From 1e1f4450e8da41a7d775066971782de3f323671a Mon Sep 17 00:00:00 2001
From: Dorian Zedler <dorian@itsblue.de>
Date: Tue, 12 Jul 2022 14:41:18 +0200
Subject: [PATCH 1/7] Feat: Only use one loop and calculte checksum on the fly

---
 Implementierung/Makefile              |  2 +-
 Implementierung/lib/md2_impls/md2_2.h | 21 ++++++++
 Implementierung/src/md2.c             |  6 +++
 Implementierung/src/md2_impls/md2_2.c | 76 +++++++++++++++++++++++++++
 4 files changed, 104 insertions(+), 1 deletion(-)
 create mode 100644 Implementierung/lib/md2_impls/md2_2.h
 create mode 100644 Implementierung/src/md2_impls/md2_2.c

diff --git a/Implementierung/Makefile b/Implementierung/Makefile
index 1c7ed9f..843d95b 100644
--- a/Implementierung/Makefile
+++ b/Implementierung/Makefile
@@ -1,6 +1,6 @@
 
 
-SRC = src/main.c src/helper.c src/io.c src/md2.c src/md2_impls/md2_common.c src/md2_impls/md2_0.c
+SRC = src/main.c src/helper.c src/io.c src/md2.c src/md2_impls/md2_common.c src/md2_impls/md2_0.c src/md2_impls/md2_2.c
 OBJ = ${subst src,build,${SRC:.c=.o}}
 CC = gcc
 CFLAGS = -Ilib -ggdb -std=c11 -g -Wall -Wextra -no-pie -O3
diff --git a/Implementierung/lib/md2_impls/md2_2.h b/Implementierung/lib/md2_impls/md2_2.h
new file mode 100644
index 0000000..3e6ff3f
--- /dev/null
+++ b/Implementierung/lib/md2_impls/md2_2.h
@@ -0,0 +1,21 @@
+#ifndef MD2_2_H
+#define MD2_2_H
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+
+/**
+ * @brief This implementation loads the file in bits and not at once
+ *
+ * @param _ unused
+ * @param filename name of the file to load
+ * @param out
+ */
+void md2_hash_2(size_t len, const uint8_t buf[len], uint8_t out[16]);
+void md2_checksum_2(size_t len, uint8_t* buf);
+
+#endif  // MD2_2_H
\ No newline at end of file
diff --git a/Implementierung/src/md2.c b/Implementierung/src/md2.c
index 8be67f4..da49453 100644
--- a/Implementierung/src/md2.c
+++ b/Implementierung/src/md2.c
@@ -2,6 +2,7 @@
 
 // include all implementations
 #include "../lib/md2_impls/md2_0.h"
+#include "../lib/md2_impls/md2_2.h"
 
 md2_hash_func md2_hash;
 md2_checksum_func md2_checksum;
@@ -22,6 +23,11 @@ bool md2_choose_implementation(int i) {
       md2_checksum = md2_checksum_0;
       return true;
 
