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liblzma: Threaded decoder: Improve setting of pending_error.

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It doesn't need to be done conditionally. The comments try
to explain it.
This commit is contained in:
Lasse Collin 2022-04-06 23:11:59 +03:00
parent 90621da7f6
commit fe87b4cd53
1 changed files with 35 additions and 16 deletions
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43
src/liblzma/common/stream_decoder_mt.c
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@ -711,16 +711,29 @@ read_output_and_wait(struct lzma_stream_coder *coder,
// Check if any thread has indicated an error. // Check if any thread has indicated an error.
if (coder->thread_error != LZMA_OK) { if (coder->thread_error != LZMA_OK) {
if (coder->pending_error == LZMA_OK)
coder->pending_error
= coder->thread_error;
// If LZMA_FAIL_FAST was used, report errors // If LZMA_FAIL_FAST was used, report errors
// from worker threads immediately. // from worker threads immediately.
if (coder->fail_fast) { if (coder->fail_fast) {
ret = coder->thread_error; ret = coder->thread_error;
break; break;
} }
// Otherwise set pending_error. The value we
// set here will not actually get used other
// than working as a flag that an error has
// occurred. This is because in SEQ_ERROR
// all output before the error will be read
// first by calling this function, and once we
// reach the location of the (first) error the
// error code from the above lzma_outq_read()
// will be returned to the application.
//
// Use LZMA_PROG_ERROR since the value should
// never leak to the application. It's
// possible that pending_error has already
// been set but that doesn't matter: if we get
// here, pending_error only works as a flag.
coder->pending_error = LZMA_PROG_ERROR;
} }
// Check if decoding of the next Block can be started. // Check if decoding of the next Block can be started.
@ -1150,9 +1163,18 @@ stream_decode_mt(void *coder_ptr, const lzma_allocator *allocator,
// See if an error occurred. // See if an error occurred.
if (ret != LZMA_STREAM_END) { if (ret != LZMA_STREAM_END) {
if (coder->pending_error == LZMA_OK) // NOTE: Here and in all other places where
// pending_error is set, it may overwrite the value
// (LZMA_PROG_ERROR) set by read_output_and_wait().
// That function might overwrite value set here too.
// These are fine because when read_output_and_wait()
// sets pending_error, it actually works as a flag
// variable only ("some error has occurred") and the
// actual value of pending_error is not used in
// SEQ_ERROR. In such cases SEQ_ERROR will eventually
// get the correct error code from the return value of
// a later read_output_and_wait() call.
coder->pending_error = ret; coder->pending_error = ret;
coder->sequence = SEQ_ERROR; coder->sequence = SEQ_ERROR;
break; break;
} }
@ -1163,9 +1185,7 @@ stream_decode_mt(void *coder_ptr, const lzma_allocator *allocator,
if (coder->mem_next_filters == UINT64_MAX) { if (coder->mem_next_filters == UINT64_MAX) {
// One or more unknown Filter IDs. // One or more unknown Filter IDs.
if (coder->pending_error == LZMA_OK)
coder->pending_error = LZMA_OPTIONS_ERROR; coder->pending_error = LZMA_OPTIONS_ERROR;
coder->sequence = SEQ_ERROR; coder->sequence = SEQ_ERROR;
break; break;
} }
@ -1254,9 +1274,7 @@ stream_decode_mt(void *coder_ptr, const lzma_allocator *allocator,
&coder->block_options), &coder->block_options),
coder->block_options.uncompressed_size); coder->block_options.uncompressed_size);
if (ret != LZMA_OK) { if (ret != LZMA_OK) {
if (coder->pending_error == LZMA_OK)
coder->pending_error = ret; coder->pending_error = ret;
coder->sequence = SEQ_ERROR; coder->sequence = SEQ_ERROR;
break; break;
} }
@ -1425,9 +1443,7 @@ stream_decode_mt(void *coder_ptr, const lzma_allocator *allocator,
// Check if memory usage calculation and Block encoder // Check if memory usage calculation and Block encoder
// initialization succeeded. // initialization succeeded.
if (ret != LZMA_OK) { if (ret != LZMA_OK) {
if (coder->pending_error == LZMA_OK)
coder->pending_error = ret; coder->pending_error = ret;
coder->sequence = SEQ_ERROR; coder->sequence = SEQ_ERROR;
break; break;
} }
@ -1712,6 +1728,9 @@ stream_decode_mt(void *coder_ptr, const lzma_allocator *allocator,
return LZMA_OK; return LZMA_OK;
} }
// We only get here if no errors were detected by the worker
// threads. Errors from worker threads would have already been
// returned by the call to read_output_and_wait() above.
return coder->pending_error; return coder->pending_error;
default: default: