Refactor filename check to be wrapped in macro that no-ops outside of Windows

Signed-off-by: Lincoln Atkinson <[email protected]>

Author: latkin

compat/mingw.c

@@ -2444,6 +2444,21 @@ int mingw_skip_dos_drive_prefix(char **path)
 	return ret;
 }
 
+int mingw_known_invalid(const char *path)
+{
+    // Colon is admissible as part of absolute path (e.g. "C:\file.txt")
+    // but otherwise invalid. Explicit checking done to prevent
+    // unintentional writing to alternate data stream path, e.g.
+    // "some\path\file:streamname"
+    if (path) {
+        path += has_dos_drive_prefix(path);
+        for (; *path; ++path)
+            if (*path == ':')
+                return 1;
+    }
+    return 0;
+}
+
 int mingw_offset_1st_component(const char *path)
 {
 	char *pos = (char *)path;

compat/mingw.h

@@ -423,6 +423,8 @@ HANDLE winansi_get_osfhandle(int fd);
 	(isalpha(*(path)) && (path)[1] == ':' ? 2 : 0)
 int mingw_skip_dos_drive_prefix(char **path);
 #define skip_dos_drive_prefix mingw_skip_dos_drive_prefix
+int mingw_known_invalid(const char *path);
+#define known_invalid mingw_known_invalid
 #define has_unc_prefix(path) (*(path) == '\\' && (path)[1] == '\\' ? 2 : 0)
 #define is_dir_sep(c) ((c) == '/' || (c) == '\\')
 static inline char *mingw_find_last_dir_sep(const char *path)

git-compat-util.h

@@ -347,6 +347,14 @@ static inline int git_skip_dos_drive_prefix(char **path)
 #define skip_dos_drive_prefix git_skip_dos_drive_prefix
 #endif
 
+#ifndef known_invalid
+static inline int git_known_invalid(const char *path)
+{
+	return 0;
+}
+#define known_invalid git_known_invalid
+#endif
+
 #ifndef has_unc_prefix
 static inline int git_has_unc_prefix(const char *path)
 {

read-cache.c

@@ -809,6 +809,9 @@ int verify_path(const char *path)
 	if (has_dos_drive_prefix(path))
 		return 0;
 
+	if (known_invalid(path))
+		return 0;
+
 	goto inside;
 	for (;;) {
 		if (!c)
@@ -821,10 +824,9 @@ int verify_path(const char *path)
 				return 0;
 			c = *path++;
 			if ((c == '.' && !verify_dotfile(path)) ||
-			    is_dir_sep(c) || c == ':' || c == '\0')
+			    is_dir_sep(c) || c == '\0')
 				return 0;
-		} else if (c == ':')
-			return 0;
+		}
 		c = *path++;
 	}
 }