Re: [libvirt] [PATCH 3/5] Introduce functions for checking whether a pidfile is valid

From: "Daniel P. Berrange" <berrange(a)redhat.com&gt; In some cases the caller of virPidFileRead might like extra checks to determine whether the pid just read is really the one they are expecting. This adds virPidFileReadIfAlive which will check whether the pid is still alive with kill(0, -1), and (on linux only) will look at /proc/$PID/path

diff --git a/src/util/virpidfile.c b/src/util/virpidfile.c index 25c3272..c7adbfc 100644 --- a/src/util/virpidfile.c +++ b/src/util/virpidfile.c

+int virPidFileReadPathIfAlive(const char *path, + pid_t *pid, + const char *binpath) +{ + int rc; + char *procpath = NULL; + + rc = virPidFileReadPath(path, pid); + if (rc < 0) + return rc; + + /* Check that it's still alive */ + if (kill(*pid, 0) < 0) { + *pid = -1; + return 0; + } + + if (virAsprintf(&procpath, "/proc/%d/exe", *pid) < 0) { + *pid = -1; + return 0; + } +#ifdef __linux__ + if (virFileLinkPointsTo(procpath, binpath) == 0) + *pid = -1; +#endif + VIR_FREE(procpath);