Add support for unsafe in-place compaction of WIM files

[wimlib] / src / blob_table.c

diff --git a/src/blob_table.c b/src/blob_table.c
index dd5bbd7e7e14c41877becc1afaaaac627a2573f0..96290e8de777afef6137f0e4d45433d5823e6e67 100644 (file)
--- a/src/blob_table.c
+++ b/src/blob_table.c
@@ -403,7 +403,12 @@ cmp_blobs_by_sequential_order(const void *p1, const void *p2)
 
        v = (int)blob1->blob_location - (int)blob2->blob_location;
 
-       /* Different locations?  */
+       /* Different locations?  Note: "unsafe compaction mode" requires that
+        * blobs in WIMs sort before all others.  For the logic here to ensure
+        * this, BLOB_IN_WIM must have the lowest value among all defined
+        * blob_locations.  Statically verify that the enum values haven't
+        * changed.  */
+       STATIC_ASSERT(BLOB_NONEXISTENT == 0 && BLOB_IN_WIM == 1);
        if (v)
                return v;
 
@@ -412,22 +417,39 @@ cmp_blobs_by_sequential_order(const void *p1, const void *p2)
                wim1 = blob1->rdesc->wim;
                wim2 = blob2->rdesc->wim;
 
-               /* Different (possibly split) WIMs?  */
+               /* Different WIM files?  */
                if (wim1 != wim2) {
+
+                       /* Resources from the WIM file currently being compacted
+                        * (if any) must always sort first.  */
+                       v = (int)wim2->being_compacted - (int)wim1->being_compacted;
+                       if (v)
+                               return v;
+
+                       /* Different split WIMs?  */
                        v = cmp_guids(wim1->hdr.guid, wim2->hdr.guid);
                        if (v)
                                return v;
+
+                       /* Different part numbers in the same split WIM?  */
+                       v = (int)wim1->hdr.part_number - (int)wim2->hdr.part_number;
+                       if (v)
+                               return v;
+
+                       /* Probably two WIMStructs for the same on-disk file.
+                        * Just sort by pointer.  */
+                       return wim1 < wim2 ? -1 : 1;
                }
 
-               /* Different part numbers in the same WIM?  */
-               v = (int)wim1->hdr.part_number - (int)wim2->hdr.part_number;
-               if (v)
-                       return v;
+               /* Same WIM file  */
 
+               /* Sort by increasing resource offset  */
                if (blob1->rdesc->offset_in_wim != blob2->rdesc->offset_in_wim)
                        return cmp_u64(blob1->rdesc->offset_in_wim,
                                       blob2->rdesc->offset_in_wim);
 
+               /* The blobs are in the same solid resource.  Sort by increasing
+                * offset in the resource.  */
                return cmp_u64(blob1->offset_in_res, blob2->offset_in_res);
 
        case BLOB_IN_FILE_ON_DISK: