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1 | /* -*-c-*- |
2 | * |
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3 | * $Id$ |
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4 | * |
5 | * Lock a file, run a program |
6 | * |
7 | * (c) 2003 Mark Wooding |
8 | */ |
9 | |
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10 | /*----- Licensing notice --------------------------------------------------* |
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11 | * |
12 | * This file is part of the Toys utilties collection. |
13 | * |
14 | * Toys is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU General Public License as published by |
16 | * the Free Software Foundation; either version 2 of the License, or |
17 | * (at your option) any later version. |
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18 | * |
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19 | * Toys is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU General Public License for more details. |
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23 | * |
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24 | * You should have received a copy of the GNU General Public License |
25 | * along with Toys; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
27 | */ |
28 | |
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29 | /*----- Header files ------------------------------------------------------*/ |
30 | |
31 | #include <errno.h> |
32 | #include <setjmp.h> |
33 | #include <signal.h> |
34 | #include <stdio.h> |
35 | #include <stdlib.h> |
36 | #include <string.h> |
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37 | #include <time.h> |
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38 | |
39 | #include <sys/types.h> |
40 | #include <sys/time.h> |
41 | #include <unistd.h> |
42 | #include <fcntl.h> |
43 | #include <sys/wait.h> |
44 | |
45 | #include <mLib/mdwopt.h> |
46 | #include <mLib/quis.h> |
47 | #include <mLib/report.h> |
48 | |
49 | /*----- Static variables --------------------------------------------------*/ |
50 | |
51 | static jmp_buf jmp; |
52 | |
53 | /*----- Main code ---------------------------------------------------------*/ |
54 | |
55 | static void alrm(int s) { longjmp(jmp, 1); } |
56 | |
57 | static void usage(FILE *fp) |
58 | { |
59 | pquis(fp, |
60 | "Usage: $ [-cfwx] [-p REALPROG] [-t TIMEOUT] FILE PROG ARGS...\n"); |
61 | } |
62 | |
63 | static void version(FILE *fp) |
64 | { |
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65 | pquis(fp, "$ (version " VERSION ")\n"); |
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66 | } |
67 | |
68 | static void help(FILE *fp) |
69 | { |
70 | version(fp); |
71 | putchar('\n'); |
72 | usage(fp); |
73 | pquis(fp, "\n\ |
74 | Lock FILE and run PROG, passing ARGS. Options are:\n\ |
75 | \n\ |
76 | -h, --help Show this help message.\n\ |
77 | -v, --version Show version string.\n\ |
78 | -u, --usage Show terse usage summary.\n\ |
79 | \n\ |
80 | -c, --[no-]create Create FILE if it doesn't exist [default: on].\n\ |
81 | -f, --[no-]fail Fail if the file is already locked [default: off].\n\ |
82 | -w, --[no-]wait Wait for the lock to be available [default: off].\n\ |
83 | -x, --[no-]exclusive Get an exclusive (writer) lock [default: on].\n\ |
84 | -p, --program=REALPROG Run REALPROG instead of PROG.\n\ |
85 | -t, --timeout=TIME Wait for TIME for lock to become available.\n\ |
86 | "); |
87 | } |
88 | |
89 | int main(int argc, char *argv[]) |
90 | { |
91 | const char *file = 0; |
92 | const char *prog = 0; |
93 | char *const *av; |
94 | void (*oalrm)(int) = 0; |
95 | int fd; |
96 | struct flock l; |
97 | char *p; |
98 | int t = -1; |
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99 | unsigned int ot = 0; |
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100 | time_t nt; |
101 | pid_t kid; |
102 | int st; |
103 | |
104 | #define f_bogus 1u |
105 | #define f_wait 2u |
106 | #define f_fail 4u |
107 | #define f_create 8u |
