* implement proper PID file locking

git-svn-id: file:///home/lennart/svn/public/libdaemon/trunk@79 153bfa13-eec0-0310-be40-b0cb6a0e1b4b
author: Lennart Poettering <lennart@poettering.net> 2005-06-04 19:07:59 +0000
committer: Lennart Poettering <lennart@poettering.net> 2005-06-04 19:07:59 +0000
commit: 360ff12ea5b1e0dc3c83a373ddce20e109efaa9a (patch)
tree: 22efd48841fbbc289d6483a2f5384cc70e604cda
parent: 146b5df7b80e1745eef752568210645b7ff4cdff (diff)
7 files changed, 98 insertions, 46 deletions
diff --git a/configure.ac b/configure.ac
index c89af5a..292a905 100644
--- a/configure.ac
+++ b/configure.ac
@@ -20,7 +20,7 @@
 # Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 
 AC_PREREQ(2.59)
-AC_INIT([libdaemon],[0.7],[mzqnrzba (at) 0pointer (dot) de])
+AC_INIT([libdaemon],[0.8],[mzqnrzba (at) 0pointer (dot) de])
 AC_CONFIG_SRCDIR([libdaemon/dfork.c])
 AC_CONFIG_HEADERS([config.h])
 AM_INIT_AUTOMAKE([foreign -Wall])
diff --git a/doc/README.html.in b/doc/README.html.in
index fb6ebbc..755a39e 100644
--- a/doc/README.html.in
+++ b/doc/README.html.in
@@ -10,7 +10,7 @@
 <body>
 <h1><a name="top">libdaemon @PACKAGE_VERSION@</a></h1>
 
-<p><i>Copyright 2003,2004 Lennart Poettering &lt;@PACKAGE_BUGREPORT@&gt;</i></p>
+<p><i>Copyright 2003-2005 Lennart Poettering &lt;@PACKAGE_BUGREPORT@&gt;</i></p>
 
 <ul class="toc">
     <li><a href="#license">License</a></li>
@@ -42,6 +42,9 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.</p>
 
 <h2><a name="news">News</a></h2>
 
+<div class="news-date">Sat Jun 4 2005: </div>
+<p class="news-text"><a href="@PACKAGE_URL@libdaemon-0.8.tar.gz">Version 0.8</a> released; changes include: proper PID file locking</p>
+
 <div class="news-date">Sat Dec 18 2004: </div>
 <p class="news-text"><a href="@PACKAGE_URL@libdaemon-0.7.tar.gz">Version 0.7</a> released; changes include: minor cleanups; C++ compatibility; gcc 2.95 compatiblity</p>
 
@@ -131,7 +134,7 @@ compilation and <tt>make install</tt> (as root) for installation of
 <p>If you want to be notified whenever I release a new version of this software use the subscription feature of <a href="http://freshmeat.net/projects/libdaemon/">Freshmeat</a>.</p>
 
 <hr/>
-<address class="grey">Lennart Poettering &lt;@PACKAGE_BUGREPORT@&gt;, December 2004</address>
+<address class="grey">Lennart Poettering &lt;@PACKAGE_BUGREPORT@&gt;, June 2005</address>
 <div class="grey"><i>$Id$</i></div>
 
 </body>
diff --git a/doc/style.css b/doc/style.css
index 995b68e..27ea945 100644
--- a/doc/style.css
+++ b/doc/style.css
@@ -18,16 +18,8 @@
  * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  ***/
 
