From 8ff8f191845a76aca15ce1f1bdbf1d28087d2bc5 Mon Sep 17 00:00:00 2001
From: Patrick McDermott <patrick.mcdermott@libiquity.com>
Date: Thu, 13 Apr 2023 10:48:12 -0400
Subject: gzip: Rewrite

---
diff --git a/src/gzip.c b/src/gzip.c
index f3fbdb9..2596739 100644
--- a/src/gzip.c
+++ b/src/gzip.c
@@ -17,115 +17,78 @@
  * along with opkg-opkg.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <stdio.h>
+#include <stdlib.h>
 #include <zlib.h>
 #include "defs.h"
 #include "gzip.h"
 
-static int
-_opkg_opk_gzip_init(struct opkg_opk_gzip_state *state)
-{
-	state->stream.zalloc = Z_NULL;
-	state->stream.zfree  = Z_NULL;
-	state->stream.opaque = Z_NULL;
-	if (inflateInit2(&state->stream, 15 + 16) != Z_OK) {
-		return OPKG_OPK_ERROR;
-	}
-	return OPKG_OPK_OK;
-}
+struct opkg_opk_gzip {
+	int      (*read)(void *, char **, size_t *);
+	void      *user_data;
+	z_stream   stream;
+};
 
-int
-opkg_opk_gzip_init_from_file(struct opkg_opk_gzip_state *state,
-		const char *file_name)
+struct opkg_opk_gzip *
+opkg_opk_gzip_init(int (*read)(void *, char **, size_t *), void *user_data)
 {
-	state->input_file = fopen(file_name, "rb");
-	if (state->input_file == NULL) {
-		return OPKG_OPK_ERROR;
+	struct opkg_opk_gzip *gzip;
+
+	gzip = malloc(sizeof(*gzip));
+	if (gzip == NULL) {
+		return NULL;
 	}
-	state->stream.next_in  = Z_NULL;
-	state->stream.avail_in = 0;
-	if (_opkg_opk_gzip_init(state) < OPKG_OPK_OK) {
-		fclose(state->input_file);
-		return OPKG_OPK_ERROR;
+
+	gzip->read      = read;
+	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, 15 + 16) != Z_OK) {
+		free(gzip);
+		return NULL;
 	}
-	return OPKG_OPK_OK;
+
+	return gzip;
 }
 
 int
-opkg_opk_gzip_init_from_memory(struct opkg_opk_gzip_state *state,
-		unsigned char *input, size_t input_size)
+opkg_opk_gzip_read(struct opkg_opk_gzip *gzip, void *record)
 {
-	state->input_file = NULL;
-	state->stream.next_in  = input;
-	state->stream.avail_in = input_size;
-	return _opkg_opk_gzip_init(state);
-}
+	gzip->stream.next_out  = record;
+	gzip->stream.avail_out = 512;
 
-static int
-_opkg_opk_gzip_next_record_from_file(struct opkg_opk_gzip_state *state)
-{
 	for (;;) {
-		if (state->stream.avail_in == 0) {
-			if (feof(state->input_file)) {
-				fclose(state->input_file);
-				state->input_file = NULL;
-				inflateEnd(&state->stream);
-				return OPKG_OPK_ERROR;
+		if (gzip->stream.avail_in == 0) {
+			/* Input buffer is empty and needs refilled. */
+			switch (gzip->read(gzip->user_data,
+						&gzip->stream.next_in,
+						&gzip->stream.avail_in)) {
+				case OPKG_OPK_OK:
+				case OPKG_OPK_END:
+					break;
+				case OPKG_OPK_ERROR:
+				default:
+					inflateEnd(&gzip->stream);
+					return OPKG_OPK_ERROR;
 			}
-			state->stream.avail_in = fread(state->input_buffer,
-					1, OPKG_OPK_GZIP_BUFFER_SIZE,
-					state->input_file);
-			if (ferror(state->input_file)) {
-				fclose(state->input_file);
-				state->input_file = NULL;
-				inflateEnd(&state->stream);
-				return OPKG_OPK_ERROR;
-			}
-			state->stream.next_in = state->input_buffer;
 		}
-		if (state->stream.avail_out == 0) {
+		if (gzip->stream.avail_out == 0) {
+			/* Output buffer is filled and ready for use. */
 			return OPKG_OPK_OK;
 		}
-		switch (inflate(&state->stream, Z_SYNC_FLUSH)) {
+		switch (inflate(&gzip->stream, Z_SYNC_FLUSH)) {
 			case Z_OK:
 			case Z_BUF_ERROR:
 				break;
 			case Z_STREAM_END:
-				fclose(state->input_file);
-				state->input_file = NULL;
-				inflateEnd(&state->stream);
+				inflateEnd(&gzip->stream);
 				return OPKG_OPK_END;
 			default:
-				fclose(state->input_file);
-				state->input_file = NULL;
-				inflateEnd(&state->stream);
+				inflateEnd(&gzip->stream);
 				return OPKG_OPK_ERROR;
 		}
 	}
 }
-
-static int
-_opkg_opk_gzip_next_record_from_memory(struct opkg_opk_gzip_state *state)
-{
-	switch (inflate(&state->stream, Z_SYNC_FLUSH)) {
-		case Z_OK:
-			return OPKG_OPK_OK;
-		case Z_STREAM_END:
-			return OPKG_OPK_END;
-		default:
-			inflateEnd(&state->stream);
-			return OPKG_OPK_ERROR;
-	}
-}
-
-int
-opkg_opk_gzip_next_record(struct opkg_opk_gzip_state *state, void *record)
-{
-	state->stream.next_out  = record;
-	state->stream.avail_out = 512;
-	if (state->input_file != NULL) {
-		return _opkg_opk_gzip_next_record_from_file(state);
-	} else {
-		return _opkg_opk_gzip_next_record_from_memory(state);
-	}
-}
diff --git a/src/gzip.h b/src/gzip.h
index bdab8f2..409de51 100644
--- a/src/gzip.h
+++ b/src/gzip.h
@@ -20,26 +20,12 @@
 #ifndef OPKG_OPK_GZIP_H_
 #define OPKG_OPK_GZIP_H_
 
-#include <stdio.h>
-#include <zlib.h>
+struct opkg_opk_gzip;
 
-#define OPKG_OPK_GZIP_BUFFER_SIZE 8192
-
-struct opkg_opk_gzip_state {
-	FILE          *input_file;
-	unsigned char  input_buffer[OPKG_OPK_GZIP_BUFFER_SIZE];
-	z_stream       stream;
-};
-
-int
-opkg_opk_gzip_init_from_file(struct opkg_opk_gzip_state *state,
-		const char *file_name);
-
-int
-opkg_opk_gzip_init_from_memory(struct opkg_opk_gzip_state *state,
-		unsigned char *input, size_t input_size);
+struct opkg_opk_gzip *
+opkg_opk_gzip_init(int (*read)(void *, char **, size_t *), void *user_data);
 
 int
-opkg_opk_gzip_next_record(struct opkg_opk_gzip_state *state, void *record);
+opkg_opk_gzip_read(struct opkg_opk_gzip *gzip, void *record);
 
 #endif  /* OPKG_OPK_GZIP_H_ */
--
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