108 | #define f_excl 16u |
109 | |
110 | unsigned f = f_create | f_excl; |
111 | |
112 | ego(argv[0]); |
113 | |
114 | for (;;) { |
115 | static const struct option opts[] = { |
116 | { "help", 0, 0, 'h' }, |
117 | { "version", 0, 0, 'v' }, |
118 | { "usage", 0, 0, 'u' }, |
119 | { "wait", OPTF_NEGATE, 0, 'w' }, |
120 | { "fail", OPTF_NEGATE, 0, 'f' }, |
121 | { "create", OPTF_NEGATE, 0, 'c' }, |
122 | { "program", OPTF_ARGREQ, 0, 'p' }, |
123 | { "timeout", OPTF_ARGREQ, 0, 't' }, |
124 | { "exclusive", OPTF_NEGATE, 0, 'x' }, |
125 | { 0, 0, 0, 0 } |
126 | }; |
127 | |
128 | int i = mdwopt(argc, argv, "-hvuw+f+c+x+p:t:", opts, |
129 | 0, 0, OPTF_NEGATION); |
130 | if (i < 0) |
131 | break; |
132 | switch (i) { |
133 | case 'h': |
134 | help(stdout); |
135 | exit(0); |
136 | case 'v': |
137 | version(stdout); |
138 | exit(0); |
139 | case 'u': |
140 | usage(stdout); |
141 | exit(0); |
142 | case 'w': |
143 | f |= f_wait; |
144 | break; |
145 | case 'w' | OPTF_NEGATED: |
146 | f &= ~f_wait; |
147 | break; |
148 | case 'f': |
149 | f |= f_fail; |
150 | break; |
151 | case 'f' | OPTF_NEGATED: |
152 | f &= ~f_fail; |
153 | break; |
154 | case 'c': |
155 | f |= f_create; |
156 | break; |
157 | case 'c' | OPTF_NEGATED: |
158 | f &= ~f_create; |
159 | break; |
160 | case 'x': |
161 | f |= f_excl; |
162 | break; |
163 | case 'x' | OPTF_NEGATED: |
164 | f &= ~f_excl; |
165 | break; |
166 | case 't': |
167 | errno = 0; |
168 | t = strtol(optarg, &p, 0); |
169 | switch (*p) { |
170 | case 'd': t *= 24; |
171 | case 'h': t *= 60; |
172 | case 'm': t *= 60; |
173 | case 's': p++; |
174 | case 0: break; |
175 | default: die(111, "unknown time unit `%c'", *p); |
176 | } |
177 | if (*p || t < 0 || errno) |
178 | die(111, "bad time value `%s'", optarg); |
179 | f |= f_wait; |
180 | break; |
181 | case 'p': |
182 | prog = optarg; |
183 | break; |
184 | case 0: |
185 | if (file) { |
186 | optind--; |
187 | goto doneopts; |
188 | } |
189 | file = optarg; |
190 | break; |
191 | default: |
192 | f |= f_bogus; |
193 | break; |
194 | } |
195 | } |
196 | |
197 | doneopts: |
198 | if (f & f_bogus || argc - optind < 1) { |
199 | usage(stderr); |
200 | exit(EXIT_FAILURE); |
201 | } |
202 | |
203 | av = &argv[optind]; |
204 | if (!prog) |
205 | prog = av[0]; |
206 | if ((fd = open(file, |
207 | ((f & f_create ? O_CREAT : 0) | |
208 | (f & f_excl ? O_RDWR : O_RDONLY)), 0666)) < 0) |
209 | die(111, "error opening `%s': %s", file, strerror(errno)); |
210 | l.l_type = f & f_excl ? F_WRLCK : F_RDLCK; |
211 | l.l_whence = SEEK_SET; |
212 | l.l_start = 0; |
213 | l.l_len = 0; |
214 | nt = time(0); |
215 | if (setjmp(jmp)) { |
216 | errno = EAGAIN; |
217 | nt = t; |
218 | } else { |
219 | ot = alarm(0); |
220 | oalrm = signal(SIGALRM, alrm); |
221 | if (t >= 0) |
222 | alarm(t); |
223 | if (fcntl(fd, f & f_wait ? F_SETLKW : F_SETLK, &l) >= 0) |
224 | errno = 0; |
225 | } |
226 | signal(SIGALRM, oalrm); |
227 | if (ot) { |
228 | nt = time(0) - nt; |
229 | if (nt > ot) |
230 | raise(SIGALRM); |
231 | else |
232 | alarm(ot - nt); |
233 | } |
234 | if (errno && |
235 | ((errno != EAGAIN && errno != EWOULDBLOCK && errno != EACCES) || |
236 | (f & f_fail))) |
237 | die(111, "error locking `%s': %s", file, strerror(errno)); |
238 | if (errno) |
239 | exit(0); |
240 | |
241 | if ((kid = fork()) < 0) |
242 | die(111, "error from fork: %s", strerror(errno)); |
243 | if (!kid) { |
244 | close(fd); |
245 | execvp(prog, av); |
246 | die(111, "couldn't exec `%s': %s", prog, strerror(errno)); |
247 | } |
248 | if (waitpid(kid, &st, 0) < 0) |
249 | die(EXIT_FAILURE, "error from wait: %s", strerror(errno)); |
250 | l.l_type = F_UNLCK; |
251 | l.l_whence = SEEK_SET; |
252 | l.l_start = 0; |
253 | l.l_len = 0; |
254 | fcntl(fd, F_SETLK, &l); |
255 | close(fd); |
256 | if (WIFEXITED(st)) |
257 | exit(WEXITSTATUS(st)); |
258 | else |
259 | exit(255); |
260 | } |
261 | |
262 | /*----- That's all, folks -------------------------------------------------*/ |