+    case 2:
+      md2_hash = md2_hash_2;
+      md2_checksum = md2_checksum_2;
+      return true;
+
     default:
       return false;
   }
diff --git a/Implementierung/src/md2_impls/md2_2.c b/Implementierung/src/md2_impls/md2_2.c
new file mode 100644
index 0000000..874c097
--- /dev/null
+++ b/Implementierung/src/md2_impls/md2_2.c
@@ -0,0 +1,76 @@
+#include "../../lib/md2_impls/md2_2.h"
+
+#include "../../lib/md2_impls/md2_common.h"
+
+void process_block_hash(uint8_t block[16], uint8_t messageDigestBuf[48]) {
+  for (int j = 0; j < 16; j++) {
+    messageDigestBuf[16 + j] = block[j];
+    messageDigestBuf[32 + j] = (messageDigestBuf[16 + j] ^ messageDigestBuf[j]);
+  }
+
+  u_int8_t t = 0;
+
+  for (int j = 0; j < 18; j++) {
+    for (int k = 0; k < 48; k++) {
+      t = messageDigestBuf[k] = messageDigestBuf[k] ^ MD2_PI_SUBST[t];
+    }
+    t = (t + j) % 256;
+  }
+}
+
+void process_block_checksum(uint8_t block[16], uint8_t checksum[16],
+                            uint8_t* l) {
+  for (int j = 0; j < 16; j++) {
+    u_int8_t c = block[j];
+    // reference is wrong. It says: Set C[j] to S[c xor L]. But it should be:
+    (*l) = checksum[j] ^= MD2_PI_SUBST[c ^ (*l)];
+  }
+}
+
+void md2_checksum_2(size_t len, uint8_t* buf) {
+  uint8_t l = 0;
+
+  for (size_t i = 0; i < len / 16; i++) {
+    process_block_checksum(buf + (i * 16), buf + len, &l);
+  }
+}
+
+void md2_hash_2(size_t len, const uint8_t buf[len], uint8_t out[16]) {
+  // === step 1 ===
+  int paddingNeeded = 16 - (len % 16);
+  uint8_t originalPadding = paddingNeeded;
+  len += paddingNeeded;
+
+  // printf("len: %d\n", len);
+
+  // +16 for the checksum
+  uint8_t* newBuf = calloc(len + 16, sizeof(uint8_t));
+  // TODO: null check
+  memcpy(newBuf, buf, len - paddingNeeded);
+
+  // printBuf(len + 16, newBuf);
+
+  while (paddingNeeded > 0) {
+    newBuf[len - paddingNeeded] = originalPadding;
+    paddingNeeded--;
+  }
+  // printf("buf with padding: ");
+  // printBuf(len + 16, newBuf);
+
+  // === step 3 ===
+  uint8_t* messageDigestBuf = calloc(48, sizeof(uint8_t));
+
+  // === step 4 ===
+  uint8_t l = 0;
+  // <= because we need to hash the last block too
+  for (size_t i = 0; i < len / 16; i++) {
+    process_block_checksum(newBuf + (i * 16), newBuf + len, &l);
+    process_block_hash(newBuf + (i * 16), messageDigestBuf);
+  }
+
+  process_block_hash(newBuf + len, messageDigestBuf);
+
+  memcpy(out, messageDigestBuf, 16);
+
+  free(newBuf);
+}

From d35d338fb1e8fa8280e687025b365167bd3d3c5f Mon Sep 17 00:00:00 2001
From: Dorian Zedler <dorian@itsblue.de>
Date: Tue, 12 Jul 2022 16:02:30 +0200
Subject: [PATCH 2/7] Fix: missing free

---
 Implementierung/src/md2_impls/md2_2.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/Implementierung/src/md2_impls/md2_2.c b/Implementierung/src/md2_impls/md2_2.c
index 874c097..1fac14a 100644
--- a/Implementierung/src/md2_impls/md2_2.c
+++ b/Implementierung/src/md2_impls/md2_2.c
@@ -27,13 +27,8 @@ void process_block_checksum(uint8_t block[16], uint8_t checksum[16],
   }
 }
 
-void md2_checksum_2(size_t len, uint8_t* buf) {
-  uint8_t l = 0;
-
-  for (size_t i = 0; i < len / 16; i++) {
-    process_block_checksum(buf + (i * 16), buf + len, &l);
-  }
-}
+// unused!
+void md2_checksum_2(size_t, uint8_t*) {}
 
 void md2_hash_2(size_t len, const uint8_t buf[len], uint8_t out[16]) {
   // === step 1 ===
@@ -44,7 +39,7 @@ void md2_hash_2(size_t len, const uint8_t buf[len], uint8_t out[16]) {
   // printf("len: %d\n", len);
 
   // +16 for the checksum
-  uint8_t* newBuf = calloc(len + 16, sizeof(uint8_t));
+  uint8_t* newBuf = calloc(len, sizeof(uint8_t));
   // TODO: null check
   memcpy(newBuf, buf, len - paddingNeeded);
 
