]>
Commit | Line | Data |
---|---|---|
1 | /* forkaftergrep (C) 2017 Tobias Girstmair, GPLv3 */ | |
2 | ||
3 | #define _XOPEN_SOURCE 500 | |
4 | #define _BSD_SOURCE | |
5 | #include <errno.h> | |
6 | #include <fcntl.h> | |
7 | #include <stdio.h> | |
8 | #include <stdlib.h> | |
9 | #include <string.h> | |
10 | #include <sysexits.h> | |
11 | #include <sys/time.h> | |
12 | #include <sys/wait.h> | |
13 | #include <unistd.h> | |
14 | #include "fag.h" | |
15 | ||
16 | struct opt opts = {0, 0, NULL, NULL, STDOUT_FILENO}; | |
17 | ||
18 | int main (int argc, char** argv) { | |
19 | int opt; | |
20 | opterr = 0; | |
21 | ||
22 | /* the `+' forces getopt to stop at the first non-option */ | |
23 | while ((opt = getopt (argc, argv, "+t:k::ehv")) != -1) { | |
24 | switch (opt) { | |
25 | case 't': | |
26 | opts.timeout = atoi (optarg); | |
27 | break; | |
28 | case 'k': | |
29 | opts.kill_sig = optarg ? atoi (optarg) : SIGTERM; | |
30 | break; | |
31 | case 'e': | |
32 | opts.stream = STDERR_FILENO; | |
33 | break; | |
34 | case 'h': | |
35 | fprintf (stderr, VERTEXT USAGE | |
36 | "Options:\n" | |
37 | "\t-t N\ttimeout after N seconds\n" | |
38 | "\t-k [M]\tsend signal M to child after timeout (default: 15/SIGTERM)\n" | |
39 | "\t-e\tgrep on stderr instead of stdout\n", argv[0]); | |
40 | return EX_OK; | |
41 | case 'v': | |
42 | fprintf (stderr, VERTEXT); | |
43 | return EX_OK; | |
44 | default: | |
45 | fprintf (stderr, "Unrecognized option: %c\n" USAGE, optopt, argv[0]); | |
46 | return EX_USAGE; | |
47 | } | |
48 | } | |
49 | ||
50 | /* the first non-option argument is the search string */ | |
51 | if (optind < argc) { | |
52 | opts.pattern = argv[optind++]; | |
53 | } else { | |
54 | fprintf (stderr, USAGE "(Missing PATTERN)\n", argv[0]); | |
55 | return EX_USAGE; | |
56 | } | |
57 | ||
58 | /* the remaining are the program to be run */ | |
59 | if (optind < argc) { | |
60 | opts.argv = &(argv[optind]); | |
61 | } else { | |
62 | fprintf (stderr, USAGE "(Missing PROGRAM)\n", argv[0]); | |
63 | return EX_USAGE; | |
64 | } | |
65 | ||
66 | int retval = fork_after_grep (opts); | |
67 | ||
68 | return retval; | |
69 | } | |
70 | ||
71 | int fork_after_grep (struct opt opts) { | |
72 | int pipefd[2]; | |
73 | pid_t cpid; | |
74 | int status; | |
75 | ||
76 | char buf[BUF_SIZE]; | |
77 | int nbytes; | |
78 | ||
79 | struct timeval begin, now, diff; | |
80 | ||
81 | if (pipe(pipefd) == -1) { | |
82 | fprintf (stderr, "pipe error\n"); | |
83 | return EX_OSERR; | |
84 | } | |
85 | ||
86 | if ((cpid = fork()) == -1) { | |
87 | fprintf (stderr, "fork error: %s", strerror (errno)); | |
88 | close (pipefd[0]); | |
89 | close (pipefd[1]); | |
90 | return EX_OSERR; | |
91 | } | |
92 | ||
93 | if (cpid == 0) { | |
94 | close (pipefd[0]); | |
95 | dup2 (pipefd[1], opts.stream); | |
96 | close (pipefd[1]); | |
97 | close (opts.stream==STDOUT_FILENO?STDERR_FILENO:STDOUT_FILENO); | |
98 | ||
99 | if (setsid () == -1) { | |
100 | fprintf (stderr, "setsid error: %s", strerror (errno)); | |
101 | _exit (EX_OSERR); | |
102 | } | |
103 | ||
104 | execvp (opts.argv[0], opts.argv); | |
105 | fprintf (stderr, "exec error: %s", strerror (errno)); | |
106 | _exit (EX_UNAVAILABLE); | |
107 | } else { | |
108 | close (pipefd[1]); | |
109 | fcntl (pipefd[0], F_SETFL, fcntl (pipefd[0], F_GETFL, 0) | O_NONBLOCK); | |
110 | ||
111 | gettimeofday (&begin, NULL); | |
112 | ||
113 | for (;;) { | |
114 | usleep (20000); | |
115 | nbytes = read (pipefd[0], buf, BUF_SIZE); | |
116 | if (nbytes == -1) { | |
117 | switch (errno) { | |
118 | case EAGAIN: | |
119 | continue; | |
120 | default: | |
121 | fprintf (stderr, "read error: %s", strerror (errno)); | |
122 | close (pipefd[0]); | |
123 | close (pipefd[1]); | |
124 | return EX_IOERR; | |
125 | } | |
126 | } else if (nbytes == 0) { | |
127 | fprintf (stderr, "Child program exited prematurely.\n"); | |
128 | close (pipefd[0]); | |
129 | close (pipefd[1]); | |
130 | if (waitpid (cpid, &status, WNOHANG) > 0 && WIFEXITED (status)) { | |
131 | return WEXITSTATUS (status); | |
132 | } | |
133 | return EX_UNAVAILABLE; | |
134 | } | |
135 | if (strstr (buf, opts.pattern) != NULL) { | |
136 | printf ("%d\n", cpid); | |
137 | /* create a new child to keep pipe alive (will exit with exec'd program) */ | |
138 | if (!fork ()) { | |
139 | while (kill(cpid, 0) != -1 && errno != ESRCH ) sleep (1); | |
140 | close (pipefd[0]); | |
141 | close (pipefd[1]); | |
142 | _exit(0); | |
143 | } | |
144 | close (pipefd[0]); | |
145 | close (pipefd[1]); | |
146 | return EX_OK; | |
147 | } | |
148 | ||
149 | if (opts.timeout > 0) { | |
150 | gettimeofday (&now, NULL); | |
151 | timersub (&now, &begin, &diff); | |
152 | if (diff.tv_sec >= opts.timeout) { | |
153 | fprintf (stderr, "Timeout reached. \n"); | |
154 | if (opts.kill_sig > 0) kill (cpid, opts.kill_sig); | |
155 | close (pipefd[0]); | |
156 | close (pipefd[1]); | |
157 | return EX_UNAVAILABLE; | |
158 | } | |
159 | } | |
160 | } | |
161 | } | |
162 | } |