compat/win32: fix const-correctness with string constants

Adjust various places in our Win32 compatibility layer where we are not
assigning string constants to `const char *` variables.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

compat/basename.c

@@ -10,7 +10,13 @@ char *gitbasename (char *path)
 		skip_dos_drive_prefix(&path);
 
 	if (!path || !*path)
-		return ".";
+		/*
+		 * basename(3P) is mis-specified because it returns a
+		 * non-constant pointer even though it is specified to return a
+		 * pointer to internal memory at times. The cast is a result of
+		 * that.
+		 */
+		return (char *) ".";
 
 	for (base = path; *path; path++) {
 		if (!is_dir_sep(*path))
@@ -34,7 +40,13 @@ char *gitdirname(char *path)
 	int dos_drive_prefix;
 
 	if (!p)
-		return ".";
+		/*
+		 * dirname(3P) is mis-specified because it returns a
+		 * non-constant pointer even though it is specified to return a
+		 * pointer to internal memory at times. The cast is a result of
+		 * that.
+		 */
+		return (char *) ".";
 
 	if ((dos_drive_prefix = skip_dos_drive_prefix(&p)) && !*p)
 		goto dot;

compat/mingw.c

@@ -2279,7 +2279,11 @@ struct passwd *getpwuid(int uid)
 	p->pw_name = user_name;
 	p->pw_gecos = get_extended_user_info(NameDisplay);
 	if (!p->pw_gecos)
-		p->pw_gecos = "unknown";
+		/*
+		 * Data returned by getpwuid(3P) is treated as internal and
+		 * must never be written to or freed.
+		 */
+		p->pw_gecos = (char *) "unknown";
 	p->pw_dir = NULL;
 
 	initialized = 1;
@@ -2800,16 +2804,16 @@ int is_path_owned_by_current_sid(const char *path, struct strbuf *report)
 			strbuf_addf(report, "'%s' is on a file system that does "
 				    "not record ownership\n", path);
 		} else if (report) {
-			LPSTR str1, str2, str3, str4, to_free1 = NULL,
-			    to_free3 = NULL, to_local_free2 = NULL,
-			    to_local_free4 = NULL;
+			PCSTR str1, str2, str3, str4;
+			LPSTR to_free1 = NULL, to_free3 = NULL,
+			    to_local_free2 = NULL, to_local_free4 = NULL;
 
-			if (user_sid_to_user_name(sid, &str1))
-				to_free1 = str1;
+			if (user_sid_to_user_name(sid, &to_free1))
+				str1 = to_free1;
 			else
 				str1 = "(inconvertible)";
-			if (ConvertSidToStringSidA(sid, &str2))
-				to_local_free2 = str2;
+			if (ConvertSidToStringSidA(sid, &to_local_free2))
+				str2 = to_local_free2;
 			else
 				str2 = "(inconvertible)";
 
@@ -2822,13 +2826,13 @@ int is_path_owned_by_current_sid(const char *path, struct strbuf *report)
 				str4 = "(invalid)";
 			} else {
 				if (user_sid_to_user_name(current_user_sid,
-							  &str3))
-					to_free3 = str3;
+							  &to_free3))
+					str3 = to_free3;
 				else
 					str3 = "(inconvertible)";
 				if (ConvertSidToStringSidA(current_user_sid,
-							   &str4))
-					to_local_free4 = str4;
+							   &to_local_free4))
+					str4 = to_local_free4;
 				else
 					str4 = "(inconvertible)";
 			}

compat/winansi.c

@@ -139,7 +139,7 @@ static void write_console(unsigned char *str, size_t len)
 	/* convert utf-8 to utf-16 */
 	int wlen = xutftowcsn(wbuf, (char*) str, ARRAY_SIZE(wbuf), len);
 	if (wlen < 0) {
-		wchar_t *err = L"[invalid]";
+		const wchar_t *err = L"[invalid]";
 		WriteConsoleW(console, err, wcslen(err), &dummy, NULL);
 		return;
 	}