advio: make read_adv() distinguish ENOENT from other errors

Make it possible to distinguish ENOENT from other "non-fatal" errors
in read_adv(), so we can try more than one filename.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/libinstaller/advio.c b/libinstaller/advio.c
index 3112fa4..7bfc098 100644 (file)
--- a/libinstaller/advio.c
+++ b/libinstaller/advio.c
@@ -36,8 +36,8 @@
 
 /*
  * Read the ADV from an existing instance, or initialize if invalid.
- * Returns -1 on fatal errors, 0 if ADV is okay, and 1 if no valid
- * ADV was found.
+ * Returns -1 on fatal errors, 0 if ADV is okay, 1 if the ADV is
+ * invalid, and 2 if the file does not exist.
  */
 int read_adv(const char *path, const char *cfg)
 {
@@ -60,6 +60,7 @@ int read_adv(const char *path, const char *cfg)
            err = -1;
        } else {
            syslinux_reset_adv(syslinux_adv);
+           err = 2;            /* Nonexistence is not a fatal error */
        }
     } else if (fstat(fd, &st)) {
        err = -1;