From 390379642356db6abdf60fb016eb4cce15f86773 Mon Sep 17 00:00:00 2001
From: nmlgc <nmlgc@nmlgc.net>
Date: Sat, 30 Dec 2017 06:53:30 +0100
Subject: [PATCH] thcrap: Log: Show an error message if thcrap_log.txt can't be
 written to. [V]
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The challenge here was avoiding a second message box if the user decides
to continue and uses vpatch. As it turns out though, this is once again
the best kind of reference counting where we only care about 0 or ≥1, so
we only need to *create* a 1-byte file mapping and not actually write a
reference counter to it.
---
 thcrap/src/log.cpp | 34 ++++++++++++++++++++++++++++++++++
 win32_utf8         |  2 +-
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/thcrap/src/log.cpp b/thcrap/src/log.cpp
index 7e963097..13ca9b39 100644
--- a/thcrap/src/log.cpp
+++ b/thcrap/src/log.cpp
@@ -14,6 +14,9 @@
 // -------
 static FILE *log_file = NULL;
 static int console_open = 0;
+// For checking nested thcrap instances that access the same log file.
+// We only want to print an error message for the first instance.
+static HANDLE log_filemapping = INVALID_HANDLE_VALUE;
 static const char LOG[] = "thcrap_log.txt";
 static const char LOG_ROTATED[] = "thcrap_log.%d.txt";
 static const int ROTATIONS = 1; // Number of backups to keep
@@ -194,6 +197,36 @@ void log_init(int console)
 		VLA_FREE(line);
 	}
 #endif
+	size_t cur_dir_len = GetCurrentDirectoryU(0, nullptr);
+	size_t full_fn_len = cur_dir_len + sizeof(LOG);
+	VLA(char, full_fn, full_fn_len);
+	defer(VLA_FREE(full_fn));
+	GetCurrentDirectoryU(cur_dir_len, full_fn);
+	full_fn[cur_dir_len - 1] = '/';
+	str_slash_normalize(full_fn); // Necessary!
+	memcpy(full_fn + cur_dir_len, LOG, sizeof(LOG));
+
+	log_filemapping = CreateFileMappingU(
+		INVALID_HANDLE_VALUE, nullptr, PAGE_READWRITE, 0, 1, full_fn
+	);
+	if(!log_file && GetLastError() != ERROR_ALREADY_EXISTS) {
+		auto ret = log_mboxf(nullptr, MB_OKCANCEL | MB_ICONHAND,
+			"Error creating %s: %s\n"
+			"\n"
+			"Logging will be unavailable. "
+			"Further writes to this directory are likely to fail as well. "
+			"Moving %s to a different directory will probably fix this.\n"
+			"\n"
+			"Continue?",
+			full_fn, strerror(errno), PROJECT_NAME_SHORT()
+		);
+		if(ret == IDCANCEL) {
+			auto pExitProcess = ((void (__stdcall*)(UINT))detour_top(
+				"kernel32.dll", "ExitProcess", (FARPROC)thcrap_ExitProcess
+			));
+			pExitProcess(-1);
+		}
+	}
 }
 
 void log_exit(void)
@@ -202,6 +235,7 @@ void log_exit(void)
 		FreeConsole();
 	}
 	if(log_file) {
+		CloseHandle(log_filemapping);
 		fclose(log_file);
 		log_file = NULL;
 	}
diff --git a/win32_utf8 b/win32_utf8
index f715ba78..50d6add1 160000
--- a/win32_utf8
+++ b/win32_utf8
@@ -1 +1 @@
-Subproject commit f715ba78a7afcc4b8a2f9ef5a77b7179815985b7
+Subproject commit 50d6add1392109c6513cba9dae5f1227643b4d27