@@ -62,15 +57,18 @@ void md2_hash_2(size_t len, const uint8_t buf[len], uint8_t out[16]) {
 
   // === step 4 ===
   uint8_t l = 0;
-  // <= because we need to hash the last block too
+  uint8_t* checksum = calloc(16, sizeof(uint8_t));
+
   for (size_t i = 0; i < len / 16; i++) {
-    process_block_checksum(newBuf + (i * 16), newBuf + len, &l);
+    process_block_checksum(newBuf + (i * 16), checksum, &l);
     process_block_hash(newBuf + (i * 16), messageDigestBuf);
   }
 
-  process_block_hash(newBuf + len, messageDigestBuf);
+  process_block_hash(checksum, messageDigestBuf);
 
   memcpy(out, messageDigestBuf, 16);
 
   free(newBuf);
+  free(messageDigestBuf);
+  free(checksum);
 }

From 4a678b863b652e00c1dd194ace37d465021fdc17 Mon Sep 17 00:00:00 2001
From: Dorian Zedler <dorian@itsblue.de>
Date: Tue, 12 Jul 2022 22:33:01 +0200
Subject: [PATCH 3/7] Feat: Implement V2

---
 Implementierung/lib/io.h              | 11 +++++
 Implementierung/lib/md2_impls/md2_2.h |  2 +
 Implementierung/src/io.c              | 43 +++++++++++--------
 Implementierung/src/main.c            | 56 +++++++++++++++++--------
 Implementierung/src/md2_impls/md2_2.c | 59 ++++++++++++++++-----------
 5 files changed, 113 insertions(+), 58 deletions(-)

diff --git a/Implementierung/lib/io.h b/Implementierung/lib/io.h
index f780a77..6887f25 100644
--- a/Implementierung/lib/io.h
+++ b/Implementierung/lib/io.h
@@ -10,6 +10,17 @@
 #include <stdlib.h>
 #include <sys/stat.h>
 
+/**
+ * @brief Open a file and load its stats
+ *
+ * @param path the filepath
+ * @param file where the pointer of the file handle should be stored
+ * @param file_stat pointer to a stat struct
+ * @return true it worked
+ * @return false there was an error
+ */
+bool open_file(const char* path, FILE** file, struct stat* file_stat);
+
 /**
  * @brief reads a file at a path
  *
diff --git a/Implementierung/lib/md2_impls/md2_2.h b/Implementierung/lib/md2_impls/md2_2.h
index 3e6ff3f..4e64689 100644
--- a/Implementierung/lib/md2_impls/md2_2.h
+++ b/Implementierung/lib/md2_impls/md2_2.h
@@ -8,6 +8,8 @@
 #include <string.h>
 #include <sys/types.h>
 
+#include "../io.h"
+
 /**
  * @brief This implementation loads the file in bits and not at once
  *
diff --git a/Implementierung/src/io.c b/Implementierung/src/io.c
index dedb5ce..4983811 100644
--- a/Implementierung/src/io.c
+++ b/Implementierung/src/io.c
@@ -1,26 +1,35 @@
 #include "../lib/io.h"
 
