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Commitdfa6eda

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Fix tar files emitted by pg_basebackup to be POSIX conformant.
Back-patch portions of commit05b555d.There doesn't seem to be any reason not to fix pg_basebackup fully, butwe can't change pg_dump's "magic" string without breaking older versionsof pg_restore. Instead, just patch pg_restore to accept either versionof the magic string, in hopes of avoiding compatibility problems when9.3 comes out. I also fixed pg_dump to write the correct 2-block EOFmarker, since that won't create a compatibility problem with pg_restoreand it could help with some versions of tar.Brian Weaver and Tom Lane
1 parentbc99397 commitdfa6eda

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3 files changed

+64
-34
lines changed

3 files changed

+64
-34
lines changed

‎doc/src/sgml/protocol.sgml‎

Lines changed: 5 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1726,9 +1726,11 @@ The commands accepted in walsender mode are:
17261726
After the second regular result set, one or more CopyResponse results
17271727
will be sent, one for PGDATA and one for each additional tablespace other
17281728
than <literal>pg_default</> and <literal>pg_global</>. The data in
1729-
the CopyResponse results will be a tar format (using ustar00
1730-
extensions) dump of the tablespace contents. After the tar data is
1731-
complete, a final ordinary result set will be sent.
1729+
the CopyResponse results will be a tar format (following the
1730+
<quote>ustar interchange format</> specified in the POSIX 1003.1-2008
1731+
standard) dump of the tablespace contents, except that the two trailing
1732+
blocks of zeroes specified in the standard are omitted.
1733+
After the tar data is complete, a final ordinary result set will be sent.
17321734
</para>
17331735

17341736
<para>

‎src/backend/replication/basebackup.c‎

Lines changed: 40 additions & 23 deletions
Original file line numberDiff line numberDiff line change
@@ -554,7 +554,7 @@ sendFileWithContent(const char *filename, const char *content)
554554

555555
/*
556556
* Include all files from the given directory in the output tar stream. If
557-
* 'sizeonly' is true, we just calculate a total length and returnig, without
557+
* 'sizeonly' is true, we just calculate a total length and returnit, without
558558
* actually sending anything.
559559
*/
560560
staticint64
@@ -744,11 +744,16 @@ _tarChecksum(char *header)
744744
inti,
745745
sum;
746746

747-
sum=0;
747+
/*
748+
* Per POSIX, the checksum is the simple sum of all bytes in the header,
749+
* treating the bytes as unsigned, and treating the checksum field (at
750+
* offset 148) as though it contained 8 spaces.
751+
*/
752+
sum=8*' ';/* presumed value for checksum field */
748753
for (i=0;i<512;i++)
749754
if (i<148||i >=156)
750755
sum+=0xFF&header[i];
751-
returnsum+256;/* Assume 8 blanks in checksum field */
756+
returnsum;
752757
}
753758

754759
/* Given the member, write the TAR header & send the file */
@@ -827,9 +832,13 @@ _tarWriteHeader(const char *filename, const char *linktarget,
827832
structstat*statbuf)
828833
{
829834
charh[512];
830-
intlastSum=0;
831-
intsum;
832835

836+
/*
837+
* Note: most of the fields in a tar header are not supposed to be
838+
* null-terminated. We use sprintf, which will write a null after the
839+
* required bytes; that null goes into the first byte of the next field.
840+
* This is okay as long as we fill the fields in order.
841+
*/
833842
memset(h,0,sizeof(h));
834843

835844
/* Name 100 */
@@ -841,8 +850,11 @@ _tarWriteHeader(const char *filename, const char *linktarget,
841850
* indicated in the tar format by adding a slash at the end of the
842851
* name, the same as for regular directories.
843852
*/
844-
h[strlen(filename)]='/';
845-
h[strlen(filename)+1]='\0';
853+
intflen=strlen(filename);
854+
855+
flen=Min(flen,99);
856+
h[flen]='/';
857+
h[flen+1]='\0';
846858
}
847859

848860
/* Mode 8 */
@@ -852,9 +864,9 @@ _tarWriteHeader(const char *filename, const char *linktarget,
852864
sprintf(&h[108],"%07o ",statbuf->st_uid);
853865

854866
/* Group 8 */
855-
sprintf(&h[117],"%07o ",statbuf->st_gid);
867+
sprintf(&h[116],"%07o ",statbuf->st_gid);
856868

857-
/* File size 12 - 11 digits, 1 space, no NUL */
869+
/* File size 12 - 11 digits, 1 space; use print_val for 64 bit support */
858870
if (linktarget!=NULL||S_ISDIR(statbuf->st_mode))
859871
/* Symbolic link or directory has size zero */
860872
print_val(&h[124],0,8,11);
@@ -865,13 +877,13 @@ _tarWriteHeader(const char *filename, const char *linktarget,
865877
/* Mod Time 12 */
866878
sprintf(&h[136],"%011o ", (int)statbuf->st_mtime);
867879

