Rewrite hostmisc C++ components to wrap C implementations by Copilot · Pull Request #126367 · dotnet/runtime

Copilot · 2026-03-31T18:43:51Z

Description

Eliminates code duplication between the C++ hostmisc library and the C hostmisc_c library by rewriting C++ components to delegate to existing C implementations.

`fx_ver.cpp` → wraps `fx_ver.c`

fx_ver_t::parse(), compare(), as_str() now delegate to c_fx_ver_parse(), c_fx_ver_compare(), c_fx_ver_as_str()
C struct renamed to c_fx_ver_t to avoid collision with the C++ class
Added palstr_to_narrow()/narrow_to_palstr() helpers for wchar_t↔char conversion on Windows

`utils.cpp` → wraps `utils.c` (non-Windows only)

get_current_arch_name(), get_runtime_id(), get_host_version_description() delegate to C equivalents
get_dotnet_root_env_var_for_arch() kept as C++ — the C version doesn't accept an arch parameter

`trace.cpp` → removed (prior commit)

trace.h is now a thin C++ wrapper over trace.c
g_trace_lock uses minipal mutex APIs
trace.c uses pal functions (pal_getenv, pal_xtoi, pal_strlen, pal_str_vprintf, pal_strlen_vprintf, pal_str_printf) instead of platform-specific inline definitions
Thread-local storage uses PAL_THREAD_LOCAL macro from pal_c.h

Header updates

Added extern "C" guards to fx_ver_c.h, utils_c.h, pal_c.h
Added #ifndef macro guards in utils_c.h to prevent redefinition conflicts with utils.h

`pal.h` includes `pal_c.h`

pal.h now includes pal_c.h to get shared definitions instead of duplicating them
Removed duplicated _X, _STRINGIFY, DIR_SEPARATOR, DIR_SEPARATOR_STR, PATH_SEPARATOR, S_OK, E_NOTIMPL, E_FAIL, SUCCEEDED, LIB_PREFIX, LIB_FILE_EXT, LIB_NAME, LIB_FILE_NAME, LIB_FILE_NAME_X, LIBFXR_NAME, HOST_RID_PLATFORM, and PATH_MAX from pal.h

File naming convention

Dropped the apphost_ prefix from all hostmisc C files so they live next to their corresponding .cpp files (e.g., trace.c next to trace.h, utils.c next to utils.cpp)
C headers use a _c suffix to distinguish from C++ headers (e.g., trace_c.h, fx_ver_c.h, pal_c.h, utils_c.h, fxr_resolver_c.h, bundle_marker_c.h)

`pal_c.h` — cross-platform PAL for C

pal_c.h is the canonical location for the pal_char_t typedef (wchar_t on Windows, char on non-Windows), _X, _STRINGIFY, and PAL_THREAD_LOCAL macros
pal_c.h is structured to be includable on all platforms: cross-platform types/macros at the top, then platform-specific sections for Windows (windows.h, wide-char string ops, pal_getenv/pal_xtoi as static inlines) and non-Windows (configure.h, POSIX string ops, pal_getenv/pal_xtoi function declarations)
Cross-platform macros: DIR_SEPARATOR, PATH_SEPARATOR, LIB_PREFIX, LIB_FILE_EXT, HOST_RID_PLATFORM, LIBFXR_NAME
Cross-platform string ops: pal_strlen, pal_str_vprintf, pal_strlen_vprintf, pal_str_printf
Macro definitions use #ifndef guards to avoid redefinition conflicts with pal.h (C++ PAL)
trace_c.h includes pal_c.h for the typedef instead of defining pal_char_t locally
All function signatures in pal_c.h, pal.c, utils_c.h, and utils.c use pal_char_t instead of raw char

Dynamic path buffer allocation

Changed hostfxr_resolver_t struct to use char* pointers instead of fixed char[4096] arrays for dotnet_root and fxr_path
Changed fxr_resolver_try_get_path API to return dynamically allocated strings via char** output parameters (caller must free)
Converted local path buffers in apphost_main.c, apphost_hostfxr_resolver.c, and fxr_resolver.c from stack-allocated APPHOST_PATH_MAX arrays to heap-allocated buffers with malloc/free
Added utils_file_exists_in_dir_alloc and utils_get_directory_alloc helper functions that return dynamically allocated strings
hostfxr_resolver_cleanup now frees the dynamically allocated dotnet_root and fxr_path strings

Build

fx_ver.c added to hostmisc on all platforms
pal.c, utils.c added on non-Windows only

