commit 341824687a619f3203d2378e82785823922a6143 Author: Alexander Færøy ahf@torproject.org Date: Wed Apr 26 03:03:29 2017 +0200

Approximate memory usage needed for the LZMA backend.

This patch adds support for measuring the approximated memory usage by the individual `tor_lzma_compress_state_t` object instances.

The LZMA library provides the functions `lzma_easy_encoder_memusage()` and `lzma_easy_decoder_memusage()` which is used to find the estimated usage in bytes.

See: https://bugs.torproject.org/22066 --- src/common/compress_lzma.c | 42 ++++++++++++++++++++++++++++++++++-------- 1 file changed, 34 insertions(+), 8 deletions(-)

diff --git a/src/common/compress_lzma.c b/src/common/compress_lzma.c index 953971b..af1ba7e 100644 --- a/src/common/compress_lzma.c +++ b/src/common/compress_lzma.c @@ -127,13 +127,44 @@ struct tor_lzma_compress_state_t { size_t allocation; };

+#ifdef HAVE_LZMA +/** Return an approximate number of bytes stored in memory to hold the LZMA + * encoder/decoder state. */ +static size_t +tor_lzma_state_size_precalc(int compress, compression_level_t level) +{ + uint64_t memory_usage; + + if (compress) + memory_usage = lzma_easy_encoder_memusage(memory_level(level)); + else + memory_usage = lzma_easy_decoder_memusage(memory_level(level)); + + if (memory_usage == UINT64_MAX) { + log_warn(LD_GENERAL, "Unsupported compression level passed to LZMA %s", + compress ? "encoder" : "decoder"); + goto err; + } + + if (memory_usage + sizeof(tor_lzma_compress_state_t) > SIZE_MAX) + memory_usage = SIZE_MAX; + else + memory_usage += sizeof(tor_lzma_compress_state_t); + + return (size_t)memory_usage; + + err: + return 0; +} +#endif // HAVE_LZMA. + /** Construct and return a tor_lzma_compress_state_t object using * <b>method</b>. If <b>compress</b>, it's for compression; otherwise it's for * decompression. */ tor_lzma_compress_state_t * tor_lzma_compress_new(int compress, compress_method_t method, - compression_level_t compression_level) + compression_level_t level) { tor_assert(method == LZMA_METHOD);

@@ -147,15 +178,10 @@ tor_lzma_compress_new(int compress, // also what `tor_malloc_zero()` does. result = tor_malloc_zero(sizeof(tor_lzma_compress_state_t)); result->compress = compress; - - // FIXME(ahf): We should either try to do the pre-calculation that is done - // with the zlib backend or use a custom allocator here where we pass our - // tor_lzma_compress_state_t as the opaque value. - result->allocation = 0; + result->allocation = tor_lzma_state_size_precalc(compress, level);

if (compress) { - lzma_lzma_preset(&stream_options, - memory_level(compression_level)); + lzma_lzma_preset(&stream_options, memory_level(level));

retval = lzma_alone_encoder(&result->stream, &stream_options);