[libvirt] [PATCH v2 1/2] util: Introduce virPidFileForceCleanupPath

[Martin Kletzander]

This function is used to cleanup a pidfile doing whatever it takes, even
killing the owning process.

Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
---
v2:
 - Don't use "/proc", but simply just try to acquire the pidfile.
 - https://www.redhat.com/archives/libvir-list/2014-October/msg00320.html

 src/libvirt_private.syms |  1 +
 src/util/virpidfile.c    | 42 ++++++++++++++++++++++++++++++++++++++++++
 src/util/virpidfile.h    |  2 ++
 3 files changed, 45 insertions(+)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index d6265ac..30d100d 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1810,6 +1810,7 @@ virPidFileBuildPath;
 virPidFileConstructPath;
 virPidFileDelete;
 virPidFileDeletePath;
+virPidFileForceCleanupPath;
 virPidFileRead;
 virPidFileReadIfAlive;
 virPidFileReadPath;
diff --git a/src/util/virpidfile.c b/src/util/virpidfile.c
index a3b8846..a64a1cf 100644
--- a/src/util/virpidfile.c
+++ b/src/util/virpidfile.c
@@ -37,6 +37,7 @@
 #include "c-ctype.h"
 #include "areadlink.h"
 #include "virstring.h"
+#include "virprocess.h"

 #define VIR_FROM_THIS VIR_FROM_NONE

@@ -567,3 +568,44 @@ virPidFileConstructPath(bool privileged,
     VIR_FREE(rundir);
     return ret;
 }
+
+
+/**
+ * virPidFileForceCleanupPath:
+ *
+ * Check if the pidfile is left around and clean it up whatever it
+ * takes.  This doesn't raise an error.  This function must not be
+ * called multiple times with the same path, be it in threads or
+ * processes.
+ *
+ * Returns 0 if the pidfile was successfully cleaned up, -1 otherwise.
+ */
+int
+virPidFileForceCleanupPath(const char *path)
+{
+    pid_t pid = 0;
+    int fd = -1;
+
+    if (!virFileExists(path))
+        return 0;
+
+    if (virPidFileReadPath(path, &pid) < 0)
+        return -1;
+
+    if (virPidFileAcquirePath(path, false, 0) == 0) {
+        virPidFileReleasePath(path, fd);
+    } else {
+        virResetLastError();
+
+        /* Only kill the process if the pid is valid one.  0 means
+         * there is somebody else doing the same pidfile cleanup
+         * machinery. */
+        if (pid)
+            virProcessKillPainfully(pid, true);
+
+        if (virPidFileDeletePath(path) < 0)
+            return -1;
+    }
+
+    return 0;
+}
diff --git a/src/util/virpidfile.h b/src/util/virpidfile.h
index ca1dbff..eb6516c 100644
--- a/src/util/virpidfile.h
+++ b/src/util/virpidfile.h
@@ -74,4 +74,6 @@ int virPidFileConstructPath(bool privileged,
                             const char *progname,
                             char **pidfile);

+int virPidFileForceCleanupPath(const char *path) ATTRIBUTE_NONNULL(1);
+
 #endif /* __VIR_PIDFILE_H__ */
--
2.1.2