lzma compressor: add support for the "extreme" flag

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

4 files changed, 58 insertions, 11 deletions

diff --git a/include/sqfs/compressor.h b/include/sqfs/compressor.h
index bdb942e..a257c3a 100644
--- a/include/sqfs/compressor.h
+++ b/include/sqfs/compressor.h
@@ -262,6 +262,17 @@ typedef enum {
 	SQFS_COMP_FLAG_LZ4_ALL = 0x0001,
 
 	/**
+	 * @brief Tell the LZMAv1 compressor to try the "extreme" option.
+	 *
+	 * The "extreme" option means that the compressor should try some
+	 * strategies that it normally wouldn't, that may drastically increase
+	 * compression time, but will not increase the decompressors memory
+	 * consumption.
+	 */
+	SQFS_COMP_FLAG_LZMA_EXTREME = 0x0001,
+	SQFS_COMP_FLAG_LZMA_ALL = 0x0001,
+
+	/**
 	 * @brief For XZ, set this to select the x86 BCJ filter.
 	 */
 	SQFS_COMP_FLAG_XZ_X86 = 0x0001,
diff --git a/lib/common/comp_opt.c b/lib/common/comp_opt.c
index 323fa4f..c279f1e 100644
--- a/lib/common/comp_opt.c
+++ b/lib/common/comp_opt.c
@@ -34,6 +34,10 @@ static const flag_t xz_flags[] = {
 	{ "extreme", SQFS_COMP_FLAG_XZ_EXTREME },
 };
 
+static const flag_t lzma_flags[] = {
+	{ "extreme", SQFS_COMP_FLAG_LZMA_EXTREME },
+};
+
 static const flag_t lz4_flags[] = {
 	{ "hc", SQFS_COMP_FLAG_LZ4_HC },
 };
@@ -131,6 +135,10 @@ int compressor_cfg_init_options(sqfs_compressor_config_t *cfg,
 		flags = xz_flags;
 		num_flags = sizeof(xz_flags) / sizeof(xz_flags[0]);
 		break;
+	case SQFS_COMP_LZMA:
+		flags = lzma_flags;
+		num_flags = sizeof(lzma_flags) / sizeof(lzma_flags[0]);
+		break;
 	case SQFS_COMP_LZ4:
 		flags = lz4_flags;
 		num_flags = sizeof(lz4_flags) / sizeof(lz4_flags[0]);
diff --git a/lib/sqfs/comp/compressor.c b/lib/sqfs/comp/compressor.c
index ea53339..2a0cebb 100644
--- a/lib/sqfs/comp/compressor.c
+++ b/lib/sqfs/comp/compressor.c
@@ -171,6 +171,7 @@ int sqfs_compressor_config_init(sqfs_compressor_config_t *cfg,
 		cfg->opt.xz.pb = SQFS_XZ_DEFAULT_PB;
 		break;
 	case SQFS_COMP_LZMA:
+		flag_mask |= SQFS_COMP_FLAG_LZMA_ALL;
 		break;
 	case SQFS_COMP_LZ4:
 		flag_mask |= SQFS_COMP_FLAG_LZ4_ALL;
diff --git a/lib/sqfs/comp/lzma.c b/lib/sqfs/comp/lzma.c
index 2a6cd1f..8db018d 100644
--- a/lib/sqfs/comp/lzma.c
+++ b/lib/sqfs/comp/lzma.c
@@ -24,6 +24,7 @@
 typedef struct {
 	sqfs_compressor_t base;
 	size_t block_size;
+	sqfs_u32 flags;
 } lzma_compressor_t;
 
 static int lzma_write_options(sqfs_compressor_t *base, sqfs_file_t *file)
@@ -39,18 +40,15 @@ static int lzma_read_options(sqfs_compressor_t *base, sqfs_file_t *file)
 	return SQFS_ERROR_UNSUPPORTED;
 }
 
