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1 | /* -*-c-*- |
2 | * |
9a4b2474 |
3 | * $Id: locking.c,v 1.3 2004/04/08 01:36:26 mdw Exp $ |
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4 | * |
5 | * Lock a file, run a program |
6 | * |
7 | * (c) 2003 Mark Wooding |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
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. |
18 | * |
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. |
23 | * |
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> |
37 | |
38 | #include <sys/types.h> |
39 | #include <sys/time.h> |
40 | #include <unistd.h> |
41 | #include <fcntl.h> |
42 | #include <sys/wait.h> |
43 | |
44 | #include <mLib/mdwopt.h> |
45 | #include <mLib/quis.h> |
46 | #include <mLib/report.h> |
47 | |
48 | /*----- Static variables --------------------------------------------------*/ |
49 | |
50 | static jmp_buf jmp; |
51 | |
52 | /*----- Main code ---------------------------------------------------------*/ |
53 | |
54 | static void alrm(int s) { longjmp(jmp, 1); } |
55 | |
56 | static void usage(FILE *fp) |
57 | { |
58 | pquis(fp, |
59 | "Usage: $ [-cfwx] [-p REALPROG] [-t TIMEOUT] FILE PROG ARGS...\n"); |
60 | } |
61 | |
62 | static void version(FILE *fp) |
63 | { |
5b11bb47 |
64 | pquis(fp, "$ (version " VERSION ")\n"); |
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65 | } |
66 | |
67 | static void help(FILE *fp) |
68 | { |
69 | version(fp); |
70 | putchar('\n'); |
71 | usage(fp); |
72 | pquis(fp, "\n\ |
73 | Lock FILE and run PROG, passing ARGS. Options are:\n\ |
74 | \n\ |
75 | -h, --help Show this help message.\n\ |
76 | -v, --version Show version string.\n\ |
77 | -u, --usage Show terse usage summary.\n\ |
78 | \n\ |
79 | -c, --[no-]create Create FILE if it doesn't exist [default: on].\n\ |
80 | -f, --[no-]fail Fail if the file is already locked [default: off].\n\ |
81 | -w, --[no-]wait Wait for the lock to be available [default: off].\n\ |
82 | -x, --[no-]exclusive Get an exclusive (writer) lock [default: on].\n\ |
83 | -p, --program=REALPROG Run REALPROG instead of PROG.\n\ |
84 | -t, --timeout=TIME Wait for TIME for lock to become available.\n\ |
85 | "); |
86 | } |
87 | |
88 | int main(int argc, char *argv[]) |
89 | { |
90 | const char *file = 0; |
91 | const char *prog = 0; |
92 | char *const *av; |
93 | void (*oalrm)(int) = 0; |
94 | int fd; |
95 | struct flock l; |
96 | char *p; |
97 | int t = -1; |
98 | unsigned int ot; |
99 | time_t nt; |
100 | pid_t kid; |
101 | int st; |
102 | |
103 | #define f_bogus 1u |
104 | #define f_wait 2u |
105 | #define f_fail 4u |
106 | #define f_create 8u |
107 | #define f_excl 16u |
108 | |
109 | unsigned f = f_create | f_excl; |
110 | |
111 | ego(argv[0]); |
112 | |
113 | for (;;) { |
114 | static const struct option opts[] = { |
115 | { "help", 0, 0, 'h' }, |
116 | { "version", 0, 0, 'v' }, |
117 | { "usage", 0, 0, 'u' }, |
118 | { "wait", OPTF_NEGATE, 0, 'w' }, |
119 | { "fail", OPTF_NEGATE, 0, 'f' }, |
120 | { "create", OPTF_NEGATE, 0, 'c' }, |
121 | { "program", OPTF_ARGREQ, 0, 'p' }, |
122 | { "timeout", OPTF_ARGREQ, 0, 't' }, |
123 | { "exclusive", OPTF_NEGATE, 0, 'x' }, |
124 | { 0, 0, 0, 0 } |
125 | }; |
126 | |
127 | int i = mdwopt(argc, argv, "-hvuw+f+c+x+p:t:", opts, |
128 | 0, 0, OPTF_NEGATION); |
