From 3119fb1ec2aa6ce7aca87844ca0581cbf3c0d193 Mon Sep 17 00:00:00 2001
From: Mattias Andrée <maandree@kth.se>
Date: Mon, 11 Jul 2016 13:35:11 +0200
Subject: Implement use of PID file
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Signed-off-by: Mattias Andrée <maandree@kth.se>
---
src/gammad.c | 176 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
src/util.c | 98 +++++++++++++++++++++++++++++++++
src/util.h | 23 ++++----
3 files changed, 286 insertions(+), 11 deletions(-)
create mode 100644 src/util.c
(limited to 'src')
diff --git a/src/gammad.c b/src/gammad.c
index 28411cf..ad1882e 100644
--- a/src/gammad.c
+++ b/src/gammad.c
@@ -17,7 +17,9 @@
*/
#include <libgamma.h>
+#include <sys/stat.h>
#include <errno.h>
+#include <fcntl.h>
#include <pwd.h>
#include <stdlib.h>
#include <stdio.h>
@@ -63,6 +65,7 @@ static char* get_pathname(libgamma_site_state_t* site, const char* suffix)
char* rc;
struct passwd* pw;
size_t n;
+ int saved_errno;
if (site->site)
{
@@ -104,7 +107,9 @@ static char* get_pathname(libgamma_site_state_t* site, const char* suffix)
return rc;
fail:
+ saved_errno = errno;
free(name);
+ errno = saved_errno;
return NULL;
}
@@ -197,6 +202,156 @@ static char* get_crtc_name(libgamma_crtc_information_t* info, libgamma_crtc_stat
}
+/**
+ * Check whether a PID file is outdated
+ *
+ * @param pidfile The PID file
+ * @param token An environment variable (including both key and value)
+ * that must exist in the process if it is a gammad process
+ * @return -1: An error occurred
+ * 0: The service is already running
+ * 1: The PID file is outdated
+ */
+static int is_pidfile_reusable(const char* pidfile, const char* token)
+{
+ /* PORTERS: /proc/$PID/environ is Linux specific */
+
+ char temp[sizeof("/proc//environ") + 3 * sizeof(pid_t)];
+ int fd = -1, saved_errno;
+ char* content = NULL;
+ char* p;
+ char* end;
+ pid_t pid = 0;
+ size_t n;
+
+ /* Get PID */
+ fd = open(pidfile, O_RDONLY);
+ if (fd < 0)
+ return -1;
+ content = nread(fd, &n);
+ if (content == NULL)
+ goto fail;
+ close(fd), fd = -1;
+
+ if (('0' > content[0]) || (content[0] > '9'))
+ goto bad;
+ if ((content[0] == '0') && ('0' <= content[1]) && (content[1] <= '9'))
+ goto bad;
+ for (p = content; *p; p++)
+ if (('0' <= *p) && (*p <= '9'))
+ pid = pid * 10 + (*p & 15);
+ else
+ break;
+ if (*p++ != '\n')
+ goto bad;
+ if (*p)
+ goto bad;
+ if ((size_t)(content - p) != n)
+ goto bad;
+ sprintf(temp, "%llu", (unsigned long long)pid);
+ if (strcmp(content, temp))
+ goto bad;
+
+ /* Validate PID */
+ sprintf(temp, "/proc/%llu/environ", (unsigned long long)pid);
+ fd = open(temp, O_RDONLY);
+ if (fd < 0)
+ return ((errno == ENOENT) || (errno == EACCES)) ? 1 : -1;
+ content = nread(fd, &n);
+ if (content == NULL)
+ goto fail;
+ close(fd), fd = -1;
+
+ for (end = (p = content) + n; p != end; p = strchr(p, '\0') + 1)
+ if (!strcmp(p, token))
+ return 0;
+
+ return 1;
+ bad:
+ fprintf(stderr, "%s: pid file contain invalid content: %s\n", argv0, pidfile);
+ errno = 0;
+ return -1;
+ fail:
+ saved_errno = errno;
+ free(content);
+ if (fd >= 0)
+ close(fd);
+ errno = saved_errno;
+ return -1;
+}
+
+
+/**
+ * Create PID file
+ *
+ * @param pidfile The pathname of the PID file
+ * @return Zero on success, -1 on error
+ */
+static int create_pidfile(char* pidfile)
+{
+ int fd, r, saved_errno;
+ char* p;
+ char* token;
+
+ /* Create token used to validate the service. */
+ token = malloc(sizeof("GAMMAD_PIDFILE_TOKEN=") + strlen(pidfile));
+ if (token == NULL)
+ return -1;
+ sprintf(token, "GAMMAD_PIDFILE_TOKEN=%s", pidfile);
+ if (putenv(token))
+ return -1;
+
+ /* Create PID file's directory. */
+ for (p = pidfile; *p == '/'; p++);
+ while ((p = strchr(p, '/')))
+ {
+ *p = '\0';
+ if (mkdir(pidfile, 0644) < 0)
+ if (errno != EEXIST)
+ return -1;
+ *p++ = '/';
+ }
+
+ /* Create PID file. */
+ retry:
+ fd = open(pidfile, O_CREAT | O_EXCL, 0644);
+ if (fd < 0)
+ {
+ if (errno == EINTR)
+ goto retry;
+ if (errno != EEXIST)
+ return -1;
+ r = is_pidfile_reusable(pidfile, token);
+ if (r > 0)
+ {
+ unlink(pidfile);
+ goto retry;
+ }
+ else if (r < 0)
+ goto fail;