-body { color: black; background-color: white; margin: 0.5cm; } 
+body { color: black; background-color: white; } 
 a:link, a:visited { color: #900000; }       
-p { margin-left: 0.5cm; margin-right: 0.5cm; }
-div.news-date { margin-left: 0.5cm; font-size: 80%; color: #4f0000; } 
-p.news-text { margin-left: 1cm; }
-h1 { color: #00009F; }
-h2 { color: #00009F; }
-h3 { color: #00004F; margin-left: 0.5cm; }
-ul { margin-left: .5cm; }
-ol { margin-left: .5cm; }
-pre { margin-left: .5cm; background-color: #f0f0f0; padding: 0.4cm;}
-.grey { color: #afafaf; }
-
+div.news-date { font-size: 80%; font-style: italic; } 
+pre { background-color: #f0f0f0; padding: 0.4cm; }
+.grey { color: #8f8f8f; font-size: 80%; }
diff --git a/libdaemon/Makefile.am b/libdaemon/Makefile.am
index c14000c..f0dd5e6 100644
--- a/libdaemon/Makefile.am
+++ b/libdaemon/Makefile.am
@@ -39,4 +39,4 @@ libdaemon_la_SOURCES = \
 	daemon.h \
 	$(pkg_include_HEADERS)
 
-libdaemon_la_LDFLAGS = -version-info 2:1:2
+libdaemon_la_LDFLAGS = -version-info 2:2:2
diff --git a/libdaemon/dlog.c b/libdaemon/dlog.c
index 1fc3e08..88c4e60 100644
--- a/libdaemon/dlog.c
+++ b/libdaemon/dlog.c
@@ -29,7 +29,7 @@
 #include "dlog.h"
 
 enum daemon_log_flags daemon_log_use = DAEMON_LOG_AUTO|DAEMON_LOG_STDERR;
-char* daemon_log_ident = 0;
+char* daemon_log_ident = NULL;
 
 void daemon_log(int prio, const char* template, ...) {
     va_list arglist;
diff --git a/libdaemon/dlog.h b/libdaemon/dlog.h
index 0f74dde..55b641a 100644
--- a/libdaemon/dlog.h
+++ b/libdaemon/dlog.h
@@ -32,7 +32,7 @@ extern "C" {
  * Contains a robust API for logging messages
  */
 
-/** Specifies where to send the log messages to
+/** Specifies where to send the log messages to. The global variable daemon_log_use takes values of this type.
  */
 enum daemon_log_flags {
     DAEMON_LOG_SYSLOG = 1,   /**< Log messages are written to syslog */
diff --git a/libdaemon/dpid.c b/libdaemon/dpid.c
index e41e37c..7c90297 100644
--- a/libdaemon/dpid.c
+++ b/libdaemon/dpid.c
@@ -32,13 +32,15 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <time.h>
+#include <fcntl.h>
+#include <stddef.h>
 
 #include "dpid.h"
 #include "dlog.h"
 
 #define VARRUN "/var/run"
 
-const char *daemon_pid_file_ident = 0;
+const char *daemon_pid_file_ident = NULL;
 daemon_pid_file_proc_t daemon_pid_file_proc = daemon_pid_file_proc_default;
 
 const char *daemon_pid_file_proc_default(void) {
@@ -47,41 +49,74 @@ const char *daemon_pid_file_proc_default(void) {
     return fn;
 }
 
+static int lock_file(int fd, int enable) {
+    struct flock f;
+
+    memset(&f, 0, sizeof(f));
+    f.l_type = enable ? F_WRLCK : F_UNLCK;
+    f.l_whence = SEEK_SET;
+    f.l_start = 0;
+    f.l_len = 0;
+    
+    if (fcntl(fd, F_SETLKW, &f) < 0) {
+        daemon_log(LOG_WARNING, "fcntl(F_SETLKW) failed: %s", strerror(errno));
+        return -1;
+    }
+
+    return 0;
+}
+
 pid_t daemon_pid_file_is_running(void) {
     const char *fn;
     static char txt[256];
-    FILE *f;
-    pid_t pid;
-
+    int fd = -1, locked = -1;
+    pid_t ret = (pid_t) -1, pid;
+    ssize_t l;
 
     if (!(fn = daemon_pid_file_proc()))
-        return (pid_t) -1;
+        goto finish;
 
