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1 | /* forkaftergrep (C) 2017 Tobias Girstmair, GPLv3 */ | |
2 | //TODO: if grep exits with an error, fag thinks a match was found (e.g. grep -BEP, killall grep) | |
3 | //TODO: allow redirect of both streams to files | |
4 | //TODO: grep is missing `-e' and `-f' options | |
5 | ||
6 | #define _XOPEN_SOURCE 500 | |
7 | #define _DEFAULT_SOURCE | |
8 | #include <errno.h> | |
9 | #include <fcntl.h> | |
10 | #include <signal.h> | |
11 | #include <stdio.h> | |
12 | #include <stdlib.h> | |
13 | #include <string.h> | |
14 | #include <sysexits.h> | |
15 | #include <sys/time.h> | |
16 | #include <sys/wait.h> | |
17 | #include <unistd.h> | |
18 | #include "fag.h" | |
19 | ||
20 | pid_t cpid = 0; | |
21 | ||
22 | void term_child(int s) { | |
23 | (void)s; /* squash -Werror=unused-parameter */ | |
24 | if (cpid != 0) kill (cpid, SIGTERM); | |
25 | exit(1); | |
26 | } | |
27 | ||
28 | int main (int argc, char** argv) { | |
29 | struct opt opts = {0, 0, 0, NULL, NULL, STDOUT_FILENO, "-q"}; | |
30 | /* `-q': don't print anything; exit with 0 on match; with 1 on error. used to interface with `grep' */ | |
31 | int opt; | |
32 | opterr = 0; | |
33 | ||
34 | /* generate grep options string */ | |
35 | char* p = opts.grepopt+2; /* move cursor behind `q' */ | |
36 | ||
37 | signal (SIGPIPE, SIG_IGN); /* ignore broken pipe between fag and grep */ | |
38 | struct sigaction sa = {0}; /* terminate child if fag gets interrupted/terminated */ | |
39 | sa.sa_handler = &term_child; /* NOTE: will also be inherited by keep-pipe-alive-child */ | |
40 | sigaction (SIGINT, &sa, NULL); | |
41 | sigaction (SIGTERM, &sa, NULL); | |
42 | ||
43 | ||
44 | /* the `+' forces getopt to stop at the first non-option */ | |
45 | while ((opt = getopt (argc, argv, "+t:k::er:VhvEFGPiwxyU")) != -1) { | |
46 | switch (opt) { | |
47 | case 't': | |
48 | opts.timeout = atoi (optarg); | |
49 | break; | |
50 | case 'k': | |
51 | opts.kill_sig = optarg ? atoi (optarg) : SIGTERM; | |
52 | break; | |
53 | case 'e': | |
54 | opts.stream = STDERR_FILENO; | |
55 | break; | |
56 | case 'V': | |
57 | opts.verbose = 1; | |
58 | break; | |
59 | case 'h': | |
60 | fprintf (stderr, VERTEXT USAGE | |
61 | "Options:\n" | |
62 | "\t-t N\ttimeout after N seconds\n" | |
63 | "\t-k[M]\tsend signal M to child after timeout (default: 15/SIGTERM)\n" | |
64 | "\t-e\tgrep on stderr instead of stdout\n" | |
65 | "\t-V\tbe verbose; print PROGRAM's stdout/stderr to stderr\n" | |
66 | "\t-[EFP]\tgrep: matcher selection\n" | |
67 | "\t-[iwxU]\tgrep: matching control\n", argv[0]); | |
68 | return EX_OK; | |
69 | case 'v': | |
70 | fprintf (stderr, VERTEXT); | |
71 | return EX_OK; | |
72 | /* `grep' options (Note: missing `-e:', `-f:') */ | |
73 | case 'E': case 'F': case 'G': case 'P': | |
74 | case 'i': case 'y': case 'w': case 'x': | |
