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alvherrealvherre
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Measure string lengths only once
Bernd Helmle complained that CreateReplicationSlot() was assigning the same value to the same variable twice, so we could remove one of them. Code inspection reveals that we can actually remove both assignments: according to the author the assignment was there for beauty of the strlen line only, and another possible fix to that is to put the strlen in its own line, so do that. To be consistent within the file, refactor all duplicated strlen() calls, which is what we do elsewhere in the backend anyway. In basebackup.c, snprintf already returns the right length; no need for strlen afterwards. Backpatch to 9.4, where replication slots were introduced, to keep code identical. Some of this is older, but the patch doesn't apply cleanly and it's only of cosmetic value anyway. Discussion: http://www.postgresql.org/message-id/[email protected]
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+70
-45
lines changed

2 files changed

+70
-45
lines changed

‎src/backend/replication/basebackup.c‎

Lines changed: 19 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -698,10 +698,15 @@ SendBackupHeader(List *tablespaces)
698698
}
699699
else
700700
{
701-
pq_sendint(&buf, strlen(ti->oid), 4); /* length */
702-
pq_sendbytes(&buf, ti->oid, strlen(ti->oid));
703-
pq_sendint(&buf, strlen(ti->path), 4); /* length */
704-
pq_sendbytes(&buf, ti->path, strlen(ti->path));
701+
Size len;
702+
703+
len = strlen(ti->oid);
704+
pq_sendint(&buf, len, 4);
705+
pq_sendbytes(&buf, ti->oid, len);
706+
707+
len = strlen(ti->path);
708+
pq_sendint(&buf, len, 4);
709+
pq_sendbytes(&buf, ti->path, len);
705710
}
706711
if (ti->size >= 0)
707712
send_int8_string(&buf, ti->size / 1024);
@@ -724,6 +729,7 @@ SendXlogRecPtrResult(XLogRecPtr ptr, TimeLineID tli)
724729
{
725730
StringInfoData buf;
726731
char str[MAXFNAMELEN];
732+
Size len;
727733

728734
pq_beginmessage(&buf, 'T'); /* RowDescription */
729735
pq_sendint(&buf, 2, 2); /* 2 fields */
@@ -742,7 +748,7 @@ SendXlogRecPtrResult(XLogRecPtr ptr, TimeLineID tli)
742748
pq_sendint(&buf, 0, 2); /* attnum */
743749

744750
/*
745-
* int8 may seem like a surprising data type for this, but in thory int4
751+
* int8 may seem like a surprising data type for this, but in theory int4
746752
* would not be wide enough for this, as TimeLineID is unsigned.
747753
*/
748754
pq_sendint(&buf, INT8OID, 4); /* type oid */
@@ -755,13 +761,15 @@ SendXlogRecPtrResult(XLogRecPtr ptr, TimeLineID tli)
755761
pq_beginmessage(&buf, 'D');
756762
pq_sendint(&buf, 2, 2); /* number of columns */
757763

758-
snprintf(str, sizeof(str), "%X/%X", (uint32) (ptr >> 32), (uint32) ptr);
759-
pq_sendint(&buf, strlen(str), 4); /* length */
760-
pq_sendbytes(&buf, str, strlen(str));
764+
len = snprintf(str, sizeof(str),
765+
"%X/%X", (uint32) (ptr >> 32), (uint32) ptr);
766+
pq_sendint(&buf, len, 4);
767+
pq_sendbytes(&buf, str, len);
768+
769+
len = snprintf(str, sizeof(str), "%u", tli);
770+
pq_sendint(&buf, len, 4);
771+
pq_sendbytes(&buf, str, len);
761772

762-
snprintf(str, sizeof(str), "%u", tli);
763-
pq_sendint(&buf, strlen(str), 4); /* length */
764-
pq_sendbytes(&buf, str, strlen(str));
765773
pq_endmessage(&buf);
766774

767775
/* Send a CommandComplete message */

‎src/backend/replication/walsender.c‎

Lines changed: 51 additions & 34 deletions
Original file line numberDiff line numberDiff line change
@@ -299,6 +299,7 @@ IdentifySystem(void)
299299
char xpos[MAXFNAMELEN];
300300
XLogRecPtr logptr;
301301
char *dbname = NULL;
302+
Size len;
302303