Create C source files for apphost that replace the C++ implementation: - apphost_main.c: main entry point - apphost_pal.c/h: platform abstraction layer (Unix) - apphost_trace.c/h: tracing system - apphost_utils.c/h: utility functions - apphost_fx_ver.c/h: semantic version parsing - apphost_fxr_resolver.c/h: hostfxr path resolution - apphost_bundle_marker.c/h: bundle detection - apphost_hostfxr_resolver.c/h: hostfxr loading Uses dn-vector from src/native/containers for collections. Windows builds retain existing C++ sources. Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/2c33d365-8b70-4325-8eee-7f004ba86639 Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>

- Add stddef.h includes for size_t in headers - Fix HAVE_DIRENT_D_TYPE guard to use config.h - Fix dn_vector_at calls to pass element size - Add test_only_getenv for test install location overrides - Add test overrides in pal_get_dotnet_self_registered_dir and pal_get_default_installation_dir - Add ctype.h include for tolower Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/2c33d365-8b70-4325-8eee-7f004ba86639 Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>

- Remove dead code block (always-false DIR_SEPARATOR check) in apphost_main.c - Remove unused free_string_entry function in apphost_fxr_resolver.c - Add explicit errno.h include in apphost_pal.c Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/2c33d365-8b70-4325-8eee-7f004ba86639 Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>

Move C source files from apphost/standalone/ to hostmisc/: - apphost_trace.c/h, apphost_pal.c/h, apphost_utils.c/h - apphost_fx_ver.c/h, apphost_fxr_resolver.c/h, apphost_bundle_marker.c/h Create hostmisc_c OBJECT library target in hostmisc/CMakeLists.txt with proper include directories and dependencies. Update apphost/standalone/CMakeLists.txt to use hostmisc_c and dn-containers CMake targets instead of compiling C files directly. Add dn-containers subdirectory to corehost and singlefilehost builds for non-Windows platforms. Update apphost_fxr_resolver.c to use <dn-vector.h> include path consistent with the dn-containers CMake target. Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/6be87a85-902f-4646-92e6-2fb6783a5f57 Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>

Rewrite bundle_marker.h as a C++ wrapper around the C implementation in apphost_bundle_marker.c. Add extern "C" guards to apphost_bundle_marker.h for C++ compatibility. Remove bundle_marker.cpp since the C implementation in hostmisc_c (apphost_bundle_marker.c) is now the single source of truth. Update standalone/CMakeLists.txt and static/CMakeLists.txt to use apphost_bundle_marker.c instead of the removed bundle_marker.cpp. Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/65fd3a5e-99f8-4acc-830f-644976f2cfb1 Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>

…mutex - Removed trace.cpp (C++ implementation) - Updated apphost_trace.h: Added pal_char_t typedef (wchar_t on Windows, char on Unix), extern C guards, va_list function variants - Updated apphost_trace.c: Added Windows support (wide chars, OutputDebugStringW, WriteConsoleW), replaced spinlock with minipal mutex, added _v versions of variadic functions for C++ forwarding - Updated trace.h: Now a thin C++ wrapper calling C functions via va_list - Updated CMakeLists.txt: Use apphost_trace.c instead of trace.cpp, add minipal/mutex.c to both hostmisc and hostmisc_c" Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/2c57cab1-6ebb-4ab7-bbbf-38835b4336b3 Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>

Inline the getenv and xtoi helpers directly in apphost_trace.c to avoid depending on apphost_pal.c which is only in hostmisc_c." Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/2c57cab1-6ebb-4ab7-bbbf-38835b4336b3 Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>

- trace_error_v: Copy va_list before any consumption to avoid using a consumed va_list (undefined behavior per C11 §7.16.1) - trace_warning: Delegate to trace_warning_v instead of duplicating the implementation inline Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/2c57cab1-6ebb-4ab7-bbbf-38835b4336b3 Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>

- fx_ver.cpp: Rewrite to delegate to apphost_fx_ver.c for parse(), compare(), and as_str() operations. Handles char/wchar_t conversion for Windows compatibility. - utils.cpp: On non-Windows, delegate get_current_arch_name(), get_runtime_id(), get_host_version_description(), and get_dotnet_root_env_var_for_arch() to apphost_utils.c. - apphost_fx_ver.h: Add extern "C" guards, rename to c_fx_ver_t to avoid collision with C++ fx_ver_t struct. - apphost_utils.h: Add extern "C" guards, guard macros with #ifndef to avoid conflicts with utils.h. - apphost_pal.h: Add extern "C" guards. - CMakeLists.txt: Add apphost_fx_ver.c to all platforms, add apphost_pal.c and apphost_utils.c on non-Windows. Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/15a555ca-6237-4c3e-9a6a-93b3c993d1e9 Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>

- Revert get_dotnet_root_env_var_for_arch to C++ implementation since the C version ignores the arch parameter - Replace 'auto' with explicit 'pal::char_t' in palstr_to_narrow Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/15a555ca-6237-4c3e-9a6a-93b3c993d1e9 Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>

dotnet-policy-service · 2026-03-31T18:56:33Z

Tagging subscribers to this area: @agocke, @jeffschwMSFT, @elinor-fung
See info in area-owners.md if you want to be subscribed.

