Remove redundant null pointer checks before free()

Per applicable standards, free() with a null pointer is a no-op.
Systems that don't observe that are ancient and no longer relevant.
Some PostgreSQL code already required this behavior, so this change
does not introduce any new requirements, just makes the code more
consistent.

Discussion: https://www.postgresql.org/message-id/flat/dac5d2d0-98f5-94d9-8e69-46da2413593d%40enterprisedb.com

8 files changed, 99 insertions, 204 deletions

diff --git a/src/interfaces/ecpg/pgtypeslib/numeric.c b/src/interfaces/ecpg/pgtypeslib/numeric.c
index 34efc9045f3..a97b3300cb8 100644
--- a/src/interfaces/ecpg/pgtypeslib/numeric.c
+++ b/src/interfaces/ecpg/pgtypeslib/numeric.c
@@ -16,11 +16,7 @@
 #define init_var(v)				memset(v,0,sizeof(numeric))
 
 #define digitbuf_alloc(size) ((NumericDigit *) pgtypes_alloc(size))
-#define digitbuf_free(buf)		\
-	   do { \
-				 if ((buf) != NULL) \
-						  free(buf); \
-		  } while (0)
+#define digitbuf_free(buf) free(buf)
 
 
 /* ----------
diff --git a/src/interfaces/ecpg/preproc/descriptor.c b/src/interfaces/ecpg/preproc/descriptor.c
index 35d94711d56..f4b1878289c 100644
--- a/src/interfaces/ecpg/preproc/descriptor.c
+++ b/src/interfaces/ecpg/preproc/descriptor.c
@@ -113,8 +113,7 @@ drop_descriptor(char *name, char *connection)
 					&& strcmp(connection, i->connection) == 0))
 			{
 				*lastptr = i->next;
-				if (i->connection)
-					free(i->connection);
+				free(i->connection);
 				free(i->name);
 				free(i);
 				return;
diff --git a/src/interfaces/libpq/fe-auth-scram.c b/src/interfaces/libpq/fe-auth-scram.c
index e6162007041..5012806fa5e 100644
--- a/src/interfaces/libpq/fe-auth-scram.c
+++ b/src/interfaces/libpq/fe-auth-scram.c
@@ -174,30 +174,21 @@ scram_free(void *opaq)
 {
 	fe_scram_state *state = (fe_scram_state *) opaq;
 
-	if (state->password)
-		free(state->password);
-	if (state->sasl_mechanism)
-		free(state->sasl_mechanism);
+	free(state->password);
+	free(state->sasl_mechanism);
 
 	/* client messages */
-	if (state->client_nonce)
-		free(state->client_nonce);
-	if (state->client_first_message_bare)
-		free(state->client_first_message_bare);
-	if (state->client_final_message_without_proof)
-		free(state->client_final_message_without_proof);
+	free(state->client_nonce);
+	free(state->client_first_message_bare);
+	free(state->client_final_message_without_proof);
 
 	/* first message from server */
-	if (state->server_first_message)
-		free(state->server_first_message);
-	if (state->salt)
-		free(state->salt);
-	if (state->nonce)
-		free(state->nonce);
+	free(state->server_first_message);
+	free(state->salt);
+	free(state->nonce);
 
 	/* final message from server */
-	if (state->server_final_message)
-		free(state->server_final_message);
+	free(state->server_final_message);
 
 	free(state);
 }
@@ -941,8 +932,7 @@ pg_fe_scram_build_secret(const char *password, const char **errstr)
 	if (!pg_strong_random(saltbuf, SCRAM_DEFAULT_SALT_LEN))
 	{
 		*errstr = _("failed to generate random salt");
-		if (prep_password)
-			free(prep_password);
+		free(prep_password);
 		return NULL;
 	}
 
@@ -950,8 +940,7 @@ pg_fe_scram_build_secret(const char *password, const char **errstr)
 								SCRAM_DEFAULT_ITERATIONS, password,
 								errstr);
 
