Ignore corrupt indexes in Js5MasterIndex::create

Signed-off-by: Graham <gpe@openrs2.org>

archive/src/main/kotlin/org/openrs2/archive/cache/CacheImporter.kt

@@ -14,6 +14,7 @@ import org.openrs2.cache.Js5Index
 import org.openrs2.cache.Js5MasterIndex
 import org.openrs2.cache.MasterIndexFormat
 import org.openrs2.cache.Store
+import org.openrs2.cache.StoreCorruptException
 import org.openrs2.cache.VersionTrailer
 import org.openrs2.crypto.Whirlpool
 import org.openrs2.db.Database
@@ -124,9 +125,14 @@ public class CacheImporter @Inject constructor(
             val indexGroups = mutableListOf<Index>()
             try {
                 for (archive in store.list(Js5Archive.ARCHIVESET)) {
+                    try {
                         val indexGroup = readIndex(store, archive)
                         indexes[archive] = indexGroup.index
                         indexGroups += indexGroup
+                    } catch (ex: StoreCorruptException) {
+                        // see the comment in Js5MasterIndex::create
+                        logger.warn(ex) { "Skipping corrupt index (archive $archive)" }
+                    }
                 }
 
                 for (index in indexGroups) {

cache/src/main/kotlin/org/openrs2/cache/Js5MasterIndex.kt

@@ -122,16 +122,8 @@ public data class Js5MasterIndex(
 
             var nextArchive = 0
             for (archive in store.list(Js5Archive.ARCHIVESET)) {
-                /*
-                 * Fill in gaps with zeroes. I think this is consistent with
-                 * the official implementation: the TFU client warns that
-                 * entries with a zero CRC are probably invalid.
-                 */
-                for (i in nextArchive until archive) {
-                    masterIndex.entries += Entry(0, 0, 0, 0, null)
-                }
-
-                val entry = store.read(Js5Archive.ARCHIVESET, archive).use { buf ->
+                val entry = try {
+                    store.read(Js5Archive.ARCHIVESET, archive).use { buf ->
                         val checksum = buf.crc32()
                         val digest = buf.whirlpool()
 
@@ -154,6 +146,31 @@ public data class Js5MasterIndex(
                             Entry(version, checksum, groups, totalUncompressedLength, digest)
                         }
                     }
+                } catch (ex: StoreCorruptException) {
+                    /**
+                     * Unused indexes are never removed from the .idx255 file
+                     * by the client. If the .dat2 file reaches its maximum
+                     * size, it is truncated and all block numbers in the
+                     * .idx255 file will be invalid.
+                     *
+                     * Any in-use indexes will be overwritten, but unused
+                     * indexes will remain in the .idx255 file with invalid
+                     * block numbers.
+                     *
+                     * We therefore expect to see corrupt indexes sometimes. We
+                     * ignore these as if they didn't exist.
+                     */
+                    continue
+                }
+
+                /*
+                 * Fill in gaps with zeroes. I think this is consistent with
+                 * the official implementation: the TFU client warns that
+                 * entries with a zero CRC are probably invalid.
+                 */
+                for (i in nextArchive until archive) {
+                    masterIndex.entries += Entry(0, 0, 0, 0, null)
+                }
 
                 masterIndex.entries += entry
                 nextArchive = archive + 1