diff --git a/lib/common/pid.c b/lib/common/pid.c index b9749c6b76..bb53153dcf 100644 --- a/lib/common/pid.c +++ b/lib/common/pid.c @@ -1,240 +1,247 @@ /* * Copyright 2004-2022 the Pacemaker project contributors * * The version control history for this file may have further details. * * This source code is licensed under the GNU Lesser General Public License * version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY. */ #include #ifndef _GNU_SOURCE # define _GNU_SOURCE #endif #include #include #include #include int pcmk__pid_active(pid_t pid, const char *daemon) { static pid_t last_asked_pid = 0; /* log spam prevention */ int rc = 0; if (pid <= 0) { return EINVAL; } rc = kill(pid, 0); if ((rc < 0) && (errno == ESRCH)) { return ESRCH; /* no such PID detected */ } else if ((daemon == NULL) || !pcmk__procfs_has_pids()) { // The kill result is all we have, we can't check the name if (rc == 0) { return pcmk_rc_ok; } rc = errno; if (last_asked_pid != pid) { crm_info("Cannot examine PID %lld: %s", (long long) pid, pcmk_rc_str(rc)); last_asked_pid = pid; } return rc; /* errno != ESRCH */ } else { /* make sure PID hasn't been reused by another process XXX: might still be just a zombie, which could confuse decisions */ bool checked_through_kill = (rc == 0); char exe_path[PATH_MAX], myexe_path[PATH_MAX]; rc = pcmk__procfs_pid2path(pid, exe_path, sizeof(exe_path)); if (rc != pcmk_rc_ok) { if (rc != EACCES) { // Check again to filter out races if ((kill(pid, 0) < 0) && (errno == ESRCH)) { return ESRCH; } } if (last_asked_pid != pid) { if (rc == EACCES) { crm_info("Could not get executable for PID %lld: %s " CRM_XS " rc=%d", (long long) pid, pcmk_rc_str(rc), rc); } else { crm_err("Could not get executable for PID %lld: %s " CRM_XS " rc=%d", (long long) pid, pcmk_rc_str(rc), rc); } last_asked_pid = pid; } if (rc == EACCES) { // Trust kill if it was OK (we can't double-check via path) return checked_through_kill? pcmk_rc_ok : EACCES; } else { return ESRCH; /* most likely errno == ENOENT */ } } if (daemon[0] != '/') { rc = snprintf(myexe_path, sizeof(myexe_path), CRM_DAEMON_DIR"/%s", daemon); } else { rc = snprintf(myexe_path, sizeof(myexe_path), "%s", daemon); } if (rc > 0 && rc < sizeof(myexe_path) && !strcmp(exe_path, myexe_path)) { return pcmk_rc_ok; } } return ESRCH; } #define LOCKSTRLEN 11 /*! * \internal * \brief Read a process ID from a file * * \param[in] filename Process ID file to read * \param[out] pid Where to put PID that was read * * \return Standard Pacemaker return code */ int pcmk__read_pidfile(const char *filename, pid_t *pid) { int fd; struct stat sbuf; - int rc = pcmk_rc_unknown_format; + int rc = pcmk_rc_ok; long long pid_read = 0; char buf[LOCKSTRLEN + 1]; CRM_CHECK((filename != NULL) && (pid != NULL), return EINVAL); fd = open(filename, O_RDONLY); if (fd < 0) { return errno; } if ((fstat(fd, &sbuf) >= 0) && (sbuf.st_size < LOCKSTRLEN)) { sleep(2); /* if someone was about to create one, * give'm a sec to do so */ } if (read(fd, buf, sizeof(buf)) < 1) { rc = errno; goto bail; } - if (sscanf(buf, "%lld", &pid_read) > 0) { + errno = 0; + rc = sscanf(buf, "%lld", &pid_read); + + if (rc > 0) { if (pid_read <= 0) { rc = ESRCH; } else { rc = pcmk_rc_ok; *pid = (pid_t) pid_read; crm_trace("Read pid %lld from %s", pid_read, filename); } + } else if (rc == 0) { + rc = ENODATA; + } else { + rc = errno; } bail: close(fd); return rc; } /*! * \internal * \brief Check whether a process from a PID file matches expected values * * \param[in] filename Path of PID file * \param[in] expected_pid If positive, compare to this PID * \param[in] expected_name If not NULL, the PID from the PID file is valid * only if it is active as a process with this name * \param[out] pid If not NULL, store PID found in PID file here * * \return Standard Pacemaker return code */ int pcmk__pidfile_matches(const char *filename, pid_t expected_pid, const char *expected_name, pid_t *pid) { pid_t pidfile_pid = 0; int rc = pcmk__read_pidfile(filename, &pidfile_pid); if (pid) { *pid = pidfile_pid; } if (rc != pcmk_rc_ok) { // Error reading PID file or invalid contents unlink(filename); rc = ENOENT; } else if ((expected_pid > 0) && (pidfile_pid == expected_pid)) { // PID in file matches what was expected rc = pcmk_rc_ok; } else if (pcmk__pid_active(pidfile_pid, expected_name) == ESRCH) { // Contains a stale value unlink(filename); rc = ENOENT; } else if ((expected_pid > 0) && (pidfile_pid != expected_pid)) { // Locked by existing process rc = EEXIST; } return rc; } /*! * \internal * \brief Create a PID file for the current process (if not already existent) * * \param[in] filename Name of PID file to create * \param[in] name Name of current process * * \return Standard Pacemaker return code */ int pcmk__lock_pidfile(const char *filename, const char *name) { pid_t mypid = getpid(); int fd = 0; int rc = 0; char buf[LOCKSTRLEN + 2]; rc = pcmk__pidfile_matches(filename, 0, name, NULL); if ((rc != pcmk_rc_ok) && (rc != ENOENT)) { // Locked by existing process return rc; } fd = open(filename, O_CREAT | O_WRONLY | O_EXCL, 0644); if (fd < 0) { return errno; } snprintf(buf, sizeof(buf), "%*lld\n", LOCKSTRLEN - 1, (long long) mypid); rc = write(fd, buf, LOCKSTRLEN); close(fd); if (rc != LOCKSTRLEN) { crm_perror(LOG_ERR, "Incomplete write to %s", filename); return errno; } rc = pcmk__pidfile_matches(filename, mypid, name, NULL); if (rc != pcmk_rc_ok) { // Something is really wrong -- maybe I/O error on read back? unlink(filename); } return rc; }