |
171 | if the execvp() fails this seems somewhat pointless, and | |
172 | increases the chance of the child process failing before it | |
173 | gets to exec(). */ | |
5e7a5e2d | 174 | afterfork(); |
baab3a63 RK |
175 | va_start(ap,arg); |
176 | args[0]=(char *)arg; /* program name */ | |
7138d0c5 SE |
177 | i=1; |
178 | while ((args[i++]=va_arg(ap,char *))); | |
179 | execvp(path,args); | |
baab3a63 RK |
180 | fprintf(stderr, "sys_cmd(%s,%s,...): %s\n", path, arg, strerror(errno)); |
181 | _exit(1); | |
7138d0c5 SE |
182 | } else { |
183 | /* Error */ | |
baab3a63 | 184 | fatal_perror("sys_cmd(%s,%s,...)", path, arg); |
7138d0c5 SE |
185 | } |
186 | ||
7138d0c5 SE |
187 | return rv; |
188 | } | |
189 | ||
190 | static beforepoll_fn signal_beforepoll; | |
191 | static int signal_beforepoll(void *st, struct pollfd *fds, int *nfds_io, | |
90a39563 | 192 | int *timeout_io) |
7138d0c5 | 193 | { |
ee697dd9 | 194 | BEFOREPOLL_WANT_FDS(1); |
7138d0c5 SE |
195 | fds[0].fd=spr; |
196 | fds[0].events=POLLIN; | |
197 | return 0; | |
198 | } | |
199 | ||
5a8a7053 RK |
200 | /* Bodge to work around Ubuntu's strict header files */ |
201 | static void discard(int anything) {} | |
202 | ||
7138d0c5 | 203 | static afterpoll_fn signal_afterpoll; |
90a39563 | 204 | static void signal_afterpoll(void *st, struct pollfd *fds, int nfds) |
7138d0c5 SE |
205 | { |
206 | uint8_t buf[16]; | |
207 | struct signotify *n; | |
208 | sigset_t todo,old; | |
209 | ||
210 | if (nfds && (fds->revents & POLLIN)) { | |
5a8a7053 RK |
211 | discard(read(spr,buf,16)); |
212 | /* We don't actually care what we read; as | |
7138d0c5 SE |
213 | long as there was at least one byte |
214 | (which there was) we'll pick up the | |
215 | signals in the pending set */ | |
216 | ||
217 | /* We reset 'pending' before processing any of the signals | |
218 | that were pending so that we don't miss any signals that | |
219 | are delivered partway-through processing (all we assume | |
220 | about signal notification routines is that they handle all | |
221 | the work available at their _start_ and only optionally any | |
222 | work that arrives part-way through their execution). */ | |
223 | sigprocmask(SIG_SETMASK,&fullset,&old); | |
224 | todo=pending; | |
225 | sigemptyset(&pending); | |
226 | sigprocmask(SIG_SETMASK,&old,NULL); | |
227 | ||
228 | for (n=sigs; n; n=n->next) | |
229 | if (sigismember(&todo,n->signum)) | |
230 | n->notify(n->cst,n->signum); | |
231 | } | |
232 | } | |
233 | ||
5e7a5e2d | 234 | void afterfork(void) |
7138d0c5 SE |
235 | { |
236 | struct signotify *n; | |
237 | sigset_t done; | |
238 | struct sigaction sa; | |
239 | ||
c72aa743 IJ |
240 | clear_phase_hooks(PHASE_SHUTDOWN); |
241 | /* Prevents calls to fatal() etc. in the child from running off | |
242 | and doing a lot of unhelpful things */ | |
243 | ||
7138d0c5 SE |
244 | sigemptyset(&done); |
245 | for (n=sigs; n; n=n->next) | |
246 | if (!sigismember(&done,n->signum)) { | |
247 | sigaddset(&done,n->signum); | |
248 | sa.sa_handler=SIG_DFL; | |
249 | sa.sa_mask=emptyset; | |
250 | sa.sa_flags=0; | |
251 | sigaction(n->signum,&sa,NULL); | |
252 | } | |
5e7a5e2d IJ |
253 | |
254 | sigemptyset(&emptyset); | |
255 | sigprocmask(SIG_SETMASK,&emptyset,NULL); | |
