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29 * $FreeBSD: head/lib/libutil/uucplock.c 255007 2013-08-28 21:10:37Z jilles $
31 * @(#)uucplock.c 8.1 (Berkeley) 6/6/93
34 #include <sys/types.h>
49 #define LOCKTMP "LCKTMP..%d"
50 #define LOCKFMT "LCK..%s"
52 #define GORET(level, val) { err = errno; uuerr = (val); \
53 goto __CONCAT(ret, level); }
55 /* Forward declarations */
56 static int put_pid (int fd, pid_t pid);
57 static pid_t get_pid (int fd,int *err);
60 * uucp style locking routines
64 uu_lock(const char *tty_name)
68 char lckname[sizeof(_PATH_UUCPLOCK) + NAME_MAX],
69 lcktmpname[sizeof(_PATH_UUCPLOCK) + NAME_MAX];
73 (void)snprintf(lcktmpname, sizeof(lcktmpname), _PATH_UUCPLOCK LOCKTMP,
75 (void)snprintf(lckname, sizeof(lckname), _PATH_UUCPLOCK LOCKFMT,
77 if ((tmpfd = open(lcktmpname, O_CREAT | O_TRUNC | O_WRONLY | O_CLOEXEC,
79 GORET(0, UU_LOCK_CREAT_ERR);
81 for (i = 0; i < MAXTRIES; i++) {
82 if (link (lcktmpname, lckname) < 0) {
84 GORET(1, UU_LOCK_LINK_ERR);
86 * file is already locked
87 * check to see if the process holding the lock
90 if ((fd = open(lckname, O_RDONLY | O_CLOEXEC)) < 0)
91 GORET(1, UU_LOCK_OPEN_ERR);
93 if ((pid_old = get_pid (fd, &err)) == -1)
94 GORET(2, UU_LOCK_READ_ERR);
98 if (kill(pid_old, 0) == 0 || errno != ESRCH)
99 GORET(1, UU_LOCK_INUSE);
101 * The process that locked the file isn't running, so
102 * we'll lock it ourselves
104 (void)unlink(lckname);
106 if (!put_pid (tmpfd, pid))
107 GORET(3, UU_LOCK_WRITE_ERR);
111 GORET(1, (i >= MAXTRIES) ? UU_LOCK_TRY_ERR : UU_LOCK_OK);
114 (void)unlink(lckname);
120 (void)unlink(lcktmpname);
127 uu_lock_txfr(const char *tty_name, pid_t pid)
130 char lckname[sizeof(_PATH_UUCPLOCK) + NAME_MAX];
132 snprintf(lckname, sizeof(lckname), _PATH_UUCPLOCK LOCKFMT, tty_name);
134 if ((fd = open(lckname, O_RDWR | O_CLOEXEC)) < 0)
135 return UU_LOCK_OWNER_ERR;
136 if (get_pid(fd, &err) != getpid())
137 err = UU_LOCK_OWNER_ERR;
139 lseek(fd, (off_t)0, SEEK_SET);
140 err = put_pid(fd, pid) ? 0 : UU_LOCK_WRITE_ERR;
148 uu_unlock(const char *tty_name)
150 char tbuf[sizeof(_PATH_UUCPLOCK) + NAME_MAX];
152 (void)snprintf(tbuf, sizeof(tbuf), _PATH_UUCPLOCK LOCKFMT, tty_name);
157 uu_lockerr(int uu_lockresult)
159 static char errbuf[128];
162 switch (uu_lockresult) {
164 return "device in use";
167 case UU_LOCK_OPEN_ERR:
168 fmt = "open error: %s";
170 case UU_LOCK_READ_ERR:
171 fmt = "read error: %s";
173 case UU_LOCK_CREAT_ERR:
174 fmt = "creat error: %s";
176 case UU_LOCK_WRITE_ERR:
177 fmt = "write error: %s";
179 case UU_LOCK_LINK_ERR:
180 fmt = "link error: %s";
182 case UU_LOCK_TRY_ERR:
183 fmt = "too many tries: %s";
185 case UU_LOCK_OWNER_ERR:
186 fmt = "not locking process: %s";
189 fmt = "undefined error: %s";
193 (void)snprintf(errbuf, sizeof(errbuf), fmt, strerror(errno));
198 put_pid(int fd, pid_t pid)
203 len = sprintf (buf, "%10d\n", (int)pid);
204 return write (fd, buf, (size_t)len) == len;
208 get_pid(int fd, int *err)
214 bytes_read = read (fd, buf, sizeof (buf) - 1);
215 if (bytes_read > 0) {
216 buf[bytes_read] = '\0';
217 pid = (pid_t)strtol (buf, NULL, 10);
220 *err = bytes_read ? errno : EINVAL;
225 /* end of uucplock.c */