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/*-------------------------------------------------------------------------
*
* pgtar.h
* Functions for manipulating tarfile datastructures (src/port/tar.c)
*
*
* Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/pgtar.h
*
*-------------------------------------------------------------------------
*/
#ifndef PG_TAR_H
#define PG_TAR_H
#define TAR_BLOCK_SIZE 512
enum tarError
{
TAR_OK = 0,
TAR_NAME_TOO_LONG,
TAR_SYMLINK_TOO_LONG,
};
/*
* Offsets of fields within a 512-byte tar header.
*
* "tar number" values should be generated using print_tar_number() and can be
* read using read_tar_number(). Fields that contain strings are generally
* both filled and read using strlcpy().
*
* The value for the checksum field can be computed using tarChecksum().
*
* Some fields are not used by PostgreSQL; see tarCreateHeader().
*/
enum tarHeaderOffset
{
TAR_OFFSET_NAME = 0, /* 100 byte string */
TAR_OFFSET_MODE = 100, /* 8 byte tar number, excludes S_IFMT */
TAR_OFFSET_UID = 108, /* 8 byte tar number */
TAR_OFFSET_GID = 116, /* 8 byte tar number */
TAR_OFFSET_SIZE = 124, /* 8 byte tar number */
TAR_OFFSET_MTIME = 136, /* 12 byte tar number */
TAR_OFFSET_CHECKSUM = 148, /* 8 byte tar number */
TAR_OFFSET_TYPEFLAG = 156, /* 1 byte file type, see TAR_FILETYPE_* */
TAR_OFFSET_LINKNAME = 157, /* 100 byte string */
TAR_OFFSET_MAGIC = 257, /* "ustar" with terminating zero byte */
TAR_OFFSET_VERSION = 263, /* "00" */
TAR_OFFSET_UNAME = 265, /* 32 byte string */
TAR_OFFSET_GNAME = 297, /* 32 byte string */
TAR_OFFSET_DEVMAJOR = 329, /* 8 byte tar number */
TAR_OFFSET_DEVMINOR = 337, /* 8 byte tar number */
TAR_OFFSET_PREFIX = 345, /* 155 byte string */
/* last 12 bytes of the 512-byte block are unassigned */
};
enum tarFileType
{
TAR_FILETYPE_PLAIN = '0',
TAR_FILETYPE_SYMLINK = '2',
TAR_FILETYPE_DIRECTORY = '5',
};
extern enum tarError tarCreateHeader(char *h, const char *filename,
const char *linktarget, pgoff_t size,
mode_t mode, uid_t uid, gid_t gid,
time_t mtime);
extern uint64 read_tar_number(const char *s, int len);
extern void print_tar_number(char *s, int len, uint64 val);
extern int tarChecksum(char *header);
/*
* Compute the number of padding bytes required for an entry in a tar
* archive. We must pad out to a multiple of TAR_BLOCK_SIZE. Since that's
* a power of 2, we can use TYPEALIGN().
*/
static inline size_t
tarPaddingBytesRequired(size_t len)
{
return TYPEALIGN(TAR_BLOCK_SIZE, len) - len;
}
#endif
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