Rename all hostmisc C files per review feedback: - apphost_trace.c → trace.c, apphost_trace.h → trace_c.h - apphost_fx_ver.c → fx_ver.c, apphost_fx_ver.h → fx_ver_c.h - apphost_pal.c → pal.c, apphost_pal.h → pal_c.h - apphost_utils.c → utils.c, apphost_utils.h → utils_c.h - apphost_fxr_resolver.c → fxr_resolver.c, apphost_fxr_resolver.h → fxr_resolver_c.h - apphost_bundle_marker.c → bundle_marker.c, apphost_bundle_marker.h → bundle_marker_c.h Update all #include directives, CMakeLists.txt references, header guards, and comments to use the new names. Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/869a7b2a-c34a-4b37-ab96-28caca72225e Co-authored-by: elinor-fung <47805090+elinor-fung@users.noreply.github.com>

Copilot · 2026-03-31T18:59:06Z

@copilot rename the hostmisc C files prefixed with apphost_ to drop the apphost_ prefix. They should be .c versions living next to their corresponding .cpp files. For the header files, they can ha...

Done in 7b1a73c. Renamed all hostmisc C files to drop the apphost_ prefix (e.g., apphost_trace.c → trace.c) and headers to use _c suffix (e.g., apphost_trace.h → trace_c.h). Updated all #include directives, CMakeLists.txt references, and header guards.

src/native/corehost/hostmisc/pal.c

Move the pal_char_t typedef from trace_c.h to pal_c.h as the canonical location. Define it cross-platform (wchar_t on Windows, char on non-Windows) with #ifndef guards to avoid redefinition conflicts with pal.h (C++ PAL). Update function signatures in pal_c.h, pal.c, utils_c.h, and utils.c to use pal_char_t instead of raw char for platform string parameters. Make trace_c.h include pal_c.h for the typedef instead of defining it locally. Restructure pal_c.h to be includable on all platforms (cross- platform types at top, POSIX-specific parts guarded with #if !defined(_WIN32)). Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/88526fd5-afd6-42dc-b551-5b6cd904b449 Co-authored-by: elinor-fung <47805090+elinor-fung@users.noreply.github.com>

jkoritzinsky · 2026-03-31T22:17:29Z

src/native/corehost/apphost/standalone/apphost_hostfxr_resolver.h

+{
+    void* hostfxr_dll;
+    char dotnet_root[4096];
+    char fxr_path[4096];


@copilot Please adjust these buffers to be dynamically allocated in case the path is longer than this buffer length (throughout).

Done in 2b8c310. Changed hostfxr_resolver_t to use char* with dynamic allocation. Changed fxr_resolver_try_get_path API to return malloc'd strings via char** (caller frees). Converted all local path buffers in apphost_main.c, apphost_hostfxr_resolver.c, and fxr_resolver.c to use malloc/free. Added utils_file_exists_in_dir_alloc and utils_get_directory_alloc helpers that return dynamically allocated strings.

Change hostfxr_resolver_t struct to use char* instead of char[4096]. Change fxr_resolver_try_get_path API to return malloc'd strings via char** instead of writing to fixed-size caller-provided buffers. Convert local path buffers in apphost_main.c and fxr_resolver.c to use malloc/free instead of stack-allocated fixed arrays. Add utils_file_exists_in_dir_alloc and utils_get_directory_alloc helpers that return dynamically allocated strings. Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/84b0096a-a181-477e-a6b7-04df74e9919c Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>

Copilot · 2026-03-31T22:29:14Z

@copilot rename the hostmisc C files prefixed with apphost_ to drop the apphost_ prefix. They should be .c versions living next to their corresponding .cpp files. For the header files, they can ha...

Already done in 7b1a73c.

Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/84b0096a-a181-477e-a6b7-04df74e9919c Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>

elinor-fung · 2026-03-31T22:52:27Z

src/native/corehost/hostmisc/trace.c

+#if defined(_WIN32)
+#include <windows.h>
+#define trace_getenv(name, buf, buf_len) (GetEnvironmentVariableW(name, buf, (DWORD)(buf_len)) > 0)
+#define trace_xtoi(s) _wtoi(s)
+#define trace_vsnprintf_len(fmt, args) _vscwprintf(fmt, args)
+#define trace_vsnprintf(buf, count, fmt, args) _vsnwprintf_s(buf, count, _TRUNCATE, fmt, args)
+#define trace_snprintf(buf, count, fmt, ...) _snwprintf_s(buf, count, _TRUNCATE, fmt, __VA_ARGS__)
+#define trace_strlen wcslen
+#else
+#define trace_xtoi(s) atoi(s)
+#define trace_vsnprintf_len(fmt, args) vsnprintf(NULL, 0, fmt, args)
+#define trace_vsnprintf(buf, count, fmt, args) vsnprintf(buf, (size_t)(count), fmt, args)
+#define trace_snprintf(buf, count, fmt, ...) snprintf(buf, (size_t)(count), fmt, __VA_ARGS__)
+#define trace_strlen strlen
+
+static bool trace_getenv(const char* name, char* recv, size_t recv_len)
+{
+    if (recv_len > 0)
+        recv[0] = '\0';
+
+    const char* result = getenv(name);
+    if (result != NULL && result[0] != '\0')
+    {
+        size_t len = strlen(result);
+        if (len >= recv_len)
+            return false;
+
+        memcpy(recv, result, len + 1);
+        return true;
+    }
+
+    return false;
+}
+#endif


@copilot these should use pal functions instead of having platform-specific definitions inside trace.c

Done in e665819. Replaced all platform-specific macros in trace.c (lines 11-44) with pal functions from pal_c.h: trace_getenv → pal_getenv, trace_xtoi → pal_xtoi, trace_vsnprintf_len → pal_strlen_vprintf, trace_vsnprintf → pal_str_vprintf, trace_snprintf → pal_str_printf, trace_strlen → pal_strlen. Also replaced the platform-specific thread-local storage with a PAL_THREAD_LOCAL macro.

elinor-fung · 2026-03-31T22:52:50Z

src/native/corehost/hostmisc/pal_c.h

+#define PAL_CHAR_T_DEFINED
+typedef wchar_t pal_char_t;
+#endif
+#ifndef _X


@copilot Make pal.h include pal_c.h and remove the duplicated defines.

Done in e665819. pal.h now includes pal_c.h and all duplicated defines have been removed: _X, _STRINGIFY, DIR_SEPARATOR, PATH_SEPARATOR, S_OK, E_NOTIMPL, E_FAIL, SUCCEEDED, LIB_PREFIX, LIB_FILE_EXT, LIB_NAME, LIB_FILE_NAME, LIB_FILE_NAME_X, LIBFXR_NAME, HOST_RID_PLATFORM, PATH_MAX, and configure.h.

…functions Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/37b4c326-f8c9-4b5f-bbf3-20b79f13538a Co-authored-by: elinor-fung <47805090+elinor-fung@users.noreply.github.com>

Copilot AI and others added 10 commits March 27, 2026 05:20

Copilot AI assigned Copilot and jkoritzinsky Mar 31, 2026

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Fix app_path buffer to be large enough for pal_fullpath resolution

93c6344

Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/84b0096a-a181-477e-a6b7-04df74e9919c Co-authored-by: jkoritzinsky <1571408+jkoritzinsky@users.noreply.github.com>

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Make pal.h include pal_c.h (removing duplicates) and trace.c use pal …

e665819

…functions Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/37b4c326-f8c9-4b5f-bbf3-20b79f13538a Co-authored-by: elinor-fung <47805090+elinor-fung@users.noreply.github.com>

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Rewrite hostmisc C++ components to wrap C implementations#126367

Rewrite hostmisc C++ components to wrap C implementations#126367
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Copilot AI commented Mar 31, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Description

fx_ver.cpp → wraps fx_ver.c

utils.cpp → wraps utils.c (non-Windows only)

trace.cpp → removed (prior commit)

Header updates

pal.h includes pal_c.h

File naming convention

pal_c.h — cross-platform PAL for C

Dynamic path buffer allocation

Build

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Copilot AI commented Mar 31, 2026 •

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`fx_ver.cpp` → wraps `fx_ver.c`

`utils.cpp` → wraps `utils.c` (non-Windows only)

`trace.cpp` → removed (prior commit)

`pal.h` includes `pal_c.h`

`pal_c.h` — cross-platform PAL for C