+bool open_file(const char* path, FILE** file, struct stat* file_stat) {
+  (*file) = fopen(path, "r");
+  if ((*file) == NULL) {
+    printf("Fopen error: %d\n", errno);
+    fclose((*file));
+    return false;
+  }
+
+  int status = fstat(fileno((*file)), file_stat);
+  if (status == -1) {
+    printf("Fstat error: %d\n", errno);
+    fclose((*file));
+    return false;
+  };
+
+  if ((file_stat->st_mode & S_IFMT) != S_IFREG) {
+    printf("File is not a regular file!\n");
+    fclose((*file));
+    return false;
+  }
+
+  return true;
+}
+
 uint8_t* read_file(const char* path, size_t* size) {
   // Read the contents of the file specified by path into a heap-allocated
   // buffer and return a pointer to that buffer.
-  FILE* f = fopen(path, "r");
-  if (f == NULL) {
-    printf("Fopen error: %d\n", errno);
-    fclose(f);
-    return NULL;
-  }
-
+  FILE* f;
   struct stat statOfFile;
-  int status = fstat(fileno(f), &statOfFile);
-  if (status == -1) {
-    printf("Fstat error: %d\n", errno);
-    fclose(f);
-    return NULL;
-  };
-
-  if ((statOfFile.st_mode & S_IFMT) != S_IFREG) {
-    printf("File is not a regular file!\n");
-    fclose(f);
+  if (!open_file(path, &f, &statOfFile)) {
     return NULL;
   }
 
diff --git a/Implementierung/src/main.c b/Implementierung/src/main.c
index 9bdb675..08d26de 100644
--- a/Implementierung/src/main.c
+++ b/Implementierung/src/main.c
@@ -62,6 +62,38 @@ unsigned runTests(struct configuration* c) {
   return failed;
 }
 
+bool calculate_hash(struct configuration c, char* hash) {
+  size_t len;
+  uint8_t* data;
+
+  if (c.implementationToUse != 2) {
+    data = read_file(c.filename, &len);
+  } else {
+    data = (uint8_t*)c.filename;
+    len = 0;
+  }
+
+  if (data == NULL) {
+    printf("Error reading file %s!", c.filename);
+    return false;
+  }
+
+  uint8_t out[16];
+  if (c.doBenchmark) {
+    double duration =
+        run_benchmark(c.benchmarkingCycles, md2_hash, len, data, out);
+    printf("Running %d cycles took %f seconds\n", c.benchmarkingCycles,
+           duration);
+  } else {
+    md2_hash(len, data, out);
+  }
+
+  md2_encode_hash(out, hash);
+
+  if (c.implementationToUse != 2) free(data);
+  return true;
+}
+
 int main(int argc, char** argv) {
   struct configuration c;
   enum argumentParseResult result = parseArguments(argc, argv, &c);
@@ -87,33 +119,21 @@ int main(int argc, char** argv) {
       "benchmark cycles: %d\n",
       c.implementationToUse, c.doBenchmark, c.benchmarkingCycles);
 
+  if (c.runTests && c.implementationToUse == 2) {
+    fprintf(stderr, "Cannot run tests on implementation 2!");
+    return EXIT_FAILURE;
+  }
+
   if (c.runTests) {
     printf("Running tests...\n\n");
     return runTests(&c);
   }
 
   printf("Hashing file %s...\n\n", c.filename);
-  size_t len;
-  uint8_t* data = read_file(c.filename, &len);
-  if (data == NULL) {
-    printf("Error reading file %s!", c.filename);
-    return EXIT_FAILURE;
-  }
 
-  uint8_t out[16];
   char hash[32];
-  if (c.doBenchmark) {
-    double duration =
-        run_benchmark(c.benchmarkingCycles, md2_hash, len, data, out);
-    printf("Running %d cycles took %f seconds\n", c.benchmarkingCycles,
-           duration);
-  } else {
-    md2_hash(len, data, out);
-  }
-  md2_encode_hash(out, hash);
+  calculate_hash(c, hash);
   printf("Hash: %s\n", hash);
 
-  free(data);
-
   return 0;
 }
diff --git a/Implementierung/src/md2_impls/md2_2.c b/Implementierung/src/md2_impls/md2_2.c
index 1fac14a..f8d54d8 100644
--- a/Implementierung/src/md2_impls/md2_2.c
+++ b/Implementierung/src/md2_impls/md2_2.c
@@ -27,30 +27,26 @@ void process_block_checksum(uint8_t block[16], uint8_t checksum[16],
   }
 }
 
