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Revision 3ba2e8653c88d220b0b22f35260477bb0afa7d7b authored by Johannes Sixt on 16 March 2011, 08:18:49 UTC, committed by Junio C Hamano on 17 March 2011, 21:54:11 UTC 
stash: copy the index using --index-output instead of cp -p
 
'git stash create' must operate with a temporary index. For this purpose,
it used 'cp -p' to create a copy. -p is needed to preserve the timestamp
of the index file. Now Jakob Pfender reported a certain combination of
a Linux NFS client, OpenBSD NFS server, and cp implementation where this
operation failed.

Luckily, the first operation in git-stash after copying the index is to
call 'git read-tree'. Therefore, use --index-output instead of 'cp -p'
to write the copy of the index.

--index-output requires that the specified file is on the same volume as
the source index, so that the lock file can be rename()d. For this reason,
the name of the temporary index is constructed in a way different from the
other temporary files. The code path of 'stash -p' also needs a temporary
index, but we do not use the new name because it does not depend on the
same precondition as --index-output.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 23a32ff
Raw File
pack.h 
#ifndef PACK_H
#define PACK_H

#include "object.h"

/*
 * Packed object header
 */
#define PACK_SIGNATURE 0x5041434b	/* "PACK" */
#define PACK_VERSION 2
#define pack_version_ok(v) ((v) == htonl(2) || (v) == htonl(3))
struct pack_header {
	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" */

/* These may be overridden by command-line parameters */
extern uint32_t pack_idx_default_version;
extern uint32_t pack_idx_off32_limit;

/*
 * Packed object index header
 */
struct pack_idx_header {
	uint32_t idx_signature;
	uint32_t idx_version;
};

/*
 * Common part of object structure used for write_idx_file
 */
struct pack_idx_entry {
	unsigned char sha1[20];
	uint32_t crc32;
	off_t offset;
};

extern const char *write_idx_file(const char *index_name, struct pack_idx_entry **objects, int nr_objects, unsigned char *sha1);
extern int check_pack_crc(struct packed_git *p, struct pack_window **w_curs, off_t offset, off_t len, unsigned int nr);
extern int verify_pack_index(struct packed_git *);
extern int verify_pack(struct packed_git *);
extern void fixup_pack_header_footer(int, unsigned char *, const char *, uint32_t, unsigned char *, off_t);
extern char *index_pack_lockfile(int fd);
extern int encode_in_pack_object_header(enum object_type, uintmax_t, unsigned char *);

#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
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