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1 | /* forkaftergrep (C) 2017 Tobias Girstmair, GPLv3 */ | |
2 | ||
3 | #define _XOPEN_SOURCE 500 | |
4 | #define _DEFAULT_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, 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::eVhv")) != -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 'V': | |
35 | opts.verbose = 1; | |
36 | break; | |
37 | case 'h': | |
38 | fprintf (stderr, VERTEXT USAGE | |
39 | "Options:\n" | |
40 | "\t-t N\ttimeout after N seconds\n" | |
41 | "\t-k [M]\tsend signal M to child after timeout (default: 15/SIGTERM)\n" | |
42 | "\t-e\tgrep on stderr instead of stdout\n", argv[0]); | |
43 | return EX_OK; | |
44 | case 'v': | |
45 | fprintf (stderr, VERTEXT); | |
46 | return EX_OK; | |
47 | default: | |
48 | fprintf (stderr, "Unrecognized option: %c\n" USAGE, optopt, argv[0]); | |
49 | return EX_USAGE; | |
50 | } | |
51 | } | |
52 | ||
53 | /* the first non-option argument is the search string */ | |
54 | if (optind < argc) { | |
55 | opts.pattern = argv[optind++]; | |
56 | } else { | |
57 | fprintf (stderr, USAGE "(Missing PATTERN)\n", argv[0]); | |
58 | return EX_USAGE; | |
59 | } | |
60 | ||
61 | /* the remaining are the program to be run */ | |
62 | if (optind < argc) { | |
63 | opts.argv = &(argv[optind]); | |
64 | } else { | |
65 | fprintf (stderr, USAGE "(Missing PROGRAM)\n", argv[0]); | |
66 | return EX_USAGE; | |
67 | } | |
68 | ||
69 | int retval = fork_after_grep (opts); | |
70 | ||
71 | return retval; | |
72 | } | |
73 | ||
74 | int fork_after_grep (struct opt opts) { | |
75 | int pipefd[2]; | |
76 | pid_t cpid; | |
77 | int status; | |
78 | ||
79 | char buf[BUF_SIZE]; | |
80 | int nbytes; | |
81 | ||
82 | struct timeval begin, now, diff; | |
83 | ||
84 | if (pipe(pipefd) == -1) { | |
85 | fprintf (stderr, "pipe error\n"); | |
86 | return EX_OSERR; | |
87 | } | |
88 | ||
89 | if ((cpid = fork()) == -1) { | |
90 | fprintf (stderr, "fork error: %s", strerror (errno)); | |
91 | close (pipefd[0]); | |
92 | close (pipefd[1]); | |
93 | return EX_OSERR; | |
94 | } | |
95 | ||
96 | if (cpid == 0) { | |
97 | close (pipefd[0]); | |
98 | dup2 (pipefd[1], opts.stream); | |
99 | close (pipefd[1]); | |
100 | close (opts.stream==STDOUT_FILENO?STDERR_FILENO:STDOUT_FILENO); | |
101 | ||
102 | if (setsid () == -1) { | |
103 | fprintf (stderr, "setsid error: %s", strerror (errno)); | |
104 | _exit (EX_OSERR); | |
105 | } | |
106 | ||
107 | execvp (opts.argv[0], opts.argv); | |
108 | fprintf (stderr, "exec error: %s", strerror (errno)); | |
109 | _exit (EX_UNAVAILABLE); | |
110 | } else { | |
111 | pid_t grep_cpid; | |
112 | int grep_pipefd[2]; | |
113 | //char grep_buf[BUF_SIZE]; | |
114 | //int grep_nbytes; | |
115 | //char* grepargv[] = {"cat", NULL}; | |
116 | char* grepargv[] = {"grep", opts.pattern, NULL};//"-E", //TODO: supply params (-E, -P, etc.) to grep from command line | |
117 | ||
118 | close (pipefd[1]); | |
119 | fcntl (pipefd[0], F_SETFL, fcntl (pipefd[0], F_GETFL, 0) | O_NONBLOCK); | |
120 | ||
121 | gettimeofday (&begin, NULL); | |
122 | ||
123 | if (pipe(grep_pipefd) == -1) { | |
124 | fprintf (stderr, "mygrep - pipe error\n"); | |
125 | return EX_OSERR; | |
126 | } | |
127 | if ((grep_cpid = fork()) == -1) { | |
128 | fprintf (stderr, "mygrep - fork error: %s", strerror (errno)); | |
129 | close (pipefd[0]); | |
130 | close (pipefd[1]); | |
131 | return EX_OSERR; | |
132 | } | |
133 | if (grep_cpid == 0) { | |
134 | close(grep_pipefd[1]); | |
135 | dup2(grep_pipefd[0], STDIN_FILENO); | |
136 | close(grep_pipefd[0]); | |
137 | close(STDERR_FILENO); | |
138 | execvp (grepargv[0], grepargv); | |
139 | fprintf (stderr, "mygrep - exec error: %s", strerror (errno)); | |
140 | _exit (EX_UNAVAILABLE); | |
141 | } else { | |
142 | for (;;) { | |
143 | usleep (20000); | |
144 | memset (buf, 0, BUF_SIZE); | |
145 | nbytes = read (pipefd[0], buf, BUF_SIZE); | |
146 | if (nbytes == -1) { | |
147 | switch (errno) { | |
148 | case EAGAIN: | |
149 | continue; | |
150 | default: | |
151 | fprintf (stderr, "read error: %s", strerror (errno)); | |
152 | close (pipefd[0]); | |
153 | close (pipefd[1]); | |
154 | return EX_IOERR; | |
155 | } | |
156 | } else if (nbytes == 0) { | |
157 | fprintf (stderr, "Child program exited prematurely.\n"); | |
158 | close (pipefd[0]); | |
159 | close (pipefd[1]); | |
160 | if (waitpid (cpid, &status, WNOHANG) > 0 && WIFEXITED (status)) { | |
161 | return WEXITSTATUS (status); | |
162 | } | |
163 | return EX_UNAVAILABLE; | |
164 | } | |
165 | if (opts.verbose) { | |
166 | fputs (buf, opts.stream==STDERR_FILENO?stderr:stdout); | |
167 | } | |
168 | write(grep_pipefd[1], buf, strlen(buf));/*************/ | |
169 | if (strstr (buf, opts.pattern) != NULL) { | |
170 | printf ("%d\n", cpid); | |
171 | /* create a new child to keep pipe alive (will exit with exec'd program) */ | |
172 | if (!fork ()) { | |
173 | while (kill(cpid, 0) != -1 && errno != ESRCH ) sleep (1); | |
174 | close (pipefd[0]); | |
175 | close (pipefd[1]); | |
176 | _exit(0); | |
177 | } | |
178 | close (pipefd[0]); | |
179 | close (pipefd[1]); | |
180 | return EX_OK; | |
181 | } | |
182 | ||
183 | if (opts.timeout > 0) { | |
184 | gettimeofday (&now, NULL); | |
185 | timersub (&now, &begin, &diff); | |
186 | if (diff.tv_sec >= opts.timeout) { | |
187 | fprintf (stderr, "Timeout reached. \n"); | |
188 | if (opts.kill_sig > 0) kill (cpid, opts.kill_sig); | |
189 | close (pipefd[0]); | |
190 | close (pipefd[1]); | |
191 | return EX_UNAVAILABLE; | |
192 | } | |
193 | } | |
194 | } | |
195 | } | |
196 | } | |
197 | } |