build: avoid unsafe functions in libgen.h

POSIX says that both basename() and dirname() may return static
storage (aka they need not be 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 thread-safe 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>

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 *\('					\

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;

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;
     }

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];

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);

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__

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;

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;