868-
/* Checksum 8 */
869-
sprintf(&h[148],"%06o ",lastSum);
880+
/* Checksum 8 cannot be calculated until we've filled all other fields */
870881

871882
if (linktarget!=NULL)
872883
{
873884
/* Type - Symbolic link */
874885
sprintf(&h[156],"2");
886+
/* Link Name 100 */
875887
sprintf(&h[157],"%.99s",linktarget);
876888
}
877889
elseif (S_ISDIR(statbuf->st_mode))
@@ -881,10 +893,11 @@ _tarWriteHeader(const char *filename, const char *linktarget,
881893
/* Type - regular file */
882894
sprintf(&h[156],"0");
883895

884-
/* Link tag 100 (NULL) */
896+
/* Magic 6 */
897+
sprintf(&h[257],"ustar");
885898

886-
/*Magic 6 +Version 2 */
887-
sprintf(&h[257],"ustar00");
899+
/* Version 2 */
900+
sprintf(&h[263],"00");
888901

889902
/* User 32 */
890903
/* XXX: Do we need to care about setting correct username? */
@@ -894,17 +907,21 @@ _tarWriteHeader(const char *filename, const char *linktarget,
894907
/* XXX: Do we need to care about setting correct group name? */
895908
sprintf(&h[297],"%.31s","postgres");
896909

897-
/*Maj Dev 8 */
898-
sprintf(&h[329],"%6o ",0);
910+
/*Major Dev 8 */
911+
sprintf(&h[329],"%07o ",0);
899912

900-
/*Min Dev 8 */
901-
sprintf(&h[337],"%6o ",0);
913+
/*Minor Dev 8 */
914+
sprintf(&h[337],"%07o ",0);
902915

903-
while ((sum=_tarChecksum(h))!=lastSum)
904-
{
905-
sprintf(&h[148],"%06o ",sum);
906-
lastSum=sum;
907-
}
916+
/* Prefix 155 - not used, leave as nulls */
917+
918+
/*
919+
* We mustn't overwrite the next field while inserting the checksum.
920+
* Fortunately, the checksum can't exceed 6 octal digits, so we just write
921+
* 6 digits, a space, and a null, which is legal per POSIX.
922+
*/
923+
sprintf(&h[148],"%06o ",_tarChecksum(h));
908924

925+
/* Now send the completed header. */
909926
pq_putmessage('d',h,512);
910927
}

‎src/bin/pg_dump/pg_backup_tar.c‎

Lines changed: 19 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -876,8 +876,10 @@ _CloseArchive(ArchiveHandle *AH)
876876

877877
tarClose(AH,th);
878878

879-
/* Add a block of NULLs since it's de-rigeur. */
880-
for (i=0;i<512;i++)
879+
/*
880+
* EOF marker for tar files is two blocks of NULLs.
881+
*/
882+
for (i=0;i<512*2;i++)
881883
{
882884
if (fputc(0,ctx->tarFH)==EOF)
883885
die_horribly(AH,modulename,
@@ -1028,11 +1030,16 @@ _tarChecksum(char *header)
10281030
inti,
10291031
sum;
10301032

1031-
sum=0;
1033+
/*
1034+
* Per POSIX, the checksum is the simple sum of all bytes in the header,
1035+
* treating the bytes as unsigned, and treating the checksum field (at
1036+
* offset 148) as though it contained 8 spaces.
1037+
*/
1038+
sum=8*' ';/* presumed value for checksum field */
10321039
for (i=0;i<512;i++)
10331040
if (i<148||i >=156)
10341041
sum+=0xFF&header[i];
1035-
returnsum+256;/* Assume 8 blanks in checksum field */
1042+
returnsum;
10361043
}
10371044

10381045
bool
@@ -1046,11 +1053,15 @@ isValidTarHeader(char *header)
10461053
if (sum!=chk)
10471054
return false;
10481055

1049-
/* POSIX format */
1050-
if (strncmp(&header[257],"ustar00",7)==0)
1056+
/* POSIX tar format */
1057+
if (memcmp(&header[257],"ustar\0",6)==0&&
1058+
memcmp(&header[263],"00",2)==0)
1059+
return true;
1060+
/* GNU tar format */
1061+
if (memcmp(&header[257],"ustar \0",8)==0)
10511062
return true;
1052-
/*older format */
1053-
if (strncmp(&header[257],"ustar",7)==0)
1063+
/*not-quite-POSIX format written by pre-9.3 pg_dump */
1064+
if (memcmp(&header[257],"ustar00\0",8)==0)
10541065
return true;
10551066

10561067
return false;

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