-	if (prep_password)
-		free(prep_password);
+	free(prep_password);
 
 	return result;
 }
diff --git a/src/interfaces/libpq/fe-auth.c b/src/interfaces/libpq/fe-auth.c
index 0a072a36dc2..49a1c626f64 100644
--- a/src/interfaces/libpq/fe-auth.c
+++ b/src/interfaces/libpq/fe-auth.c
@@ -107,8 +107,7 @@ pg_GSS_continue(PGconn *conn, int payloadlen)
 									NULL,
 									NULL);
 
-	if (ginbuf.value)
-		free(ginbuf.value);
+	free(ginbuf.value);
 
 	if (goutbuf.length != 0)
 	{
@@ -270,8 +269,7 @@ pg_SSPI_continue(PGconn *conn, int payloadlen)
 								  NULL);
 
 	/* we don't need the input anymore */
-	if (inputbuf)
-		free(inputbuf);
+	free(inputbuf);
 
 	if (r != SEC_E_OK && r != SEC_I_CONTINUE_NEEDED)
 	{
@@ -604,21 +602,18 @@ pg_SASL_init(PGconn *conn, int payloadlen)
 		goto error;
 
 	termPQExpBuffer(&mechanism_buf);
-	if (initialresponse)
-		free(initialresponse);
+	free(initialresponse);
 
 	return STATUS_OK;
 
 error:
 	termPQExpBuffer(&mechanism_buf);
-	if (initialresponse)
-		free(initialresponse);
+	free(initialresponse);
 	return STATUS_ERROR;
 
 oom_error:
 	termPQExpBuffer(&mechanism_buf);
-	if (initialresponse)
-		free(initialresponse);
+	free(initialresponse);
 	appendPQExpBufferStr(&conn->errorMessage,
 						 libpq_gettext("out of memory\n"));
 	return STATUS_ERROR;
@@ -831,8 +826,7 @@ pg_password_sendauth(PGconn *conn, const char *password, AuthRequest areq)
 			return STATUS_ERROR;
 	}
 	ret = pqPacketSend(conn, 'p', pwd_to_send, strlen(pwd_to_send) + 1);
-	if (crypt_pwd)
-		free(crypt_pwd);
+	free(crypt_pwd);
 	return ret;
 }
 
diff --git a/src/interfaces/libpq/fe-connect.c b/src/interfaces/libpq/fe-connect.c
index 6e936bbff30..057c9da0ede 100644
--- a/src/interfaces/libpq/fe-connect.c
+++ b/src/interfaces/libpq/fe-connect.c
@@ -540,8 +540,7 @@ pqFreeCommandQueue(PGcmdQueueEntry *queue)
 		PGcmdQueueEntry *cur = queue;
 
 		queue = cur->next;
-		if (cur->query)
-			free(cur->query);
+		free(cur->query);
 		free(cur);
 	}
 }
@@ -593,8 +592,7 @@ pqDropServerData(PGconn *conn)
 	conn->sversion = 0;
 
 	/* Drop large-object lookup data */
-	if (conn->lobjfuncs)
-		free(conn->lobjfuncs);
+	free(conn->lobjfuncs);
 	conn->lobjfuncs = NULL;
 
 	/* Reset assorted other per-connection state */
@@ -602,8 +600,7 @@ pqDropServerData(PGconn *conn)
 	conn->auth_req_received = false;
 	conn->password_needed = false;
 	conn->write_failed = false;
-	if (conn->write_err_msg)
-		free(conn->write_err_msg);
+	free(conn->write_err_msg);
 	conn->write_err_msg = NULL;
 	conn->be_pid = 0;
 	conn->be_key = 0;
@@ -898,8 +895,7 @@ fillPGconn(PGconn *conn, PQconninfoOption *connOptions)
 			{
 				char	  **connmember = (char **) ((char *) conn + option->connofs);
 
-				if (*connmember)
-					free(*connmember);
+				free(*connmember);
 				*connmember = strdup(tmp);
 				if (*connmember == NULL)
 				{
@@ -1113,8 +1109,7 @@ connectOptions2(PGconn *conn)
 		}
 		else
 		{
-			if (ch->host)
-				free(ch->host);
+			free(ch->host);
 