7138d0c5 SE |
256 | } |
257 | ||
32654a31 IJ |
258 | void childpersist_closefd_hook(void *fd_vp, uint32_t newphase) |
259 | { | |
260 | int *fd_p=fd_vp; | |
261 | int fd=*fd_p; | |
262 | if (fd<0) return; | |
263 | *fd_p=-1; | |
264 | setnonblock(fd); /* in case close() might block */ | |
265 | close(fd); /* discard errors - we don't care, in the child */ | |
266 | } | |
267 | ||
7138d0c5 SE |
268 | static void signal_handler(int signum) |
269 | { | |
ff05a229 | 270 | int saved_errno; |
7138d0c5 SE |
271 | uint8_t thing=0; |
272 | sigaddset(&pending,signum); | |
ff05a229 SE |
273 | /* XXX the write() may set errno, which can make the main program fail. |
274 | However, signal handlers aren't allowed to modify anything which | |
275 | is not of type sig_atomic_t. The world is broken. */ | |
276 | /* I have decided to save and restore errno anyway; on most | |
277 | architectures on which secnet can run modifications to errno | |
278 | will be atomic, and it seems to be the lesser of the two | |
279 | evils. */ | |
280 | saved_errno=errno; | |
5a8a7053 RK |
281 | discard(write(spw,&thing,1)); |
282 | /* We don't care if this fails (i.e. the pipe | |
7138d0c5 SE |
283 | is full) because the service routine will |
284 | spot the pending signal anyway */ | |
ff05a229 | 285 | errno=saved_errno; |
7138d0c5 SE |
286 | } |
287 | ||
288 | static void register_signal_handler(struct signotify *s) | |
289 | { | |
290 | struct sigaction sa; | |
291 | int rv; | |
292 | ||
293 | if (!signal_handling) return; | |
294 | ||
295 | if (sigismember(®istered,s->signum)) return; | |
296 | sigaddset(®istered,s->signum); | |
297 | ||
298 | sa.sa_handler=signal_handler; | |
299 | sa.sa_mask=fullset; | |
300 | sa.sa_flags=0; | |
301 | rv=sigaction(s->signum,&sa,NULL); | |
302 | if (rv!=0) { | |
303 | fatal_perror("register_signal_handler: sigaction(%d)",s->signum); | |
304 | } | |
305 | } | |
306 | ||
307 | void request_signal_notification(int signum, signal_notify_fn *notify, | |
308 | void *cst) | |
309 | { | |
310 | struct signotify *s; | |
311 | sigset_t old; | |
312 | ||
b7886fd4 | 313 | NEW(s); |
7138d0c5 SE |
314 | s->signum=signum; |
315 | s->notify=notify; | |
316 | s->cst=cst; | |
317 | s->next=sigs; | |
318 | sigprocmask(SIG_SETMASK,&fullset,&old); | |
319 | sigs=s; | |
320 | register_signal_handler(s); | |
321 | sigprocmask(SIG_SETMASK,&old,NULL); | |
322 | } | |
323 | ||
324 | void start_signal_handling(void) | |
325 | { | |
326 | int p[2]; | |
327 | struct signotify *i; | |
328 | ||
329 | sigemptyset(&emptyset); | |
330 | sigfillset(&fullset); | |
331 | sigemptyset(®istered); | |
332 | sigemptyset(&pending); | |
333 | ||
6a06198c | 334 | pipe_cloexec(p); |
7138d0c5 SE |
335 | spw=p[1]; |
336 | spr=p[0]; | |
f54d5ada | 337 | setnonblock(spw); |
ba703386 | 338 | setnonblock(spr); |
7138d0c5 | 339 | |
32fc582f | 340 | register_for_poll(NULL,signal_beforepoll,signal_afterpoll,"signal"); |
7138d0c5 SE |
341 | signal_handling=True; |
342 | ||
343 | /* Register signal handlers for all the signals we're interested in */ | |
344 | for (i=sigs; i; i=i->next) { | |
345 | register_signal_handler(i); | |
346 | } | |
347 | ||
348 | request_signal_notification(SIGCHLD,sigchld_handler,NULL); | |
349 | } |