[PATCH libdrm] xf86drm: fallback to normal path when realpath fails

[Emil Velikov]

From: Emil Velikov <emil.velikov at collabora.com>

Earlier commit reworked our sysfs handling to use realpath.
Sadly that backfired since the Firefox sandboxing mechanism rejects
that. Despite the files/folders being in the allowed list, of the
sandboxing mechanism.

Oddly enough, the Chromium sandboxing doesn't complain about any of
this.

Since there are no Firefox releases with the fix, add a temporary
solution which falls back to the original handling.

Sadly, this won't work for virgl.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107516
Cc: Michel Dänzer <michel.daenzer at amd.com>
Cc: Mike <bugs.freedesktop.org at pm.port0.org>
Fixes: a02900133b3 ("xf86drm: introduce a get_real_pci_path() helper")
Signed-off-by: Emil Velikov <emil.velikov at collabora.com>
---
Gents, this should bring things back to normal. Can you please give it a
try?

Would be great to see Firefox roll out updates which make this workaround
unnessesary ;-)
---
 xf86drm.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/xf86drm.c b/xf86drm.c
index 336d64de..964bedf9 100644
--- a/xf86drm.c
+++ b/xf86drm.c
@@ -3014,6 +3014,14 @@ get_real_pci_path(int maj, int min, char *real_path)
     return real_path;
 }
 
+static char *
+get_normal_pci_path(int maj, int min, char *normal_path)
+{
+    snprintf(normal_path, PATH_MAX, "/sys/dev/char/%d:%d/device", maj, min);
+
+    return normal_path;
+}
+
 static int drmParsePciBusInfo(int maj, int min, drmPciBusInfoPtr info)
 {
 #ifdef __linux__
@@ -3021,7 +3029,8 @@ static int drmParsePciBusInfo(int maj, int min, drmPciBusInfoPtr info)
     char real_path[PATH_MAX + 1], *value;
     int num;
 
-    if (get_real_pci_path(maj, min, real_path) == NULL)
+    if (get_real_pci_path(maj, min, real_path) == NULL &&
+        get_normal_pci_path(maj, min, real_path) == NULL)
         return -ENOENT;
 
     value = sysfs_uevent_get(real_path, "PCI_SLOT_NAME");
@@ -3142,7 +3151,8 @@ static int parse_separate_sysfs_files(int maj, int min,
     FILE *fp;
     int ret;
 
-    if (get_real_pci_path(maj, min, real_path) == NULL)
+    if (get_real_pci_path(maj, min, real_path) == NULL &&
+        get_normal_pci_path(maj, min, real_path) == NULL)
         return -ENOENT;
 
     for (unsigned i = ignore_revision ? 1 : 0; i < ARRAY_SIZE(attrs); i++) {
@@ -3174,7 +3184,8 @@ static int parse_config_sysfs_file(int maj, int min,
     unsigned char config[64];
     int fd, ret;
 
-    if (get_real_pci_path(maj, min, real_path) == NULL)
+    if (get_real_pci_path(maj, min, real_path) == NULL &&
+        get_normal_pci_path(maj, min, real_path) == NULL)
         return -ENOENT;
 
     snprintf(path, PATH_MAX, "%s/config", real_path);
-- 
2.18.0