Change to execution paths to binary paths (#200)

Previously, it used argv[0] for the execution path, which is fine in
most cases, but in my case, it is not.
The thing is, I use NixOS, and I have created a Nix module for BeamMP.
When running BeamMP-Launcher, it tries to check for updates, and fails
because of the SHA hash.
There are other ways around this, such as setting the execution
directory, but I think this is a far clearer approach

---

By creating this pull request, I understand that code that is AI
generated or otherwise automatically generated may be rejected without
further discussion.
I declare that I fully understand all code I pushed into this PR, and
wrote all this code myself and own the rights to this code.

include/Http.h

@@ -11,7 +11,7 @@
 #include <string>
 class HTTP {
 public:
-    static bool Download(const std::string& IP, const beammp_fs_string& Path);
+    static bool Download(const std::string& IP, const beammp_fs_string& Path, const std::string& Hash);
     static std::string Post(const std::string& IP, const std::string& Fields);
     static std::string Get(const std::string& IP);
     static bool ProgressBar(size_t c, size_t t);

include/Startup.h

@@ -13,6 +13,7 @@
 
 void InitLauncher();
 beammp_fs_string GetEP(const beammp_fs_char* P = nullptr);
+std::filesystem::path GetBP(const beammp_fs_char* P = nullptr);
 std::filesystem::path GetGamePath();
 std::string GetVer();
 std::string GetPatch();

include/Utils.h

@@ -29,7 +29,6 @@
 #endif
 
 namespace Utils {
-
     inline std::vector<std::string> Split(const std::string& String, const std::string& delimiter) {
         std::vector<std::string> Val;
         size_t pos;
@@ -185,7 +184,7 @@ inline std::wstring ToWString(const std::string& s) {
         return s;
     }
 #endif
-    inline std::string GetSha256HashReallyFast(const beammp_fs_string& filename) {
+    inline std::string GetSha256HashReallyFastFile(const beammp_fs_string& filename) {
         try {
             EVP_MD_CTX* mdctx;
             const EVP_MD* md;
@@ -237,7 +236,51 @@ inline std::wstring ToWString(const std::string& s) {
             for (size_t i = 0; i < sha256_len; i++) {
                 char buf[3];
                 sprintf(buf, "%02x", sha256_value[i]);
-                buf[2] = 0;
+                buf[2] = '\0';
+                result += buf;
+            }
+            return result;
+        } catch (const std::exception& e) {
+            error(beammp_wide("Sha256 hashing of '") + filename + beammp_wide("' failed: ") + ToWString(e.what()));
+            return "";
+        }
+    }
+    inline std::string GetSha256HashReallyFast(const std::string& text, const beammp_fs_string& filename) {
+        try {
+            EVP_MD_CTX* mdctx;
+            const EVP_MD* md;
+            uint8_t sha256_value[EVP_MAX_MD_SIZE];
+            md = EVP_sha256();
+            if (md == nullptr) {
+                throw std::runtime_error("EVP_sha256() failed");
+            }
+
+            mdctx = EVP_MD_CTX_new();
+            if (mdctx == nullptr) {
+                throw std::runtime_error("EVP_MD_CTX_new() failed");
+            }
+            if (!EVP_DigestInit_ex2(mdctx, md, NULL)) {
+                EVP_MD_CTX_free(mdctx);
+                throw std::runtime_error("EVP_DigestInit_ex2() failed");
+            }
+
+            if (!EVP_DigestUpdate(mdctx, text.data(), text.size())) {
+                EVP_MD_CTX_free(mdctx);
+                throw std::runtime_error("EVP_DigestUpdate() failed");
+            }
+
+            unsigned int sha256_len = 0;
+            if (!EVP_DigestFinal_ex(mdctx, sha256_value, &sha256_len)) {
+                EVP_MD_CTX_free(mdctx);
+                throw std::runtime_error("EVP_DigestFinal_ex() failed");
+            }
+            EVP_MD_CTX_free(mdctx);
+
+            std::string result;
+            for (size_t i = 0; i < sha256_len; i++) {
+                char buf[3];
+                sprintf(buf, "%02x", sha256_value[i]);
+                buf[2] = '\0';
                 result += buf;
             }
             return result;

src/Network/Http.cpp

@@ -127,7 +127,7 @@ std::string HTTP::Post(const std::string& IP, const std::string& Fields) {
     return Ret;
 }
 
-bool HTTP::Download(const std::string& IP, const beammp_fs_string& Path) {
+bool HTTP::Download(const std::string& IP, const beammp_fs_string& Path, const std::string& Hash) {
     static std::mutex Lock;
     std::scoped_lock Guard(Lock);
 
@@ -139,6 +139,16 @@ bool HTTP::Download(const std::string& IP, const beammp_fs_string& Path) {
         return false;
     }
 