75 | case 'U': *(p++)=opt; break; | |
76 | ||
77 | default: | |
78 | fprintf (stderr, "Unrecognized option: %c\n" USAGE, optopt, argv[0]); | |
79 | return EX_USAGE; | |
80 | } | |
81 | } | |
82 | *p = '\0'; /* terminate grep_options string */ | |
83 | ||
84 | /* the first non-option argument is the search string */ | |
85 | if (optind < argc) { | |
86 | opts.pattern = argv[optind++]; | |
87 | } else { | |
88 | fprintf (stderr, USAGE "(Missing PATTERN)\n", argv[0]); | |
89 | return EX_USAGE; | |
90 | } | |
91 | ||
92 | /* the remaining are the program to be run */ | |
93 | if (optind < argc) { | |
94 | opts.argv = &(argv[optind]); | |
95 | } else { | |
96 | fprintf (stderr, USAGE "(Missing PROGRAM)\n", argv[0]); | |
97 | return EX_USAGE; | |
98 | } | |
99 | ||
100 | int retval = fork_after_grep (opts); | |
101 | ||
102 | return retval; | |
103 | } | |
104 | ||
105 | int fork_after_grep (struct opt opts) { | |
106 | int pipefd[2]; | |
107 | //pid_t cpid; | |
108 | int status; | |
109 | ||
110 | char buf[BUF_SIZE]; | |
111 | int nbytes; | |
112 | ||
113 | struct timeval begin, now, diff; | |
114 | ||
115 | if (pipe(pipefd) == -1) { | |
116 | fprintf (stderr, "pipe error (userprog)\n"); | |
117 | return EX_OSERR; | |
118 | } | |
119 | ||
120 | if ((cpid = fork()) == -1) { | |
121 | fprintf (stderr, "fork error (userprog): %s", strerror (errno)); | |
122 | close (pipefd[0]); | |
123 | close (pipefd[1]); | |
124 | return EX_OSERR; | |
125 | } | |
126 | ||
127 | if (cpid == 0) { | |
128 | close (pipefd[0]); | |
129 | dup2 (pipefd[1], opts.stream); | |
130 | close (pipefd[1]); | |
131 | //dup2 (open("/dev/null", O_WRONLY), opts.stream==STDOUT_FILENO?STDERR_FILENO:STDOUT_FILENO); | |
132 | close (opts.stream==STDOUT_FILENO?STDERR_FILENO:STDOUT_FILENO); | |
133 | ||
134 | if (setsid () == -1) { | |
135 | fprintf (stderr, "setsid error (userprog): %s", strerror (errno)); | |
136 | _exit (EX_OSERR); | |
137 | } | |
138 | ||
139 | execvp (opts.argv[0], opts.argv); | |
140 | fprintf (stderr, "exec error (userprog): %s", strerror (errno)); | |
141 | _exit (EX_UNAVAILABLE); | |
142 | } else { | |
143 | pid_t grep_cpid; | |
144 | int grep_pipefd[2]; | |
145 | int grep_status; | |
146 | ||
147 | close (pipefd[1]); | |
148 | fcntl (pipefd[0], F_SETFL, fcntl (pipefd[0], F_GETFL, 0) | O_NONBLOCK); | |
149 | ||
150 | gettimeofday (&begin, NULL); /* for timeout */ | |
151 | ||
152 | if (pipe(grep_pipefd) == -1) { | |
153 | fprintf (stderr, "pipe error (grep)\n"); | |
154 | close (pipefd[0]); | |
155 | return EX_OSERR; | |
156 | } | |
157 | ||
158 | if ((grep_cpid = fork()) == -1) { | |
159 | fprintf (stderr, "fork error (grep): %s", strerror (errno)); | |
160 | close (pipefd[0]); | |
161 | close (grep_pipefd[0]); | |
162 | close (grep_pipefd[1]); | |
163 | return EX_OSERR; | |
164 | } | |
165 | ||
166 | if (grep_cpid == 0) { | |
167 | close (grep_pipefd[1]); | |
