Command-line converter from GZIP to DEFLATE.

deflater.c

@@ -1,82 +0,0 @@
-#include <stdio.h>
-#include <stdlib.h>
-#include <zlib.h>
-
-#define IN_SIZE_MAX 60000
-#define OUT_SIZE_MAX 60000
-
-int main(int argc, char* argv[])
-{
-	FILE* fp;
-	char* inbuf;
-	char* outbuf;
-	size_t inlen;
-	size_t outlen;
-	z_stream stream;
-
-	/* check command line */
-	if (argc != 3) {
-		fprintf(stderr,
-			"Compresses a file to DEFLATE format.\n"
-			"24-08-2002, fox@scene.pl\n"
-			"Usage: deflater input_file deflated_file\n"
-		);
-		return 3;
-	}
-
-	/* alloc buffers */
-	inbuf = malloc(IN_SIZE_MAX);
-	outbuf = malloc(OUT_SIZE_MAX);
-	if (inbuf == NULL || outbuf == NULL) {
-		fprintf(stderr, "deflater: Out of memory!\n");
-		return 1;
-	}
-
-	/* read input file */
-	fp = fopen(argv[1], "rb");
-	if (fp == NULL) {
-		perror(argv[1]);
-		return 1;
-	}
-	inlen = fread(inbuf, 1, IN_SIZE_MAX, fp);
-	fclose(fp);
-
-	/* compress */
-	stream.next_in = inbuf;
-	stream.avail_in = inlen;
-	stream.next_out = outbuf;
-	stream.avail_out = OUT_SIZE_MAX;
-	stream.zalloc = (alloc_func) 0;
-	stream.zfree = (free_func) 0;
-	if (deflateInit2(&stream, Z_BEST_COMPRESSION, Z_DEFLATED,
-		-MAX_WBITS, 9, Z_DEFAULT_STRATEGY) != Z_OK) {
-		fprintf(stderr, "deflater: deflateInit2 failed\n");
-		return 1;
-	}
-	if (deflate(&stream, Z_FINISH) != Z_STREAM_END) {
-		fprintf(stderr, "deflater: deflate failed\n");
-		return 1;
-	}
-	if (deflateEnd(&stream) != Z_OK) {
-		fprintf(stderr, "deflater: deflateEnd failed\n");
-		return 1;
-	}
-
-	/* write output */
-	fp = fopen(argv[2], "wb");
-	if (fp == NULL) {
-		perror(argv[2]);
-		return 1;
-	}
-	outlen = fwrite(outbuf, 1, stream.total_out, fp);
-	fclose(fp);
-	if (outlen != stream.total_out) {
-		perror(argv[2]);
-		return 1;
-	}
-
-	/* display summary */
-	printf("Compressed %s (%d bytes) to %s (%d bytes)\n",
-		argv[1], inlen, argv[2], outlen);
-	return 0;
-}

gzip2deflate.c

@@ -0,0 +1,78 @@
+// gzip2deflate by Piotr Fusik <fox@scene.pl>
+// http://xasm.atari.org
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#ifdef __WIN32
+#include <fcntl.h>
+#endif
+
+static int get_byte(void)
+{
+	int b = getchar();
+	if (b == EOF) {
+		fputs("gzip2deflate: unexpected end of stream\n", stderr);
+		exit(1);
+	}
+	return b;
+}
+
+static void skip_bytes(int n)
+{
+	while (--n >= 0)
+		get_byte();
+}
+
+static void skip_string(void)
+{
+	while (get_byte() != 0);
+}
+
+int main (int argc, char *argv[])
+{
+	int flg;
+	char buf[8 + 4096];
+	size_t len;
+#ifdef __WIN32
+	_setmode(_fileno(stdin), _O_BINARY);
+	_setmode(_fileno(stdout), _O_BINARY);
+#endif
+	if (get_byte() != 0x1f || get_byte() != 0x8b || get_byte() != 8) {
+		fputs("gzip2deflate: not a gzip file on stdin\n", stderr);
+		return 1;
+	}
+	flg = get_byte();
+	skip_bytes(6);
+	if ((flg & 4) != 0) {
+		int xlen = get_byte();
+		xlen += get_byte() << 8;
+		skip_bytes(xlen);
+	}
+	if ((flg & 8) != 0)
+		skip_string();
+	if ((flg & 16) != 0)
+		skip_string();
+	if ((flg & 2) != 0)
+		skip_bytes(2);
+	/* copy everything except the last 8 bytes */
+	len = 0;
+	for (;;) {
+		len += fread(buf + len, 1, sizeof(buf) - len, stdin);
+		if (len != sizeof(buf))
+			break;
+		fwrite(buf, 1, sizeof(buf) - 8, stdout);
+		memcpy(buf, buf + sizeof(buf) - 8, 8);
+		len = 8;
+	}
+	if (ferror(stdin)) {
+		fputs("gzip2deflate: read error\n", stderr);
+		return 1;
+	}
+	if (len < 8) {
+		fputs("gzip2deflate: unexpected end of stream\n", stderr);
+		return 1;
+	}
+	fwrite(buf, 1, len - 8, stdout);
+	return 0;
+}