Add ability to specify a directory to extract files to

Author: VitaSmith

README.md

@@ -21,8 +21,15 @@ directory as the NUS content, and can be compiled for Linux or macOS.
 ### Usage
 
 ```
-cdecrypt <NUS file or directory>
+cdecrypt <NUS file or directory> [<target directory or existing file>]
 ```
 
-The content is extracted into the same directory where the NUS files reside.  
-On Windows, you can also drag and drop a directory/file directly onto `cdecrypt.exe`.
+If only one parameter is specified, the content is extracted into the same
+directory where the NUS files reside. If an existing file is provided as the
+second parameter, it is ignored (to preserve compatibility with the previous
+versions of CDecrypt). If the second parameter is not an existing file, then
+it is used as the target directory to extract files in, with any intermediate
+directories created if needed.
+
+Note that on Windows, you can drag and drop a directory/file directly onto
+`cdecrypt.exe`.

cdecrypt.c

@@ -497,6 +497,9 @@ int main_utf8(int argc, char** argv)
 
     printf("FST entries: %u\n", entries);
 
+    char* dst_dir = ((argc <= 2) || is_file(argv[2])) ? argv[1] : argv[2];
+    printf("Extracting to directory: '%s'\n", dst_dir);
+    create_path(dst_dir);
     char path[PATH_MAX] = { 0 };
     uint32_t entry[16];
     uint32_t l_entry[16];
@@ -519,7 +522,7 @@ int main_utf8(int argc, char** argv)
         } else {
             uint32_t offset;
             memset(path, 0, sizeof(path));
-            strcpy(path, argv[1]);
+            strcpy(path, dst_dir);
 
             size_t short_path = strlen(path) + 1;
             for (uint32_t j = 0; j < level; j++) {

util.c

@@ -75,7 +75,7 @@ bool is_directory(const char* path)
 
 char* change_extension(const char* path, const char* extension)
 {
-    static char new_path[256];
+    static char new_path[PATH_MAX];
     strncpy(new_path, basename((char*)path), sizeof(new_path) - 1);
     for (size_t i = 0; i < sizeof(new_path); i++) {
         if (new_path[i] == '.')