sandbox: Open host file for read-only access if needed

Some files cannot be written but read-only access is still useful for
tests. Add a fallback to read-only access when needed.

This is useful in CI when opening a large data file provided by docker,
where read/write access would result in copying the file, thus needing
a lot of extra disk space.

Signed-off-by: Simon Glass <sjg@chromium.org>

diff --git a/drivers/block/sandbox.c b/drivers/block/sandbox.c
index 53925ce..1388498 100644 (file)
--- a/drivers/block/sandbox.c
+++ b/drivers/block/sandbox.c
@@ -125,9 +125,14 @@ int host_dev_bind(int devnum, char *filename, bool removable)
 
        fd = os_open(filename, OS_O_RDWR);
        if (fd == -1) {
-               printf("Failed to access host backing file '%s'\n", filename);
-               ret = -ENOENT;
-               goto err;
+               printf("Failed to access host backing file '%s', trying read-only\n",
+                      filename);
+               fd = os_open(filename, OS_O_RDONLY);
+               if (fd == -1) {
+                       printf("- still failed\n");
+                       ret = -ENOENT;
+                       goto err;
+               }
        }
        ret = blk_create_device(gd->dm_root, "sandbox_host_blk", str,
                                IF_TYPE_HOST, devnum, 512,