[libvirt] [PATCH 07/10] qemuDomainCreateDevice: Properly deal with symlinks

[Martin Kletzander]

On Fri, Jan 20, 2017 at 10:42:47AM +0100, Michal Privoznik wrote:
>Imagine you have a disk with the following source set up:
>
>/dev/disk/by-uuid/$uuid (symlink to) -> /dev/sda
>
>After cbc45525cb21 the transitive end of the symlink chain is
>created (/dev/sda), but we need to create any item in chain too.
>Others might rely on that.
>In this case, /dev/disk/by-uuid/$uuid comes from domain XML thus
>it is this path that secdriver tries to relabel. Not the resolved
>one.
>
>Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>---
> src/qemu/qemu_domain.c | 150 +++++++++++++++++++++++++++++++++++--------------
> 1 file changed, 108 insertions(+), 42 deletions(-)
>
>diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
>index 0f45f753e..8cbfb2d16 100644
>--- a/src/qemu/qemu_domain.c
>+++ b/src/qemu/qemu_domain.c
>@@ -68,6 +68,7 @@
> #endif
>
> #include <libxml/xpathInternals.h>
>+#include "dosname.h"
>
> #define VIR_FROM_THIS VIR_FROM_QEMU
>
>@@ -6958,70 +6959,135 @@ qemuDomainCreateDevice(const char *device,
>                        bool allow_noent)
> {
>     char *devicePath = NULL;
>-    char *canonDevicePath = NULL;
>+    char *target = NULL;
>     struct stat sb;
>     int ret = -1;
>+    bool isLink = false;
>+    bool create = false;
> #ifdef WITH_SELINUX
>     char *tcon = NULL;
> #endif
>
>-    if (virFileResolveAllLinks(device, &canonDevicePath) < 0) {
>+    if (lstat(device, &sb) < 0) {
>         if (errno == ENOENT && allow_noent) {
>             /* Ignore non-existent device. */
>-            ret = 0;
>-            goto cleanup;
>+            return 0;
>         }
>-
>-        virReportError(errno, _("Unable to canonicalize %s"), device);
>-        goto cleanup;
>-    }
>-
>-    if (!STRPREFIX(canonDevicePath, DEVPREFIX)) {
>-        ret = 0;
>-        goto cleanup;
>+        virReportSystemError(errno, _("Unable to stat %s"), device);
>+        return ret;
>     }
>
>-    if (virAsprintf(&devicePath, "%s/%s",
>-                    path, canonDevicePath + strlen(DEVPREFIX)) < 0)
>-        goto cleanup;
>+    isLink = S_ISLNK(sb.st_mode);
>
>-    if (stat(canonDevicePath, &sb) < 0) {
>-        if (errno == ENOENT && allow_noent) {
>-            /* Ignore non-existent device. */
>-            ret = 0;
>+    /* Here, @device might be whatever path in the system. We
>+     * should create the path in the namespace iff its "/dev"

s/its/it's/

ACK
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