129 | if (i < 0) |
130 | break; |
131 | switch (i) { |
132 | case 'h': |
133 | help(stdout); |
134 | exit(0); |
135 | case 'v': |
136 | version(stdout); |
137 | exit(0); |
138 | case 'u': |
139 | usage(stdout); |
140 | exit(0); |
141 | case 'w': |
142 | f |= f_wait; |
143 | break; |
144 | case 'w' | OPTF_NEGATED: |
145 | f &= ~f_wait; |
146 | break; |
147 | case 'f': |
148 | f |= f_fail; |
149 | break; |
150 | case 'f' | OPTF_NEGATED: |
151 | f &= ~f_fail; |
152 | break; |
153 | case 'c': |
154 | f |= f_create; |
155 | break; |
156 | case 'c' | OPTF_NEGATED: |
157 | f &= ~f_create; |
158 | break; |
159 | case 'x': |
160 | f |= f_excl; |
161 | break; |
162 | case 'x' | OPTF_NEGATED: |
163 | f &= ~f_excl; |
164 | break; |
165 | case 't': |
166 | errno = 0; |
167 | t = strtol(optarg, &p, 0); |
168 | switch (*p) { |
169 | case 'd': t *= 24; |
170 | case 'h': t *= 60; |
171 | case 'm': t *= 60; |
172 | case 's': p++; |
173 | case 0: break; |
174 | default: die(111, "unknown time unit `%c'", *p); |
175 | } |
176 | if (*p || t < 0 || errno) |
177 | die(111, "bad time value `%s'", optarg); |
178 | f |= f_wait; |
179 | break; |
180 | case 'p': |
181 | prog = optarg; |
182 | break; |
183 | case 0: |
184 | if (file) { |
185 | optind--; |
186 | goto doneopts; |
187 | } |
188 | file = optarg; |
189 | break; |
190 | default: |
191 | f |= f_bogus; |
192 | break; |
193 | } |
194 | } |
195 | |
196 | doneopts: |
197 | if (f & f_bogus || argc - optind < 1) { |
198 | usage(stderr); |
199 | exit(EXIT_FAILURE); |
200 | } |
201 | |
202 | av = &argv[optind]; |
203 | if (!prog) |
204 | prog = av[0]; |
205 | if ((fd = open(file, |
206 | ((f & f_create ? O_CREAT : 0) | |
207 | (f & f_excl ? O_RDWR : O_RDONLY)), 0666)) < 0) |
208 | die(111, "error opening `%s': %s", file, strerror(errno)); |
209 | l.l_type = f & f_excl ? F_WRLCK : F_RDLCK; |
210 | l.l_whence = SEEK_SET; |
211 | l.l_start = 0; |
212 | l.l_len = 0; |
213 | nt = time(0); |
214 | if (setjmp(jmp)) { |
215 | errno = EAGAIN; |
216 | nt = t; |
217 | } else { |
218 | ot = alarm(0); |
219 | oalrm = signal(SIGALRM, alrm); |
220 | if (t >= 0) |
221 | alarm(t); |
222 | if (fcntl(fd, f & f_wait ? F_SETLKW : F_SETLK, &l) >= 0) |
223 | errno = 0; |
224 | } |
225 | signal(SIGALRM, oalrm); |
226 | if (ot) { |
227 | nt = time(0) - nt; |
228 | if (nt > ot) |
229 | raise(SIGALRM); |
230 | else |
231 | alarm(ot - nt); |
232 | } |
233 | if (errno && |
234 | ((errno != EAGAIN && errno != EWOULDBLOCK && errno != EACCES) || |
235 | (f & f_fail))) |
236 | die(111, "error locking `%s': %s", file, strerror(errno)); |
237 | if (errno) |
238 | exit(0); |
239 | |
240 | if ((kid = fork()) < 0) |
241 | die(111, "error from fork: %s", strerror(errno)); |
242 | if (!kid) { |
243 | close(fd); |
244 | execvp(prog, av); |
245 | die(111, "couldn't exec `%s': %s", prog, strerror(errno)); |
246 | } |
247 | if (waitpid(kid, &st, 0) < 0) |
248 | die(EXIT_FAILURE, "error from wait: %s", strerror(errno)); |
249 | l.l_type = F_UNLCK; |
250 | l.l_whence = SEEK_SET; |
251 | l.l_start = 0; |
252 | l.l_len = 0; |
253 | fcntl(fd, F_SETLK, &l); |
254 | close(fd); |
255 | if (WIFEXITED(st)) |
256 | exit(WEXITSTATUS(st)); |
257 | else |
258 | exit(255); |
259 | } |
260 | |
261 | /*----- That's all, folks -------------------------------------------------*/ |