303304
/*
304305
* Reply with a result set with one row, four columns. First col is system
@@ -380,21 +381,32 @@ IdentifySystem(void)
380381
/* Send a DataRow message */
381382
pq_beginmessage(&buf, 'D');
382383
pq_sendint(&buf, 4, 2); /* # of columns */
383-
pq_sendint(&buf, strlen(sysid), 4); /* col1 len */
384-
pq_sendbytes(&buf, (char *) &sysid, strlen(sysid));
385-
pq_sendint(&buf, strlen(tli), 4); /* col2 len */
386-
pq_sendbytes(&buf, (char *) tli, strlen(tli));
387-
pq_sendint(&buf, strlen(xpos), 4); /* col3 len */
388-
pq_sendbytes(&buf, (char *) xpos, strlen(xpos));
389-
/* send NULL if not connected to a database */
384+
385+
/* column 1: system identifier */
386+
len = strlen(sysid);
387+
pq_sendint(&buf, len, 4);
388+
pq_sendbytes(&buf, (char *) &sysid, len);
389+
390+
/* column 2: timeline */
391+
len = strlen(tli);
392+
pq_sendint(&buf, len, 4);
393+
pq_sendbytes(&buf, (char *) tli, len);
394+
395+
/* column 3: xlog position */
396+
len = strlen(xpos);
397+
pq_sendint(&buf, len, 4);
398+
pq_sendbytes(&buf, (char *) xpos, len);
399+
400+
/* column 4: database name, or NULL if none */
390401
if (dbname)
391402
{
392-
pq_sendint(&buf, strlen(dbname), 4); /* col4 len */
393-
pq_sendbytes(&buf, (char *) dbname, strlen(dbname));
403+
len = strlen(dbname);
404+
pq_sendint(&buf, len, 4);
405+
pq_sendbytes(&buf, (char *) dbname, len);
394406
}
395407
else
396408
{
397-
pq_sendint(&buf, -1, 4); /* col4 len, NULL */
409+
pq_sendint(&buf, -1, 4);
398410
}
399411

400412
pq_endmessage(&buf);
@@ -413,6 +425,7 @@ SendTimeLineHistory(TimeLineHistoryCmd *cmd)
413425
int fd;
414426
off_t histfilelen;
415427
off_t bytesleft;
428+
Size len;
416429

417430
/*
418431
* Reply with a result set with one row, and two columns. The first col is
@@ -448,8 +461,9 @@ SendTimeLineHistory(TimeLineHistoryCmd *cmd)
448461
/* Send a DataRow message */
449462
pq_beginmessage(&buf, 'D');
450463
pq_sendint(&buf, 2, 2); /* # of columns */
451-
pq_sendint(&buf, strlen(histfname), 4); /* col1 len */
452-
pq_sendbytes(&buf, histfname, strlen(histfname));
464+
len = strlen(histfname);
465+
pq_sendint(&buf, len, 4); /* col1 len */
466+
pq_sendbytes(&buf, histfname, len);
453467

454468
fd = OpenTransientFile(path, O_RDONLY | PG_BINARY, 0666);
455469
if (fd < 0)
@@ -674,6 +688,7 @@ StartReplication(StartReplicationCmd *cmd)
674688
{
675689
char tli_str[11];
676690
char startpos_str[8 + 1 + 8 + 1];
691+
Size len;
677692

678693
snprintf(tli_str, sizeof(tli_str), "%u", sendTimeLineNextTLI);
679694
snprintf(startpos_str, sizeof(startpos_str), "%X/%X",
@@ -710,11 +725,13 @@ StartReplication(StartReplicationCmd *cmd)
710725
pq_beginmessage(&buf, 'D');
711726
pq_sendint(&buf, 2, 2); /* number of columns */
712727

713-
pq_sendint(&buf, strlen(tli_str), 4); /* length */
714-
pq_sendbytes(&buf, tli_str, strlen(tli_str));
728+
len = strlen(tli_str);
729+
pq_sendint(&buf, len, 4); /* length */
730+
pq_sendbytes(&buf, tli_str, len);
715731