-static sqfs_s32 lzma_comp_block(sqfs_compressor_t *base, const sqfs_u8 *in,
-				sqfs_u32 size, sqfs_u8 *out, sqfs_u32 outsize)
+static sqfs_s32 try_compress(lzma_compressor_t *lzma, sqfs_u32 preset,
+			     const sqfs_u8 *in, size_t size,
+			     sqfs_u8 *out, size_t outsize)
 {
-	lzma_compressor_t *lzma = (lzma_compressor_t *)base;
 	lzma_stream strm = LZMA_STREAM_INIT;
 	lzma_options_lzma opt;
 	int ret;
 
-	if (outsize < LZMA_HEADER_SIZE || size >= 0x7FFFFFFF)
-		return SQFS_ERROR_ARG_INVALID;
-
-	lzma_lzma_preset(&opt, LZMA_DEFAULT_LEVEL);
+	lzma_lzma_preset(&opt, preset);
 	opt.dict_size = lzma->block_size;
 
 	if (lzma_alone_encoder(&strm, &opt) != LZMA_OK) {
@@ -83,6 +81,33 @@ static sqfs_s32 lzma_comp_block(sqfs_compressor_t *base, const sqfs_u8 *in,
 	return strm.total_out;
 }
 
+static sqfs_s32 lzma_comp_block(sqfs_compressor_t *base, const sqfs_u8 *in,
+				sqfs_u32 size, sqfs_u8 *out, sqfs_u32 outsize)
+{
+	lzma_compressor_t *lzma = (lzma_compressor_t *)base;
+	sqfs_s32 ret, smallest;
+	sqfs_u32 preset;
+
+	if (outsize < LZMA_HEADER_SIZE || size >= 0x7FFFFFFF)
+		return SQFS_ERROR_ARG_INVALID;
+
+	preset = LZMA_DEFAULT_LEVEL;
+	ret = try_compress(lzma, preset, in, size, out, outsize);
+	if (ret < 0 || !(lzma->flags & SQFS_COMP_FLAG_LZMA_EXTREME))
+		return ret;
+
+	preset |= LZMA_PRESET_EXTREME;
+	smallest = ret;
+
+	ret = try_compress(lzma, preset, in, size, out, outsize);
+	if (ret < 0 || (ret > 0 && (smallest == 0 || ret < smallest)))
+		return ret;
+
+	preset &= ~LZMA_PRESET_EXTREME;
+	return smallest == 0 ? 0 :
+		try_compress(lzma, preset, in, size, out, outsize);
+}
+
 static sqfs_s32 lzma_uncomp_block(sqfs_compressor_t *base, const sqfs_u8 *in,
 				  sqfs_u32 size, sqfs_u8 *out, sqfs_u32 outsize)
 {
@@ -151,9 +176,7 @@ static void lzma_get_configuration(const sqfs_compressor_t *base,
 	memset(cfg, 0, sizeof(*cfg));
 	cfg->id = SQFS_COMP_LZMA;
 	cfg->block_size = lzma->block_size;
-
-	if (base->do_block == lzma_uncomp_block)
-		cfg->flags |= SQFS_COMP_FLAG_UNCOMPRESS;
+	cfg->flags = lzma->flags;
 }
 
 static sqfs_object_t *lzma_create_copy(const sqfs_object_t *cmp)
@@ -176,8 +199,11 @@ int lzma_compressor_create(const sqfs_compressor_config_t *cfg,
 {
 	sqfs_compressor_t *base;
 	lzma_compressor_t *lzma;
+	sqfs_u32 mask;
+
+	mask = SQFS_COMP_FLAG_GENERIC_ALL | SQFS_COMP_FLAG_LZMA_ALL;
 
-	if (cfg->flags & ~SQFS_COMP_FLAG_GENERIC_ALL)
+	if (cfg->flags & ~mask)
 		return SQFS_ERROR_UNSUPPORTED;
 
 	lzma = calloc(1, sizeof(*lzma));
@@ -186,6 +212,7 @@ int lzma_compressor_create(const sqfs_compressor_config_t *cfg,
 		return SQFS_ERROR_ALLOC;
 
 	lzma->block_size = cfg->block_size;
+	lzma->flags = cfg->flags;
 
 	if (lzma->block_size < SQFS_META_BLOCK_SIZE)
 		lzma->block_size = SQFS_META_BLOCK_SIZE;