Intercept loader_log in testing framework

Allows capturing the output of loader_log and comparing it with expected
values using fputs/fputc on *nix, and OutputDebugString on Windows.

This interception is necessary due to the differing behavior between the
debug log (through debug utils messenger) and the actual stderr output.

tests/framework/shim/shim.h

@@ -134,12 +134,15 @@ struct FrameworkEnvironment;  // forward declaration
 // Necessary to have inline definitions as shim is a dll and thus functions
 // defined in the .cpp wont be found by the rest of the application
 struct PlatformShim {
-    PlatformShim() = default;
-    PlatformShim(std::vector<fs::FolderManager>* folders) : folders(folders) {}
+    PlatformShim() { fputs_stderr_log.reserve(65536); }
+    PlatformShim(std::vector<fs::FolderManager>* folders) : folders(folders) { fputs_stderr_log.reserve(65536); }
 
     // Used to get info about which drivers & layers have been added to folders
     std::vector<fs::FolderManager>* folders;
 
+    // Captures the output to stderr from fputs & fputc - aka the output of loader_log()
+    std::string fputs_stderr_log;
+
     // Test Framework interface
     void reset();
 
@@ -156,6 +159,9 @@ struct PlatformShim {
     void add_manifest(ManifestCategory category, std::filesystem::path const& path);
     void add_unsecured_manifest(ManifestCategory category, std::filesystem::path const& path);
 
+    void clear_logs() { fputs_stderr_log.clear(); }
+    bool find_in_log(std::string const& search_text) const { return fputs_stderr_log.find(search_text) != std::string::npos; }
+
 // platform specific shim interface
 #if defined(WIN32)
     // Control Platform Elevation Level

tests/framework/shim/unix_shim.cpp

@@ -63,6 +63,9 @@ FRAMEWORK_EXPORT PlatformShim* get_platform_shim(std::vector<fs::FolderManager>*
 #if defined(HAVE___SECURE_GETENV)
 #define __SECURE_GETENV_FUNC_NAME __secure_getenv
 #endif
+#define PRINTF_FUNC_NAME printf
+#define FPUTS_FUNC_NAME fputs
+#define FPUTC_FUNC_NAME fputc
 #elif defined(__APPLE__)
 #define OPENDIR_FUNC_NAME my_opendir
 #define READDIR_FUNC_NAME my_readdir
@@ -80,6 +83,8 @@ FRAMEWORK_EXPORT PlatformShim* get_platform_shim(std::vector<fs::FolderManager>*
 #define __SECURE_GETENV_FUNC_NAME my__secure_getenv
 #endif
 #endif
+#define FPUTS_FUNC_NAME my_fputs
+#define FPUTC_FUNC_NAME my_fputc
 #endif
 
 using PFN_OPENDIR = DIR* (*)(const char* path_name);
@@ -93,6 +98,8 @@ using PFN_GETEGID = gid_t (*)(void);
 #if defined(HAVE_SECURE_GETENV) || defined(HAVE___SECURE_GETENV)
 using PFN_SEC_GETENV = char* (*)(const char* name);
 #endif
+using PFN_FPUTS = int (*)(const char* str, FILE* stream);
+using PFN_FPUTC = int (*)(int c, FILE* stream);
 
 #if defined(__APPLE__)
 #define real_opendir opendir
@@ -109,6 +116,8 @@ using PFN_SEC_GETENV = char* (*)(const char* name);
 #if defined(HAVE___SECURE_GETENV)
 #define real__secure_getenv __secure_getenv
 #endif
+#define real_fputs fputs
+#define real_fputc fputc
 #else
 PFN_OPENDIR real_opendir = nullptr;
 PFN_READDIR real_readdir = nullptr;
@@ -124,6 +133,8 @@ PFN_SEC_GETENV real_secure_getenv = nullptr;
 #if defined(HAVE___SECURE_GETENV)
 PFN_SEC_GETENV real__secure_getenv = nullptr;
 #endif
+PFN_FPUTS real_fputs = nullptr;
+PFN_FPUTC real_fputc = nullptr;
 #endif
 
