From b7e5ca48f8c753a85ae77be3430fef83629d2178 Mon Sep 17 00:00:00 2001 From: "Daniel P. Berrange" Date: Fri, 5 Aug 2011 14:41:25 +0100 Subject: [PATCH] Introduce functions for checking whether a pidfile is valid 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 * libvirt_private.syms, util/virpidfile.c, util/virpidfile.h: Add virPidFileReadIfValid and virPidFileReadPathIfValid * network/bridge_driver.c: Use new APIs to check PID validity --- src/libvirt_private.syms | 2 + src/network/bridge_driver.c | 35 +++----------- src/util/virpidfile.c | 94 +++++++++++++++++++++++++++++++++++++ src/util/virpidfile.h | 8 ++++ 4 files changed, 110 insertions(+), 29 deletions(-) diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index 7a96c1e398..fee3520308 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms @@ -1122,7 +1122,9 @@ virFileFdopen; # virpidfile.h virPidFileBuildPath; virPidFileRead; +virPidFileReadIfAlive; virPidFileReadPath; +virPidFileReadPathIfAlive; virPidFileWrite; virPidFileWritePath; virPidFileDelete; diff --git a/src/network/bridge_driver.c b/src/network/bridge_driver.c index 8b2732057f..cea8771774 100644 --- a/src/network/bridge_driver.c +++ b/src/network/bridge_driver.c @@ -217,40 +217,17 @@ networkFindActiveConfigs(struct network_driver *driver) { /* Try and read dnsmasq/radvd pids if any */ if (obj->def->ips && (obj->def->nips > 0)) { - char *pidpath, *radvdpidbase; - - if (virPidFileRead(NETWORK_PID_DIR, obj->def->name, - &obj->dnsmasqPid) == 0) { - /* Check that it's still alive */ - if (kill(obj->dnsmasqPid, 0) != 0) - obj->dnsmasqPid = -1; - if (virAsprintf(&pidpath, "/proc/%d/exe", obj->dnsmasqPid) < 0) { - virReportOOMError(); - goto cleanup; - } - if (virFileLinkPointsTo(pidpath, DNSMASQ) == 0) - obj->dnsmasqPid = -1; - VIR_FREE(pidpath); - } + char *radvdpidbase; + + ignore_value(virPidFileReadIfAlive(NETWORK_PID_DIR, obj->def->name, + &obj->dnsmasqPid, DNSMASQ)); if (!(radvdpidbase = networkRadvdPidfileBasename(obj->def->name))) { virReportOOMError(); goto cleanup; } - if (virPidFileRead(NETWORK_PID_DIR, radvdpidbase, - &obj->radvdPid) == 0) { - /* Check that it's still alive */ - if (kill(obj->radvdPid, 0) != 0) - obj->radvdPid = -1; - if (virAsprintf(&pidpath, "/proc/%d/exe", obj->radvdPid) < 0) { - virReportOOMError(); - VIR_FREE(radvdpidbase); - goto cleanup; - } - if (virFileLinkPointsTo(pidpath, RADVD) == 0) - obj->radvdPid = -1; - VIR_FREE(pidpath); - } + ignore_value(virPidFileReadIfAlive(NETWORK_PID_DIR, radvdpidbase, + &obj->radvdPid, RADVD)); VIR_FREE(radvdpidbase); } } diff --git a/src/util/virpidfile.c b/src/util/virpidfile.c index 25c3272b38..c0b12867db 100644 --- a/src/util/virpidfile.c +++ b/src/util/virpidfile.c @@ -24,6 +24,7 @@ #include #include +#include #include "virpidfile.h" #include "virfile.h" @@ -164,6 +165,99 @@ int virPidFileRead(const char *dir, } + +/** + * virPidFileReadPathIfAlive: + * @path: path to pidfile + * @pid: variable to return pid in + * @binpath: path of executable associated with the pidfile + * + * This will attempt to read a pid from @path, and store it + * in @pid. The @pid will only be set, however, if the + * pid in @path is running, and its executable path + * resolves to @binpath. This adds protection against + * recycling of previously reaped pids. + * + * 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; + } + + 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); + + return 0; +} + + +/** + * virPidFileReadIfAlive: + * @dir: directory containing pidfile + * @name: base filename of pidfile + * @pid: variable to return pid in + * @binpath: path of executable associated with the pidfile + * + * This will attempt to read a pid from the pidfile @name + * in directory @dir, and store it in @pid. The @pid will + * only be set, however, if the pid in @name is running, + * and its executable path resolves to @binpath. This adds + * protection against recycling of previously reaped pids. + * + * 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 virPidFileReadIfAlive(const char *dir, + const char *name, + pid_t *pid, + const char *binpath) +{ + int rc = 0; + char *pidfile = NULL; + + if (name == NULL || dir == NULL) { + rc = -EINVAL; + goto cleanup; + } + + if (!(pidfile = virPidFileBuildPath(dir, name))) { + rc = -ENOMEM; + goto cleanup; + } + + rc = virPidFileReadPathIfAlive(pidfile, pid, binpath); + +cleanup: + VIR_FREE(pidfile); + return rc; +} + + int virPidFileDeletePath(const char *pidfile) { int rc = 0; diff --git a/src/util/virpidfile.h b/src/util/virpidfile.h index e28a3c1689..6659f1c1a4 100644 --- a/src/util/virpidfile.h +++ b/src/util/virpidfile.h @@ -42,6 +42,14 @@ int virPidFileRead(const char *dir, const char *name, pid_t *pid) ATTRIBUTE_RETURN_CHECK; +int virPidFileReadPathIfAlive(const char *path, + pid_t *pid, + const char *binpath) ATTRIBUTE_RETURN_CHECK; +int virPidFileReadIfAlive(const char *dir, + const char *name, + pid_t *pid, + const char *binpath) ATTRIBUTE_RETURN_CHECK; + int virPidFileDeletePath(const char *path); int virPidFileDelete(const char *dir, const char *name); -- GitLab