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1479465f GJ |
1 | /* |
2 | * libdpkg - Debian packaging suite library routines | |
3 | * file.c - file handling functions | |
4 | * | |
5 | * Copyright © 1994, 1995 Ian Jackson <ijackson@chiark.greenend.org.uk> | |
6 | * Copyright © 2008-2012 Guillem Jover <guillem@debian.org> | |
7 | * | |
8 | * This is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License as published by | |
10 | * the Free Software Foundation; either version 2 of the License, or | |
11 | * (at your option) any later version. | |
12 | * | |
13 | * This is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU General Public License | |
19 | * along with this program. If not, see <https://www.gnu.org/licenses/>. | |
20 | */ | |
21 | ||
22 | #include <config.h> | |
23 | #include <compat.h> | |
24 | ||
25 | #include <sys/types.h> | |
26 | #include <sys/stat.h> | |
27 | ||
28 | #include <assert.h> | |
29 | #include <errno.h> | |
30 | #include <fcntl.h> | |
31 | #include <unistd.h> | |
32 | ||
33 | #include <dpkg/dpkg.h> | |
34 | #include <dpkg/i18n.h> | |
35 | #include <dpkg/subproc.h> | |
36 | #include <dpkg/command.h> | |
37 | #include <dpkg/file.h> | |
38 | ||
39 | /** | |
40 | * Copy file ownership and permissions from one file to another. | |
41 | * | |
42 | * @param src The source filename. | |
43 | * @param dst The destination filename. | |
44 | */ | |
45 | void | |
46 | file_copy_perms(const char *src, const char *dst) | |
47 | { | |
48 | struct stat stab; | |
49 | ||
50 | if (stat(src, &stab) == -1) { | |
51 | if (errno == ENOENT) | |
52 | return; | |
53 | ohshite(_("unable to stat source file '%.250s'"), src); | |
54 | } | |
55 | ||
56 | if (chown(dst, stab.st_uid, stab.st_gid) == -1) | |
57 | ohshite(_("unable to change ownership of target file '%.250s'"), | |
58 | dst); | |
59 | ||
60 | if (chmod(dst, (stab.st_mode & ~S_IFMT)) == -1) | |
61 | ohshite(_("unable to set mode of target file '%.250s'"), dst); | |
62 | } | |
63 | ||
64 | static void | |
65 | file_lock_setup(struct flock *fl, short type) | |
66 | { | |
67 | fl->l_type = type; | |
68 | fl->l_whence = SEEK_SET; | |
69 | fl->l_start = 0; | |
70 | fl->l_len = 0; | |
71 | fl->l_pid = 0; | |
72 | } | |
73 | ||
74 | /** | |
75 | * Unlock a previously locked file. | |
76 | */ | |
77 | void | |
78 | file_unlock(int lockfd, const char *lock_desc) | |
79 | { | |
80 | struct flock fl; | |
81 | ||
82 | assert(lockfd >= 0); | |
83 | ||
84 | file_lock_setup(&fl, F_UNLCK); | |
85 | ||
86 | if (fcntl(lockfd, F_SETLK, &fl) == -1) | |
87 | ohshite(_("unable to unlock %s"), lock_desc); | |
88 | } | |
89 | ||
90 | static void | |
91 | file_unlock_cleanup(int argc, void **argv) | |
92 | { | |
93 | int lockfd = *(int *)argv[0]; | |
94 | const char *lock_desc = argv[1]; | |
95 | ||
96 | file_unlock(lockfd, lock_desc); | |
97 | } | |
98 | ||
99 | /** | |
100 | * Check if a file has a lock acquired. | |
101 | * | |
102 | * @param lockfd The file descriptor for the lock. | |
103 | * @param filename The file name associated to the file descriptor. | |
104 | */ | |
105 | bool | |
106 | file_is_locked(int lockfd, const char *filename) | |
107 | { | |
108 | struct flock fl; | |
109 | ||
110 | file_lock_setup(&fl, F_WRLCK); | |
111 | ||
112 | if (fcntl(lockfd, F_GETLK, &fl) == -1) | |
113 | ohshit(_("unable to check file '%s' lock status"), filename); | |
114 | ||
115 | if (fl.l_type == F_WRLCK && fl.l_pid != getpid()) | |
116 | return true; | |
117 | else | |
118 | return false; | |
119 | } | |
120 | ||
121 | /** | |
122 | * Lock a file. | |
123 | * | |
124 | * @param lockfd The pointer to the lock file descriptor. It must be allocated | |
125 | * statically as its addresses is passed to a cleanup handler. | |
126 | * @param flags The lock flags specifying what type of locking to perform. | |
127 | * @param filename The name of the file to lock. | |
128 | * @param desc The description of the file to lock. | |
129 | */ | |
130 | void | |
131 | file_lock(int *lockfd, enum file_lock_flags flags, const char *filename, | |
132 | const char *desc) | |
133 | { | |
134 | struct flock fl; | |
135 | int lock_cmd; | |
136 | ||
137 | setcloexec(*lockfd, filename); | |
138 | ||
139 | file_lock_setup(&fl, F_WRLCK); | |
140 | ||
141 | if (flags == FILE_LOCK_WAIT) | |
142 | lock_cmd = F_SETLKW; | |
143 | else | |
144 | lock_cmd = F_SETLK; | |
145 | ||
146 | if (fcntl(*lockfd, lock_cmd, &fl) == -1) { | |
147 | if (errno == EACCES || errno == EAGAIN) | |
148 | ohshit(_("%s is locked by another process"), desc); | |
149 | else | |
150 | ohshite(_("unable to lock %s"), desc); | |
151 | } | |
152 | ||
153 | push_cleanup(file_unlock_cleanup, ~0, NULL, 0, 2, lockfd, desc); | |
154 | } | |
155 | ||
156 | void | |
157 | file_show(const char *filename) | |
158 | { | |
159 | pid_t pid; | |
160 | ||
161 | if (filename == NULL) | |
162 | internerr("file '%s' does not exist", filename); | |
163 | ||
164 | pid = subproc_fork(); | |
165 | if (pid == 0) { | |
166 | struct command cmd; | |
167 | const char *pager; | |
168 | ||
169 | pager = command_get_pager(); | |
170 | ||
171 | command_init(&cmd, pager, _("showing file on pager")); | |
172 | command_add_arg(&cmd, pager); | |
173 | command_add_arg(&cmd, filename); | |
174 | command_exec(&cmd); | |
175 | } | |
176 | subproc_reap(pid, _("showing file on pager"), SUBPROC_NOCHECK); | |
177 | } |