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1 | /* forkaftergrep (C) 2017 Tobias Girstmair, GPLv3 */ | |
2 | //TODO: supply user arguments to grep | |
3 | //demo: ./fag -e -V "MPD server running at" mopidy | |
4 | ||
5 | #define _XOPEN_SOURCE 500 | |
6 | #define _DEFAULT_SOURCE | |
7 | #include <errno.h> | |
8 | #include <fcntl.h> | |
9 | #include <stdio.h> | |
10 | #include <stdlib.h> | |
11 | #include <string.h> | |
12 | #include <sysexits.h> | |
13 | #include <sys/time.h> | |
14 | #include <sys/wait.h> | |
15 | #include <unistd.h> | |
16 | #include "fag.h" | |
17 | ||
18 | struct opt opts = {0, 0, 0, NULL, NULL, STDOUT_FILENO}; | |
19 | ||
20 | int main (int argc, char** argv) { | |
21 | int opt; | |
22 | opterr = 0; | |
23 | ||
24 | /* the `+' forces getopt to stop at the first non-option */ | |
25 | while ((opt = getopt (argc, argv, "+t:k::eVhv")) != -1) { | |
26 | switch (opt) { | |
27 | case 't': | |
28 | opts.timeout = atoi (optarg); | |
29 | break; | |
30 | case 'k': | |
31 | opts.kill_sig = optarg ? atoi (optarg) : SIGTERM; | |
32 | break; | |
33 | case 'e': | |
34 | opts.stream = STDERR_FILENO; | |
35 | break; | |
36 | case 'V': | |
37 | opts.verbose = 1; | |
38 | break; | |
39 | case 'h': | |
40 | fprintf (stderr, VERTEXT USAGE | |
41 | "Options:\n" | |
42 | "\t-t N\ttimeout after N seconds\n" | |
43 | "\t-k [M]\tsend signal M to child after timeout (default: 15/SIGTERM)\n" | |
44 | "\t-e\tgrep on stderr instead of stdout\n" | |
45 | "\t-V\tbe verbose; print PROGRAM's stdout/stderr to stderr\n", argv[0]); | |
46 | return EX_OK; | |
47 | case 'v': | |
48 | fprintf (stderr, VERTEXT); | |
49 | return EX_OK; | |
50 | default: | |
51 | fprintf (stderr, "Unrecognized option: %c\n" USAGE, optopt, argv[0]); | |
52 | return EX_USAGE; | |
53 | } | |
54 | } | |
55 | ||
56 | /* the first non-option argument is the search string */ | |
57 | if (optind < argc) { | |
58 | opts.pattern = argv[optind++]; | |
59 | } else { | |
60 | fprintf (stderr, USAGE "(Missing PATTERN)\n", argv[0]); | |
61 | return EX_USAGE; | |
62 | } | |
63 | ||
64 | /* the remaining are the program to be run */ | |
65 | if (optind < argc) { | |
66 | opts.argv = &(argv[optind]); | |
67 | } else { | |
68 | fprintf (stderr, USAGE "(Missing PROGRAM)\n", argv[0]); | |
69 | return EX_USAGE; | |
70 | } | |
71 | ||
72 | int retval = fork_after_grep (opts); | |
73 | ||
74 | return retval; | |
75 | } | |
76 | ||
77 | int fork_after_grep (struct opt opts) { | |
78 | int pipefd[2]; | |
79 | pid_t cpid; | |
80 | int status; | |
81 | ||
82 | char buf[BUF_SIZE]; | |
83 | int nbytes; | |
84 | ||
85 | struct timeval begin, now, diff; | |
86 | ||
87 | if (pipe(pipefd) == -1) { | |
88 | fprintf (stderr, "pipe error (userprog)\n"); | |
89 | return EX_OSERR; | |
90 | } | |
91 | ||
92 | if ((cpid = fork()) == -1) { | |
93 | fprintf (stderr, "fork error (userprog): %s", strerror (errno)); | |
94 | close (pipefd[0]); | |
95 | close (pipefd[1]); | |
96 | return EX_OSERR; | |
97 | } | |
98 | ||
99 | if (cpid == 0) { | |
100 | close (pipefd[0]); | |
101 | dup2 (pipefd[1], opts.stream); | |
102 | close (pipefd[1]); | |
103 | close (opts.stream==STDOUT_FILENO?STDERR_FILENO:STDOUT_FILENO); | |
104 | ||
105 | if (setsid () == -1) { | |
106 | fprintf (stderr, "setsid error (userprog): %s", strerror (errno)); | |
107 | _exit (EX_OSERR); | |
108 | } | |
109 | ||
110 | execvp (opts.argv[0], opts.argv); | |
111 | fprintf (stderr, "exec error (userprog): %s", strerror (errno)); | |
112 | _exit (EX_UNAVAILABLE); | |
113 | } else { | |
114 | pid_t grep_cpid; | |
115 | int pipefd_togrep[2]; | |
116 | int grep_status; | |
117 | /* `-q': don't print anything; exit with 0 on match; with 1 on error */ | |
