1 /* $NetBSD: postlock.c,v 1.4 2022/10/08 16:12:47 christos Exp $ */
2
3 /*++
4 /* NAME
5 /* postlock 1
6 /* SUMMARY
7 /* lock mail folder and execute command
8 /* SYNOPSIS
9 /* .fi
10 /* \fBpostlock\fR [\fB-c \fIconfig_dir\fR] [\fB-l \fIlock_style\fR]
11 /* [\fB-v\fR] \fIfile command...\fR
12 /* DESCRIPTION
13 /* The \fBpostlock\fR(1) command locks \fIfile\fR for exclusive
14 /* access, and executes \fIcommand\fR. The locking method is
15 /* compatible with the Postfix UNIX-style local delivery agent.
16 /*
17 /* Options:
18 /* .IP "\fB-c \fIconfig_dir\fR"
19 /* Read the \fBmain.cf\fR configuration file in the named directory
20 /* instead of the default configuration directory.
21 /* .IP "\fB-l \fIlock_style\fR"
22 /* Override the locking method specified via the
23 /* \fBmailbox_delivery_lock\fR configuration parameter (see below).
24 /* .IP \fB-v\fR
25 /* Enable verbose logging for debugging purposes. Multiple \fB-v\fR
26 /* options make the software increasingly verbose.
27 /* .PP
28 /* Arguments:
29 /* .IP \fIfile\fR
30 /* A mailbox file. The user should have read/write permission.
31 /* .IP \fIcommand...\fR
32 /* The command to execute while \fIfile\fR is locked for exclusive
33 /* access. The command is executed directly, i.e. without
34 /* interpretation by a shell command interpreter.
35 /* DIAGNOSTICS
36 /* The result status is 75 (EX_TEMPFAIL) when \fBpostlock\fR(1)
37 /* could not perform the requested operation. Otherwise, the
38 /* exit status is the exit status from the command.
39 /* BUGS
40 /* With remote file systems, the ability to acquire a lock does not
41 /* necessarily eliminate access conflicts. Avoid file access by
42 /* processes running on different machines.
43 /* ENVIRONMENT
44 /* .ad
45 /* .fi
46 /* .IP \fBMAIL_CONFIG\fR
47 /* Directory with Postfix configuration files.
48 /* .IP \fBMAIL_VERBOSE\fR
49 /* Enable verbose logging for debugging purposes.
50 /* CONFIGURATION PARAMETERS
51 /* .ad
52 /* .fi
53 /* The following \fBmain.cf\fR parameters are especially relevant to
54 /* this program.
55 /* The text below provides only a parameter summary. See
56 /* \fBpostconf\fR(5) for more details including examples.
57 /* LOCKING CONTROLS
58 /* .ad
59 /* .fi
60 /* .IP "\fBdeliver_lock_attempts (20)\fR"
61 /* The maximal number of attempts to acquire an exclusive lock on a
62 /* mailbox file or \fBbounce\fR(8) logfile.
63 /* .IP "\fBdeliver_lock_delay (1s)\fR"
64 /* The time between attempts to acquire an exclusive lock on a mailbox
65 /* file or \fBbounce\fR(8) logfile.
66 /* .IP "\fBstale_lock_time (500s)\fR"
67 /* The time after which a stale exclusive mailbox lockfile is removed.
68 /* .IP "\fBmailbox_delivery_lock (see 'postconf -d' output)\fR"
69 /* How to lock a UNIX-style \fBlocal\fR(8) mailbox before attempting delivery.
70 /* RESOURCE AND RATE CONTROLS
71 /* .ad
72 /* .fi
73 /* .IP "\fBfork_attempts (5)\fR"
74 /* The maximal number of attempts to fork() a child process.
75 /* .IP "\fBfork_delay (1s)\fR"
76 /* The delay between attempts to fork() a child process.
77 /* MISCELLANEOUS CONTROLS
78 /* .ad
79 /* .fi
80 /* .IP "\fBconfig_directory (see 'postconf -d' output)\fR"
81 /* The default location of the Postfix main.cf and master.cf
82 /* configuration files.
83 /* .IP "\fBimport_environment (see 'postconf -d' output)\fR"
84 /* The list of environment parameters that a privileged Postfix
85 /* process will import from a non-Postfix parent process, or name=value
86 /* environment overrides.
87 /* SEE ALSO
88 /* postconf(5), configuration parameters
89 /* LICENSE
90 /* .ad
91 /* .fi
92 /* The Secure Mailer license must be distributed with this software.
93 /* AUTHOR(S)
94 /* Wietse Venema
95 /* IBM T.J. Watson Research
96 /* P.O. Box 704
97 /* Yorktown Heights, NY 10598, USA
98 /*
99 /* Wietse Venema
100 /* Google, Inc.