168 | dup2 (grep_pipefd[0], STDIN_FILENO); | |
169 | close (grep_pipefd[0]); | |
170 | ||
171 | close (STDOUT_FILENO); | |
172 | ||
173 | execlp ("grep", "grep", opts.grepopt, "--", opts.pattern, NULL); | |
174 | fprintf (stderr, "exec error (grep): %s", strerror (errno)); | |
175 | _exit (EX_SOFTWARE); | |
176 | } else { | |
177 | close (grep_pipefd[0]); | |
178 | for (;;) { | |
179 | usleep (20000); | |
180 | nbytes = read (pipefd[0], buf, BUF_SIZE); | |
181 | if (nbytes == -1) { | |
182 | switch (errno) { | |
183 | case EAGAIN: | |
184 | break; | |
185 | default: | |
186 | fprintf (stderr, "read error (userprog): %s", strerror (errno)); | |
187 | close (pipefd[0]); | |
188 | close (grep_pipefd[1]); | |
189 | kill (grep_cpid, SIGTERM); | |
190 | return EX_IOERR; | |
191 | } | |
192 | } else if (nbytes == 0) { | |
193 | fprintf (stderr, "Child program exited prematurely (userprog).\n"); | |
194 | close (pipefd[0]); | |
195 | close (grep_pipefd[1]); | |
196 | kill (grep_cpid, SIGTERM); | |
197 | if (waitpid (cpid, &status, WNOHANG) > 0 && WIFEXITED (status)) { | |
198 | return WEXITSTATUS (status); | |
199 | } | |
200 | return EX_UNAVAILABLE; | |
201 | } else { | |
202 | /* have new userprog-data, send it to grep */ | |
203 | if (opts.verbose) { | |
204 | write(STDERR_FILENO, buf, nbytes); | |
205 | } | |
206 | ||
207 | write(grep_pipefd[1], buf, nbytes); /* can cause SIGPIPE if grep exited, therefore signal will be ignored */ | |
208 | } | |
209 | ||
210 | if (waitpid (grep_cpid, &grep_status, WNOHANG) > 0 && WIFEXITED (grep_status)) { | |
211 | close (grep_pipefd[1]); | |
212 | ||
213 | if (WEXITSTATUS(grep_status) == 0) { | |
214 | /* grep exited with match found */ | |
215 | printf ("%d\n", cpid); | |
216 | ||
217 | /* create a new child to keep pipe alive (will exit with exec'd program) */ | |
218 | if (!fork ()) { | |
219 | int devnull = open("/dev/null", O_WRONLY); | |
220 | dup2 (devnull, pipefd[0]); | |
221 | close (devnull); | |
222 | while (kill(cpid, 0) != -1 && errno != ESRCH ) sleep (1); | |
223 | close (pipefd[0]); | |
224 | _exit(0); | |
225 | } | |
226 | close (pipefd[0]); | |
227 | return EX_OK; | |
228 | } else { | |
229 | /* grep exited due to an error */ | |
230 | fprintf (stderr, "grep exited due to an error.\n"); | |
231 | close (pipefd[0]); | |
232 | close (grep_pipefd[1]); | |
233 | return EX_IOERR; | |
234 | } | |
235 | } | |
236 | ||
237 | if (opts.timeout > 0) { | |
238 | gettimeofday (&now, NULL); | |
239 | timersub (&now, &begin, &diff); | |
240 | if (diff.tv_sec >= opts.timeout) { | |
241 | fprintf (stderr, "Timeout reached. \n"); | |
242 | if (opts.kill_sig > 0) kill (cpid, opts.kill_sig); | |
243 | close (pipefd[0]); | |
244 | close (grep_pipefd[1]); | |
245 | kill (grep_cpid, SIGTERM); | |
246 | return EX_UNAVAILABLE; | |
247 | } | |
248 | } | |
249 | } | |
250 | } | |
251 | } | |
252 | } |