[PATCH v5 2/9] cryptodisk: Refactor to discard have_it global

[Glenn Washburn]

The global "have_it" was never used by the crypto-backends, but was used to
determine if a crypto-backend successfully mounted a cryptodisk with a given
uuid. This is not needed however, because grub_device_iterate() will return
1 if and only if grub_cryptodisk_scan_device() returns 1. And
grub_cryptodisk_scan_device() will now only return 1 if a search_uuid has
been specified and a cryptodisk was successfully setup by a crypto-backend or
a cryptodisk of the requested uuid is already open.

To implement this grub_cryptodisk_scan_device_real is modified to return a
cryptodisk or NULL on failure and having the appropriate grub_errno set to
indicated failure. Note that grub_cryptodisk_scan_device_real will fail now
with a new errno GRUB_ERR_BAD_MODULE when none of the cryptodisk backend
modules succeed in identifying the source disk.

With this change grub_device_iterate() will return 1 when a crypto device is
successfully decrypted or when the source device has already been
successfully opened. Prior to this change, trying to mount an already
successfully opened device would trigger an error with the message "no such
cryptodisk found", which is at best misleading. The mount should silently
succeed in this case, which is what happens with this patch.

Signed-off-by: Glenn Washburn <development@efficientek.com>
---
 grub-core/disk/cryptodisk.c | 56 +++++++++++++++++++++++--------------
 1 file changed, 35 insertions(+), 21 deletions(-)

diff --git a/grub-core/disk/cryptodisk.c b/grub-core/disk/cryptodisk.c
index 90f82b2d3..9df3d310f 100644
--- a/grub-core/disk/cryptodisk.c
+++ b/grub-core/disk/cryptodisk.c
@@ -983,7 +983,7 @@ grub_util_cryptodisk_get_uuid (grub_disk_t disk)
 
 #endif
 
-static int check_boot, have_it;
+static int check_boot;
 static char *search_uuid;
 
 static void
@@ -995,7 +995,7 @@ cryptodisk_close (grub_cryptodisk_t dev)
   grub_free (dev);
 }
 
-static grub_err_t
+static grub_cryptodisk_t
 grub_cryptodisk_scan_device_real (const char *name, grub_disk_t source)
 {
   grub_err_t err;
@@ -1005,13 +1005,13 @@ grub_cryptodisk_scan_device_real (const char *name, 
grub_disk_t source)
   dev = grub_cryptodisk_get_by_source_disk (source);
 
   if (dev)
-    return GRUB_ERR_NONE;
+    return dev;
 
   FOR_CRYPTODISK_DEVS (cr)
   {
     dev = cr->scan (source, search_uuid, check_boot);
     if (grub_errno)
-      return grub_errno;
+      return NULL;
     if (!dev)
       continue;
     
@@ -1019,16 +1019,16 @@ grub_cryptodisk_scan_device_real (const char *name, 
grub_disk_t source)
     if (err)
     {
       cryptodisk_close (dev);
-      return err;
+      return NULL;
     }
 
     grub_cryptodisk_insert (dev, name, source);
 
-    have_it = 1;
-
-    return GRUB_ERR_NONE;
+    return dev;
   }
-  return GRUB_ERR_NONE;
+
+  grub_error (GRUB_ERR_BAD_MODULE, "no cryptodisk module can handle this 
device");
+  return NULL;
 }
 
 #ifdef GRUB_UTIL
@@ -1082,8 +1082,10 @@ static int
 grub_cryptodisk_scan_device (const char *name,
                             void *data __attribute__ ((unused)))
 {
-  grub_err_t err;
+  int ret = 0;
   grub_disk_t source;
+  grub_cryptodisk_t dev;
+  grub_errno = GRUB_ERR_NONE;
 
   /* Try to open disk.  */
   source = grub_disk_open (name);
@@ -1093,13 +1095,26 @@ grub_cryptodisk_scan_device (const char *name,
       return 0;
     }
 
-  err = grub_cryptodisk_scan_device_real (name, source);
+  dev = grub_cryptodisk_scan_device_real (name, source);
+  if (dev)
+    {
+      ret = (search_uuid != NULL && grub_strcasecmp (search_uuid, dev->uuid) 
== 0);
+      goto cleanup;
+    }
 
-  grub_disk_close (source);
-  
-  if (err)
+  /*
+   * Do not print error when err is GRUB_ERR_BAD_MODULE to avoid many unhelpful
+   * error messages.
+   */
+  if (grub_errno == GRUB_ERR_BAD_MODULE)
+    grub_error_pop ();
+
+  if (grub_errno != GRUB_ERR_NONE)
     grub_print_error ();
-  return have_it && search_uuid ? 1 : 0;
+
+ cleanup:
+  grub_disk_close (source);
+  return ret;
 }
 
 static grub_err_t
@@ -1110,9 +1125,9 @@ grub_cmd_cryptomount (grub_extcmd_context_t ctxt, int 
argc, char **args)
   if (argc < 1 && !state[1].set && !state[2].set)
     return grub_error (GRUB_ERR_BAD_ARGUMENT, "device name required");
 
-  have_it = 0;
   if (state[0].set)
     {
+      int found_uuid;
       grub_cryptodisk_t dev;
 
       dev = grub_cryptodisk_get_by_uuid (args[0]);
@@ -1125,10 +1140,10 @@ grub_cmd_cryptomount (grub_extcmd_context_t ctxt, int 
argc, char **args)
 
       check_boot = state[2].set;
       search_uuid = args[0];
-      grub_device_iterate (&grub_cryptodisk_scan_device, NULL);
+      found_uuid = grub_device_iterate (&grub_cryptodisk_scan_device, NULL);
       search_uuid = NULL;
 
-      if (!have_it)
+      if (!found_uuid)
        return grub_error (GRUB_ERR_BAD_ARGUMENT, "no such cryptodisk found");
       return GRUB_ERR_NONE;
     }
@@ -1142,7 +1157,6 @@ grub_cmd_cryptomount (grub_extcmd_context_t ctxt, int 
argc, char **args)
     }
   else
     {
-      grub_err_t err;
       grub_disk_t disk;
       grub_cryptodisk_t dev;
       char *diskname;
@@ -1178,13 +1192,13 @@ grub_cmd_cryptomount (grub_extcmd_context_t ctxt, int 
argc, char **args)
          return GRUB_ERR_NONE;
        }
 
-      err = grub_cryptodisk_scan_device_real (diskname, disk);
+      dev = grub_cryptodisk_scan_device_real (diskname, disk);
 
       grub_disk_close (disk);
       if (disklast)
        *disklast = ')';
 
-      return err;
+      return (dev == NULL) ? grub_errno : GRUB_ERR_NONE;
     }
 }
 
-- 
2.27.0