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Joachim Wiberg
6537b11e34
Framework from libuEv. Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
136 lines
3.5 KiB
C
136 lines
3.5 KiB
C
/* Functions for dealing with PID files (client side)
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*
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* Copyright (c) 2009-2021 Joachim Wiberg <troglobit@gmail.com>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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/**
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* @file pidfilefn.c
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* @author Joachim Wiberg
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* @date 2009-2021
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* @copyright ISC License
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*/
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <signal.h>
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#include <unistd.h>
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extern char *chomp(char *str);
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/**
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* Reads a PID value from a pidfile.
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* @param pidfile File containing PID, usually in @c /var/run/PROCNAME.pid
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*
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* This function takes a @p pidfile and returns the PID found therein.
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*
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* @returns On invalid @p pidfile, -1 with @a errno set. If the @p
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* pidfile is empty, or when its contents cannot be translated, this
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* function returns zero (0), on success this function returns a PID
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* value greater than one.
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*
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* @note PID 1 is reserved for the system init process.
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*
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* @exception EINVAL on invalid @p pidfile, or
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* @exception ENOENT when @p pidfile does not exist.
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*/
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pid_t pidfile_read(const char *pidfile)
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{
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int pid = 0;
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char buf[16];
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FILE *fp;
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if (!pidfile) {
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errno = EINVAL;
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return -1;
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}
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fp = fopen(pidfile, "r");
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if (!fp)
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return -1;
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if (fgets(buf, sizeof(buf), fp)) {
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char *ptr = chomp(buf);
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if (ptr) {
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errno = 0;
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pid = strtoul(ptr, NULL, 0);
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if (errno)
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pid = 0; /* Failed conversion. */
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}
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}
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fclose(fp);
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return pid;
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}
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/**
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* Poll for the existence of a pidfile and return PID.
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* @param pidfile Path to pidfile to poll for
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*
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* This function polls for the pidfile at @p pidfile for at most 5
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* seconds before timing out. If the file is created within that time
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* span the file is read and its PID contents returned.
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*
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* @returns The PID read from @p pidfile, or zero on timeout.
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*/
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pid_t pidfile_poll(const char *pidfile)
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{
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pid_t pid = 0;
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int tries = 0;
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/* Timeout = 100 * 50ms = 5s */
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while ((pid = pidfile_read(pidfile)) <= 0 && tries++ < 100)
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usleep(50000); /* Wait 50ms between retries */
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if (pid < 0)
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pid = 0;
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return pid;
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}
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/**
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* Send signal to a PID and cleanup pidfile afterwards.
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* @param pidfile File containing PID, usually in @c /var/run/PROCNAME.pid
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* @param signal Signal to send to PID found in @p pidfile.
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*
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* If @p signal is any of @c SIGTERM or @c SIGKILL, or if kill(2)
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* returns -1, the @p pidfile is removed.
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*
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* @returns POSIX OK(0) on success, non-zero otherwise.
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*/
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int pidfile_signal(const char *pidfile, int signal)
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{
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int pid = -1, ret = -1;
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pid = pidfile_read(pidfile);
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if (pid <= 0)
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return 1;
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ret = kill(pid, signal);
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if (!ret && signal == SIGKILL)
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ret = remove(pidfile);
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return ret;
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}
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/**
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* Local Variables:
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* compile-command: "make V=1 -f pidfilefn.mk"
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* indent-tabs-mode: t
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* c-file-style: "linux"
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* End:
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*/
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