real_path: do not assume '/' is the path seperator

real_path currently assumes it's input had '/' as path seperator.
This assumption does not hold true for the code-path from
prefix_path (on Windows), where real_path can be called before
normalize_path_copy.

Fix real_path so it doesn't make this assumption. Create a helper
function to reverse-search for the last path-seperator in a string.
Signed-off-by: NTheo Niessink <theo@taletn.com>
Signed-off-by: NErik Faye-Lund <kusmabite@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

abspath.c

@@ -33,7 +33,7 @@ const char *make_absolute_path(const char *path)
 
 	while (depth--) {
 		if (!is_directory(buf)) {
-			char *last_slash = strrchr(buf, '/');
+			char *last_slash = find_last_dir_sep(buf);
 			if (last_slash) {
 				*last_slash = '\0';
 				last_elem = xstrdup(last_slash + 1);
@@ -58,7 +58,7 @@ const char *make_absolute_path(const char *path)
 			if (len + strlen(last_elem) + 2 > PATH_MAX)
 				die ("Too long path name: '%s/%s'",
 						buf, last_elem);
-			if (len && buf[len-1] != '/')
+			if (len && !is_dir_sep(buf[len-1]))
 				buf[len++] = '/';
 			strcpy(buf + len, last_elem);
 			free(last_elem);

compat/mingw.h

@@ -299,6 +299,15 @@ int winansi_fprintf(FILE *stream, const char *format, ...) __attribute__((format
 
 #define has_dos_drive_prefix(path) (isalpha(*(path)) && (path)[1] == ':')
 #define is_dir_sep(c) ((c) == '/' || (c) == '\\')
+static inline char *mingw_find_last_dir_sep(const char *path)
+{
+	char *ret = NULL;
+	for (; *path; ++path)
+		if (is_dir_sep(*path))
+			ret = (char *)path;
+	return ret;
+}
+#define find_last_dir_sep mingw_find_last_dir_sep
 #define PATH_SEP ';'
 #define PRIuMAX "I64u"
 

git-compat-util.h

@@ -215,6 +215,10 @@ extern char *gitbasename(char *);
 #define is_dir_sep(c) ((c) == '/')
 #endif
 
+#ifndef find_last_dir_sep
+#define find_last_dir_sep(path) strrchr(path, '/')
+#endif
+
 #if __HP_cc >= 61000
 #define NORETURN __attribute__((noreturn))
 #define NORETURN_PTR