[PATCH xserver 03/11] modesetting: Simplify mst path blob parsing

[Daniel Martin]

The kernel guarantees that the MST path property blob of a connector
has a certain format and this property is immutable - can't be changed
from user space. With that in mind, reduce the parsing code to a minimum
matching the format criteria.

(Preparation to fold the parsing into output name creation function.)

Signed-off-by: Daniel Martin <consume.noise at gmail.com>
---
 hw/xfree86/drivers/modesetting/drmmode_display.c | 41 +++++++++---------------
 1 file changed, 15 insertions(+), 26 deletions(-)

diff --git a/hw/xfree86/drivers/modesetting/drmmode_display.c b/hw/xfree86/drivers/modesetting/drmmode_display.c
index 404bb1dc2..7ff55ef24 100644
--- a/hw/xfree86/drivers/modesetting/drmmode_display.c
+++ b/hw/xfree86/drivers/modesetting/drmmode_display.c
@@ -1636,48 +1636,37 @@ static xf86OutputPtr find_output(ScrnInfoPtr pScrn, int id)
     return NULL;
 }
 
-static int parse_path_blob(drmModePropertyBlobPtr path_blob, int *conn_base_id, char **path)
+static Bool
+parse_path_blob(drmModePropertyBlobPtr path_blob,
+        int *conn_base_id, char **extra_path)
 {
-    char *conn;
-    char conn_id[5];
-    int id, len;
-    char *blob_data;
+    char *colon, *dash;
 
     if (!path_blob)
-        return -1;
+        return FALSE;
 
-    blob_data = path_blob->data;
-    /* we only handle MST paths for now */
-    if (strncmp(blob_data, "mst:", 4))
-        return -1;
+    colon = strchr(path_blob->data, ':');
+    dash = strchr(path_blob->data, '-');
 
-    conn = strchr(blob_data + 4, '-');
-    if (!conn)
-        return -1;
-    len = conn - (blob_data + 4);
-    if (len + 1> 5)
-        return -1;
-    memcpy(conn_id, blob_data + 4, len);
-    conn_id[len + 1] = '\0';
-    id = strtoul(conn_id, NULL, 10);
+    if (colon && dash) {
+        *conn_base_id = strtoul(colon + 1, NULL, 10);
+        *extra_path = dash + 1;
 
-    *conn_base_id = id;
+        return TRUE;
+    }
 
-    *path = conn + 1;
-    return 0;
+    return FALSE;
 }
 
 static void
 drmmode_create_name(ScrnInfoPtr pScrn, drmModeConnectorPtr koutput, char *name,
-		    drmModePropertyBlobPtr path_blob)
+        drmModePropertyBlobPtr path_blob)
 {
-    int ret;
     char *extra_path;
     int conn_id;
     xf86OutputPtr output;
 
-    ret = parse_path_blob(path_blob, &conn_id, &extra_path);
-    if (ret == -1)
+    if (!parse_path_blob(path_blob, &conn_id, &extra_path))
         goto fallback;
 
     output = find_output(pScrn, conn_id);
-- 
2.13.6