gzip: Add write direction

3 files changed, 150 insertions, 19 deletions

diff --git a/src/gzip.c b/src/gzip.c
index a53be83..2717f54 100644
--- a/src/gzip.c
+++ b/src/gzip.c
@@ -25,43 +25,104 @@
 
 #define OPKG_OPK_GZIP_WINDOW_BITS_ (15 + 16)
 
+enum _opkg_opk_gzip_dir {
+	_OPKG_OPK_GZIP_DIR_READ,
+	_OPKG_OPK_GZIP_DIR_WRITE,
+};
+
 struct opkg_opk_gzip {
-	int      (*read)(void *, char **, size_t *);
-	void      *user_data;
-	z_stream   stream;
+	enum _opkg_opk_gzip_dir   dir;
+	char                     *buffer;
+	size_t                    buffer_size;
+	opkg_opk_gzip_read_func  *read_func;
+	opkg_opk_gzip_write_func *write_func;
+	void                     *user_data;
+	z_stream                  stream;
 };
 
-struct opkg_opk_gzip *
-opkg_opk_gzip_init(opkg_opk_gzip_read_func *read, void *user_data)
+static struct opkg_opk_gzip *
+_opkg_opk_gzip_init(enum _opkg_opk_gzip_dir dir, char *buffer, size_t size,
+		opkg_opk_gzip_read_func *read_func,
+		opkg_opk_gzip_write_func *write_func, void *user_data)
 {
 	struct opkg_opk_gzip *gzip;
+	gz_header             gz_header;
 
 	gzip = malloc(sizeof(*gzip));
 	if (gzip == NULL) {
 		return NULL;
 	}
 
-	gzip->read      = read;
-	gzip->user_data = user_data;
+	gzip->dir         = dir;
+	gzip->buffer      = buffer;
+	gzip->buffer_size = size;
+	gzip->read_func   = read_func;
+	gzip->write_func  = write_func;
+	gzip->user_data   = user_data;
 
-	gzip->stream.next_in  = Z_NULL;
-	gzip->stream.avail_in = 0;
 	gzip->stream.zalloc   = Z_NULL;
 	gzip->stream.zfree    = Z_NULL;
 	gzip->stream.opaque   = Z_NULL;
-	if (inflateInit2(&gzip->stream, OPKG_OPK_GZIP_WINDOW_BITS_) != Z_OK) {
-		free(gzip);
-		return NULL;
+
+	if (dir == _OPKG_OPK_GZIP_DIR_READ) {
+		gzip->stream.next_in  = Z_NULL;
+		gzip->stream.avail_in = 0;
+		if (inflateInit2(&gzip->stream, OPKG_OPK_GZIP_WINDOW_BITS_) !=
+				Z_OK) {
+			free(gzip);
+			return NULL;
+		}
+	} else {
+		gzip->stream.next_out  = buffer;
+		gzip->stream.avail_out = size;
+		if (deflateInit2(&gzip->stream, 9, Z_DEFLATED,
+					OPKG_OPK_GZIP_WINDOW_BITS_, 9,
+					Z_DEFAULT_STRATEGY) != Z_OK) {
+			free(gzip);
+			return NULL;
+		}
+		gz_header.text    = 0;
+		gz_header.time    = 0;       /* Stored as 32-bit unsigned int */
+		gz_header.os      = 3;       /* Unix, per RFC 1952 */
+		gz_header.extra   = Z_NULL;
+		gz_header.name    = Z_NULL;
+		gz_header.comment = Z_NULL;
+		gz_header.hcrc    = 0;
+		if (deflateSetHeader(&gzip->stream, &gz_header) != Z_OK) {
+			deflateEnd(&gzip->stream);
+			free(gzip);
+			return NULL;
+		}
 	}
 
 	return gzip;
 }
 
+struct opkg_opk_gzip *
+opkg_opk_gzip_init_read(opkg_opk_gzip_read_func *read, void *user_data)
+{
+	return _opkg_opk_gzip_init(_OPKG_OPK_GZIP_DIR_READ, NULL, 0,
+			read, NULL, user_data);
+}
+
+struct opkg_opk_gzip *
+opkg_opk_gzip_init_write(char *buffer, size_t size,
+		opkg_opk_gzip_write_func *write, void *user_data)
+{
+	return _opkg_opk_gzip_init(_OPKG_OPK_GZIP_DIR_WRITE, buffer, size,
+			NULL, write, user_data);
+}
+
 int
 opkg_opk_gzip_read(struct opkg_opk_gzip *gzip, void *record)
 {
 	int end;
 
+	/* Sanity check */
+	if (gzip->dir != _OPKG_OPK_GZIP_DIR_READ) {
+		return OPKG_OPK_ERROR;
+	}
+
 	gzip->stream.next_out  = record;
 	gzip->stream.avail_out = OPKG_OPK_USTAR_RECORD_SIZE;
 
@@ -69,7 +130,7 @@ opkg_opk_gzip_read(struct opkg_opk_gzip *gzip, void *record)
 		end = 0;
 		if (gzip->stream.avail_in == 0) {
 			/* Input buffer is empty and needs refilled. */
-			switch (gzip->read(gzip->user_data,
+			switch (gzip->read_func(gzip->user_data,
 						(char **) &gzip->stream.next_in,
 						(size_t *) &gzip->stream.
 							avail_in)) {
@@ -107,9 +168,69 @@ opkg_opk_gzip_read(struct opkg_opk_gzip *gzip, void *record)
 	}
 }
 
