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[libvirt] [PATCH] build: avoid unsafe functions in libgen.h



POSIX says that both basename() and dirname() may return static
storage (aka they are not thread-safe); and that they may but
not must modify their input argument.  Furthermore, <libgen.h>
is not available on all platforms.  For these reasons, you should
never use these functions in a multi-threaded library.

Gnulib instead recommends a way to avoid the portability nightmare:
gnulib's "dirname.h" provides useful counterparts.  The obvious
dir_name() and base_name() are GPL (because they malloc(), but call
exit() on failure) so we can't use them; but the LGPL variants
mdir_name() (malloc's or returns NULL) and last_component (always
points into the incoming string without modifying it, differing
from basename semantics only on corner cases like the empty string
that we shouldn't be hitting in the first place) are already in use
in libvirt.  This finishes the swap over to the safe functions.

* cfg.mk (sc_prohibit_libgen): New rule.
* src/util/vircgroup.c: Fix offenders.
* src/parallels/parallels_storage.c (parallelsPoolAddByDomain):
Likewise.
* src/parallels/parallels_network.c (parallelsGetBridgedNetInfo):
Likewise.
* src/node_device/node_device_udev.c (udevProcessSCSIHost)
(udevProcessSCSIDevice): Likewise.
* src/storage/storage_backend_disk.c
(virStorageBackendDiskDeleteVol): Likewise.
* src/util/virpci.c (virPCIGetDeviceAddressFromSysfsLink):
Likewise.
* src/util/virstoragefile.h (_virStorageFileMetadata): Avoid false
positive.

Signed-off-by: Eric Blake <eblake redhat com>
---

Spotted during a review of Laine's pending work.

 cfg.mk                             | 6 ++++++
 src/node_device/node_device_udev.c | 7 ++++---
 src/parallels/parallels_network.c  | 4 +++-
 src/parallels/parallels_storage.c  | 8 ++++----
 src/storage/storage_backend_disk.c | 5 +++--
 src/util/vircgroup.c               | 3 +--
 src/util/virpci.c                  | 3 ++-
 src/util/virstoragefile.h          | 2 +-
 8 files changed, 24 insertions(+), 14 deletions(-)

diff --git a/cfg.mk b/cfg.mk
index ebb6613..f0f78f5 100644
--- a/cfg.mk
+++ b/cfg.mk
@@ -493,6 +493,12 @@ sc_prohibit_gethostby:
 	halt='use getaddrinfo, not gethostby*'				\
 	  $(_sc_search_regexp)

+# dirname and basename from <libgen.h> are not required to be thread-safe
+sc_prohibit_libgen:
+	@prohibit='( (base|dir)name *\(|include .libgen\.h)'		\
+	halt='use functions from gnulib "dirname.h", not <libgen.h>'	\
+	  $(_sc_search_regexp)
+
 # raw xmlGetProp requires some nasty casts
 sc_prohibit_xmlGetProp:
 	@prohibit='\<xmlGetProp *\('					\
diff --git a/src/node_device/node_device_udev.c b/src/node_device/node_device_udev.c
index 92292be..f98841e 100644
--- a/src/node_device/node_device_udev.c
+++ b/src/node_device/node_device_udev.c
@@ -1,7 +1,7 @@
 /*
  * node_device_udev.c: node device enumeration - libudev implementation
  *
- * Copyright (C) 2009-2012 Red Hat, Inc.
+ * Copyright (C) 2009-2013 Red Hat, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -26,6 +26,7 @@
 #include <scsi/scsi.h>
 #include <c-ctype.h>

+#include "dirname.h"
 #include "node_device_udev.h"
 #include "virerror.h"
 #include "node_device_conf.h"
@@ -653,7 +654,7 @@ static int udevProcessSCSIHost(struct udev_device *device ATTRIBUTE_UNUSED,
     union _virNodeDevCapData *data = &def->caps->data;
     char *filename = NULL;

-    filename = basename(def->sysfs_path);
+    filename = last_component(def->sysfs_path);

     if (!STRPREFIX(filename, "host")) {
         VIR_ERROR(_("SCSI host found, but its udev name '%s' does "
@@ -774,7 +775,7 @@ static int udevProcessSCSIDevice(struct udev_device *device ATTRIBUTE_UNUSED,
     union _virNodeDevCapData *data = &def->caps->data;
     char *filename = NULL, *p = NULL;

-    filename = basename(def->sysfs_path);
+    filename = last_component(def->sysfs_path);

     if (udevStrToLong_ui(filename, &p, 10, &data->scsi.host) == -1) {
         goto out;
diff --git a/src/parallels/parallels_network.c b/src/parallels/parallels_network.c
index c61e280..7a9436f 100644
--- a/src/parallels/parallels_network.c
+++ b/src/parallels/parallels_network.c
@@ -2,6 +2,7 @@
  * parallels_storage.c: core privconn functions for managing
  * Parallels Cloud Server hosts
  *
+ * Copyright (C) 2013 Red Hat, Inc.
  * Copyright (C) 2012 Parallels, Inc.
  *
  * This library is free software; you can redistribute it and/or
@@ -23,6 +24,7 @@
 #include <config.h>

