Commit | Line | Data |
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7138d0c5 SE |
1 | #include "secnet.h" |
2 | #include <unistd.h> | |
3 | #include <fcntl.h> | |
4 | #include <errno.h> | |
5 | #include <sys/wait.h> | |
6 | #include "process.h" | |
7 | ||
8 | /* Process handling - subprocesses, signals, etc. */ | |
9 | ||
10 | static bool_t signal_handling=False; | |
11 | static sigset_t emptyset, fullset; | |
12 | static sigset_t registered,pending; | |
13 | ||
14 | struct child { | |
15 | pid_t pid; | |
16 | string_t desc; | |
17 | process_callback_fn *cb; | |
18 | void *cst; | |
19 | bool_t finished; | |
20 | struct child *next; | |
21 | }; | |
22 | ||
23 | static struct child *children=NULL; | |
24 | ||
25 | struct signotify { | |
26 | int signum; | |
27 | signal_notify_fn *notify; | |
28 | void *cst; | |
29 | struct signotify *next; | |
30 | }; | |
31 | ||
32 | static struct signotify *sigs=NULL; | |
33 | ||
34 | static int spw,spr; /* file descriptors for signal notification pipe */ | |
35 | ||
36 | static void set_default_signals(void); | |
37 | ||
38 | /* Long-lived subprocesses can only be started once we've started | |
39 | signal processing so that we can catch SIGCHLD for them and report | |
40 | their exit status using the callback function. We block SIGCHLD | |
41 | until signal processing has begun. */ | |
042a8da9 SE |
42 | pid_t makesubproc(process_entry_fn *entry, process_callback_fn *cb, |
43 | void *est, void *cst, string_t desc) | |
7138d0c5 SE |
44 | { |
45 | struct child *c; | |
7138d0c5 SE |
46 | pid_t p; |
47 | ||
48 | c=safe_malloc(sizeof(*c),"makesubproc"); | |
49 | c->desc=desc; | |
50 | c->cb=cb; | |
51 | c->cst=cst; | |
52 | ||
53 | if (!signal_handling) { | |
042a8da9 | 54 | fatal("makesubproc called before signal handling started\n"); |
7138d0c5 SE |
55 | } |
56 | p=fork(); | |
57 | if (p==0) { | |
58 | /* Child process */ | |
59 | set_default_signals(); | |
60 | sigprocmask(SIG_SETMASK,&emptyset,NULL); | |
61 | entry(est); | |
62 | abort(); | |
63 | } else if (p==-1) { | |
64 | fatal_perror("makesubproc (%s): fork",desc); | |
65 | } | |
66 | c->pid=p; | |
67 | c->finished=False; | |
68 | c->next=children; | |
69 | children=c; | |
042a8da9 | 70 | return p; |
7138d0c5 SE |
71 | } |
72 | ||
73 | static signal_notify_fn sigchld_handler; | |
74 | static void sigchld_handler(void *st, int signum) | |
75 | { | |
76 | struct child *i,*n,**p; | |
77 | struct work { | |
78 | pid_t pid; | |
79 | process_callback_fn *cb; | |
80 | void *cst; | |
81 | int status; | |
82 | struct work *next; | |
83 | }; | |
84 | struct work *w=NULL, *nw; | |
85 | pid_t rv; | |
86 | int status; | |
87 | ||
88 | for (i=children; i; i=i->next) { | |
89 | rv=waitpid(i->pid,&status,WNOHANG); | |
90 | if (rv==-1) { | |
91 | fatal_perror("sigchld_handler: waitpid"); | |
92 | } | |
93 | if (rv==i->pid) { | |
94 | i->finished=True; | |
95 | ||
96 | nw=safe_malloc(sizeof(*nw),"sigchld_handler"); | |
97 | nw->pid=i->pid; | |
98 | nw->cb=i->cb; | |
99 | nw->cst=i->cst; | |
100 | nw->status=status; | |
101 | nw->next=w; | |
102 | w=nw; | |
103 | } | |
104 | } | |
105 | ||
106 | /* Remove all the finished tasks from the list of children */ | |
107 | for (i=children, p=&children; i; i=n) { | |
108 | n=i->next; | |
109 | if (i->finished) { | |
110 | free(i); | |
111 | *p=n; | |
112 | } else { | |
113 | p=&i->next; | |
114 | } | |
115 | } | |
116 | ||
117 | /* Notify as appropriate, then free the list */ | |
118 | while (w) { | |
119 | w->cb(w->cst,w->pid,w->status); | |
120 | nw=w; | |
121 | w=w->next; | |
122 | free(nw); | |
123 | } | |
124 | } | |
125 | ||
126 | int sys_cmd(const char *path, char *arg, ...) | |
127 | { | |
128 | va_list ap; | |
129 | int rv; | |
130 | pid_t c; | |
131 | ||
132 | va_start(ap,arg); | |
133 | c=fork(); | |
134 | if (c) { | |
135 | /* Parent -> wait for child */ | |
136 | waitpid(c,&rv,0); | |
137 | } else if (c==0) { | |
138 | char *args[100]; | |
139 | int i; | |
140 | /* Child -> exec command */ | |
141 | args[0]=arg; | |
142 | i=1; | |
143 | while ((args[i++]=va_arg(ap,char *))); | |
144 | execvp(path,args); | |
145 | exit(1); | |
146 | } else { | |
147 | /* Error */ | |
148 | fatal_perror("sys_cmd(%s,%s,...)"); | |
149 | } | |
150 | ||
151 | va_end(ap); | |
152 | return rv; | |
153 | } | |
154 | ||
155 | static beforepoll_fn signal_beforepoll; | |
156 | static int signal_beforepoll(void *st, struct pollfd *fds, int *nfds_io, | |