118 | char* grepargv[] = {"grep", "-q", opts.pattern, NULL}; | |
119 | ||
120 | close (pipefd[1]); | |
121 | fcntl (pipefd[0], F_SETFL, fcntl (pipefd[0], F_GETFL, 0) | O_NONBLOCK); | |
122 | ||
123 | gettimeofday (&begin, NULL); /* for timeout */ | |
124 | ||
125 | if (pipe(pipefd_togrep) == -1) { | |
126 | fprintf (stderr, "pipe error (grep)\n"); | |
127 | close (pipefd[0]); | |
128 | close (pipefd[1]); | |
129 | return EX_OSERR; | |
130 | } | |
131 | ||
132 | if ((grep_cpid = fork()) == -1) { | |
133 | fprintf (stderr, "fork error (grep): %s", strerror (errno)); | |
134 | close (pipefd[0]); | |
135 | close (pipefd[1]); | |
136 | close (pipefd_togrep[0]); | |
137 | close (pipefd_togrep[1]); | |
138 | return EX_OSERR; | |
139 | } | |
140 | ||
141 | if (grep_cpid == 0) { | |
142 | close (pipefd_togrep[1]); | |
143 | dup2 (pipefd_togrep[0], STDIN_FILENO); | |
144 | close (pipefd_togrep[0]); | |
145 | ||
146 | close (STDERR_FILENO); | |
147 | close (STDOUT_FILENO); | |
148 | ||
149 | execvp (grepargv[0], grepargv); | |
150 | fprintf (stderr, "exec error (grep): %s", strerror (errno)); | |
151 | _exit (EX_UNAVAILABLE); | |
152 | } else { | |
153 | close (pipefd_togrep[0]); | |
154 | for (;;) { | |
155 | usleep (20000); | |
156 | memset (buf, 0, BUF_SIZE); /* necessary for opts.verbose */ | |
157 | nbytes = read (pipefd[0], buf, BUF_SIZE); | |
158 | if (nbytes == -1) { | |
159 | switch (errno) { | |
160 | case EAGAIN: | |
161 | break; | |
162 | default: | |
163 | fprintf (stderr, "read error (userprog): %s", strerror (errno)); | |
164 | close (pipefd[0]); | |
165 | close (pipefd[1]); | |
166 | close (pipefd_togrep[1]); | |
167 | //TODO: kill grep? | |
168 | return EX_IOERR; | |
169 | } | |
170 | } else if (nbytes == 0) { | |
171 | fprintf (stderr, "Child program exited prematurely (userprog).\n"); | |
172 | close (pipefd[0]); | |
173 | close (pipefd[1]); | |
174 | close (pipefd_togrep[1]); | |
175 | //TODO: kill grep? | |
176 | if (waitpid (cpid, &status, WNOHANG) > 0 && WIFEXITED (status)) { | |
177 | return WEXITSTATUS (status); | |
178 | } | |
179 | return EX_UNAVAILABLE; | |
180 | } else { | |
181 | /* have new userprog-data, send it to grep */ | |
182 | if (opts.verbose) { | |
183 | fputs (buf, stderr); | |
184 | } | |
185 | ||
186 | write(pipefd_togrep[1], buf, strlen(buf)); | |
187 | } | |
188 | ||
189 | if (waitpid (grep_cpid, &grep_status, WNOHANG) > 0 && WIFEXITED (grep_status)) { | |
190 | close (pipefd_togrep[1]); | |
191 | ||
192 | if (WEXITSTATUS(grep_status) == 0) { | |
193 | /* grep exited with match found */ | |
194 | printf ("%d\n", cpid); | |
195 | ||
196 | /* create a new child to keep pipe alive (will exit with exec'd program) */ | |
197 | if (!fork ()) { | |
198 | while (kill(cpid, 0) != -1 && errno != ESRCH ) sleep (1); | |
199 | close (pipefd[0]); | |
200 | close (pipefd[1]); | |
201 | _exit(0); | |
202 | } | |
203 | close (pipefd[0]); | |
204 | close (pipefd[1]); | |
205 | return EX_OK; | |
206 | } else { | |
207 | /* grep exited due to an error */ | |
208 | fprintf (stderr, "grep exited due to an error."); | |
209 | close (pipefd[0]); | |
210 | close (pipefd[1]); | |
211 | close (pipefd_togrep[1]); | |
212 | return EX_IOERR; | |
213 | } | |
214 | } | |
215 | ||
216 | if (opts.timeout > 0) { | |
217 | gettimeofday (&now, NULL); | |
218 | timersub (&now, &begin, &diff); | |
219 | if (diff.tv_sec >= opts.timeout) { | |
220 | fprintf (stderr, "Timeout reached. \n"); | |
221 | if (opts.kill_sig > 0) kill (cpid, opts.kill_sig); | |
222 | close (pipefd[0]); | |
223 | close (pipefd[1]); | |
224 | close (pipefd_togrep[1]); | |
225 | //TODO: kill grep? | |
226 | return EX_UNAVAILABLE; | |
227 | } | |
228 | } | |
229 | } | |
230 | } | |
231 | } | |
232 | } |