Create /etc/openvswitch dir when package is installed.

[openvswitch] / lib / daemon.c

diff --git a/lib/daemon.c b/lib/daemon.c
index 6b61879dbb76723a926dea8683716bc39eaacca7..bc28973fc6a2d3d62c3aa7c270659387b8e3f0e1 100644 (file)
--- a/lib/daemon.c
+++ b/lib/daemon.c
@@ -23,6 +23,7 @@
 #include <string.h>
 #include <sys/resource.h>
 #include <sys/wait.h>
+#include <sys/stat.h>
 #include <unistd.h>
 #include "command-line.h"
 #include "fatal-signal.h"
@@ -42,6 +43,10 @@ static bool detach;
 /* --pidfile: Name of pidfile (null if none). */
 static char *pidfile;
 
+/* Device and inode of pidfile, so we can avoid reopening it. */
+static dev_t pidfile_dev;
+static ino_t pidfile_ino;
+
 /* --overwrite-pidfile: Create pidfile even if one already exists and is
    locked? */
 static bool overwrite_pidfile;
@@ -208,6 +213,15 @@ make_pidfile(void)
                         close(fd);
                     } else {
                         /* Keep 'fd' open to retain the lock. */
+                        struct stat s;
+
+                        if (!fstat(fd, &s)) {
+                            pidfile_dev = s.st_dev;
+                            pidfile_ino = s.st_ino;
+                        } else {
+                            VLOG_ERR("%s: fstat failed: %s",
+                                     pidfile, strerror(errno));
+                        }
                     }
                     free(text);
                 } else {
@@ -494,9 +508,21 @@ read_pidfile(const char *pidfile)
 {
     char line[128];
     struct flock lck;
+    struct stat s;
     FILE *file;
     int error;
 
+    if ((pidfile_ino || pidfile_dev)
+        && !stat(pidfile, &s)
+        && s.st_ino == pidfile_ino && s.st_dev == pidfile_dev) {
+        /* It's our own pidfile.  We can't afford to open it, because closing
+         * *any* fd for a file that a process has locked also releases all the
+         * locks on that file.
+         *
+         * Fortunately, we know the associated pid anyhow: */
+        return getpid();
+    }
+
     file = fopen(pidfile, "r");
     if (!file) {
         error = errno;