157 | int *timeout_io, const struct timeval *tv_now, | |
158 | uint64_t *now) | |
159 | { | |
160 | if (*nfds_io<1) { | |
161 | *nfds_io=1; | |
162 | return ERANGE; | |
163 | } | |
164 | *nfds_io=1; | |
165 | fds[0].fd=spr; | |
166 | fds[0].events=POLLIN; | |
167 | return 0; | |
168 | } | |
169 | ||
170 | static afterpoll_fn signal_afterpoll; | |
171 | static void signal_afterpoll(void *st, struct pollfd *fds, int nfds, | |
172 | const struct timeval *tv, uint64_t *now) | |
173 | { | |
174 | uint8_t buf[16]; | |
175 | struct signotify *n; | |
176 | sigset_t todo,old; | |
177 | ||
178 | if (nfds && (fds->revents & POLLIN)) { | |
179 | read(spr,buf,16); /* We don't actually care what we read; as | |
180 | long as there was at least one byte | |
181 | (which there was) we'll pick up the | |
182 | signals in the pending set */ | |
183 | ||
184 | /* We reset 'pending' before processing any of the signals | |
185 | that were pending so that we don't miss any signals that | |
186 | are delivered partway-through processing (all we assume | |
187 | about signal notification routines is that they handle all | |
188 | the work available at their _start_ and only optionally any | |
189 | work that arrives part-way through their execution). */ | |
190 | sigprocmask(SIG_SETMASK,&fullset,&old); | |
191 | todo=pending; | |
192 | sigemptyset(&pending); | |
193 | sigprocmask(SIG_SETMASK,&old,NULL); | |
194 | ||
195 | for (n=sigs; n; n=n->next) | |
196 | if (sigismember(&todo,n->signum)) | |
197 | n->notify(n->cst,n->signum); | |
198 | } | |
199 | } | |
200 | ||
201 | static void set_default_signals(void) | |
202 | { | |
203 | struct signotify *n; | |
204 | sigset_t done; | |
205 | struct sigaction sa; | |
206 | ||
207 | sigemptyset(&done); | |
208 | for (n=sigs; n; n=n->next) | |
209 | if (!sigismember(&done,n->signum)) { | |
210 | sigaddset(&done,n->signum); | |
211 | sa.sa_handler=SIG_DFL; | |
212 | sa.sa_mask=emptyset; | |
213 | sa.sa_flags=0; | |
214 | sigaction(n->signum,&sa,NULL); | |
215 | } | |
216 | } | |
217 | ||
218 | static void signal_handler(int signum) | |
219 | { | |
220 | uint8_t thing=0; | |
221 | sigaddset(&pending,signum); | |
222 | write(spw,&thing,1); /* We don't care if this fails (i.e. the pipe | |
223 | is full) because the service routine will | |
224 | spot the pending signal anyway */ | |
225 | } | |
226 | ||
227 | static void register_signal_handler(struct signotify *s) | |
228 | { | |
229 | struct sigaction sa; | |
230 | int rv; | |
231 | ||
232 | if (!signal_handling) return; | |
233 | ||
234 | if (sigismember(®istered,s->signum)) return; | |
235 | sigaddset(®istered,s->signum); | |
236 | ||
237 | sa.sa_handler=signal_handler; | |
238 | sa.sa_mask=fullset; | |
239 | sa.sa_flags=0; | |
240 | rv=sigaction(s->signum,&sa,NULL); | |
241 | if (rv!=0) { | |
242 | fatal_perror("register_signal_handler: sigaction(%d)",s->signum); | |
243 | } | |
244 | } | |
245 | ||
246 | void request_signal_notification(int signum, signal_notify_fn *notify, | |
247 | void *cst) | |
248 | { | |
249 | struct signotify *s; | |
250 | sigset_t old; | |
251 | ||
252 | s=safe_malloc(sizeof(*s),"request_signal_notification"); | |
253 | s->signum=signum; | |
254 | s->notify=notify; | |
255 | s->cst=cst; | |
256 | s->next=sigs; | |
257 | sigprocmask(SIG_SETMASK,&fullset,&old); | |
258 | sigs=s; | |
259 | register_signal_handler(s); | |
260 | sigprocmask(SIG_SETMASK,&old,NULL); | |
261 | } | |
262 | ||
263 | void start_signal_handling(void) | |
264 | { | |
265 | int p[2]; | |
266 | struct signotify *i; | |
267 | ||
268 | sigemptyset(&emptyset); | |
269 | sigfillset(&fullset); | |
270 | sigemptyset(®istered); | |
271 | sigemptyset(&pending); | |
272 | ||
273 | if (pipe(p)!=0) { | |
274 | fatal_perror("start_signal_handling: pipe"); | |
275 | } | |
276 | spw=p[1]; | |
277 | spr=p[0]; | |
278 | if (fcntl(spw, F_SETFL, fcntl(spw, F_GETFL)|O_NONBLOCK)==-1) { | |
279 | fatal_perror("start_signal_handling: fcntl(O_NONBLOCK)"); | |
280 | } | |
281 | ||
282 | register_for_poll(NULL,signal_beforepoll,signal_afterpoll,1,"signal"); | |
283 | signal_handling=True; | |
284 | ||
285 | /* Register signal handlers for all the signals we're interested in */ | |
286 | for (i=sigs; i; i=i->next) { | |
287 | register_signal_handler(i); | |
288 | } | |
289 | ||
290 | request_signal_notification(SIGCHLD,sigchld_handler,NULL); | |
291 | } |