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git.gir.st - forkaftergrep.git/blob - fag.c
32fde76040ae6da2f08c35701d2900314367842b
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) (line 190)
5 #define _XOPEN_SOURCE 500
6 #define _DEFAULT_SOURCE
18 int main (int argc
, char** argv
) {
19 struct opt opts
= {0, 0, 0, NULL
, NULL
, STDOUT_FILENO
, "-q"};
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' */
28 /* the `+' forces getopt to stop at the first non-option */
29 while ((opt
= getopt (argc
, argv
, "+t:k::eVhvEFGPiwxyU")) != -1) {
32 opts
.timeout
= atoi (optarg
);
35 opts
.kill_sig
= optarg
? atoi (optarg
) : SIGTERM
;
38 opts
.stream
= STDERR_FILENO
;
44 fprintf (stderr
, VERTEXT USAGE
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]);
53 fprintf (stderr
, VERTEXT
);
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;
61 fprintf (stderr
, "Unrecognized option: %c\n" USAGE
, optopt
, argv
[0]);
65 *p
= '\0'; /* finish grep_options string */
67 /* the first non-option argument is the search string */
69 opts
.pattern
= argv
[optind
++];
71 fprintf (stderr
, USAGE
"(Missing PATTERN)\n", argv
[0]);
75 /* the remaining are the program to be run */
77 opts
.argv
= &(argv
[optind
]);
79 fprintf (stderr
, USAGE
"(Missing PROGRAM)\n", argv
[0]);
83 int retval
= fork_after_grep (opts
);
88 int fork_after_grep (struct opt opts
) {
96 struct timeval begin
, now
, diff
;
98 if (pipe(pipefd
) == -1) {
99 fprintf (stderr
, "pipe error (userprog)\n");
103 if ((cpid
= fork()) == -1) {
104 fprintf (stderr
, "fork error (userprog): %s", strerror (errno
));
112 dup2 (pipefd
[1], opts
.stream
);
114 close (opts
.stream
==STDOUT_FILENO
?STDERR_FILENO
:STDOUT_FILENO
);
116 if (setsid () == -1) {
117 fprintf (stderr
, "setsid error (userprog): %s", strerror (errno
));
121 execvp (opts
.argv
[0], opts
.argv
);
122 fprintf (stderr
, "exec error (userprog): %s", strerror (errno
));
123 _exit (EX_UNAVAILABLE
);
130 fcntl (pipefd
[0], F_SETFL
, fcntl (pipefd
[0], F_GETFL
, 0) | O_NONBLOCK
);
132 gettimeofday (&begin
, NULL
); /* for timeout */
134 if (pipe(grep_pipefd
) == -1) {
135 fprintf (stderr
, "pipe error (grep)\n");
140 if ((grep_cpid
= fork()) == -1) {
141 fprintf (stderr
, "fork error (grep): %s", strerror (errno
));
143 close (grep_pipefd
[0]);
144 close (grep_pipefd
[1]);
148 if (grep_cpid
== 0) {
149 close (grep_pipefd
[1]);
150 dup2 (grep_pipefd
[0], STDIN_FILENO
);
151 close (grep_pipefd
[0]);
153 close (STDERR_FILENO
);
154 close (STDOUT_FILENO
);
156 execlp ("grep", "grep", opts
.grepopt
, opts
.pattern
, NULL
);
157 fprintf (stderr
, "exec error (grep): %s", strerror (errno
));
160 close (grep_pipefd
[0]);
163 nbytes
= read (pipefd
[0], buf
, BUF_SIZE
);
169 fprintf (stderr
, "read error (userprog): %s", strerror (errno
));
171 close (grep_pipefd
[1]);
175 } else if (nbytes
== 0) {
176 fprintf (stderr
, "Child program exited prematurely (userprog).\n");
178 close (grep_pipefd
[1]);
180 if (waitpid (cpid
, &status
, WNOHANG
) > 0 && WIFEXITED (status
)) {
181 return WEXITSTATUS (status
);
183 return EX_UNAVAILABLE
;
185 /* have new userprog-data, send it to grep */
187 write(STDERR_FILENO
, buf
, nbytes
);
190 write(grep_pipefd
[1], buf
, nbytes
); //TODO: sometimes gets SIGPIPE here
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]);
197 if (WEXITSTATUS(grep_status
) == 0) {
198 /* grep exited with match found */
199 printf ("%d\n", cpid
);
201 /* create a new child to keep pipe alive (will exit with exec'd program) */
203 while (kill(cpid
, 0) != -1 && errno
!= ESRCH
) sleep (1);
210 /* grep exited due to an error */
211 fprintf (stderr
, "grep exited due to an error.\n");
213 close (grep_pipefd
[1]);
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
);
225 close (grep_pipefd
[1]);
227 return EX_UNAVAILABLE
;