From e378fd8cbb69892d0af4110a7e3968d074700769 Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Fri, 17 Jul 2026 20:32:44 +0200
Subject: Beispiel für gzip-Dateien hinzugefügt
MIME-Version: 1.0
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---
 src/gzip.c | 125 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100644 src/gzip.c

(limited to 'src/gzip.c')

diff --git a/src/gzip.c b/src/gzip.c
new file mode 100644
index 0000000..11828db
--- /dev/null
+++ b/src/gzip.c
@@ -0,0 +1,125 @@
+// Standard C
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+// System
+#include <unistd.h>
+
+// zlib
+#include <zlib.h>
+
+enum { BUFFER_SIZE = 8192 };
+
+static void
+usage(void)
+{
+	(void) fprintf(stderr, "stream [-d] infile outfile\n");
+}
+
+static void
+error(const char *msg)
+{
+	perror(msg);
+	exit(EXIT_FAILURE);
+}
+
+void
+do_compress(const char *in_name, const char *out_name, int compress_level)
+{
+	FILE *in_file = fopen(in_name, "rb");
+	if ( in_file == NULL ) {
+		error("fopen() on in_file failed");
+	}
+
+	char mode[10];
+	(void) snprintf(mode, sizeof mode, "wb%d", compress_level);
+
+	gzFile out_file = gzopen(out_name, mode);
+	if ( out_file == NULL ) {
+		(void) fclose(in_file);
+		error("gzopen() on out_file failed");
+	}
+
+	unsigned char buffer[BUFFER_SIZE];
+
+	size_t bytes_read = 0;
+	while ( (bytes_read = fread(buffer, 1, BUFFER_SIZE, in_file)) != 0 ) {
+		gzfwrite(buffer, 1, bytes_read, out_file);
+	}
+
+	(void) fclose(in_file);
+	gzclose(out_file);
+}
+
+void
+do_uncompress(const char *in_name, const char *out_name)
+{
+	gzFile in_file = gzopen(in_name, "rb");
+	if ( in_file == NULL ) {
+		error("gzopen() on in_file failed");
+	}
+
+	FILE *out_file = fopen(out_name, "wb");
+	if ( out_file == NULL ) {
+		(void) gzclose(in_file);
+		error("fopen() on out_file failed");
+	}
+
+	unsigned char buffer[BUFFER_SIZE];
+
+	size_t bytes_read = 0;
+	while ( (bytes_read = gzfread(buffer, 1, BUFFER_SIZE, in_file)) != 0 ) {
+		(void) fwrite(buffer, 1, bytes_read, out_file);
+	}
+
+	gzclose(in_file);
+	(void) fclose(out_file);
+}
+
+int
+main(int argc, char *argv[])
+{
+	enum {
+		COMPRESSION_STD  = 5,
+		COMPRESSION_BEST = 9
+	};
+
+	int decompress     = 0;
+	int compress_level = COMPRESSION_STD;
+
+	int opt = 0;
+	while ( (opt = getopt(argc, argv, "dl")) != -1 ) {
+		switch ( opt ) {
+		case 'd':
+			decompress = 1;
+			break;
+
+		case 'l':
+			compress_level = COMPRESSION_BEST;
+			break;
+
+		case '?':
+		default:
+			usage();
+			return EXIT_SUCCESS;
+		}
+	}
+	argc -= optind;
+	argv += optind;
+
+	if ( argc != 2 ) {
+		usage();
+		return EXIT_FAILURE;
+	}
+
+	if ( !decompress ) {
+		do_compress(argv[0], argv[1], compress_level);
+	}
+	else {
+		do_uncompress(argv[0], argv[1]);
+	}
+
+	return EXIT_SUCCESS;
+}
-- 
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