 			/*
 			 * This bit selects the default host location.  If you change
@@ -1186,8 +1181,7 @@ connectOptions2(PGconn *conn)
 	 */
 	if (conn->pguser == NULL || conn->pguser[0] == '\0')
 	{
-		if (conn->pguser)
-			free(conn->pguser);
+		free(conn->pguser);
 		conn->pguser = pg_fe_getauthname(&conn->errorMessage);
 		if (!conn->pguser)
 		{
@@ -1201,8 +1195,7 @@ connectOptions2(PGconn *conn)
 	 */
 	if (conn->dbName == NULL || conn->dbName[0] == '\0')
 	{
-		if (conn->dbName)
-			free(conn->dbName);
+		free(conn->dbName);
 		conn->dbName = strdup(conn->pguser);
 		if (!conn->dbName)
 			goto oom_error;
@@ -1221,8 +1214,7 @@ connectOptions2(PGconn *conn)
 
 			if (pqGetHomeDirectory(homedir, sizeof(homedir)))
 			{
-				if (conn->pgpassfile)
-					free(conn->pgpassfile);
+				free(conn->pgpassfile);
 				conn->pgpassfile = malloc(MAXPGPATH);
 				if (!conn->pgpassfile)
 					goto oom_error;
@@ -1548,8 +1540,7 @@ PQsetdbLogin(const char *pghost, const char *pgport, const char *pgoptions,
 		/* Insert dbName parameter value into struct */
 		if (dbName && dbName[0] != '\0')
 		{
-			if (conn->dbName)
-				free(conn->dbName);
+			free(conn->dbName);
 			conn->dbName = strdup(dbName);
 			if (!conn->dbName)
 				goto oom_error;
@@ -1562,8 +1553,7 @@ PQsetdbLogin(const char *pghost, const char *pgport, const char *pgoptions,
 	 */
 	if (pghost && pghost[0] != '\0')
 	{
-		if (conn->pghost)
-			free(conn->pghost);
+		free(conn->pghost);
 		conn->pghost = strdup(pghost);
 		if (!conn->pghost)
 			goto oom_error;
@@ -1571,8 +1561,7 @@ PQsetdbLogin(const char *pghost, const char *pgport, const char *pgoptions,
 
 	if (pgport && pgport[0] != '\0')
 	{
-		if (conn->pgport)
-			free(conn->pgport);
+		free(conn->pgport);
 		conn->pgport = strdup(pgport);
 		if (!conn->pgport)
 			goto oom_error;
@@ -1580,8 +1569,7 @@ PQsetdbLogin(const char *pghost, const char *pgport, const char *pgoptions,
 
 	if (pgoptions && pgoptions[0] != '\0')
 	{
-		if (conn->pgoptions)
-			free(conn->pgoptions);
+		free(conn->pgoptions);
 		conn->pgoptions = strdup(pgoptions);
 		if (!conn->pgoptions)
 			goto oom_error;
@@ -1589,8 +1577,7 @@ PQsetdbLogin(const char *pghost, const char *pgport, const char *pgoptions,
 
 	if (login && login[0] != '\0')
 	{
-		if (conn->pguser)
-			free(conn->pguser);
+		free(conn->pguser);
 		conn->pguser = strdup(login);
 		if (!conn->pguser)
 			goto oom_error;
@@ -1598,8 +1585,7 @@ PQsetdbLogin(const char *pghost, const char *pgport, const char *pgoptions,
 
 	if (pwd && pwd[0] != '\0')
 	{
-		if (conn->pgpass)
-			free(conn->pgpass);
+		free(conn->pgpass);
 		conn->pgpass = strdup(pwd);
 		if (!conn->pgpass)
 			goto oom_error;
@@ -4044,10 +4030,8 @@ makeEmptyPGconn(void)
 static void
 freePGconn(PGconn *conn)
 {
-	int			i;
-
 	/* let any event procs clean up their state data */
-	for (i = 0; i < conn->nEvents; i++)
+	for (int i = 0; i < conn->nEvents; i++)
 	{
 		PGEventConnDestroy evt;
 