+    std::string RetHash = Utils::GetSha256HashReallyFast(Ret, Path);
+
+    debug("Return hash: " + RetHash);
+    debug("Expected hash: " + Hash);
+
+    if (RetHash != Hash) {
+        error("Downloaded file hash does not match expected hash");
+        return false;
+    }
+
     std::ofstream File(Path, std::ios::binary);
     if (File.is_open()) {
         File << Ret;

src/Network/Resources.cpp

@@ -445,7 +445,7 @@ void NewSyncResources(SOCKET Sock, const std::string& Mods, const std::vector<Mo
         }
         auto FileName = std::filesystem::path(ModInfoIter->FileName).stem().string() + "-" + ModInfoIter->Hash.substr(0, 8) + std::filesystem::path(ModInfoIter->FileName).extension().string();
         auto PathToSaveTo = (CachingDirectory / FileName);
-        if (fs::exists(PathToSaveTo) && Utils::GetSha256HashReallyFast(PathToSaveTo) == ModInfoIter->Hash) {
+        if (fs::exists(PathToSaveTo) && Utils::GetSha256HashReallyFastFile(PathToSaveTo) == ModInfoIter->Hash) {
             debug("Mod '" + FileName + "' found in cache");
             UpdateUl(false, std::to_string(ModNo) + "/" + std::to_string(TotalMods) + ": " + ModInfoIter->FileName);
             std::this_thread::sleep_for(std::chrono::milliseconds(50));
@@ -476,7 +476,7 @@ void NewSyncResources(SOCKET Sock, const std::string& Mods, const std::vector<Mo
             WaitForConfirm();
             continue;
         } else if (auto OldCachedPath = CachingDirectory / std::filesystem::path(ModInfoIter->FileName).filename();
-                   fs::exists(OldCachedPath) && Utils::GetSha256HashReallyFast(OldCachedPath) == ModInfoIter->Hash) {
+                   fs::exists(OldCachedPath) && Utils::GetSha256HashReallyFastFile(OldCachedPath) == ModInfoIter->Hash) {
             debug("Mod '" + FileName + "' found in old cache, copying it to the new cache");
             UpdateUl(false, std::to_string(ModNo) + "/" + std::to_string(TotalMods) + ": " + ModInfoIter->FileName);
             std::this_thread::sleep_for(std::chrono::milliseconds(50));
@@ -562,7 +562,7 @@ void NewSyncResources(SOCKET Sock, const std::string& Mods, const std::vector<Mo
                 Terminate = true;
             }
 
-            if (Utils::GetSha256HashReallyFast(PathToSaveTo) != ModInfoIter->Hash) {
+            if (Utils::GetSha256HashReallyFastFile(PathToSaveTo) != ModInfoIter->Hash) {
                 error(beammp_wide("Failed to write or download the entire file '") + beammp_fs_string(PathToSaveTo) + beammp_wide("' correctly (hash mismatch)"));
                 Terminate = true;
             }

src/Security/BeamNG.cpp

@@ -187,6 +187,7 @@ void LegitimacyCheck() {
     // Right now only steam is supported
     std::vector<std::filesystem::path> steamappsCommonPaths = {
         ".steam/root/steamapps", // default
+        ".steam/steam/steamapps", // Legacy Steam installations
         ".var/app/com.valvesoftware.Steam/.steam/root/steamapps", // flatpak
         "snap/steam/common/.local/share/Steam/steamapps" // snap
     };

src/Startup.cpp

@@ -14,7 +14,10 @@
 #if defined(_WIN32)
 #elif defined(__linux__)
 #include <unistd.h>
-#endif
+#elif defined (__APPLE__)
+#include <unistd.h>
+#include <libproc.h>
+#endif // __APPLE__
 #include "Http.h"
 #include "Logger.h"
 #include "Network/network.hpp"
@@ -94,6 +97,34 @@ beammp_fs_string GetEP(const beammp_fs_char* P) {
     }();
     return Ret;
 }
+
+fs::path GetBP(const beammp_fs_char* P) {
+    fs::path fspath = {};
+#if defined(_WIN32)
+    beammp_fs_char path[256];
+    GetModuleFileNameW(nullptr, path, sizeof(path));
+    fspath = path;
+#elif defined(__linux__)
+    fspath = fs::canonical("/proc/self/exe");
+#elif defined(__APPLE__)
+    pid_t pid = getpid();
+    char path[PROC_PIDPATHINFO_MAXSIZE];
+    // While this is fine for a raw executable,
+    // an application bundle is read-only and these files
+    // should instead be placed in Application Support.
+    proc_pidpath(pid, path, sizeof(path));
+    fspath = std::string(path);
+ #else
+    fspath = beammp_fs_string(P);
+#endif
+    fspath = fs::weakly_canonical(fspath.string() + "/..");
+#if defined(_WIN32)
+    return fspath.wstring();
+#else
+    return fspath.string();
+#endif
+}
+
 #if defined(_WIN32)
 void ReLaunch() {
     std::wstring Arg;
@@ -103,7 +134,7 @@ void ReLaunch() {
     }
     info("Relaunch!");
     system("cls");
-    ShellExecuteW(nullptr, L"runas", (GetEP() + GetEN()).c_str(), Arg.c_str(), nullptr, SW_SHOWNORMAL);
+    ShellExecuteW(nullptr, L"runas", (GetBP() / GetEN()).c_str(), Arg.c_str(), nullptr, SW_SHOWNORMAL);
     ShowWindow(GetConsoleWindow(), 0);
     std::this_thread::sleep_for(std::chrono::seconds(1));
     exit(1);
@@ -114,7 +145,7 @@ void URelaunch() {
         Arg += Utils::ToWString(options.argv[c - 1]);
         Arg += L" ";
     }
-    ShellExecuteW(nullptr, L"open", (GetEP() + GetEN()).c_str(), Arg.c_str(), nullptr, SW_SHOWNORMAL);
+    ShellExecuteW(nullptr, L"open", (GetBP() / GetEN()).c_str(), Arg.c_str(), nullptr, SW_SHOWNORMAL);
     ShowWindow(GetConsoleWindow(), 0);
     std::this_thread::sleep_for(std::chrono::seconds(1));
     exit(1);
@@ -128,7 +159,7 @@ void ReLaunch() {
     }
     info("Relaunch!");
     system("clear");
-    int ret = execv(options.executable_name.c_str(), const_cast<char**>(options.argv));
+    int ret = execv((GetBP() / GetEN()).c_str(), const_cast<char**>(options.argv));
     if (ret < 0) {
         error(std::string("execv() failed with: ") + strerror(errno) + ". Failed to relaunch");
         exit(1);
@@ -137,7 +168,7 @@ void ReLaunch() {
     exit(1);
 }
 void URelaunch() {
-    int ret = execv(options.executable_name.c_str(), const_cast<char**>(options.argv));
+    int ret = execv((GetBP() / GetEN()).c_str(), const_cast<char**>(options.argv));
     if (ret < 0) {
         error(std::string("execv() failed with: ") + strerror(errno) + ". Failed to relaunch");
         exit(1);
@@ -169,9 +200,9 @@ void CheckForUpdates(const std::string& CV) {
         "https://backend.beammp.com/version/launcher?branch=" + Branch + "&pk=" + PublicKey);
 
