Fix non-ab fuse ota fail bug

Fix the 'Calculate the offset to last partial block' logic in
ReadBlockAligndData. If file_size % fuse_block_size_ < source_block_size_,
the origin map logic will get a wrong block address of last block.
This bug leads to the non-ab fuse ota fail.

Test: compare the md5 of origin pkg and pkg reading from fuse.
Change-Id: Ic5132a7e9919cc2e91390231be342b97421ea23e

1 files changed, 7 insertions, 2 deletions

diff --git a/fuse_sideload/fuse_provider.cpp b/fuse_sideload/fuse_provider.cpp
index 8fa1b5c2..2183d084 100644
--- a/fuse_sideload/fuse_provider.cpp
+++ b/fuse_sideload/fuse_provider.cpp
@@ -118,11 +118,16 @@ bool FuseBlockDataProvider::ReadBlockAlignedData(uint8_t* buffer, uint32_t fetch
   }
 
   if (uint64_t tailing_bytes = fetch_size % source_block_size_; tailing_bytes != 0) {
-    // Calculate the offset to last partial block.
+    // Calculate the offset to last partial block. Two possibilities as below:
+    // 1: fetch_size < source_block_size_, the read_ranges is a blank range_set.
+    //    Get the last block num through GetBlockNumber() of the offset block.
+    // 2: fetch_size >= source_block_size_, the last block num is already stored
+    //    in read-ranges by GetSubRanges() above.
     uint64_t tailing_offset =
         read_ranges.value()
             ? static_cast<uint64_t>((read_ranges->cend() - 1)->second) * source_block_size_
-            : static_cast<uint64_t>(start_block) * source_block_size_;
+            : static_cast<uint64_t>(ranges_.GetBlockNumber(offset / source_block_size_)) *
+                  source_block_size_;
     if (!android::base::ReadFullyAtOffset(fd_, next_out, tailing_bytes, tailing_offset)) {
       PLOG(ERROR) << "Failed to read tailing " << tailing_bytes << " bytes at offset "
                   << tailing_offset;