loader.cpp: improved file extension checking, made Upper/LowerStr useful

Instead of forcibly taking the last 4 characters, it now finds the last extension separator (the period) and takes a substr of its location.

src/common/string_util.cpp

@@ -18,19 +18,15 @@
 #endif
 
 /// Make a string lowercase
-void LowerStr(char* str) {
-    for (int i = 0; str[i]; i++) {
-        str[i] = tolower(str[ i ]);
-    }
+std::string LowerStr(std::string str) {
+    std::transform(str.begin(), str.end(), str.begin(), ::tolower);
+    return str;
 }
 
 /// Make a string uppercase
-void UpperStr(char* str) {
-    for (int i=0; i < strlen(str); i++) {
-        if(str[i] >= 'a' && str[i] <= 'z') {
-            str[i] &= 0xDF;
-        }
-    }
+std::string UpperStr(std::string str) {
+    std::transform(str.begin(), str.end(), str.begin(), ::toupper);
+    return str;
 }
 
 // faster than sscanf

src/common/string_util.h

@@ -13,10 +13,11 @@
 #include "common/common.h"
 
 /// Make a string lowercase
-void LowerStr(char* str);
+
+std::string LowerStr(std::string str);
 
 /// Make a string uppercase
-void UpperStr(char* str);
+std::string UpperStr(std::string str);
 
 std::string StringFromFormat(const char* format, ...);
 // Cheap!

src/core/loader/loader.cpp

@@ -26,21 +26,23 @@ FileType IdentifyFile(const std::string &filename) {
         ERROR_LOG(LOADER, "invalid filename %s", filename.c_str());
         return FileType::Error;
     }
-    std::string extension = filename.size() >= 5 ? filename.substr(filename.size() - 4) : "";
 
-    if (!strcasecmp(extension.c_str(), ".elf")) {
+    size_t extension_loc = filename.find_last_of('.');
+    std::string extension = extension_loc != std::string::npos ? filename.substr(extension_loc) : "";
+
+    if (LowerStr(extension) == ".elf") {
         return FileType::ELF; // TODO(bunnei): Do some filetype checking :p
     }
-    else if (!strcasecmp(extension.c_str(), ".axf")) {
+    else if (LowerStr(extension) == ".axf") {
         return FileType::ELF; // TODO(bunnei): Do some filetype checking :p
     }
-    else if (!strcasecmp(extension.c_str(), ".cxi")) {
+    else if (LowerStr(extension) == ".cxi") {
         return FileType::CXI; // TODO(bunnei): Do some filetype checking :p
     }
-    else if (!strcasecmp(extension.c_str(), ".cci")) {
+    else if (LowerStr(extension) == ".cci") {
         return FileType::CCI; // TODO(bunnei): Do some filetype checking :p
     }
-    else if (!strcasecmp(extension.c_str(), ".bin")) {
+    else if (LowerStr(extension) == ".bin") {
         return FileType::BIN; // TODO(bunnei): Do some filetype checking :p
     }
     return FileType::Unknown;