     transform(LatestHash.begin(), LatestHash.end(), LatestHash.begin(), ::tolower);
-    beammp_fs_string EP(GetEP() + GetEN()), Back(GetEP() + beammp_wide("BeamMP-Launcher.back"));
+    beammp_fs_string BP(GetBP() / GetEN()), Back(GetBP() / beammp_wide("BeamMP-Launcher.back"));
 
-    std::string FileHash = Utils::GetSha256HashReallyFast(EP);
+    std::string FileHash = Utils::GetSha256HashReallyFastFile(BP);
 
     if (FileHash != LatestHash && IsOutdated(Version(VersionStrToInts(GetVer() + GetPatch())), Version(VersionStrToInts(LatestVersion)))) {
         if (!options.no_update) {
@@ -179,14 +210,21 @@ void CheckForUpdates(const std::string& CV) {
 #if defined(__linux__)
             error("Auto update is NOT implemented for the Linux version. Please update manually ASAP as updates contain security patches.");
 #else
-            fs::remove(Back);
-            fs::rename(EP, Back);
             info("Downloading Launcher update " + LatestHash);
             HTTP::Download(
                 "https://backend.beammp.com/builds/launcher?download=true"
                 "&pk="
                     + PublicKey + "&branch=" + Branch,
-                EP);
+                beammp_wide("new_") + BP, LatestHash);
+            std::error_code ec;
+            fs::remove(Back, ec);
+            if (ec == std::errc::permission_denied) {
+                error("Failed to remove old backup file: " + ec.message() + ". Using alternative name.");
+                fs::rename(BP, Back + beammp_wide(".") + Utils::ToWString(FileHash.substr(0, 8)));
+            } else {
+                fs::rename(BP, Back);
+            }
+            fs::rename(beammp_wide("new_") + BP, BP);
             URelaunch();
 #endif
         } else {
@@ -247,8 +285,8 @@ void InitLauncher() {
 }
 #endif
 
-size_t DirCount(const std::filesystem::path& path) {
-    return (size_t)std::distance(std::filesystem::directory_iterator { path }, std::filesystem::directory_iterator {});
+size_t DirCount(const fs::path& path) {
+    return (size_t)std::distance(fs::directory_iterator { path }, fs::directory_iterator {});
 }
 
 void CheckMP(const beammp_fs_string& Path) {
@@ -329,14 +367,14 @@ void PreGame(const beammp_fs_string& GamePath) {
         std::string ZipPath(GetGamePath() / R"(mods/multiplayer/beammp.zip)");
 #endif
 
-        std::string FileHash = fs::exists(ZipPath) ? Utils::GetSha256HashReallyFast(ZipPath) : "";
+        std::string FileHash = fs::exists(ZipPath) ? Utils::GetSha256HashReallyFastFile(ZipPath) : "";
 
         if (FileHash != LatestHash) {
             info("Downloading BeamMP Update " + LatestHash);
             HTTP::Download("https://backend.beammp.com/builds/client?download=true"
                            "&pk="
                     + PublicKey + "&branch=" + Branch,
-                ZipPath);
+                ZipPath, LatestHash);
         }
 
         beammp_fs_string Target(GetGamePath() / beammp_wide("mods/unpacked/beammp"));