 FRAMEWORK_EXPORT DIR* OPENDIR_FUNC_NAME(const char* path_name) {
@@ -327,6 +338,27 @@ FRAMEWORK_EXPORT char* __SECURE_GETENV_FUNC_NAME(const char* name) {
 }
 #endif
 #endif
+
+FRAMEWORK_EXPORT int FPUTS_FUNC_NAME(const char* str, FILE* stream) {
+#if !defined(__APPLE__)
+    if (!real_fputs) real_fputs = (PFN_FPUTS)dlsym(RTLD_NEXT, "fputs");
+#endif
+    if (stream == stderr) {
+        platform_shim.fputs_stderr_log += str;
+    }
+    return real_fputs(str, stream);
+}
+
+FRAMEWORK_EXPORT int FPUTC_FUNC_NAME(int ch, FILE* stream) {
+#if !defined(__APPLE__)
+    if (!real_fputc) real_fputc = (PFN_FPUTC)dlsym(RTLD_NEXT, "fputc");
+#endif
+    if (stream == stderr) {
+        platform_shim.fputs_stderr_log += ch;
+    }
+    return real_fputc(ch, stream);
+}
+
 #if defined(__APPLE__)
 FRAMEWORK_EXPORT CFBundleRef my_CFBundleGetMainBundle() {
     static CFBundleRef global_bundle{};
@@ -383,6 +415,7 @@ __attribute__((used)) static Interposer _interpose__secure_getenv MACOS_ATTRIB =
                                                                                   VOIDP_CAST(__secure_getenv)};
 #endif
 #endif
+__attribute__((used)) static Interposer _interpose_fputs MACOS_ATTRIB = {VOIDP_CAST(my_fputs), VOIDP_CAST(fputs)};
 __attribute__((used)) static Interposer _interpose_CFBundleGetMainBundle MACOS_ATTRIB = {VOIDP_CAST(my_CFBundleGetMainBundle),
                                                                                          VOIDP_CAST(CFBundleGetMainBundle)};
 __attribute__((used)) static Interposer _interpose_CFBundleCopyResourcesDirectoryURL MACOS_ATTRIB = {

tests/framework/shim/windows_shim.cpp

@@ -31,6 +31,9 @@
 #include <ntstatus.h>
 #endif
 
+#include <windows.h>
+#include <debugapi.h>
+
 #include "shim.h"
 
 #include "detours.h"
@@ -405,6 +408,15 @@ LONG WINAPI ShimGetPackagePathByFullName(_In_ PCWSTR packageFullName, _Inout_ UI
     return 0;
 }
 
+using PFN_OutputDebugStringA = void (*)(LPCSTR lpOutputString);
+static PFN_OutputDebugStringA fp_OutputDebugStringA = OutputDebugStringA;
+
+void intercept_OutputDebugStringA(LPCSTR lpOutputString) {
+    if (lpOutputString != nullptr) {
+        platform_shim.fputs_stderr_log += lpOutputString;
+    }
+}
+
 // Initialization
 void WINAPI DetourFunctions() {
     if (!gdi32_dll) {
@@ -454,6 +466,7 @@ void WINAPI DetourFunctions() {
     DetourAttach(&(PVOID &)fpRegCloseKey, (PVOID)ShimRegCloseKey);
     DetourAttach(&(PVOID &)fpGetPackagesByPackageFamily, (PVOID)ShimGetPackagesByPackageFamily);
     DetourAttach(&(PVOID &)fpGetPackagePathByFullName, (PVOID)ShimGetPackagePathByFullName);
+    DetourAttach(&(PVOID &)fp_OutputDebugStringA, (PVOID)intercept_OutputDebugStringA);
     LONG error = DetourTransactionCommit();
 
     if (error != NO_ERROR) {
@@ -483,6 +496,7 @@ void DetachFunctions() {
     DetourDetach(&(PVOID &)fpRegCloseKey, (PVOID)ShimRegCloseKey);
     DetourDetach(&(PVOID &)fpGetPackagesByPackageFamily, (PVOID)ShimGetPackagesByPackageFamily);
     DetourDetach(&(PVOID &)fpGetPackagePathByFullName, (PVOID)ShimGetPackagePathByFullName);
+    DetourDetach(&(PVOID &)fp_OutputDebugStringA, (PVOID)intercept_OutputDebugStringA);
     DetourTransactionCommit();
 }