From a904ef7abf8358548650f31e5a257592ceebe710 Mon Sep 17 00:00:00 2001
From: Vreixo Formoso Lopes <metalpain2002@yahoo.es>
Date: Fri, 21 Sep 2007 15:37:04 +0000
Subject: [PATCH] Little code changes to improve isoburn_start_emulation().

---
 src/isofs_wrap.c | 41 +++++++++++++++++++++--------------------
 1 file changed, 21 insertions(+), 20 deletions(-)

diff --git a/src/isofs_wrap.c b/src/isofs_wrap.c
index e282a877..7add8fcf 100644
--- a/src/isofs_wrap.c
+++ b/src/isofs_wrap.c
@@ -202,7 +202,7 @@ int isoburn_free_rwopts(struct isoburn *o)
 */
 int isoburn_start_emulation(struct isoburn *o, int flag)
 {
- int ret;
+ int ret, i;
  off_t *data_count;
  struct burn_drive *drive;
  struct ecma119_pri_vol_desc *pvm;
@@ -213,22 +213,34 @@ int isoburn_start_emulation(struct isoburn *o, int flag)
  // TODO what about ms? where we validate valid iso image in ms disc?
  ret = burn_read_data(drive, (off_t) 0, o->target_iso_head, 
                       sizeof(o->target_iso_head), &data_count, 0);
+ // TODO mmm, can a read error mean an empty disc (e.g. CD-R)?
  if (ret <= 0)
    return -1;
 
- pvm = (struct ecma119_pri_vol_desc *)(o->target_iso_head + 16 * 2048);
+ /* check first 64K. If 0's, the disc is treated as a blank disc, and thus
+    overwritten without extra check. */
+ i = sizeof(o->target_iso_head);
+ while (i && !o->target_iso_head[i-1]) 
+   --i;
 
- /* sanity check */
- if (pvm->vol_desc_type[0] != 1 || pvm->vol_desc_version[0] != 1 
-     || pvm->file_structure_version[0] != 1 ) {
-   // TODO for now I treat this as a full disc
-   o->fabricated_disc_status= BURN_DISC_FULL;
+ if (!i) {
+   o->fabricated_disc_status= BURN_DISC_BLANK;
    return 1;
  }
 
+ pvm = (struct ecma119_pri_vol_desc *)(o->target_iso_head + 16 * 2048);
+
  if (!strncmp((char*)pvm->std_identifier, "CD001", 5)) {
    off_t size;
 
+   /* sanity check */
+   if (pvm->vol_desc_type[0] != 1 || pvm->vol_desc_version[0] != 1 
+       || pvm->file_structure_version[0] != 1 ) {
+     // TODO for now I treat this as a full disc
+     o->fabricated_disc_status= BURN_DISC_FULL;
+     return 1;
+   }
+
    /* ok, PVM found, set size */
    size = (off_t) iso_read_lsb(pvm->vol_space_size, 4);
    size *= (off_t) 2048; /* block size in bytes */
@@ -240,19 +252,8 @@ int isoburn_start_emulation(struct isoburn *o, int flag)
    isoburn_set_start_byte(o, (off_t) 0, 0);
    o->fabricated_disc_status= BURN_DISC_BLANK;
  } else {
-   int i;
-
-   /* check first 64K. If 0's, the disc is treated as a blank disc, and thus
-      overwritten without extra check. If not, the disc is treated as full,
-      and user needs to isoburn_disc_erase() it before burn it again */
-   i = sizeof(o->target_iso_head);
-   while (i && !o->target_iso_head[i-1]) 
-     --i;
-
-   if (i) 
-     o->fabricated_disc_status= BURN_DISC_FULL;
-   else
-     o->fabricated_disc_status= BURN_DISC_BLANK;
+   /* treat any disc in an unknown format as full */
+   o->fabricated_disc_status= BURN_DISC_FULL;
  }
  return 1;
 }