101 /* 111 8th Avenue
102 /* New York, NY 10011, USA
103 /*--*/
104
105 /* System library. */
106
107 #include <sys_defs.h>
108 #include <sys/stat.h>
109 #include <sys/wait.h>
110 #include <stdlib.h>
111 #include <unistd.h>
112 #include <fcntl.h>
113 #include <errno.h>
114
115 /* Utility library. */
116
117 #include <msg.h>
118 #include <vstring.h>
119 #include <vstream.h>
120 #include <msg_vstream.h>
121 #include <iostuff.h>
122 #include <warn_stat.h>
123 #include <clean_env.h>
124
125 /* Global library. */
126
127 #include <mail_params.h>
128 #include <mail_version.h>
129 #include <dot_lockfile.h>
130 #include <deliver_flock.h>
131 #include <mail_conf.h>
132 #include <sys_exits.h>
133 #include <mbox_conf.h>
134 #include <mbox_open.h>
135 #include <dsn_util.h>
136 #include <mail_parm_split.h>
137
138 /* Application-specific. */
139
140 /* usage - explain */
141
usage(char * myname)142 static NORETURN usage(char *myname)
143 {
144 msg_fatal("usage: %s [-c config_dir] [-l lock_style] [-v] folder command...", myname);
145 }
146
147 /* fatal_exit - all failures are deemed recoverable */
148
fatal_exit(void)149 static void fatal_exit(void)
150 {
151 exit(EX_TEMPFAIL);
152 }
153
154 MAIL_VERSION_STAMP_DECLARE;
155
156 /* main - go for it */
157
main(int argc,char ** argv)158 int main(int argc, char **argv)
159 {
160 DSN_BUF *why;
161 char *folder;
162 char **command;
163 int ch;
164 int fd;
165 struct stat st;
166 int count;
167 WAIT_STATUS_T status;
168 pid_t pid;
169 int lock_mask;
170 char *lock_style = 0;
171 MBOX *mp;
172 ARGV *import_env;
173
174 /*
175 * Fingerprint executables and core dumps.
176 */
177 MAIL_VERSION_STAMP_ALLOCATE;
178
179 /*
180 * Be consistent with file permissions.
181 */
182 umask(022);
183
184 /*
185 * To minimize confusion, make sure that the standard file descriptors
186 * are open before opening anything else. XXX Work around for 44BSD where
187 * fstat can return EBADF on an open file descriptor.
188 */
189 for (fd = 0; fd < 3; fd++)
190 if (fstat(fd, &st) == -1
191 && (close(fd), open("/dev/null", O_RDWR, 0)) != fd)
192 msg_fatal("open /dev/null: %m");
193
194 /*
195 * Process environment options as early as we can. We are not set-uid,
196 * and we are supposed to be running in a controlled environment.
197 */
198 if (getenv(CONF_ENV_VERB))
199 msg_verbose = 1;
200
201 /*
202 * Set up logging and error handling. Intercept fatal exits so we can
203 * return a distinguished exit status.
204 */
205 msg_vstream_init(argv[0], VSTREAM_ERR);
206 msg_cleanup(fatal_exit);
207
208 /*
209 * Check the Postfix library version as soon as we enable logging.
210 */
211 MAIL_VERSION_CHECK;
212
213 /*
214 * Parse JCL.
215 */
216 while ((ch = GETOPT(argc, argv, "c:l:v")) > 0) {
217 switch (ch) {
218 default:
219 usage(argv[0]);
220 break;
221 case 'c':
222 if (setenv(CONF_ENV_PATH, optarg, 1) < 0)
223 msg_fatal("out of memory");
224 break;
225 case 'l':
226 lock_style = optarg;
227 break;
228 case 'v':
229 msg_verbose++;
230 break;
231 }
232 }
233 if (optind + 2 > argc)
234 usage(argv[0]);
235 folder = argv[optind];
236 command = argv + optind + 1;
237
238 /*
239 * Read the config file. The command line lock style can override the
240 * configured lock style.
241 */
242 mail_conf_read();
243 /* Enforce consistent operation of different Postfix parts. */
244 import_env = mail_parm_split(VAR_IMPORT_ENVIRON, var_import_environ);
245 update_env(import_env->argv);
246 argv_free(import_env);
247 lock_mask = mbox_lock_mask(lock_style ? lock_style :
248 get_mail_conf_str(VAR_MAILBOX_LOCK, DEF_MAILBOX_LOCK, 1, 0));
249
250 /*
251 * Lock the folder for exclusive access. Lose the lock upon exit. The
252 * command is not supposed to disappear into the background.
253 */
254 why = dsb_create();
255 if ((mp = mbox_open(folder, O_APPEND | O_WRONLY | O_CREAT,
256 S_IRUSR | S_IWUSR, (struct stat *) 0,
257 -1, -1, lock_mask, "5.2.0", why)) == 0)
258 msg_fatal("open file %s: %s", folder, vstring_str(why->reason));
259 dsb_free(why);
260
261 /*
262 * Run the command. Remove the lock after completion.
263 */
264 for (count = 1; (pid = fork()) == -1; count++) {
265 msg_warn("fork %s: %m", command[0]);
266 if (count >= var_fork_tries) {
267 mbox_release(mp);
268 exit(EX_TEMPFAIL);
269 }
270 sleep(var_fork_delay);
271 }
272 switch (pid) {
273 case 0:
274 (void) msg_cleanup((MSG_CLEANUP_FN) 0);
275 execvp(command[0], command);
276 msg_fatal("execvp %s: %m", command[0]);
277 default:
278 if (waitpid(pid, &status, 0) < 0)
279 msg_fatal("waitpid: %m");
280 vstream_fclose(mp->fp);
281 mbox_release(mp);
282 exit(WIFEXITED(status) ? WEXITSTATUS(status) : 1);
283 }
284 }
285