-// unused!
-void md2_checksum_2(size_t, uint8_t*) {}
-
-void md2_hash_2(size_t len, const uint8_t buf[len], uint8_t out[16]) {
-  // === step 1 ===
+void apply_padding(size_t len, uint8_t buf[16]) {
   int paddingNeeded = 16 - (len % 16);
   uint8_t originalPadding = paddingNeeded;
   len += paddingNeeded;
 
-  // printf("len: %d\n", len);
-
-  // +16 for the checksum
-  uint8_t* newBuf = calloc(len, sizeof(uint8_t));
-  // TODO: null check
-  memcpy(newBuf, buf, len - paddingNeeded);
-
-  // printBuf(len + 16, newBuf);
-
   while (paddingNeeded > 0) {
-    newBuf[len - paddingNeeded] = originalPadding;
+    buf[len - paddingNeeded] = originalPadding;
     paddingNeeded--;
   }
-  // printf("buf with padding: ");
-  // printBuf(len + 16, newBuf);
+  printf("buf with padding: ");
+  md2_print_buf(len, buf);
+}
+
+// unused!
+void md2_checksum_2(size_t, uint8_t*) {}
+
+void md2_hash_2(size_t len, const uint8_t buf[len], uint8_t out[16]) {
+  FILE* file;
+  struct stat file_stat;
+  open_file((char*)buf, &file, &file_stat);
 
   // === step 3 ===
   uint8_t* messageDigestBuf = calloc(48, sizeof(uint8_t));
@@ -59,16 +55,33 @@ void md2_hash_2(size_t len, const uint8_t buf[len], uint8_t out[16]) {
   uint8_t l = 0;
   uint8_t* checksum = calloc(16, sizeof(uint8_t));
 
-  for (size_t i = 0; i < len / 16; i++) {
-    process_block_checksum(newBuf + (i * 16), checksum, &l);
-    process_block_hash(newBuf + (i * 16), messageDigestBuf);
-  }
+  uint8_t* data = malloc(16);
+  size_t bytes_left_to_read = file_stat.st_size;
+  size_t bytes_left_to_process = 0;
+
+  while (bytes_left_to_read != 0) {
+    bytes_left_to_process = bytes_left_to_read >= 16 ? 16 : bytes_left_to_read;
+
+    fread(data, 1, bytes_left_to_process, file);
+    if (ferror(file) || feof(file)) {
+      fprintf(stderr, "Error reading the file!");
+      return;
+    }
+
+    process_block_checksum(data, checksum, &l);
+    process_block_hash(data, messageDigestBuf);
+
+    bytes_left_to_read -= bytes_left_to_process;
+  };
+
+  apply_padding(bytes_left_to_process % 16, data);
+  process_block_checksum(data, checksum, &l);
+  process_block_hash(data, messageDigestBuf);
 
   process_block_hash(checksum, messageDigestBuf);
-
   memcpy(out, messageDigestBuf, 16);
 
-  free(newBuf);
+  free(data);
   free(messageDigestBuf);
   free(checksum);
 }

From 03016a1979ad0adde298763e07c2e63779ae6739 Mon Sep 17 00:00:00 2001
From: Dorian Zedler <dorian@itsblue.de>
Date: Tue, 12 Jul 2022 22:35:13 +0200
Subject: [PATCH 4/7] Fix: close file

---
 Implementierung/src/md2_impls/md2_2.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Implementierung/src/md2_impls/md2_2.c b/Implementierung/src/md2_impls/md2_2.c
index f8d54d8..f1ab4b6 100644
--- a/Implementierung/src/md2_impls/md2_2.c
+++ b/Implementierung/src/md2_impls/md2_2.c
@@ -74,6 +74,8 @@ void md2_hash_2(size_t len, const uint8_t buf[len], uint8_t out[16]) {
     bytes_left_to_read -= bytes_left_to_process;
   };
 
+  fclose(file);
+
   apply_padding(bytes_left_to_process % 16, data);
   process_block_checksum(data, checksum, &l);
   process_block_hash(data, messageDigestBuf);

