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106764e651
There is a subtle (but important) linkage between receive-pack and index-pack that allows index-pack to create a packfile but protect it from being deleted by a concurrent `git repack -a -d` operation. The linkage works by having index-pack mark the newly created pack with a ".keep" file and then it passes the SHA-1 name of that new packfile to receive-pack along its stdout channel. The receive-pack process must unkeep the packfile by deleting the .keep file, but can it can only do so after all elgible refs have been updated in the receiving repository. This ensures that the packfile is either kept or its objects are reachable, preventing a concurrent repacker from deleting the packfile before it can determine that its objects are actually needed by the repository. The new builtin-fetch code needs to perform the same actions if it choose to run index-pack rather than unpack-objects, so I am moving this code out to its own function where both receive-pack and fetch-pack are able to invoke it when necessary. The caller is responsible for deleting the returned ".keep" and freeing the path if the returned path is not NULL. Signed-off-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
69 lines
2 KiB
C
69 lines
2 KiB
C
#ifndef PACK_H
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#define PACK_H
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#include "object.h"
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/*
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* Packed object header
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*/
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#define PACK_SIGNATURE 0x5041434b /* "PACK" */
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#define PACK_VERSION 2
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#define pack_version_ok(v) ((v) == htonl(2) || (v) == htonl(3))
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struct pack_header {
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uint32_t hdr_signature;
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uint32_t hdr_version;
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uint32_t hdr_entries;
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};
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/*
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* The first four bytes of index formats later than version 1 should
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* start with this signature, as all older git binaries would find this
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* value illegal and abort reading the file.
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*
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* This is the case because the number of objects in a packfile
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* cannot exceed 1,431,660,000 as every object would need at least
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* 3 bytes of data and the overall packfile cannot exceed 4 GiB with
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* version 1 of the index file due to the offsets limited to 32 bits.
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* Clearly the signature exceeds this maximum.
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*
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* Very old git binaries will also compare the first 4 bytes to the
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* next 4 bytes in the index and abort with a "non-monotonic index"
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* error if the second 4 byte word is smaller than the first 4
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* byte word. This would be true in the proposed future index
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* format as idx_signature would be greater than idx_version.
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*/
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#define PACK_IDX_SIGNATURE 0xff744f63 /* "\377tOc" */
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/* These may be overridden by command-line parameters */
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extern uint32_t pack_idx_default_version;
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extern uint32_t pack_idx_off32_limit;
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/*
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* Packed object index header
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*/
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struct pack_idx_header {
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uint32_t idx_signature;
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uint32_t idx_version;
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};
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/*
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* Common part of object structure used for write_idx_file
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*/
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struct pack_idx_entry {
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unsigned char sha1[20];
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uint32_t crc32;
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off_t offset;
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};
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extern const char *write_idx_file(const char *index_name, struct pack_idx_entry **objects, int nr_objects, unsigned char *sha1);
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extern int verify_pack(struct packed_git *, int);
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extern void fixup_pack_header_footer(int, unsigned char *, const char *, uint32_t);
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extern char *index_pack_lockfile(int fd);
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#define PH_ERROR_EOF (-1)
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#define PH_ERROR_PACK_SIGNATURE (-2)
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#define PH_ERROR_PROTOCOL (-3)
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extern int read_pack_header(int fd, struct pack_header *);
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#endif
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