-    if (!(f = fopen(fn, "r")))
-        return (pid_t) -1;
+    if ((fd = open(fn, O_RDWR, 0644)) < 0) {
+        if (errno != ENOENT)
+            daemon_log(LOG_WARNING, "Failed to open PID file: %s", strerror(errno));
 
-        if (!(fgets(txt, sizeof(txt), f))) {
-        daemon_log(LOG_WARNING, "PID file corrupt, removing. (%s)", fn);
-        unlink(fn);
-        fclose(f);
-        return (pid_t) -1;
+        goto finish;
     }
 
-    fclose(f);
+    if ((locked = lock_file(fd, 1)) < 0)
+        goto finish;
+    
+    if ((l = read(fd, txt, sizeof(txt)-1)) < 0) {
+        daemon_log(LOG_WARNING, "read(): %s", strerror(errno));
+        unlink(fn);
+        goto finish;
+    }
 
+    txt[l] = 0;
+    
     if ((pid = (pid_t) atoi(txt)) <= 0) {
         daemon_log(LOG_WARNING, "PID file corrupt, removing. (%s)", fn);
         unlink(fn);
-        return (pid_t) -1;
+        goto finish;
     }
 
     if (kill(pid, 0) != 0 && errno != EPERM) {
-        daemon_log(LOG_WARNING, "Daemon %u killed: %s; removing PID file. (%s)", pid, strerror(errno), fn);
+        daemon_log(LOG_WARNING, "Process %lu died: %s; removing PID file. (%s)", (unsigned long) pid, strerror(errno), fn);
         unlink(fn);
-        return (pid_t) -1;
+        goto finish;
     }
+
+    ret = pid;
     
-    return pid;
+finish:
+
+    if (fd >= 0) {
+        if (locked >= 0)
+            lock_file(fd, 0);
+        close(fd);
+    }
+    
+    return ret;
 }
 
 int daemon_pid_file_kill(int s) {
@@ -128,23 +163,45 @@ int daemon_pid_file_kill_wait(int s, int m) {
 
 int daemon_pid_file_create(void) {
     const char *fn;
-    FILE *f;
-    mode_t save;
+    int fd = -1;
+    int ret = -1;
+    int locked = -1;
+    char t[64];
+    ssize_t l;
 
     if (!(fn = daemon_pid_file_proc()))
-        return -1;
+        goto finish;
 
-    save = umask(022);
-    
-    if (!(f = fopen(fn, "w")))
-        return -1;
+    if ((fd = open(fn, O_CREAT|O_RDWR|O_EXCL, 0644)) < 0) {
+        fprintf(stderr, "open(%s): %s", fn, strerror(errno));
+        goto finish;
+    }
 
-    fprintf(f, "%u\n", getpid());
-    fclose(f);
+    if ((locked = lock_file(fd, 1)) < 0) {
+        unlink(fn);
+        goto finish;
+    }
 
-    umask(save);
+    snprintf(t, sizeof(t), "%lu\n", (unsigned long) getpid());
 
-    return 0;
+    if (write(fd, t, l = strlen(t)) != l) {
+        daemon_log(LOG_WARNING, "write(): %s", strerror(errno));
+        unlink(fn);
+        goto finish;
+    }
+
+    ret = 0;
+
+finish:
+
+    if (fd >= 0) {
+        if (locked >= 0)
+            lock_file(fd, 0);
+            
+        close(fd);
+    }
+    
+    return ret;
 }
 
 int daemon_pid_file_remove(void) {
author	Lennart Poettering <lennart@poettering.net>	2005-06-04 19:07:59 +0000
committer	Lennart Poettering <lennart@poettering.net>	2005-06-04 19:07:59 +0000
commit	360ff12ea5b1e0dc3c83a373ddce20e109efaa9a (patch)
tree	22efd48841fbbc289d6483a2f5384cc70e604cda
parent	146b5df7b80e1745eef752568210645b7ff4cdff (diff)