Add deep-copy function to compressor interface

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

6 files changed, 104 insertions, 0 deletions

diff --git a/include/compress.h b/include/compress.h
index 7c90b2c..1dfba12 100644
--- a/include/compress.h
+++ b/include/compress.h
@@ -44,6 +44,10 @@ struct compressor_t {
 	ssize_t (*do_block)(compressor_t *cmp, const uint8_t *in, size_t size,
 			    uint8_t *out, size_t outsize);
 
+	/* create another compressor just like this one, i.e.
+	   with the exact same settings */
+	compressor_t *(*create_copy)(compressor_t *cmp);
+
 	void (*destroy)(compressor_t *stream);
 };
 
diff --git a/lib/comp/gzip.c b/lib/comp/gzip.c
index 1068520..1fdc051 100644
--- a/lib/comp/gzip.c
+++ b/lib/comp/gzip.c
@@ -308,6 +308,36 @@ fail_value:
 	return -1;
 }
 
+static compressor_t *gzip_create_copy(compressor_t *cmp)
+{
+	gzip_compressor_t *gzip = malloc(sizeof(*gzip));
+	int ret;
+
+	if (gzip == NULL) {
+		perror("creating additional gzip compressor");
+		return NULL;
+	}
+
+	memcpy(gzip, cmp, sizeof(*gzip));
+	memset(&gzip->strm, 0, sizeof(gzip->strm));
+
+	if (gzip->compress) {
+		ret = deflateInit2(&gzip->strm, gzip->opt.level, Z_DEFLATED,
+				   gzip->opt.window, 8, Z_DEFAULT_STRATEGY);
+	} else {
+		ret = inflateInit(&gzip->strm);
+	}
+
+	if (ret != Z_OK) {
+		fputs("internal error creating additional zlib stream\n",
+		      stderr);
+		free(gzip);
+		return NULL;
+	}
+
+	return (compressor_t *)gzip;
+}
+
 compressor_t *create_gzip_compressor(bool compress, size_t block_size,
 				     char *options)
 {
@@ -340,6 +370,7 @@ compressor_t *create_gzip_compressor(bool compress, size_t block_size,
 	base->destroy = gzip_destroy;
 	base->write_options = gzip_write_options;
 	base->read_options = gzip_read_options;
+	base->create_copy = gzip_create_copy;
 
 	if (compress) {
 		ret = deflateInit2(&gzip->strm, level, Z_DEFLATED, window, 8,
diff --git a/lib/comp/lz4.c b/lib/comp/lz4.c
index ffa84dc..abb6c5c 100644
--- a/lib/comp/lz4.c
+++ b/lib/comp/lz4.c
@@ -97,6 +97,19 @@ static ssize_t lz4_uncomp_block(compressor_t *base, const uint8_t *in,
 	return ret;
 }
 
+static compressor_t *lz4_create_copy(compressor_t *cmp)
+{
+	lz4_compressor_t *lz4 = malloc(sizeof(*lz4));
+
+	if (lz4 == NULL) {
+		perror("creating additional lz4 compressor");
+		return NULL;
+	}
+
+	memcpy(lz4, cmp, sizeof(*lz4));
+	return (compressor_t *)lz4;
+}
+
 static void lz4_destroy(compressor_t *base)
 {
 	free(base);
@@ -131,6 +144,7 @@ compressor_t *create_lz4_compressor(bool compress, size_t block_size,
 	base->do_block = compress ? lz4_comp_block : lz4_uncomp_block;
 	base->write_options = lz4_write_options;
 	base->read_options = lz4_read_options;
+	base->create_copy = lz4_create_copy;
 	return base;
 }
 
diff --git a/lib/comp/lzo.c b/lib/comp/lzo.c
index 98cc200..66c2f59 100644
--- a/lib/comp/lzo.c
+++ b/lib/comp/lzo.c
@@ -177,6 +177,22 @@ static ssize_t lzo_uncomp_block(compressor_t *base, const uint8_t *in,
 	return len;
 }
 
+static compressor_t *lzo_create_copy(compressor_t *cmp)
+{
+	lzo_compressor_t *other = (lzo_compressor_t *)cmp;
+	lzo_compressor_t *lzo;
+
+	lzo = calloc(1, sizeof(*lzo) + lzo_algs[other->algorithm].bufsize);
+
+	if (lzo == NULL) {
+		perror("creating additional lzo compressor");
+		return NULL;
+	}
+
+	memcpy(lzo, other, sizeof(*lzo));
+	return (compressor_t *)lzo;
+}
+
 static void lzo_destroy(compressor_t *base)
 {
 	free(base);
@@ -281,6 +297,7 @@ compressor_t *create_lzo_compressor(bool compress, size_t block_size,
 	base->do_block = compress ? lzo_comp_block : lzo_uncomp_block;
 	base->write_options = lzo_write_options;
 	base->read_options = lzo_read_options;
+	base->create_copy = lzo_create_copy;
 	return base;
 }
 
diff --git a/lib/comp/xz.c b/lib/comp/xz.c
index 3e63050..d38aab6 100644
--- a/lib/comp/xz.c
+++ b/lib/comp/xz.c
@@ -195,6 +195,19 @@ static ssize_t xz_uncomp_block(compressor_t *base, const uint8_t *in,
 	return -1;
 }
 
+static compressor_t *xz_create_copy(compressor_t *cmp)
+{
+	xz_compressor_t *xz = malloc(sizeof(*xz));
+
+	if (xz == NULL) {
+		perror("creating additional xz compressor");
+		return NULL;
+	}
+
+	memcpy(xz, cmp, sizeof(*xz));
+	return (compressor_t *)xz;
+}
+
 static void xz_destroy(compressor_t *base)
 {
 	free(base);
@@ -318,6 +331,7 @@ compressor_t *create_xz_compressor(bool compress, size_t block_size,
 	base->do_block = compress ? xz_comp_block : xz_uncomp_block;
 	base->write_options = xz_write_options;
 	base->read_options = xz_read_options;
+	base->create_copy = xz_create_copy;
 	return base;
 }
 
diff --git a/lib/comp/zstd.c b/lib/comp/zstd.c
index 252e1bf..e206338 100644
--- a/lib/comp/zstd.c
+++ b/lib/comp/zstd.c
@@ -88,6 +88,29 @@ static ssize_t zstd_uncomp_block(compressor_t *base, const uint8_t *in,
 	return ret;
 }
 
+static compressor_t *zstd_create_copy(compressor_t *cmp)
+{
+	zstd_compressor_t *zstd = malloc(sizeof(*zstd));
+
+	if (zstd == NULL) {
+		perror("creating additional zstd compressor");
+		return NULL;
+	}
+
+	memcpy(zstd, cmp, sizeof(*zstd));
+
+	zstd->zctx = ZSTD_createCCtx();
+
+	if (zstd->zctx == NULL) {
+		fputs("error creating addtional zstd compression context\n",
+		      stderr);
+		free(zstd);
+		return NULL;
+	}
+
+	return (compressor_t *)zstd;
+}
+
 static void zstd_destroy(compressor_t *base)
 {
 	zstd_compressor_t *zstd = (zstd_compressor_t *)base;
@@ -141,6 +164,7 @@ compressor_t *create_zstd_compressor(bool compress, size_t block_size,
 	base->do_block = compress ? zstd_comp_block : zstd_uncomp_block;
 	base->write_options = zstd_write_options;
 	base->read_options = zstd_read_options;
+	base->create_copy = zstd_create_copy;
 	return base;
 fail_level:
 	fprintf(stderr, "zstd compression level must be a number in the range "