From 6eb05f5bd007561fac9dcd3328d888d06d2a3712 Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Thu, 16 Jul 2026 22:02:49 +0200
Subject: Fehlerbehandlung hinzugefügt
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/simple.c | 75 ++++++++++++++++++++++++++++++++++++++++++++----------------
 1 file changed, 55 insertions(+), 20 deletions(-)

(limited to 'src/simple.c')

diff --git a/src/simple.c b/src/simple.c
index 36f7e48..da79562 100644
--- a/src/simple.c
+++ b/src/simple.c
@@ -1,6 +1,7 @@
 // Standard C
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 // System
 #include <unistd.h>
@@ -12,38 +13,61 @@ static void
 usage(void)
 {
 	(void) fprintf(stderr, "compress [-d] infile outfile\n");
+}
+
+static void
+error(const char *msg)
+{
+	perror(msg);
 	exit(EXIT_FAILURE);
 }
 
-unsigned long
+size_t
 get_filesize(FILE *file)
 {
-	(void) fseek(file, 0, SEEK_END);
-	unsigned long size = ftell(file);
-	(void) fseek(file, 0, SEEK_SET);
-	return size;
+	long current_pos = ftell(file);
+	if ( current_pos == -1 ) {
+		error("ftell() failed");
+	}
+
+	if ( fseek(file, 0, SEEK_END) != 0 ) {
+		error("fseek() failed");
+	}
+
+	long size = ftell(file);
+	if ( size == -1 ) {
+		error("ftell() failed");
+	}
+
+	if ( fseek(file, current_pos, SEEK_SET) != 0 ) {
+		error("fseek() failed");
+	}
+
+	return (size_t) size;
 }
 
 void
 do_compress(FILE *in_file, FILE *out_file, int compress_level)
 {
-	const unsigned long in_size = get_filesize(in_file);
+	size_t in_size = get_filesize(in_file);
 
 	(void) fwrite(&in_size, sizeof in_size, 1, out_file);
 
 	unsigned char *in_data = malloc(in_size);
 	(void) fread(in_data, 1, in_size, in_file);
 
-	unsigned long  out_size = compressBound(in_size);
+	size_t         out_size = compressBound(in_size);
 	unsigned char *out_data = malloc(out_size);
 
-	const int error = compress2(out_data, &out_size, in_data, in_size, compress_level);
+	const int error = compress2(out_data, &out_size,
+	                            in_data, in_size,
+	                            compress_level);
 
 	if ( !error ) {
 		(void) fwrite(out_data, 1, out_size, out_file);
 	}
 	else {
-		printf("Error: %d\n", error);
+		(void) fprintf(stderr, "Error: %s\n", zError(error));
 	}
 
 	free(out_data);
@@ -53,26 +77,32 @@ do_compress(FILE *in_file, FILE *out_file, int compress_level)
 void
 do_uncompress(FILE *in_file, FILE *out_file)
 {
-	const unsigned long in_size = get_filesize(in_file);
+	size_t in_size = get_filesize(in_file);
 
 	unsigned char *in_data = malloc(in_size);
 	(void) fread(in_data, 1, in_size, in_file);
 
-	unsigned long  out_size = *(unsigned long *) in_data;
+	size_t out_size = 0;
+	memcpy(&out_size, in_data, sizeof out_size);
+
 	unsigned char *out_data = malloc(out_size);
 
-	unsigned long tmp = in_size - sizeof(unsigned long);
+	const size_t compressed_data_size = in_size - sizeof(size_t);
+	size_t       consumed_size        = compressed_data_size;
 
-	const int error = uncompress2(out_data,
-	                              &out_size,
-	                              in_data + sizeof(unsigned long),
-	                              &tmp);
+	const int error = uncompress2(out_data, &out_size,
+	                              in_data + sizeof(size_t),
+	                              &consumed_size);
 
 	if ( !error ) {
+		if ( compressed_data_size != consumed_size ) {
+			(void) fputs("Warning: Trailing data detected.\n", stderr);
+		}
+
 		(void) fwrite(out_data, 1, out_size, out_file);
 	}
 	else {
-		printf("Error: %d\n", error);
+		(void) fprintf(stderr, "Error: %s\n", zError(error));
 	}
 
 	free(out_data);
@@ -82,8 +112,13 @@ do_uncompress(FILE *in_file, FILE *out_file)
 int
 main(int argc, char *argv[])
 {
+	enum {
+		COMPRESSION_STD  = 5,
+		COMPRESSION_BEST = 9
+	};
+
 	int decompress     = 0;
-	int compress_level = 5;
+	int compress_level = COMPRESSION_STD;
 
 	int opt = 0;
 	while ( (opt = getopt(argc, argv, "dl")) != -1 ) {
@@ -93,13 +128,13 @@ main(int argc, char *argv[])
 			break;
 
 		case 'l':
-			compress_level = 9;
+			compress_level = COMPRESSION_BEST;
 			break;
 
 		case '?':
 		default:
 			usage();
-			break;
+			return EXIT_SUCCESS;
 		}
 	}
 	argc -= optind;
-- 
cgit v1.3