fsck-objects: support platforms without d_ino in struct dirent.

The d_ino field is only used for performance reasons in
fsck-objects.  On a typical filesystem, i-number tends to have a
strong correlation with where the actual bits sit on the disk
platter, and we sort the entries to allow us scan things that
ought to be close together together.

If the platform lacks support for it, it is not a big deal.
Just do not use d_ino for sorting, and scan them unsorted.

Signed-off-by: Junio C Hamano <junkio@cox.net>

Makefile

@@ -19,6 +19,8 @@ all:
 # Define NO_EXPAT if you do not have expat installed.  git-http-push is
 # not built, and you cannot push using http:// and https:// transports.
 #
+# Define NO_D_INO_IN_DIRENT if you don't have d_ino in your struct dirent.
+#
 # Define NO_STRCASESTR if you don't have strcasestr.
 #
 # Define NO_SETENV if you don't have setenv in the C library.
@@ -234,6 +236,7 @@ ifeq ($(uname_S),SunOS)
 	ALL_CFLAGS += -D__EXTENSIONS__
 endif
 ifeq ($(uname_O),Cygwin)
+	NO_D_INO_IN_DIRENT = YesPlease
 	NO_STRCASESTR = YesPlease
 	NEEDS_LIBICONV = YesPlease
 	# There are conflicting reports about this.
@@ -334,6 +337,9 @@ ifdef NEEDS_NSL
 	LIBS += -lnsl
 	SIMPLE_LIB += -lnsl
 endif
+ifdef NO_D_INO_IN_DIRENT
+	ALL_CFLAGS += -DNO_D_INO_IN_DIRENT
+endif
 ifdef NO_STRCASESTR
 	COMPAT_CFLAGS += -DNO_STRCASESTR
 	COMPAT_OBJS += compat/strcasestr.o

fsck-objects.c

@@ -20,6 +20,13 @@ static int check_strict = 0;
 static int keep_cache_objects = 0; 
 static unsigned char head_sha1[20];
 
+#if NO_D_INO_IN_DIRENT
+#define SORT_DIRENT 0
+#define DIRENT_SORT_HINT(de) 0
+#else
+#define SORT_DIRENT 1
+#define DIRENT_SORT_HINT(de) ((de)->d_ino)
+#endif
 
 static void objreport(struct object *obj, const char *severity,
                       const char *err, va_list params)
@@ -307,7 +314,9 @@ static void fsck_sha1_list(void)
 {
 	int i, nr = sha1_list.nr;
 
-	qsort(sha1_list.entry, nr, sizeof(struct sha1_entry *), ino_compare);
+	if (SORT_DIRENT)
+		qsort(sha1_list.entry, nr,
+		      sizeof(struct sha1_entry *), ino_compare);
 	for (i = 0; i < nr; i++) {
 		struct sha1_entry *entry = sha1_list.entry[i];
 		unsigned char *sha1 = entry->sha1;
@@ -361,7 +370,7 @@ static int fsck_dir(int i, char *path)
 			memcpy(name+2, de->d_name, len+1);
 			if (get_sha1_hex(name, sha1) < 0)
 				break;
-			add_sha1_list(sha1, de->d_ino);
+			add_sha1_list(sha1, DIRENT_SORT_HINT(de));
 			continue;
 		}
 		fprintf(stderr, "bad sha1 file: %s/%s\n", path, de->d_name);