Revision aba91192ae39cd1a2f79e7ed91e966df3cfe10b7 authored by Carlos Rica on 09 September 2007, 00:39:29 UTC, committed by Junio C Hamano on 10 September 2007, 04:30:54 UTC
Most of this patch code and message was written by Shawn O. Pearce.
I made some tests to know what the problem was, and then I changed
the code related with the SIGPIPE signal.

If the user has misconfigured `user.signingkey` in their .git/config
or just doesn't have any secret keys on their keyring and they ask
for a signed tag with `git tag -s` we better make sure the resulting
tag was actually signed by gpg.

Prior versions of builtin git-tag allowed this failure to slip
by without error as they were not checking the return value of
the finish_command() so they did not notice when gpg exited with
an error exit status.  They also did not fail if gpg produced an
empty output or if read_in_full received an error from the read
system call while trying to read the pipe back from gpg.

Finally, we did not actually honor any return value from the do_sign
function as it returns ssize_t but was being stored into an unsigned
long.  This caused the compiler to optimize out the die condition,
allowing git-tag to continue along and create the tag object.

However, when gpg gets a wrong username, it exits before any read was done
and then the writing process receives SIGPIPE and program is terminated.
By ignoring this signal, anyway, the function write_or_die gets EPIPE from
write_in_full and exits returning 0 to the system without a message.
Here we better call to write_in_full directly so we can fail
printing a message and return safely to the caller.

With these issues fixed `git-tag -s` will now fail to create the
tag and will report a non-zero exit status to its caller, thereby
allowing automated helper scripts to detect (and recover from)
failure if gpg is not working properly.

Proposed-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Carlos Rica <jasampler@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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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 verify_pack(struct packed_git *, int);
extern void fixup_pack_header_footer(int, unsigned char *, const char *, uint32_t);

#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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