Remove fstream usage from hostmisc

src/native/corehost/hostmisc/pal.h

@@ -6,7 +6,6 @@
 
 #include <string>
 #include <vector>
-#include <fstream>
 #include <sstream>
 #include <iostream>
 #include <cstring>
@@ -118,14 +117,6 @@ namespace pal
     typedef wchar_t char_t;
     typedef std::wstring string_t;
     typedef std::wstringstream stringstream_t;
-    // TODO: Agree on the correct encoding of the files: The PoR for now is to
-    // temporarily wchar for Windows and char for Unix. Current implementation
-    // implicitly expects the contents on both Windows and Unix as char and
-    // converts them to wchar in code for Windows. This line should become:
-    // typedef std::basic_ifstream<char_t> ifstream_t.
-    typedef std::basic_ifstream<char> ifstream_t;
-    typedef std::istreambuf_iterator<ifstream_t::char_type> istreambuf_iterator_t;
-    typedef std::basic_istream<char> istream_t;
     typedef HRESULT hresult_t;
     typedef HMODULE dll_t;
     typedef FARPROC proc_t;
@@ -207,9 +198,6 @@ namespace pal
     typedef char char_t;
     typedef std::string string_t;
     typedef std::stringstream stringstream_t;
-    typedef std::basic_ifstream<char> ifstream_t;
-    typedef std::istreambuf_iterator<ifstream_t::char_type> istreambuf_iterator_t;
-    typedef std::basic_istream<char> istream_t;
     typedef int hresult_t;
     typedef void* dll_t;
     typedef void* proc_t;

src/native/corehost/hostmisc/pal.unix.cpp

@@ -456,7 +456,7 @@ bool get_install_location_from_file(const pal::string_t& file_path, bool& file_f
 {
     file_found = true;
     bool install_location_found = false;
-    FILE* install_location_file = pal::file_open(file_path, "r");
+    FILE* install_location_file = pal::file_open(file_path, _X("r"));
     if (install_location_file != nullptr)
     {
         if (!get_line_from_file(install_location_file, install_location))
@@ -819,12 +819,10 @@ pal::string_t pal::get_current_os_rid_platform()
     {
         // Read the file to get ID and VERSION_ID data that will be used
         // to construct the RID.
-        std::fstream fsVersionFile;
-
-        fsVersionFile.open(versionFile, std::fstream::in);
+        FILE* fsVersionFile = pal::file_open(versionFile, _X("r"));
 
         // Proceed only if we were able to open the file
-        if (fsVersionFile.good())
+        if (fsVersionFile != nullptr)
         {
             pal::string_t line;
             pal::string_t strID(_X("ID="));
@@ -834,11 +832,8 @@ pal::string_t pal::get_current_os_rid_platform()
 
             bool fFoundID = false, fFoundVersion = false;
 
-            // Read the first line
-            std::getline(fsVersionFile, line);
-
             // Loop until we are at the end of file
-            while (!fsVersionFile.eof())
+            while (get_line_from_file(fsVersionFile, line))
             {
                 // Look for ID if we have not found it already
                 if (!fFoundID)
@@ -872,13 +867,10 @@ pal::string_t pal::get_current_os_rid_platform()
                     // We have everything we need to form the RID - break out of the loop.
                     break;
                 }
-
-                // Read the next line
-                std::getline(fsVersionFile, line);
             }
 
             // Close the file now that we are done with it.
-            fsVersionFile.close();
+            fclose(fsVersionFile);
 
             if (fFoundID)
             {

src/native/corehost/json_parser.cpp

@@ -18,22 +18,23 @@
 namespace {
 
 // Try to match 0xEF 0xBB 0xBF byte sequence (no endianness here.)
-std::streampos get_utf8_bom_length(pal::istream_t& stream)
+int get_utf8_bom_length(FILE *stream)
 {
-    if (stream.eof())
+    if (feof(stream))
     {
         return 0;
     }
 
-    auto peeked = stream.peek();
+    auto peeked = fgetc(stream);
     if (peeked == EOF || ((peeked & 0xFF) != 0xEF))
     {
+        ungetc(peeked, stream);
         return 0;
     }
 
     unsigned char bytes[3];
-    stream.read(reinterpret_cast<char*>(bytes), 3);
-    if ((stream.gcount() < 3) || (bytes[1] != 0xBB) || (bytes[2] != 0xBF))
+    size_t ret = fread(reinterpret_cast<char*>(bytes), 1, 3, stream);
+    if ((ret < 3) || (bytes[1] != 0xBB) || (bytes[2] != 0xBF))
     {
         return 0;
     }
@@ -132,26 +133,34 @@ bool json_parser_t::parse_file(const pal::string_t& path)
         }
     }
 
-    pal::ifstream_t file{ path };
-    if (!file.good())
+    FILE *file = pal::file_open(path, _X("r"));
+    if (file == nullptr)
     {
         trace::error(_X("Cannot use file stream for [%s]: %s"), path.c_str(), pal::strerror(errno).c_str());
         return false;
     }
 
     auto current_pos = ::get_utf8_bom_length(file);
-    file.seekg(0, file.end);
-    auto stream_size = file.tellg();
+    fseek(file, 0, SEEK_END);
+    auto stream_size = ftell(file);
     if (stream_size == -1)
     {
+        fclose(file);
         trace::error(_X("Failed to get size of file [%s]"), path.c_str());
         return false;
     }
 
-    file.seekg(current_pos, file.beg);
+    fseek(file, current_pos, SEEK_SET);
 
     realloc_buffer(static_cast<size_t>(stream_size - current_pos));
-    file.read(m_json.data(), stream_size - current_pos);
+    auto ret = fread(m_json.data(), 1, stream_size - current_pos, file);
+    fclose(file);
+
+    if (ret != (size_t)(stream_size - current_pos))
+    {
+        trace::error(_X("Failed to read contents of file [%s]"), path.c_str());
+        return false;
+    }
 
     return parse_raw_data(m_json.data(), m_json.size(), path);
 }

src/native/corehost/test/nativehost/host_context_test.cpp

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 #include <iostream>
+#include <fstream>
 #include <pal.h>
 #include <error_codes.h>
 #include <future>