716-
pq_sendint(&buf, strlen(startpos_str), 4); /* length */
717-
pq_sendbytes(&buf, startpos_str, strlen(startpos_str));
732+
len = strlen(startpos_str);
733+
pq_sendint(&buf, len, 4); /* length */
734+
pq_sendbytes(&buf, startpos_str, len);
718735

719736
pq_endmessage(&buf);
720737
}
@@ -762,10 +779,10 @@ logical_read_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, int req
762779
static void
763780
CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
764781
{
765-
const char *slot_name;
766782
const char *snapshot_name = NULL;
767783
char xpos[MAXFNAMELEN];
768784
StringInfoData buf;
785+
Size len;
769786

770787
Assert(!MyReplicationSlot);
771788

@@ -791,14 +808,11 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
791808

792809
initStringInfo(&output_message);
793810

794-
slot_name = NameStr(MyReplicationSlot->data.name);
795-
796811
if (cmd->kind == REPLICATION_KIND_LOGICAL)
797812
{
798813
LogicalDecodingContext *ctx;
799814

800-
ctx = CreateInitDecodingContext(
801-
cmd->plugin, NIL,
815+
ctx = CreateInitDecodingContext(cmd->plugin, NIL,
802816
logical_read_xlog_page,
803817
WalSndPrepareWrite, WalSndWriteData);
804818

@@ -834,7 +848,6 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
834848
ReplicationSlotSave();
835849
}
836850

837-
slot_name = NameStr(MyReplicationSlot->data.name);
838851
snprintf(xpos, sizeof(xpos), "%X/%X",
839852
(uint32) (MyReplicationSlot->data.confirmed_flush >> 32),
840853
(uint32) MyReplicationSlot->data.confirmed_flush);
@@ -885,30 +898,34 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
885898
pq_sendint(&buf, 4, 2); /* # of columns */
886899

887900
/* slot_name */
888-
pq_sendint(&buf, strlen(slot_name), 4); /* col1 len */
889-
pq_sendbytes(&buf, slot_name, strlen(slot_name));
901+
len = strlen(NameStr(MyReplicationSlot->data.name));
902+
pq_sendint(&buf, len, 4); /* col1 len */
903+
pq_sendbytes(&buf, NameStr(MyReplicationSlot->data.name), len);
890904

891905
/* consistent wal location */
892-
pq_sendint(&buf, strlen(xpos), 4); /* col2 len */
893-
pq_sendbytes(&buf, xpos, strlen(xpos));
906+
len = strlen(xpos);
907+
pq_sendint(&buf, len, 4);
908+
pq_sendbytes(&buf, xpos, len);
894909

895-
/* snapshot name */
910+
/* snapshot name, or NULL if none */
896911
if (snapshot_name != NULL)
897912
{
898-
pq_sendint(&buf, strlen(snapshot_name), 4); /* col3 len */
899-
pq_sendbytes(&buf, snapshot_name, strlen(snapshot_name));
913+
len = strlen(snapshot_name);
914+
pq_sendint(&buf, len, 4);
915+
pq_sendbytes(&buf, snapshot_name, len);
900916
}
901917
else
902-
pq_sendint(&buf, -1, 4); /* col3 len, NULL */
918+
pq_sendint(&buf, -1, 4);
903919

904-
/* plugin */
920+
/* plugin, or NULL if none */
905921
if (cmd->plugin != NULL)
906922
{
907-
pq_sendint(&buf, strlen(cmd->plugin), 4); /* col4 len */
908-
pq_sendbytes(&buf, cmd->plugin, strlen(cmd->plugin));
923+
len = strlen(cmd->plugin);
924+
pq_sendint(&buf, len, 4);
925+
pq_sendbytes(&buf, cmd->plugin, len);
909926
}
910927
else
911-
pq_sendint(&buf, -1, 4); /* col4 len, NULL */
928+
pq_sendint(&buf, -1, 4);
912929

913930
pq_endmessage(&buf);
914931

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