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Remove XLogFileNameP() from the tree

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XLogFileNameP() is a wrapper routine able to build a palloc'd string for
a WAL segment name, which is used for error string generation.  There
were several code paths where it gets called in a critical section,
where memory allocation is not allowed.  This results in triggering
an assertion failure instead of generating the wanted error message.

Another, more annoying, problem is that if the allocation to generate
the WAL segment name fails on OOM, then the failure would be escalated
to a PANIC.

This removes the routine and all its callers are replaced with a logic
using a fixed-size buffer.  This way, all the existing mistakes are
fixed and future ones are prevented.

Author: Masahiko Sawada
Reviewed-by: Michael Paquier, Álvaro Herrera
Discussion: https://postgr.es/m/CA+fd4k5gC9H4uoWMLg9K_QfNrnkkdEw+-AFveob9YX7z8JnKTA@mail.gmail.com
This commit is contained in:
Michael Paquier
2019-12-03 15:06:04 +09:00
parent e5532f194c
commit 9989d37d1c
6 changed files with 96 additions and 44 deletions
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6
src/backend/access/transam/xlogutils.c
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@@ -776,7 +776,7 @@ XLogReadDetermineTimeline(XLogReaderState *state, XLogRecPtr wantPage, uint32 wa
/* openSegment callback for WALRead */
static int
wal_segment_open(XLogSegNo nextSegNo, WALSegmentContext *segcxt,
wal_segment_open(XLogSegNo nextSegNo, WALSegmentContext * segcxt,
TimeLineID *tli_p)
{
TimeLineID tli = *tli_p;
@@ -944,7 +944,9 @@ void
WALReadRaiseError(WALReadError *errinfo)
{
WALOpenSegment *seg = &errinfo->wre_seg;
char *fname = XLogFileNameP(seg->ws_tli, seg->ws_segno);
char fname[MAXFNAMELEN];
XLogFileName(fname, seg->ws_tli, seg->ws_segno, wal_segment_size);
if (errinfo->wre_read < 0)
{