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