✨ Parse command line arguments

src/main.c

@@ -1,5 +1,7 @@
 #include <errno.h>
+#include <stdbool.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 //Import our code
@@ -7,49 +9,89 @@
 #include "fileReader.h"
 #include "utils/min.h"
 
+#define BUFFER_SIZE 0xffffUL
+#define ENCRYPTION_HEADER_LENGTH 12UL
+
+uint16_t getUint16(char* buffer) {
+  return (uint16_t)buffer[0] | \
+    (uint16_t)buffer[1] << 8;
+}
+uint32_t getUint32(char* buffer) {
+  return (uint32_t)buffer[0] | \
+    (uint32_t)buffer[1] << 8 | \
+    (uint32_t)buffer[2] << 16  | \
+    (uint32_t)buffer[3] << 24;
+}
+
 int main(int argc, unsigned char *argv[]) {
-  printf("Hello World!\n");
+  if (argc != 4 && argc != 7) {
+    fprintf(stderr, "Wrong arguments. Usage: patcher-installer <disk_name> <disk_offset> <file_size> [<key0> <key1> <key2>]");
+    exit(1);
+  }
   //TODO: verify argv and assign it to variables
-  char* archiveName = "1234";
+  char* archiveName = argv[1];
-  const unsigned long archiveOffset = 0UL;
+  const unsigned long archiveOffset = atol(argv[2]);
-  const unsigned long fileLength = 0xffffUL;
+  const unsigned long fileLength = atol(argv[3]);
-  uint32_t key0 = 0;
+
-  uint32_t key1 = 0;
+  const bool isEncrypted = argc == 7;
-  uint32_t key2 = 0;
+  if (isEncrypted) {
+    uint32_t key0 = atoi(argv[4]);
+    uint32_t key1 = atoi(argv[5]);
+    uint32_t key2 = atoi(argv[6]);
+    //Initialise decryption (pass decryption keys)
+    initDecryptor(key0, key1, key2);
+  }
+
+  //-------------------------------------------------
 
   //Initialise file reader
   initFileReader(archiveName, archiveOffset);
 
-  //Skip header (30 bytes + additional length)
+  //Skip local file header (30 bytes + additional length)
   char* fileHeader = getBytes(30UL);
-  printf(fileHeader);
+  //Check that header is correct
-  //TODO: check that header is correct
+  const uint32_t magic = getUint32(fileHeader);
-  //TODO: read additional length
+  if (magic != (uint32_t)0x06054b50) {
-  const unsigned long additionalLength = 0UL;
+    fprintf(stderr, "Wrong magic in local file header, expected 0x06054b50 but found %#010x.", magic);
-  getBytes(additionalLength);
+    exit(1);
+  }
+  free(fileHeader);
+  //Read additional length
+  const unsigned long additionalLength = getUint16(fileHeader + 26) + getUint16(fileHeader + 28);
+  char* additionalBytes = getBytes(additionalLength);
+  free(additionalBytes);
 
-  //Initialise decryption (pass decryption keys)
+  //If file is encrypted, skip 12-byte encryption header
-  initDecryptor(key0, key1, key2);
+  if (isEncrypted) {
+    char* encrHeader = getBytes(ENCRYPTION_HEADER_LENGTH);
+    decrypt(encrHeader, ENCRYPTION_HEADER_LENGTH);
+    free(encrHeader);
+  }
 
-  //Skip 12-byte encryption header
+  //-------------------------------------------------
-  const unsigned long encrHeaderLength = 12UL;
-  char* encrHeader = getBytes(encrHeaderLength);
-  decrypt(encrHeader, encrHeaderLength);
 
   //Read actual file
   unsigned long remainingBytes = fileLength;
   while (remainingBytes > 0) {
-    const unsigned long chunkSize = min(0xFF, remainingBytes);
+    const unsigned long chunkSize = min(BUFFER_SIZE, remainingBytes);
     char* chunk = getBytes(chunkSize);
     remainingBytes -= chunkSize;
 
+    //Decrypt file if it is encrypted
+    if (isEncrypted) {
+      //TODO: For highest performance, we need to move if condition outside of while loop
       decrypt(chunk, chunkSize);
+    }
 
     //Decompress file
     //TODO
 
     //Optionally perform xdelta3
     //TODO
+
+    //release memory
+    //TODO: need to malloc once outside of while loop, and then reuse it instead of a new malloc() each loop
+    free(chunk);
   }
 
   return 0;

src/utils/decryptUtilities.c

@@ -1,6 +1,6 @@
 #include "decryptUtilities.h"
 
-static uint32_t crc32_tab[] = {
+const uint32_t crc32_tab[] = {
 	0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
 	0xe963a535, 0x9e6495a3,	0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
 	0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,

src/utils/decryptUtilities.h

@@ -2,8 +2,6 @@
 
 #include <stdint.h>
 
-uint32_t getCrc(uint32_t old_crc, unsigned char c);
-
 void updateKeys(uint32_t *key_0, uint32_t *key_1, uint32_t *key_2, unsigned char c);
 
 unsigned char decryptByte(unsigned short keyPart);