From 2a6bb4354ed1b8b979c74775d2e4b56730e09735 Mon Sep 17 00:00:00 2001
From: Dorian Zedler <dorian@itsblue.de>
Date: Tue, 12 Jul 2022 22:36:26 +0200
Subject: [PATCH 5/7] Fix: fail on error

---
 Implementierung/src/md2_impls/md2_2.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/Implementierung/src/md2_impls/md2_2.c b/Implementierung/src/md2_impls/md2_2.c
index f1ab4b6..e250f05 100644
--- a/Implementierung/src/md2_impls/md2_2.c
+++ b/Implementierung/src/md2_impls/md2_2.c
@@ -46,7 +46,10 @@ void md2_checksum_2(size_t, uint8_t*) {}
 void md2_hash_2(size_t len, const uint8_t buf[len], uint8_t out[16]) {
   FILE* file;
   struct stat file_stat;
-  open_file((char*)buf, &file, &file_stat);
+  if (!open_file((char*)buf, &file, &file_stat)) {
+    fprintf(stderr, "Error opening the file!");
+    return;
+  }
 
   // === step 3 ===
   uint8_t* messageDigestBuf = calloc(48, sizeof(uint8_t));

From 21d351c7e2b1672a4abb49be8bc5a646d544d838 Mon Sep 17 00:00:00 2001
From: Dorian Zedler <dorian@itsblue.de>
Date: Tue, 12 Jul 2022 22:37:54 +0200
Subject: [PATCH 6/7] Fix: handle file opening errors

---
 Implementierung/src/io.c              | 1 -
 Implementierung/src/md2_impls/md2_2.c | 2 +-
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/Implementierung/src/io.c b/Implementierung/src/io.c
index 4983811..00840d2 100644
--- a/Implementierung/src/io.c
+++ b/Implementierung/src/io.c
@@ -4,7 +4,6 @@ bool open_file(const char* path, FILE** file, struct stat* file_stat) {
   (*file) = fopen(path, "r");
   if ((*file) == NULL) {
     printf("Fopen error: %d\n", errno);
-    fclose((*file));
     return false;
   }
 
diff --git a/Implementierung/src/md2_impls/md2_2.c b/Implementierung/src/md2_impls/md2_2.c
index e250f05..b51a47a 100644
--- a/Implementierung/src/md2_impls/md2_2.c
+++ b/Implementierung/src/md2_impls/md2_2.c
@@ -47,7 +47,7 @@ void md2_hash_2(size_t len, const uint8_t buf[len], uint8_t out[16]) {
   FILE* file;
   struct stat file_stat;
   if (!open_file((char*)buf, &file, &file_stat)) {
-    fprintf(stderr, "Error opening the file!");
+    fprintf(stderr, "Error opening the file!\n");
     return;
   }
 

From 82f3f7efa83f7ce053bc24f6de60f6274ede66ea Mon Sep 17 00:00:00 2001
From: Dorian Zedler <dorian@itsblue.de>
Date: Tue, 12 Jul 2022 22:53:17 +0200
Subject: [PATCH 7/7] Chore: improove error handling and logging

---
 Implementierung/src/io.c              |  7 ++++---
 Implementierung/src/main.c            | 19 +++++++++++++++----
 Implementierung/src/md2_impls/md2_2.c |  5 +----
 3 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/Implementierung/src/io.c b/Implementierung/src/io.c
index 00840d2..339bd75 100644
--- a/Implementierung/src/io.c
+++ b/Implementierung/src/io.c
@@ -3,19 +3,20 @@
 bool open_file(const char* path, FILE** file, struct stat* file_stat) {
   (*file) = fopen(path, "r");
   if ((*file) == NULL) {
-    printf("Fopen error: %d\n", errno);
+    if (errno == 0) errno = EIO;
     return false;
   }
 
