From 801224749fa4d2aa0e2ee0e095983b121cfb9a23 Mon Sep 17 00:00:00 2001
From: elsid <elsid.mail@gmail.com>
Date: Fri, 19 Sep 2025 19:26:22 +0200
Subject: [PATCH] Handle errors when computing stream size for BSA

---
 components/CMakeLists.txt            |  2 +-
 components/bsa/ba2dx10file.cpp       |  9 ++-----
 components/bsa/ba2gnrlfile.cpp       |  9 ++-----
 components/bsa/bsafile.cpp           |  8 ++----
 components/bsa/compressedbsafile.cpp |  9 ++-----
 components/files/utils.hpp           | 38 ++++++++++++++++++++++++++++
 6 files changed, 47 insertions(+), 28 deletions(-)
 create mode 100644 components/files/utils.hpp

diff --git a/components/CMakeLists.txt b/components/CMakeLists.txt
index f23d54eb56..8b48080a79 100644
--- a/components/CMakeLists.txt
+++ b/components/CMakeLists.txt
@@ -321,7 +321,7 @@ ENDIF()
 add_component_dir (files
     linuxpath androidpath windowspath macospath fixedpath multidircollection collections configurationmanager
     constrainedfilestream memorystream hash configfileparser openfile constrainedfilestreambuf conversion
-    istreamptr streamwithbuffer
+    istreamptr streamwithbuffer utils
     )
 
 if(NOT CMAKE_CXX_COMPILER_ID STREQUAL "MSVC" AND NOT CMAKE_CXX_COMPILER_FRONTEND_VARIANT STREQUAL "MSVC")
diff --git a/components/bsa/ba2dx10file.cpp b/components/bsa/ba2dx10file.cpp
index c0922d905c..c426b258dd 100644
--- a/components/bsa/ba2dx10file.cpp
+++ b/components/bsa/ba2dx10file.cpp
@@ -12,6 +12,7 @@
 #include <components/esm/fourcc.hpp>
 #include <components/files/constrainedfilestream.hpp>
 #include <components/files/conversion.hpp>
+#include <components/files/utils.hpp>
 #include <components/misc/strings/lower.hpp>
 
 #include "ba2file.hpp"
@@ -80,13 +81,7 @@ namespace Bsa
 
         std::ifstream input(mFilepath, std::ios_base::binary);
 
-        // Total archive size
-        std::streamoff fsize = 0;
-        if (input.seekg(0, std::ios_base::end))
-        {
-            fsize = input.tellg();
-            input.seekg(0);
-        }
+        const std::streamsize fsize = Files::getStreamSizeLeft(input);
 
         if (fsize < 24) // header is 24 bytes
             fail("File too small to be a valid BSA archive");
diff --git a/components/bsa/ba2gnrlfile.cpp b/components/bsa/ba2gnrlfile.cpp
index fec7b9a255..5e8b835651 100644
--- a/components/bsa/ba2gnrlfile.cpp
+++ b/components/bsa/ba2gnrlfile.cpp
@@ -11,6 +11,7 @@
 #include <components/esm/fourcc.hpp>
 #include <components/files/constrainedfilestream.hpp>
 #include <components/files/conversion.hpp>
+#include <components/files/utils.hpp>
 #include <components/misc/strings/lower.hpp>
 
 #include "ba2file.hpp"
@@ -75,13 +76,7 @@ namespace Bsa
 
         std::ifstream input(mFilepath, std::ios_base::binary);
 
-        // Total archive size
-        std::streamoff fsize = 0;
-        if (input.seekg(0, std::ios_base::end))
-        {
-            fsize = input.tellg();
-            input.seekg(0);
-        }
+        const std::streamsize fsize = Files::getStreamSizeLeft(input);
 
         if (fsize < 24) // header is 24 bytes
             fail("File too small to be a valid BSA archive");
diff --git a/components/bsa/bsafile.cpp b/components/bsa/bsafile.cpp
index 636fda6b68..92116bced5 100644
--- a/components/bsa/bsafile.cpp
+++ b/components/bsa/bsafile.cpp
@@ -31,6 +31,7 @@
 
 #include <components/esm/fourcc.hpp>
 #include <components/files/constrainedfilestream.hpp>
+#include <components/files/utils.hpp>
 
 using namespace Bsa;
 
@@ -106,12 +107,7 @@ void BSAFile::readHeader()
     std::ifstream input(mFilepath, std::ios_base::binary);
 
     // Total archive size
-    std::streamoff fsize = 0;
-    if (input.seekg(0, std::ios_base::end))
-    {
-        fsize = input.tellg();
-        input.seekg(0);
-    }
+    const std::streamsize fsize = Files::getStreamSizeLeft(input);
 
     if (fsize < 12)
         fail("File too small to be a valid BSA archive");
diff --git a/components/bsa/compressedbsafile.cpp b/components/bsa/compressedbsafile.cpp
index 64fc187def..06eee80539 100644
--- a/components/bsa/compressedbsafile.cpp
+++ b/components/bsa/compressedbsafile.cpp
@@ -37,6 +37,7 @@
 
 #include <components/files/constrainedfilestream.hpp>
 #include <components/files/conversion.hpp>
+#include <components/files/utils.hpp>
 #include <components/misc/strings/lower.hpp>
 
 #include "memorystream.hpp"
@@ -50,13 +51,7 @@ namespace Bsa
 
         std::ifstream input(mFilepath, std::ios_base::binary);
 
-        // Total archive size
-        std::streamoff fsize = 0;
-        if (input.seekg(0, std::ios_base::end))
-        {
-            fsize = input.tellg();
-            input.seekg(0);
-        }
+        const std::streamsize fsize = Files::getStreamSizeLeft(input);
 
         if (fsize < 36) // Header is 36 bytes
             fail("File too small to be a valid BSA archive");
diff --git a/components/files/utils.hpp b/components/files/utils.hpp
new file mode 100644
index 0000000000..732a7d39cd
--- /dev/null
+++ b/components/files/utils.hpp
@@ -0,0 +1,38 @@
+#ifndef COMPONENTS_FILES_UTILS_H
+#define COMPONENTS_FILES_UTILS_H
+
+#include <cerrno>
+#include <format>
+#include <istream>
+#include <stdexcept>
+#include <system_error>
+
+namespace Files
+{
+    inline std::streamsize getStreamSizeLeft(std::istream& stream)
+    {
+        const auto begin = stream.tellg();
+        if (stream.fail())
+            throw std::runtime_error(
+                std::format("Failed to get current file position: {}", std::generic_category().message(errno)));
+
+        stream.seekg(0, std::ios_base::end);
+        if (stream.fail())
+            throw std::runtime_error(
+                std::format("Failed to seek end file position: {}", std::generic_category().message(errno)));
+
+        const auto end = stream.tellg();
+        if (stream.fail())
+            throw std::runtime_error(
+                std::format("Failed to get current file position: {}", std::generic_category().message(errno)));
+
+        stream.seekg(begin);
+        if (stream.fail())
+            throw std::runtime_error(
+                std::format("Failed to seek original file position: {}", std::generic_category().message(errno)));
+
+        return end - begin;
+    }
+}
+
+#endif