pack.h

   1 #ifndef PACK_H
   2 #define PACK_H
   3
   4 #include "object.h"
   5 #include "csum-file.h"
   6
   7 /*
   8  * Packed object header
   9  */
  10 #define PACK_SIGNATURE 0x5041434b       /* "PACK" */
  11 #define PACK_VERSION 2
  12 #define pack_version_ok(v) ((v) == htonl(2) || (v) == htonl(3))
  13 struct pack_header {
  14         uint32_t hdr_signature;
  15         uint32_t hdr_version;
  16         uint32_t hdr_entries;
  17 };
  18
  19 /*
  20  * The first four bytes of index formats later than version 1 should
  21  * start with this signature, as all older git binaries would find this
  22  * value illegal and abort reading the file.
  23  *
  24  * This is the case because the number of objects in a packfile
  25  * cannot exceed 1,431,660,000 as every object would need at least
  26  * 3 bytes of data and the overall packfile cannot exceed 4 GiB with
  27  * version 1 of the index file due to the offsets limited to 32 bits.
  28  * Clearly the signature exceeds this maximum.
  29  *
  30  * Very old git binaries will also compare the first 4 bytes to the
  31  * next 4 bytes in the index and abort with a "non-monotonic index"
  32  * error if the second 4 byte word is smaller than the first 4
  33  * byte word.  This would be true in the proposed future index
  34  * format as idx_signature would be greater than idx_version.
  35  */
  36 #define PACK_IDX_SIGNATURE 0xff744f63   /* "\377tOc" */
  37
  38 struct pack_idx_option {
  39         unsigned flags;
  40         /* flag bits */
  41 #define WRITE_IDX_VERIFY 01 /* verify only, do not write the idx file */
  42 #define WRITE_IDX_STRICT 02
  43
  44         uint32_t version;
  45         uint32_t off32_limit;
  46
  47         /*
  48          * List of offsets that would fit within off32_limit but
  49          * need to be written out as 64-bit entity for byte-for-byte
  50          * verification.
  51          */
  52         int anomaly_alloc, anomaly_nr;
  53         uint32_t *anomaly;
  54 };
  55
  56 extern void reset_pack_idx_option(struct pack_idx_option *);
  57
  58 /*
  59  * Packed object index header
  60  */
  61 struct pack_idx_header {
  62         uint32_t idx_signature;
  63         uint32_t idx_version;
  64 };
  65
  66 /*
  67  * Common part of object structure used for write_idx_file
  68  */
  69 struct pack_idx_entry {
  70         unsigned char sha1[20];
  71         uint32_t crc32;
  72         off_t offset;
  73 };
  74
  75
  76 struct progress;
  77 typedef int (*verify_fn)(const unsigned char*, enum object_type, unsigned long, void*, int*);
  78
  79 extern const char *write_idx_file(const char *index_name, struct pack_idx_entry **objects, int nr_objects, const struct pack_idx_option *, const unsigned char *sha1);
  80 extern int check_pack_crc(struct packed_git *p, struct pack_window **w_curs, off_t offset, off_t len, unsigned int nr);
  81 extern int verify_pack_index(struct packed_git *);
  82 extern int verify_pack(struct packed_git *, verify_fn fn, struct progress *, uint32_t);
  83 extern off_t write_pack_header(struct sha1file *f, uint32_t);
  84 extern void fixup_pack_header_footer(int, unsigned char *, const char *, uint32_t, unsigned char *, off_t);
  85 extern char *index_pack_lockfile(int fd);
  86 extern int encode_in_pack_object_header(enum object_type, uintmax_t, unsigned char *);
  87
  88 #define PH_ERROR_EOF            (-1)
  89 #define PH_ERROR_PACK_SIGNATURE (-2)
  90 #define PH_ERROR_PROTOCOL       (-3)
  91 extern int read_pack_header(int fd, struct pack_header *);
  92
  93 extern struct sha1file *create_tmp_packfile(char **pack_tmp_name);
  94 extern void finish_tmp_packfile(struct strbuf *name_buffer, const char *pack_tmp_name, struct pack_idx_entry **written_list, uint32_t nr_written, struct pack_idx_option *pack_idx_opts, unsigned char sha1[]);
  95
  96 #endif