   int status = fstat(fileno((*file)), file_stat);
   if (status == -1) {
-    printf("Fstat error: %d\n", errno);
+    if (errno == 0) errno = EIO;
     fclose((*file));
     return false;
   };
 
   if ((file_stat->st_mode & S_IFMT) != S_IFREG) {
     printf("File is not a regular file!\n");
+    errno = ENOENT;
     fclose((*file));
     return false;
   }
@@ -38,8 +39,8 @@ uint8_t* read_file(const char* path, size_t* size) {
       fread(data, statOfFile.st_blksize, statOfFile.st_blocks, f);
   // size_t bytesRead = fread(data, sizeof(uint8_t), statOfFile.st_size, f);
   if (bytesRead != 0 && !feof(f)) {
-    printf("Error reading file!\n");
     fclose(f);
+    if (errno == 0) errno = EIO;
     return NULL;
   }
 
diff --git a/Implementierung/src/main.c b/Implementierung/src/main.c
index 08d26de..42b8e6f 100644
--- a/Implementierung/src/main.c
+++ b/Implementierung/src/main.c
@@ -74,10 +74,11 @@ bool calculate_hash(struct configuration c, char* hash) {
   }
 
   if (data == NULL) {
-    printf("Error reading file %s!", c.filename);
+    printf("Error reading file %s!\n", c.filename);
     return false;
   }
 
+  errno = 0;
   uint8_t out[16];
   if (c.doBenchmark) {
     double duration =
@@ -88,6 +89,10 @@ bool calculate_hash(struct configuration c, char* hash) {
     md2_hash(len, data, out);
   }
 
+  if (errno != 0) {
+    return false;
+  }
+
   md2_encode_hash(out, hash);
 
   if (c.implementationToUse != 2) free(data);
@@ -120,7 +125,7 @@ int main(int argc, char** argv) {
       c.implementationToUse, c.doBenchmark, c.benchmarkingCycles);
 
   if (c.runTests && c.implementationToUse == 2) {
-    fprintf(stderr, "Cannot run tests on implementation 2!");
+    fprintf(stderr, "Cannot run tests on implementation 2!\n");
     return EXIT_FAILURE;
   }
 
@@ -132,8 +137,14 @@ int main(int argc, char** argv) {
   printf("Hashing file %s...\n\n", c.filename);
 
   char hash[32];
-  calculate_hash(c, hash);
+  if (!calculate_hash(c, hash)) {
+    if (errno != 0) {
+      fprintf(stderr, "\n\033[0;31mAn error occured: %s\033[0m\n",
+              strerror(errno));
+    }
+    return EXIT_FAILURE;
+  }
   printf("Hash: %s\n", hash);
 
-  return 0;
+  return EXIT_SUCCESS;
 }
diff --git a/Implementierung/src/md2_impls/md2_2.c b/Implementierung/src/md2_impls/md2_2.c
index b51a47a..1349c0f 100644
--- a/Implementierung/src/md2_impls/md2_2.c
+++ b/Implementierung/src/md2_impls/md2_2.c
@@ -36,8 +36,6 @@ void apply_padding(size_t len, uint8_t buf[16]) {
     buf[len - paddingNeeded] = originalPadding;
     paddingNeeded--;
   }
-  printf("buf with padding: ");
-  md2_print_buf(len, buf);
 }
 
 // unused!
@@ -47,7 +45,6 @@ void md2_hash_2(size_t len, const uint8_t buf[len], uint8_t out[16]) {
   FILE* file;
   struct stat file_stat;
   if (!open_file((char*)buf, &file, &file_stat)) {
-    fprintf(stderr, "Error opening the file!\n");
     return;
   }
 
@@ -67,7 +64,7 @@ void md2_hash_2(size_t len, const uint8_t buf[len], uint8_t out[16]) {
 
     fread(data, 1, bytes_left_to_process, file);
     if (ferror(file) || feof(file)) {
-      fprintf(stderr, "Error reading the file!");
+      if (errno == 0) errno = EIO;
       return;
     }