give the redirect location its own field

This implies a file version change.

Later in the project, we would want to upgrade existing files, but for
now, I assume the number of users be so close to zero that we can put
the burdon on them to lose their existing uploads once during upgrade.

src/tus_file.c

@@ -665,6 +665,16 @@ tus_touch(struct tus_file_core *fcore, VCL_DURATION expires)
 	tus_exp_touch(fcore);
 }
 
+static inline void
+tus_file_fdisk_init(struct tus_file_disk *fdisk)
+{
+	INIT_OBJ(fdisk, VMOD_TUS_FILE_DISK_MAGIC);
+	fdisk->guard_magic = VMOD_TUS_FILE_DISK_MAGIC;
+	fdisk->guard2_magic = VMOD_TUS_FILE_DISK_MAGIC;
+	fdisk->guard3_magic = VMOD_TUS_FILE_DISK_MAGIC;
+	fdisk->version = 2;
+}
+
 /* under tus_server mtx to protect tus_files */
 struct tus_file_core *
 tus_file_lookup(struct VPFX(tus_server) *srv, const char *url_path)
@@ -679,10 +689,7 @@ tus_file_lookup(struct VPFX(tus_server) *srv, const char *url_path)
 	}
 
 	INIT_OBJ(&fcore, VMOD_TUS_FILE_CORE_MAGIC);
-	INIT_OBJ(&needle, VMOD_TUS_FILE_DISK_MAGIC);
-	needle.guard_magic = VMOD_TUS_FILE_DISK_MAGIC;
-	needle.guard2_magic = VMOD_TUS_FILE_DISK_MAGIC;
-	needle.version = 1;
+	tus_file_fdisk_init(&needle);
 	strcpy(needle.url_path, url_path);
 
 	needle.url_path_length = l;
@@ -793,10 +800,8 @@ tus_file_new(VRT_CTX, struct VPFX(tus_server) *srv, enum tus_f_type type,
 		goto err;
 	}
 
-	INIT_OBJ(fdisk, VMOD_TUS_FILE_DISK_MAGIC);
-	fdisk->guard_magic = VMOD_TUS_FILE_DISK_MAGIC;
-	fdisk->guard2_magic = VMOD_TUS_FILE_DISK_MAGIC;
-	fdisk->version = 1;
+	tus_file_fdisk_init(fdisk);
+
 	fdisk->type = type;
 
 	fdisk->url_path_length = strlen(url_path);

src/tus_file.h

@@ -29,6 +29,9 @@ struct tus_file_disk {
 	char				metadata[TUS_METADATA_MAX];
 	unsigned			guard2_magic;
 	unsigned			metadata_length;
+	char				location[TUS_PATH_MAX];
+	unsigned			guard3_magic;
+	unsigned			location_length;
 	ssize_t			upload_length;	// -1 == defer
 	ssize_t			upload_offset;
 	VCL_TIME			upload_expires;
@@ -64,10 +67,14 @@ tus_file_disk_err(const struct tus_file_disk *d)
 		return ("bad guard_magic");
 	if (d->guard2_magic != VMOD_TUS_FILE_DISK_MAGIC)
 		return ("bad guard2_magic");
-	if (d->version != 1)
-		return ("version != 1");
+	if (d->guard2_magic != VMOD_TUS_FILE_DISK_MAGIC)
+		return ("bad guard3_magic");
+	if (d->version != 2)
+		return ("version != 2");
 	if (strnlen(d->url_path, TUS_PATH_MAX) != d->url_path_length)
 		return ("url_path_length mismatch");
+	if (strnlen(d->location, TUS_PATH_MAX) != d->location_length)
+		return ("location_length mismatch");
 	if (strnlen(d->metadata, TUS_METADATA_MAX) != d->metadata_length)
 		return ("metadata_length mismatch");
 	return (NULL);