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Fix tar files emitted by pg_dump and pg_basebackup to be POSIX conformant.

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Both programs got the "magic" string wrong, causing standard-conforming tar
implementations to believe the output was just legacy tar format without
any POSIX extensions.  This doesn't actually matter that much, especially
since pg_dump failed to fill the POSIX fields anyway, but still there is
little point in emitting tar format if we can't be compliant with the
standard.  In addition, pg_dump failed to write the EOF marker correctly
(there should be 2 blocks of zeroes not just one), pg_basebackup put the
numeric group ID in the wrong place, and both programs had a pretty
brain-dead idea of how to compute the checksum.  Fix all that and improve
the comments a bit.

pg_restore is modified to accept either the correct POSIX-compliant "magic"
string or the previous value.  This part of the change will need to be
back-patched to avoid an unnecessary compatibility break when a previous
version tries to read tar-format output from 9.3 pg_dump.

Brian Weaver and Tom Lane
This commit is contained in:
Tom Lane
2012-09-28 15:19:15 -04:00
parent edc9109c42
commit 05b555d12b
4 changed files with 110 additions and 69 deletions
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21
src/bin/pg_dump/pg_backup_tar.h
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@@ -1,28 +1,31 @@
/*
* src/bin/pg_dump/pg_backup_tar.h
*
* TAR Header
* TAR Header (see "ustar interchange format" in POSIX 1003.1)
*
* Offset Length Contents
* 0 100 bytes File name ('\0' terminated, 99 maximum length)
* 100 8 bytes File mode (in octal ascii)
* 108 8 bytes User ID (in octal ascii)
* 116 8 bytes Group ID (in octal ascii)
* 124 12 bytes File size (s) (in octal ascii)
* 136 12 bytes Modify time (in octal ascii)
* 124 12 bytes File size (in octal ascii)
* 136 12 bytes Modify time (Unix timestamp in octal ascii)
* 148 8 bytes Header checksum (in octal ascii)
* 156 1 bytes Link flag
* 157 100 bytes Linkname ('\0' terminated, 99 maximum length)
* 257 8 bytes Magic ("ustar \0")
* 156 1 bytes Type flag (see below)
* 157 100 bytes Linkname, if symlink ('\0' terminated, 99 maximum length)
* 257 6 bytes Magic ("ustar\0")
* 263 2 bytes Version ("00")
* 265 32 bytes User name ('\0' terminated, 31 maximum length)
* 297 32 bytes Group name ('\0' terminated, 31 maximum length)
* 329 8 bytes Major device ID (in octal ascii)
* 337 8 bytes Minor device ID (in octal ascii)
* 345 167 bytes Padding
* 512 (s+p)bytes File contents (s+p) := (((s) + 511) & ~511), round up to 512 bytes
* 345 155 bytes File name prefix (not used in our implementation)
* 500 12 bytes Padding
*
* 512 (s+p)bytes File contents, padded out to 512-byte boundary
*/
/* The linkflag defines the type of file */
/* The type flag defines the type of file */
#define LF_OLDNORMAL '\0' /* Normal disk file, Unix compatible */
#define LF_NORMAL '0' /* Normal disk file */
#define LF_LINK '1' /* Link to previously dumped file */