From 71b196531f5d52aaf2c0ee45cc902658f0d93a29 Mon Sep 17 00:00:00 2001
From: Darrell Wright <beached@users.noreply.github.com>
Date: Sat, 3 Oct 2026 15:23:45 -0400
Subject: [PATCH] Refactor `read_file` and `read_wfile`: switch to
 `daw::string_view`, improve error handling, and ensure proper file closure.

---
 include/daw/daw_read_file.h | 70 +++++++++++++++++++++----------------
 1 file changed, 39 insertions(+), 31 deletions(-)

diff --git a/include/daw/daw_read_file.h b/include/daw/daw_read_file.h
index e5885746d..cc09495c8 100644
--- a/include/daw/daw_read_file.h
+++ b/include/daw/daw_read_file.h
@@ -8,9 +8,10 @@
 
 #pragma once
 
-#include "ciso646.h"
-#include "daw_attributes.h"
-#include "daw_traits.h"
+#include "daw/ciso646.h"
+#include "daw/daw_attributes.h"
+#include "daw/daw_string_view.h"
+#include "daw/daw_traits.h"
 
 #include <cstddef>
 #include <cstdio>
@@ -19,45 +20,48 @@
 #include <iostream>
 #include <optional>
 #include <string>
+#include <string_view>
 #include <utility>
 
 namespace daw {
 	template<typename CharT = char>
 	DAW_ATTRIB_NOINLINE std::optional<std::basic_string<CharT>>
-	read_file( std::string const &path ) {
+	read_file( daw::string_view path ) {
 		auto ec = std::error_code{ };
-		auto const fsize = std::filesystem::file_size( path, ec );
+		auto const fsize =
+		  std::filesystem::file_size( std::string_view( path ), ec );
 		if( ec ) {
 			return std::nullopt;
 		}
-		if( fsize == 0 ) {
-			return std::basic_string<CharT>{ };
+		if( fsize % sizeof( CharT ) != 0 ) {
+			return std::nullopt;
 		}
+		auto const element_count = fsize / sizeof( CharT );
 		if( static_cast<std::uintmax_t>( std::basic_string<CharT>{ }.max_size( ) ) <
-		    fsize ) {
+		    element_count ) {
 			// File is too big to fit into string(WIN32)
 			return std::nullopt;
 		}
-		auto result =
-		  std::basic_string<CharT>( static_cast<std::size_t>( fsize ), CharT{ } );
+		auto result = std::basic_string<CharT>(
+		  static_cast<std::size_t>( element_count ), CharT{ } );
 #if defined( _MSC_VER )
 		FILE *f = nullptr;
-		auto err = fopen_s( &f, path.c_str( ), "rb" );
-		if( err ) {
+		auto err = fopen_s( &f, path.get_c_str( ).c_str( ), "rb" );
+		if( err or not f ) {
 			return std::nullopt;
 		}
 #else
-		auto *f = fopen( path.c_str( ), "rb" );
+		auto *f = fopen( path.get_c_str( ).c_str( ), "rb" );
 		if( not f ) {
 			return std::nullopt;
 		}
 #endif
-		auto num_read = fread( result.data( ), sizeof( CharT ), result.size( ), f );
-		if( num_read != ( result.size( ) / sizeof( CharT ) ) ) {
-			fclose( f );
+		auto const num_read =
+		  fread( result.data( ), sizeof( CharT ), result.size( ), f );
+		auto const close_result = fclose( f );
+		if( num_read != result.size( ) or close_result != 0 ) {
 			return std::nullopt;
 		}
-		fclose( f );
 		return result;
 	}
 
@@ -65,49 +69,53 @@ namespace daw {
 	inline constexpr auto terminate_on_read_file_error =
 	  terminate_on_read_file_error_t{ };
 
-	inline std::string read_file( std::string const &path,
+	inline std::string read_file( daw::string_view path,
 	                              terminate_on_read_file_error_t ) {
 		auto result = read_file( path );
 		if( not result ) {
 			std::cerr << "Error: could not open file '" << path << "'\n";
 			std::terminate( );
 		}
-		return *result;
+		return std::move( *result );
 	}
 
 #if defined( _MSC_VER )
 	DAW_ATTRIB_NOINLINE inline std::optional<std::wstring>
-	read_wfile( std::wstring path ) {
+	read_wfile( daw::wstring_view path ) {
 		using CharT = wchar_t;
 		auto ec = std::error_code{ };
-		auto const fsize = std::filesystem::file_size( path, ec );
+		auto const fsize =
+		  std::filesystem::file_size( std::wstring_view( path ), ec );
 		if( ec ) {
 			return std::nullopt;
 		}
-		if( fsize == 0 ) {
-			return std::basic_string<CharT>{ };
+		if( fsize % sizeof( CharT ) != 0 ) {
+			return std::nullopt;
 		}
+		auto const element_count = fsize / sizeof( CharT );
 		if( static_cast<std::uintmax_t>( std::basic_string<CharT>{ }.max_size( ) ) <
-		    fsize ) {
+		    element_count ) {
 			// File is too big to fit into string(WIN32)
 			return std::nullopt;
 		}
-		auto result =
-		  std::basic_string<CharT>( static_cast<std::size_t>( fsize ), CharT{ } );
+		auto result = std::basic_string<CharT>(
+		  static_cast<std::size_t>( element_count ), CharT{ } );
 		FILE *f = nullptr;
-		auto err = _wfopen_s( &f, path.c_str( ), L"rb" );
-		if( err ) {
+		auto err = _wfopen_s( &f, path.get_c_str( ).c_str( ), L"rb" );
+		if( err or not f ) {
 			return std::nullopt;
 		}
-		auto num_read = fread( result.data( ), sizeof( CharT ), result.size( ), f );
-		if( num_read != ( result.size( ) / sizeof( CharT ) ) ) {
+		auto const num_read =
+		  fread( result.data( ), sizeof( CharT ), result.size( ), f );
+		auto const close_result = fclose( f );
+		if( num_read != result.size( ) or close_result != 0 ) {
 			return std::nullopt;
 		}
 		return result;
 	}
 
 	DAW_ATTRIB_NOINLINE inline std::wstring
-	read_wfile( std::wstring const &path, terminate_on_read_file_error_t ) {
+	read_wfile( daw::wstring_view path, terminate_on_read_file_error_t ) {
 		auto result = read_wfile( path );
 		if( not result ) {
 			std::wcerr << L"Error: could not open file '" << path << L'\n';