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Fix tar files emitted by pg_basebackup to be POSIX conformant.

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Back-patch portions of commit 05b555d12bc2ad0d581f48a12b45174db41dc10d.
There doesn't seem to be any reason not to fix pg_basebackup fully, but
we can't change pg_dump's "magic" string without breaking older versions
of pg_restore.  Instead, just patch pg_restore to accept either version
of the magic string, in hopes of avoiding compatibility problems when
9.3 comes out.  I also fixed pg_dump to write the correct 2-block EOF
marker, since that won't create a compatibility problem with pg_restore
and it could help with some versions of tar.

Brian Weaver and Tom Lane
This commit is contained in:
Tom Lane 2012-09-28 15:35:46 -04:00
parent f2366e584a
commit 900d77fa57
3 changed files with 64 additions and 34 deletions
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8
doc/src/sgml/protocol.sgml
View File

@ -1759,9 +1759,11 @@ The commands accepted in walsender mode are:
After the second regular result set, one or more CopyResponse results
will be sent, one for PGDATA and one for each additional tablespace other
than <literal>pg_default</> and <literal>pg_global</>. The data in
the CopyResponse results will be a tar format (using ustar00
extensions) dump of the tablespace contents. After the tar data is
complete, a final ordinary result set will be sent.
the CopyResponse results will be a tar format (following the
<quote>ustar interchange format</> specified in the POSIX 1003.1-2008
standard) dump of the tablespace contents, except that the two trailing
blocks of zeroes specified in the standard are omitted.
After the tar data is complete, a final ordinary result set will be sent.
</para>
<para>

63
src/backend/replication/basebackup.c
View File

@ -572,7 +572,7 @@ sendFileWithContent(const char *filename, const char *content)
/*
* Include all files from the given directory in the output tar stream. If
* 'sizeonly' is true, we just calculate a total length and return ig, without
* 'sizeonly' is true, we just calculate a total length and return it, without
* actually sending anything.
*/
static int64
@ -767,11 +767,16 @@ _tarChecksum(char *header)
int i,
sum;
sum = 0;
/*
* Per POSIX, the checksum is the simple sum of all bytes in the header,
* treating the bytes as unsigned, and treating the checksum field (at
* offset 148) as though it contained 8 spaces.
*/
sum = 8 * ' '; /* presumed value for checksum field */
for (i = 0; i < 512; i++)
if (i < 148 || i >= 156)
sum += 0xFF & header[i];
return sum + 256; /* Assume 8 blanks in checksum field */
return sum;
}
/* Given the member, write the TAR header & send the file */
@ -850,9 +855,13 @@ _tarWriteHeader(const char *filename, const char *linktarget,
struct stat * statbuf)
{
char h[512];
int lastSum = 0;
int sum;
/*
* Note: most of the fields in a tar header are not supposed to be
* null-terminated. We use sprintf, which will write a null after the
* required bytes; that null goes into the first byte of the next field.
* This is okay as long as we fill the fields in order.
*/
memset(h, 0, sizeof(h));
/* Name 100 */
@ -864,8 +873,11 @@ _tarWriteHeader(const char *filename, const char *linktarget,
* indicated in the tar format by adding a slash at the end of the
* name, the same as for regular directories.
*/
h[strlen(filename)] = '/';
h[strlen(filename) + 1] = '\0';
int flen = strlen(filename);
flen = Min(flen, 99);
h[flen] = '/';
h[flen + 1] = '\0';
}
/* Mode 8 */
@ -875,9 +887,9 @@ _tarWriteHeader(const char *filename, const char *linktarget,
sprintf(&h[108], "%07o ", statbuf->st_uid);
/* Group 8 */
sprintf(&h[117], "%07o ", statbuf->st_gid);
sprintf(&h[116], "%07o ", statbuf->st_gid);
/* File size 12 - 11 digits, 1 space, no NUL */
/* File size 12 - 11 digits, 1 space; use print_val for 64 bit support */
if (linktarget != NULL || S_ISDIR(statbuf->st_mode))
/* Symbolic link or directory has size zero */
print_val(&h[124], 0, 8, 11);
@ -888,13 +900,13 @@ _tarWriteHeader(const char *filename, const char *linktarget,
/* Mod Time 12 */
sprintf(&h[136], "%011o ", (int) statbuf->st_mtime);
/* Checksum 8 */
sprintf(&h[148], "%06o ", lastSum);
/* Checksum 8 cannot be calculated until we've filled all other fields */
if (linktarget != NULL)
{
/* Type - Symbolic link */
sprintf(&h[156], "2");
/* Link Name 100 */
sprintf(&h[157], "%.99s", linktarget);
}
else if (S_ISDIR(statbuf->st_mode))
@ -904,10 +916,11 @@ _tarWriteHeader(const char *filename, const char *linktarget,
/* Type - regular file */
sprintf(&h[156], "0");
/* Link tag 100 (NULL) */
/* Magic 6 */
sprintf(&h[257], "ustar");
/* Magic 6 + Version 2 */
sprintf(&h[257], "ustar00");
/* Version 2 */
sprintf(&h[263], "00");
/* User 32 */
/* XXX: Do we need to care about setting correct username? */
@ -917,17 +930,21 @@ _tarWriteHeader(const char *filename, const char *linktarget,
/* XXX: Do we need to care about setting correct group name? */
sprintf(&h[297], "%.31s", "postgres");
/* Maj Dev 8 */
sprintf(&h[329], "%6o ", 0);
/* Major Dev 8 */
sprintf(&h[329], "%07o ", 0);
/* Min Dev 8 */
sprintf(&h[337], "%6o ", 0);
/* Minor Dev 8 */
sprintf(&h[337], "%07o ", 0);
while ((sum = _tarChecksum(h)) != lastSum)
{
sprintf(&h[148], "%06o ", sum);
lastSum = sum;
}
/* Prefix 155 - not used, leave as nulls */
/*
* We mustn't overwrite the next field while inserting the checksum.
* Fortunately, the checksum can't exceed 6 octal digits, so we just write
* 6 digits, a space, and a null, which is legal per POSIX.
*/
sprintf(&h[148], "%06o ", _tarChecksum(h));
/* Now send the completed header. */
pq_putmessage('d', h, 512);
}

