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Commit71edbb6

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Avoid use of non-portable strnlen() in pgstat_clip_activity().
The use of strnlen rather than strlen was just paranoia. Instead ofgiving up on the paranoia, just implement the safeguarddifferently. And add a comment explaining why we're careful.Author: Andres FreundDiscussion:https://postgr.es/m/E1duOkJ-0001Mc-U5@gemulon.postgresql.org
1 parent54b6cd5 commit71edbb6

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2 files changed

+22
-5
lines changed

2 files changed

+22
-5
lines changed

‎src/backend/postmaster/pgstat.c

Lines changed: 21 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -6288,10 +6288,24 @@ pgstat_db_requested(Oid databaseid)
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* freed.
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*/
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char*
6291-
pgstat_clip_activity(constchar*activity)
6291+
pgstat_clip_activity(constchar*raw_activity)
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{
6293-
intrawlen=strnlen(activity,pgstat_track_activity_query_size-1);
6294-
intcliplen;
6293+
char*activity;
6294+
intrawlen;
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intcliplen;
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/*
6298+
* Some callers, like pgstat_get_backend_current_activity(), do not
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* guarantee that the buffer isn't concurrently modified. We try to take
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* care that the buffer is always terminated by a NULL byte regardless,
6301+
* but let's still be paranoid about the string's length. In those cases
6302+
* the underlying buffer is guaranteed to be
6303+
* pgstat_track_activity_query_size large.
6304+
*/
6305+
activity=pnstrdup(raw_activity,pgstat_track_activity_query_size-1);
6306+
6307+
/* now double-guaranteed to be NULL terminated */
6308+
rawlen=strlen(activity);
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/*
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* All supported server-encodings make it possible to determine the length
@@ -6303,5 +6317,8 @@ pgstat_clip_activity(const char *activity)
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*/
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cliplen=pg_mbcliplen(activity,rawlen,
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pgstat_track_activity_query_size-1);
6306-
returnpnstrdup(activity,cliplen);
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activity[cliplen]='\0';
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returnactivity;
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}

‎src/include/pgstat.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1199,7 +1199,7 @@ extern PgStat_BackendFunctionEntry *find_funcstat_entry(Oid func_id);
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externvoidpgstat_initstats(Relationrel);
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1202-
externchar*pgstat_clip_activity(constchar*activity);
1202+
externchar*pgstat_clip_activity(constchar*raw_activity);
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/* ----------
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* pgstat_report_wait_start() -

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