+ fprintf(stderr, "%s: service is already running\n", argv0);
+ errno = 0;
+ return -1;
+ }
+
+ /* Write PID to PID file. */
+ if (dprintf(fd, "%llu\n", (unsigned long long)getpid()) < 0)
+ goto fail;
+
+ /* Done */
+ if (close(fd) < 0)
+ if (errno != EINTR)
+ return -1;
+ return 0;
+ fail:
+ saved_errno = errno;
+ close(fd);
+ unlink(pidfile);
+ errno = saved_errno;
+ return -1;
+}
+
+
/**
* Print usage information and exit
*/
@@ -210,11 +365,13 @@ static void usage(void)
int main(int argc, char** argv)
{
int method = -1, gerror, rc = 1, preserve = 0;
- char *sitename = NULL;
+ char* sitename = NULL;
libgamma_site_state_t site;
libgamma_partition_state_t* partitions = NULL;
libgamma_crtc_state_t* crtcs = NULL;
size_t i, j, n, n0;
+ char* pidpath = NULL;
+ char* socketpath = NULL;
memset(&site, 0, sizeof(site));
@@ -246,6 +403,19 @@ int main(int argc, char** argv)
if ((gerror = libgamma_site_initialise(&site, method, sitename)))
goto fail_libgamma;
+ /* Get PID file and socket pathname */
+ if (!(pidpath = get_pidfile_pathname(&site)))
+ goto fail;
+ if (!(socketpath = get_socket_pathname(&site)))
+ goto fail;
+
+ /* Create PID file */
+ if (create_pidfile(pidpath) < 0)
+ {
+ free(pidpath), pidpath = NULL;
+ goto fail;
+ }
+
/* Get partitions */
if (site.partitions_available)
if (!(partitions = calloc(site.partitions_available, sizeof(*partitions))))
@@ -426,6 +596,10 @@ int main(int argc, char** argv)
libgamma_partition_destroy(partitions + i);
free(partitions);
libgamma_site_destroy(&site);
+ free(socketpath);
+ if (pidpath)
+ unlink(pidpath);
+ free(pidpath);
return rc;
/* Fail */
fail:
diff --git a/src/util.c b/src/util.c
new file mode 100644
index 0000000..cb8c155
--- /dev/null
+++ b/src/util.c
@@ -0,0 +1,98 @@
+/**
+ * gammad -- Cooperative gamma server
+ * Copyright (C) 2016 Mattias Andrée (maandree@kth.se)
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+#include "util.h"
+
+#include <sys/stat.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+
+
+/**
+ * Duplicate a memory segment
+ *
+ * @param src The memory segment, must not be `NULL`
+ * @param n The size of the memory segment, must not be zero
+ * @return The duplicate of the memory segment,
+ * `NULL` on error
+ */
+void* memdup(const void* src, size_t n)
+{
+ void* dest = malloc(n);
+ if (dest == NULL)
+ return NULL;
+ memcpy(dest, src, n);
+ return dest;
+}
+
+
+/**
+ * Read an entire file
+ *
+ * @param fd The file descriptor
+ * @param n Output for the size of the file
+ * @return The read content, plus a NUL byte at
+ * the end (not counted in `*n`)
+ */
+void* nread(int fd, size_t* n)
+{
+ size_t size = 32;
+ ssize_t got;
+ struct stat st;
+ char* buf = NULL;
+ char* new;
+ int saved_errno;
+
+ *n = 0;
+
+ if (!fstat(fd, &st))
+ size = st.st_size <= 0 ? 32 : (size_t)(st.st_size);
+
+ buf = malloc(size + 1);
+ if (buf == NULL)
+ return NULL;
+
+ for (;;)
+ {
+ if (*n == size)
+ {
+ new = realloc(buf, (size <<= 1) + 1);
+ if (new == NULL)
+ goto fail;
+ buf = new;
+ }
+
+ got = read(fd, buf + *n, size - *n);
+ if (got < 0)
+ goto fail;
+ if (got == 0)
+ break;
+ *n += (size_t)got;
+ }
+
+ buf[*n] = '\0';
+ return buf;
+ fail:
+ saved_errno = errno;
+ free(buf);
+ errno = saved_errno;
+ return NULL;
+}
+
diff --git a/src/util.h b/src/util.h
index 4f9cbde..c44164b 100644
--- a/src/util.h
+++ b/src/util.h
@@ -15,8 +15,7 @@
* You should have received a copy of the GNU General Public License
* along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
-#include <stdlib.h>
-#include <string.h>
+#include <stddef.h>
@@ -28,12 +27,16 @@
* @return The duplicate of the memory segment,
* `NULL` on error
*/
-static inline void* memdup(const void* src, size_t n)
-{
- void* dest = malloc(n);
- if (dest == NULL)
- return NULL;
- memcpy(dest, src, n);
- return dest;
-}
+void* memdup(const void* src, size_t n);
+
+
+/**
+ * Read an entire file
+ *
+ * @param fd The file descriptor
+ * @param n Output for the size of the file
+ * @return The read content, plus a NUL byte at
+ * the end (not counted in `*n`)
+ */
+void* nread(int fd, size_t* n);
--
cgit v1.2.3-70-g09d2