Add destroyStringInfo function for cleaning up StringInfos

danielgustafsson · danielgustafsson · commit b7831865159d · 2024-03-16T23:18:28.000+01:00
destroyStringInfo() is a counterpart to makeStringInfo(), freeing a palloc'd StringInfo and its data. This is a convenience function to align the StringInfo API with the PQExpBuffer API. Originally added in the OAuth patchset, it was extracted and committed separately in order to aid upcoming JSON work. Author: Daniel Gustafsson <daniel@yesql.se> Author: Jacob Champion <jacob.champion@enterprisedb.com> Reviewed-by: Michael Paquier <michael@paquier.xyz> Discussion: https://postgr.es/m/CAOYmi+mWdTd6ujtyF7MsvXvk7ToLRVG_tYAcaGbQLvf=N4KrQw@mail.gmail.com
diff --git a/src/backend/backup/basebackup.c b/src/backend/backup/basebackup.c
@@ -397,8 +397,7 @@ perform_base_backup(basebackup_options *opt, bbsink *sink,
 		endtli = backup_state->stoptli;
 
 		/* Deallocate backup-related variables. */
-		pfree(tablespace_map->data);
-		pfree(tablespace_map);
+		destroyStringInfo(tablespace_map);
 		pfree(backup_state);
 	}
 	PG_END_ENSURE_ERROR_CLEANUP(do_pg_abort_backup, BoolGetDatum(false));
diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
@@ -506,8 +506,7 @@ check_publications(WalReceiverConn *wrconn, List *publications)
 	appendStringInfoChar(cmd, ')');
 
 	res = walrcv_exec(wrconn, cmd->data, 1, tableRow);
-	pfree(cmd->data);
-	pfree(cmd);
+	destroyStringInfo(cmd);
 
 	if (res->status != WALRCV_OK_TUPLES)
 		ereport(ERROR,
diff --git a/src/backend/utils/adt/jsonb.c b/src/backend/utils/adt/jsonb.c
@@ -133,8 +133,7 @@ jsonb_send(PG_FUNCTION_ARGS)
 	pq_begintypsend(&buf);
 	pq_sendint8(&buf, version);
 	pq_sendtext(&buf, jtext->data, jtext->len);
-	pfree(jtext->data);
-	pfree(jtext);
+	destroyStringInfo(jtext);
 
 	PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
 }
diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
@@ -2163,8 +2163,7 @@ xml_errorHandler(void *data, PgXmlErrorPtr error)
 		appendBinaryStringInfo(&xmlerrcxt->err_buf, errorBuf->data,
 							   errorBuf->len);
 
-		pfree(errorBuf->data);
-		pfree(errorBuf);
+		destroyStringInfo(errorBuf);
 		return;
 	}
 
@@ -2195,8 +2194,7 @@ xml_errorHandler(void *data, PgXmlErrorPtr error)
 				(errmsg_internal("%s", errorBuf->data)));
 	}
 
-	pfree(errorBuf->data);
-	pfree(errorBuf);
+	destroyStringInfo(errorBuf);
 }
 
 
diff --git a/src/bin/pg_combinebackup/pg_combinebackup.c b/src/bin/pg_combinebackup/pg_combinebackup.c
@@ -526,10 +526,7 @@ check_backup_label_files(int n_backups, char **backup_dirs)
 
 	/* Free memory that we don't need any more. */
 	if (lastbuf != buf)
-	{
-		pfree(buf->data);
-		pfree(buf);
-	}
+		destroyStringInfo(buf);
 
 	/*
 	 * Return the data from the first backup_info that we read (which is the
diff --git a/src/common/stringinfo.c b/src/common/stringinfo.c
@@ -350,3 +350,19 @@ enlargeStringInfo(StringInfo str, int needed)
 