-void
+int
+opkg_opk_gzip_write(struct opkg_opk_gzip *gzip, void *record, size_t size,
+		int last)
+{
+	/* Sanity check */
+	if (gzip->dir != _OPKG_OPK_GZIP_DIR_WRITE) {
+		return OPKG_OPK_ERROR;
+	}
+
+	gzip->stream.next_in  = record;
+	gzip->stream.avail_in = size;
+
+	do {
+		switch (deflate(&gzip->stream,
+					(last > 0 ? Z_FINISH : Z_NO_FLUSH))) {
+			case Z_OK:
+			case Z_BUF_ERROR:
+			case Z_STREAM_END:
+				break;
+			default:
+				return OPKG_OPK_ERROR;
+		}
+		/* Process output buffer. */
+		switch (gzip->write_func(gzip->user_data,
+					gzip->buffer_size
+					- gzip->stream.avail_out)) {
+			case OPKG_OPK_OK:
+				gzip->stream.next_out  = gzip->buffer;
+				gzip->stream.avail_out = gzip->buffer_size;
+				break;
+			case OPKG_OPK_END:
+			case OPKG_OPK_ERROR:
+			default:
+				return OPKG_OPK_ERROR;
+		}
+	} while (gzip->stream.avail_out == 0);
+
+	if (gzip->stream.avail_in != 0) {
+		return OPKG_OPK_ERROR;
+	}
+	if (last == 0) {
+		/* Input buffer is empty and needs refilled. */
+		return OPKG_OPK_OK;
+	} else {
+		return OPKG_OPK_END;
+	}
+}
+
+int
 opkg_opk_gzip_free(struct opkg_opk_gzip *gzip)
 {
-	inflateEnd(&gzip->stream);
+	int ret;
+
+	ret = OPKG_OPK_OK;
+	if (gzip->dir == _OPKG_OPK_GZIP_DIR_READ) {
+		if (inflateEnd(&gzip->stream) != Z_OK) {
+			ret = OPKG_OPK_ERROR;
+		}
+	} else {
+		if (deflateEnd(&gzip->stream) != Z_OK) {
+			ret = OPKG_OPK_ERROR;
+		}
+	}
 	free(gzip);
+	return ret;
 }
diff --git a/src/gzip.h b/src/gzip.h
index e4c3f52..1fd5d5e 100644
--- a/src/gzip.h
+++ b/src/gzip.h
@@ -23,6 +23,7 @@
 struct opkg_opk_gzip;
 
 typedef int (opkg_opk_gzip_read_func)(void *, char **, size_t *);
+typedef int (opkg_opk_gzip_write_func)(void *, size_t);
 
 /*
  * Allocates and initializes a decompression structure.
@@ -41,7 +42,11 @@ typedef int (opkg_opk_gzip_read_func)(void *, char **, size_t *);
  * - NULL on memory exhaustion.
  */
 struct opkg_opk_gzip *
-opkg_opk_gzip_init(opkg_opk_gzip_read_func *read, void *user_data);
+opkg_opk_gzip_init_read(opkg_opk_gzip_read_func *read, void *user_data);
+
+struct opkg_opk_gzip *
+opkg_opk_gzip_init_write(char *buffer, size_t size,
+		opkg_opk_gzip_write_func *write, void *user_data);
 
 /*
  * Reads and decompresses data to output the next record (512 octets).
@@ -57,12 +62,16 @@ opkg_opk_gzip_init(opkg_opk_gzip_read_func *read, void *user_data);
 int
 opkg_opk_gzip_read(struct opkg_opk_gzip *gzip, void *record);
 
+int
+opkg_opk_gzip_write(struct opkg_opk_gzip *gzip, void *record, size_t size,
+		int last);
+
 /*
  * Frees a decompression structure.
  * Parameters:
  * - gzip: Decompression structure.
  */
-void
+int
 opkg_opk_gzip_free(struct opkg_opk_gzip *gzip);
 
 #endif  /* OPKG_OPK_GZIP_H_ */
diff --git a/src/opk.c b/src/opk.c
index 2747345..982ad3f 100644
--- a/src/opk.c
+++ b/src/opk.c
@@ -76,7 +76,8 @@ opkg_opk_opk_init(const char *file_name)
 	}
 
 	/* Initialize outer gzip decompressor. */
-	opk->outer_gzip = opkg_opk_gzip_init(&_opkg_opk_opk_file_read, opk);
+	opk->outer_gzip = opkg_opk_gzip_init_read(&_opkg_opk_opk_file_read,
+			opk);
 	if (opk->outer_gzip == NULL) {
 		fputs(_("Error: Failed to initialize\n"), stderr);
 		goto error2;
@@ -146,7 +147,7 @@ _opkg_opk_opk_init_inner(struct opkg_opk_opk *opk, const char *member)
 	}
 
 	/* Initialize inner gzip decompressor. */
-	opk->inner_gzip = opkg_opk_gzip_init(
+	opk->inner_gzip = opkg_opk_gzip_init_read(
 			(opkg_opk_gzip_read_func *) &opkg_opk_ustar_read,
 			opk->outer_ustar);
 	if (opk->inner_gzip == NULL) {