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Bug fixes with block memory lifetime and handling reads that cross the end of file barrier.

This commit is contained in:
Steve Atherton 2021-07-31 11:33:53 -07:00
parent 353efe7db2
commit 494acf7a54
1 changed files with 12 additions and 5 deletions
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17
fdbrpc/AsyncFileEncrypted.actor.cpp
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@ -53,7 +53,7 @@ public:
return Standalone<StringRef>(decrypted, arena);
}
ACTOR static Future<int> read(AsyncFileEncrypted* self, void* data, int length, int offset) {
ACTOR static Future<int> read(AsyncFileEncrypted* self, void* data, int length, int64_t offset) {
state const uint16_t firstBlock = offset / FLOW_KNOBS->ENCRYPTION_BLOCK_SIZE;
state const uint16_t lastBlock = (offset + length - 1) / FLOW_KNOBS->ENCRYPTION_BLOCK_SIZE;
state uint16_t block;
@ -61,15 +61,14 @@ public:
state int bytesRead = 0;
ASSERT(self->mode == AsyncFileEncrypted::Mode::READ_ONLY);
for (block = firstBlock; block <= lastBlock; ++block) {
state StringRef plaintext;
state Standalone<StringRef> plaintext;
auto cachedBlock = self->readBuffers.get(block);
if (cachedBlock.present()) {
plaintext = cachedBlock.get();
} else {
Standalone<StringRef> _plaintext = wait(readBlock(self, block));
self->readBuffers.insert(block, _plaintext);
plaintext = _plaintext;
wait(store(plaintext, readBlock(self, block)));
self->readBuffers.insert(block, plaintext);
}
auto start = (block == firstBlock) ? plaintext.begin() + (offset % FLOW_KNOBS->ENCRYPTION_BLOCK_SIZE)
: plaintext.begin();
@ -79,6 +78,14 @@ public:
if ((offset + length) % FLOW_KNOBS->ENCRYPTION_BLOCK_SIZE == 0) {
end = plaintext.end();
}
// The block could be short if it includes or is after the end of the file.
end = std::min(end, plaintext.end());
// If the start position is at or after the end of the block, the read is complete.
if (start == end || start >= plaintext.end()) {
break;
}
std::copy(start, end, output);
output += (end - start);
bytesRead += (end - start);