ANSIfy output from invalid parameter handler, and write it to stderr

The function, file and expression are very unlikely to contain anything
requiring UTF-16 output, and the output is less likely to interfere with
anything when written to stderr rather than stdout.

Note that the function doesn't currently do anything without hacking the
makefiles because we don't currently build with _DEBUG and the debug CRT.
I haven't changed that yet (other than locally) because there is actually
some output from it which causes a couple of tests to fail.

1 files changed, 31 insertions, 3 deletions

diff --git a/win32/win32.c b/win32/win32.c
index 9e11231398..4f292b2a4d 100644
--- a/win32/win32.c
+++ b/win32/win32.c
@@ -136,6 +136,7 @@ static void	remove_dead_process(long child);
 static int	terminate_process(DWORD pid, HANDLE process_handle, int sig);
 static int	my_kill(int pid, int sig);
 static void	out_of_memory(void);
+static char*	wstr_to_str(const wchar_t* wstr);
 static long	filetime_to_clock(PFILETIME ft);
 static BOOL	filetime_from_time(PFILETIME ft, time_t t);
 static char*	create_command_line(char *cname, STRLEN clen,
@@ -171,9 +172,18 @@ my_invalid_parameter_handler(const wchar_t* expression,
     uintptr_t pReserved)
 {
 #  ifdef _DEBUG
-    wprintf(L"Invalid parameter detected in function %s."
-            L" File: %s Line: %d\n", function, file, line);
-    wprintf(L"Expression: %s\n", expression);
+    char* ansi_expression;
+    char* ansi_function;
+    char* ansi_file;
+    ansi_expression = wstr_to_str(expression);
+    ansi_function = wstr_to_str(function);
+    ansi_file = wstr_to_str(file);
+    fprintf(stderr, "Invalid parameter detected in function %s. "
+                    "File: %s, line: %d\n", ansi_function, ansi_file, line);
+    fprintf(stderr, "Expression: %s\n", ansi_expression);
+    free(ansi_expression);
+    free(ansi_function);
+    free(ansi_file);
 #  endif
 }
 #endif
@@ -1651,6 +1661,24 @@ out_of_memory(void)
     exit(1);
 }
 
+/* Converts a wide character (UTF-16) string to the Windows ANSI code page,
+ * potentially using the system's default replacement character for any
+ * unrepresentable characters. The caller must free() the returned string. */
+static char*
+wstr_to_str(const wchar_t* wstr)
+{
+    BOOL used_default = FALSE;
+    size_t wlen = wcslen(wstr) + 1;
+    int len = WideCharToMultiByte(CP_ACP, WC_NO_BEST_FIT_CHARS, wstr, wlen,
+                                   NULL, 0, NULL, NULL);
+    char* str = malloc(len);
+    if (!str)
+        out_of_memory();
+    WideCharToMultiByte(CP_ACP, WC_NO_BEST_FIT_CHARS, wstr, wlen,
+                        str, len, NULL, &used_default);
+    return str;
+}
+
 /* The win32_ansipath() function takes a Unicode filename and converts it
  * into the current Windows codepage. If some characters cannot be mapped,
  * then it will convert the short name instead.