#define PACK_VERSION 2
#define pack_version_ok(v) ((v) == htonl(2) || (v) == htonl(3))
struct pack_header {
- unsigned int hdr_signature;
- unsigned int hdr_version;
- unsigned int hdr_entries;
+ uint32_t hdr_signature;
+ uint32_t hdr_version;
+ uint32_t hdr_entries;
};
+/*
+ * The first four bytes of index formats later than version 1 should
+ * start with this signature, as all older git binaries would find this
+ * value illegal and abort reading the file.
+ *
+ * This is the case because the number of objects in a packfile
+ * cannot exceed 1,431,660,000 as every object would need at least
+ * 3 bytes of data and the overall packfile cannot exceed 4 GiB with
+ * version 1 of the index file due to the offsets limited to 32 bits.
+ * Clearly the signature exceeds this maximum.
+ *
+ * Very old git binaries will also compare the first 4 bytes to the
+ * next 4 bytes in the index and abort with a "non-monotonic index"
+ * error if the second 4 byte word is smaller than the first 4
+ * byte word. This would be true in the proposed future index
+ * format as idx_signature would be greater than idx_version.
+ */
+#define PACK_IDX_SIGNATURE 0xff744f63 /* "\377tOc" */
+
+/*
+ * Packed object index header
+ */
+struct pack_idx_header {
+ uint32_t idx_signature;
+ uint32_t idx_version;
+};
+
+
extern int verify_pack(struct packed_git *, int);
+
+#define PH_ERROR_EOF (-1)
+#define PH_ERROR_PACK_SIGNATURE (-2)
+#define PH_ERROR_PROTOCOL (-3)
+extern int read_pack_header(int fd, struct pack_header *);
#endif