index: Fix backwards search for bestblock

mzumsande · mzumsande · commit 698c524698c3 · 2021-11-26T16:27:25.000+01:00
This allows filters to be reconstructed when the best known block is the Genesis block without needing to reindex. It fixes Init errors seen in bitcoin#23289.
diff --git a/src/index/base.cpp b/src/index/base.cpp
@@ -91,11 +91,12 @@ bool BaseIndex::Init()
             const CBlockIndex* block = active_chain.Tip();
             prune_violation = true;
             // check backwards from the tip if we have all block data until we reach the indexes bestblock
-            while (block_to_test && block->pprev && (block->pprev->nStatus & BLOCK_HAVE_DATA)) {
+            while (block_to_test && block && (block->nStatus & BLOCK_HAVE_DATA)) {
                 if (block_to_test == block) {
                     prune_violation = false;
                     break;
                 }
+                assert(block->pprev);
                 block = block->pprev;
             }
         }

Original file line number	Diff line number	Diff line change
`@@ -91,11 +91,12 @@ bool BaseIndex::Init()`
`91`	`91`	`const CBlockIndex* block = active_chain.Tip();`
`92`	`92`	`prune_violation = true;`
`93`	`93`	`// check backwards from the tip if we have all block data until we reach the indexes bestblock`
`94`		`- while (block_to_test && block->pprev && (block->pprev->nStatus & BLOCK_HAVE_DATA)) {`
	`94`	`+ while (block_to_test && block && (block->nStatus & BLOCK_HAVE_DATA)) {`
`95`	`95`	`if (block_to_test == block) {`
`96`	`96`	`prune_violation = false;`
`97`	`97`	`break;`
`98`	`98`	`}`
	`99`	`+ assert(block->pprev);`
`99`	`100`	`block = block->pprev;`
`100`	`101`	`}`
`101`	`102`	`}`