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

From: "Daniel P. Berrange"<berrange(a)redhat.com> 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

+ * Returns -errno upon error, or zero on successful + * reading of the pidfile. If the PID was not still + * alive, zero will be returned, but @pid will be + * set to -1. + */ +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; + }