 	str->maxlen = newlen;
 }
+
+/*
+ * destroyStringInfo
+ *
+ * Frees a StringInfo and its buffer (opposite of makeStringInfo()).
+ * This must only be called on palloc'd StringInfos.
+ */
+void
+destroyStringInfo(StringInfo str)
+{
+	/* don't allow destroys of read-only StringInfos */
+	Assert(str->maxlen != 0);
+
+	pfree(str->data);
+	pfree(str);
+}
diff --git a/src/include/lib/stringinfo.h b/src/include/lib/stringinfo.h
@@ -87,7 +87,8 @@ typedef StringInfoData *StringInfo;
  *		to be len + 1 in size.
  *
  * To destroy a StringInfo, pfree() the data buffer, and then pfree() the
- * StringInfoData if it was palloc'd.  There's no special support for this.
+ * StringInfoData if it was palloc'd.  For StringInfos created with
+ * makeStringInfo(), destroyStringInfo() is provided for this purpose.
  * However, if the StringInfo was initialized using initReadOnlyStringInfo()
  * then the caller will need to consider if it is safe to pfree the data
  * buffer.
@@ -233,4 +234,10 @@ extern void appendBinaryStringInfoNT(StringInfo str,
  */
 extern void enlargeStringInfo(StringInfo str, int needed);
 
+/*------------------------
+ * destroyStringInfo
+ * Frees a StringInfo and its buffer (opposite of makeStringInfo()).
+ */
+extern void destroyStringInfo(StringInfo str);
+
 #endif							/* STRINGINFO_H */
diff --git a/src/test/regress/pg_regress.c b/src/test/regress/pg_regress.c
@@ -1174,8 +1174,7 @@ psql_end_command(StringInfo buf, const char *database)
 	}
 
 	/* Clean up */
-	pfree(buf->data);
-	pfree(buf);
+	destroyStringInfo(buf);
 }
 
 /*

Original file line number	Diff line number	Diff line change
`@@ -397,8 +397,7 @@ perform_base_backup(basebackup_options opt, bbsink sink,`
`397`	`397`	`endtli = backup_state->stoptli;`
`398`	`398`
`399`	`399`	`/* Deallocate backup-related variables. */`
`400`		`- pfree(tablespace_map->data);`
`401`		`- pfree(tablespace_map);`
	`400`	`+ destroyStringInfo(tablespace_map);`
`402`	`401`	`pfree(backup_state);`
`403`	`402`	`}`
`404`	`403`	`PG_END_ENSURE_ERROR_CLEANUP(do_pg_abort_backup, BoolGetDatum(false));`
Original file line number	Diff line number	Diff line change
`@@ -133,8 +133,7 @@ jsonb_send(PG_FUNCTION_ARGS)`
`133`	`133`	`pq_begintypsend(&buf);`
`134`	`134`	`pq_sendint8(&buf, version);`
`135`	`135`	`pq_sendtext(&buf, jtext->data, jtext->len);`
`136`		`- pfree(jtext->data);`
`137`		`- pfree(jtext);`
	`136`	`+ destroyStringInfo(jtext);`
`138`	`137`
`139`	`138`	`PG_RETURN_BYTEA_P(pq_endtypsend(&buf));`
`140`	`139`	`}`
Original file line number	Diff line number	Diff line change
`@@ -2163,8 +2163,7 @@ xml_errorHandler(void *data, PgXmlErrorPtr error)`
`2163`	`2163`	`appendBinaryStringInfo(&xmlerrcxt->err_buf, errorBuf->data,`
`2164`	`2164`	`errorBuf->len);`
`2165`	`2165`
`2166`		`- pfree(errorBuf->data);`
`2167`		`- pfree(errorBuf);`
	`2166`	`+ destroyStringInfo(errorBuf);`
`2168`	`2167`	`return;`
`2169`	`2168`	`}`
`2170`	`2169`
`@@ -2195,8 +2194,7 @@ xml_errorHandler(void *data, PgXmlErrorPtr error)`
`2195`	`2194`	`(errmsg_internal("%s", errorBuf->data)));`
`2196`	`2195`	`}`
`2197`	`2196`
`2198`		`- pfree(errorBuf->data);`
`2199`		`- pfree(errorBuf);`
	`2197`	`+ destroyStringInfo(errorBuf);`
`2200`	`2198`	`}`
`2201`	`2199`
`2202`	`2200`
Original file line number	Diff line number	Diff line change
`@@ -1174,8 +1174,7 @@ psql_end_command(StringInfo buf, const char *database)`
`1174`	`1174`	`}`
`1175`	`1175`
`1176`	`1176`	`/* Clean up */`
`1177`		`- pfree(buf->data);`
`1178`		`- pfree(buf);`
	`1177`	`+ destroyStringInfo(buf);`
`1179`	`1178`	`}`
`1180`	`1179`
`1181`	`1180`	`/*`