27
src/bin/pg_dump/pg_backup_tar.c
View File

@ -882,8 +882,10 @@ _CloseArchive(ArchiveHandle *AH)
tarClose(AH, th);
/* Add a block of NULLs since it's de-rigeur. */
for (i = 0; i < 512; i++)
/*
* EOF marker for tar files is two blocks of NULLs.
*/
for (i = 0; i < 512 * 2; i++)
{
if (fputc(0, ctx->tarFH) == EOF)
exit_horribly(modulename,
@ -1032,11 +1034,16 @@ _tarChecksum(char *header)
int i,
sum;
sum = 0;
/*
* Per POSIX, the checksum is the simple sum of all bytes in the header,
* treating the bytes as unsigned, and treating the checksum field (at
* offset 148) as though it contained 8 spaces.
*/
sum = 8 * ' '; /* presumed value for checksum field */
for (i = 0; i < 512; i++)
if (i < 148 || i >= 156)
sum += 0xFF & header[i];
return sum + 256; /* Assume 8 blanks in checksum field */
return sum;
}
bool
@ -1050,11 +1057,15 @@ isValidTarHeader(char *header)
if (sum != chk)
return false;
/* POSIX format */
if (strncmp(&header[257], "ustar00", 7) == 0)
/* POSIX tar format */
if (memcmp(&header[257], "ustar\0", 6) == 0 &&
memcmp(&header[263], "00", 2) == 0)
return true;
/* older format */
if (strncmp(&header[257], "ustar ", 7) == 0)
/* GNU tar format */
if (memcmp(&header[257], "ustar \0", 8) == 0)
return true;
/* not-quite-POSIX format written by pre-9.3 pg_dump */
if (memcmp(&header[257], "ustar00\0", 8) == 0)
return true;
return false;