 #include "datatypes.h"
+#include "dirname.h"
 #include "viralloc.h"
 #include "virerror.h"
 #include "md5.h"
@@ -64,7 +66,7 @@ static int parallelsGetBridgedNetInfo(virNetworkDefPtr def, virJSONValuePtr jobj
         goto cleanup;
     }

-    if (!(def->bridge = strdup(basename(bridgePath)))) {
+    if (!(def->bridge = strdup(last_component(bridgePath)))) {
         virReportOOMError();
         goto cleanup;
     }
diff --git a/src/parallels/parallels_storage.c b/src/parallels/parallels_storage.c
index cf2f790..271f370 100644
--- a/src/parallels/parallels_storage.c
+++ b/src/parallels/parallels_storage.c
@@ -2,6 +2,7 @@
  * parallels_storage.c: core driver functions for managing
  * Parallels Cloud Server hosts
  *
+ * Copyright (C) 2013 Red Hat, Inc.
  * Copyright (C) 2012 Parallels, Inc.
  *
  * This library is free software; you can redistribute it and/or
@@ -28,9 +29,9 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
-#include <libgen.h>

 #include "datatypes.h"
+#include "dirname.h"
 #include "viralloc.h"
 #include "configmake.h"
 #include "virstoragefile.h"
@@ -230,13 +231,12 @@ parallelsPoolAddByDomain(virConnectPtr conn, virDomainObjPtr dom)
     virStoragePoolObjPtr pool = NULL;
     int j;

-    if (!(poolPath = strdup(pdom->home))) {
+    poolPath = mdir_name(pdom->home);
+    if (!poolPath) {
         virReportOOMError();
         return NULL;
     }

-    poolPath = dirname(poolPath);
-
     for (j = 0; j < pools->count; j++) {
         if (STREQ(poolPath, pools->objs[j]->def->target.path)) {
             pool = pools->objs[j];
diff --git a/src/storage/storage_backend_disk.c b/src/storage/storage_backend_disk.c
index 40da306..1faf1ae 100644
--- a/src/storage/storage_backend_disk.c
+++ b/src/storage/storage_backend_disk.c
@@ -26,6 +26,7 @@
 #include <unistd.h>
 #include <stdio.h>

+#include "dirname.h"
 #include "virerror.h"
 #include "virlog.h"
 #include "storage_backend_disk.h"
@@ -728,8 +729,8 @@ virStorageBackendDiskDeleteVol(virConnectPtr conn ATTRIBUTE_UNUSED,
         goto cleanup;
     }

-    dev_name = basename(devpath);
-    srcname = basename(pool->def->source.devices[0].path);
+    dev_name = last_component(devpath);
+    srcname = last_component(pool->def->source.devices[0].path);
     VIR_DEBUG("dev_name=%s, srcname=%s", dev_name, srcname);

     isDevMapperDevice = virIsDevMapperDevice(devpath);
diff --git a/src/util/vircgroup.c b/src/util/vircgroup.c
index 5a2a75c..4c836c7 100644
--- a/src/util/vircgroup.c
+++ b/src/util/vircgroup.c
@@ -1,7 +1,7 @@
 /*
  * vircgroup.c: methods for managing control cgroups
  *
- * Copyright (C) 2010-2012 Red Hat, Inc.
+ * Copyright (C) 2010-2013 Red Hat, Inc.
  * Copyright IBM Corp. 2008
  *
  * This library is free software; you can redistribute it and/or
@@ -37,7 +37,6 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <signal.h>
-#include <libgen.h>
 #include <dirent.h>

 #define __VIR_CGROUP_ALLOW_INCLUDE_PRIV_H__
diff --git a/src/util/virpci.c b/src/util/virpci.c
index e58010b..5811f22 100644
--- a/src/util/virpci.c
+++ b/src/util/virpci.c
@@ -36,6 +36,7 @@
 #include <unistd.h>
 #include <stdlib.h>

+#include "dirname.h"
 #include "virlog.h"
 #include "viralloc.h"
 #include "vircommand.h"
@@ -1925,7 +1926,7 @@ virPCIGetDeviceAddressFromSysfsLink(const char *device_link,
         return ret;
     }

-    config_address = basename(device_path);
+    config_address = last_component(device_path);
     if (VIR_ALLOC(*bdf) != 0) {
         virReportOOMError();
         goto out;
diff --git a/src/util/virstoragefile.h b/src/util/virstoragefile.h
index d7b4508..ffe7a54 100644
--- a/src/util/virstoragefile.h
+++ b/src/util/virstoragefile.h
@@ -56,7 +56,7 @@ typedef virStorageFileMetadata *virStorageFileMetadataPtr;
 struct _virStorageFileMetadata {
     char *backingStore; /* Canonical name (absolute file, or protocol) */
     char *backingStoreRaw; /* If file, original name, possibly relative */
-    char *directory; /* The directory containing basename(backingStoreRaw) */
+    char *directory; /* The directory containing basename of backingStoreRaw */
     int backingStoreFormat; /* enum virStorageFileFormat */
     bool backingStoreIsFile;
     virStorageFileMetadataPtr backingMeta;
-- 
1.8.1.4


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