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