@@ -4058,114 +4042,69 @@ freePGconn(PGconn *conn)
 	}
 
 	/* clean up pg_conn_host structures */
-	if (conn->connhost != NULL)
+	for (int i = 0; i < conn->nconnhost; ++i)
 	{
-		for (i = 0; i < conn->nconnhost; ++i)
+		free(conn->connhost[i].host);
+		free(conn->connhost[i].hostaddr);
+		free(conn->connhost[i].port);
+		if (conn->connhost[i].password != NULL)
 		{
-			if (conn->connhost[i].host != NULL)
-				free(conn->connhost[i].host);
-			if (conn->connhost[i].hostaddr != NULL)
-				free(conn->connhost[i].hostaddr);
-			if (conn->connhost[i].port != NULL)
-				free(conn->connhost[i].port);
-			if (conn->connhost[i].password != NULL)
-			{
-				explicit_bzero(conn->connhost[i].password, strlen(conn->connhost[i].password));
-				free(conn->connhost[i].password);
-			}
+			explicit_bzero(conn->connhost[i].password, strlen(conn->connhost[i].password));
+			free(conn->connhost[i].password);
 		}
-		free(conn->connhost);
 	}
-
-	if (conn->client_encoding_initial)
-		free(conn->client_encoding_initial);
-	if (conn->events)
-		free(conn->events);
-	if (conn->pghost)
-		free(conn->pghost);
-	if (conn->pghostaddr)
-		free(conn->pghostaddr);
-	if (conn->pgport)
-		free(conn->pgport);
-	if (conn->connect_timeout)
-		free(conn->connect_timeout);
-	if (conn->pgtcp_user_timeout)
-		free(conn->pgtcp_user_timeout);
-	if (conn->pgoptions)
-		free(conn->pgoptions);
-	if (conn->appname)
-		free(conn->appname);
-	if (conn->fbappname)
-		free(conn->fbappname);
-	if (conn->dbName)
-		free(conn->dbName);
-	if (conn->replication)
-		free(conn->replication);
-	if (conn->pguser)
-		free(conn->pguser);
+	free(conn->connhost);
+
+	free(conn->client_encoding_initial);
+	free(conn->events);
+	free(conn->pghost);
+	free(conn->pghostaddr);
+	free(conn->pgport);
+	free(conn->connect_timeout);
+	free(conn->pgtcp_user_timeout);
+	free(conn->pgoptions);
+	free(conn->appname);
+	free(conn->fbappname);
+	free(conn->dbName);
+	free(conn->replication);
+	free(conn->pguser);
 	if (conn->pgpass)
 	{
 		explicit_bzero(conn->pgpass, strlen(conn->pgpass));
 		free(conn->pgpass);
 	}
-	if (conn->pgpassfile)
-		free(conn->pgpassfile);
-	if (conn->channel_binding)
-		free(conn->channel_binding);
-	if (conn->keepalives)
-		free(conn->keepalives);
-	if (conn->keepalives_idle)
-		free(conn->keepalives_idle);
-	if (conn->keepalives_interval)
-		free(conn->keepalives_interval);
-	if (conn->keepalives_count)
-		free(conn->keepalives_count);
-	if (conn->sslmode)
-		free(conn->sslmode);
-	if (conn->sslcert)
-		free(conn->sslcert);
-	if (conn->sslkey)
-		free(conn->sslkey);
+	free(conn->pgpassfile);
+	free(conn->channel_binding);
+	free(conn->keepalives);
+	free(conn->keepalives_idle);
+	free(conn->keepalives_interval);
+	free(conn->keepalives_count);
+	free(conn->sslmode);
+	free(conn->sslcert);
+	free(conn->sslkey);
 	if (conn->sslpassword)
 	{
 		explicit_bzero(conn->sslpassword, strlen(conn->sslpassword));
 		free(conn->sslpassword);
 	}
-	if (conn->sslrootcert)
-		free(conn->sslrootcert);
-	if (conn->sslcrl)
-		free(conn->sslcrl);
-	if (conn->sslcrldir)
-		free(conn->sslcrldir);
-	if (conn->sslcompression)
-		free(conn->sslcompression);
-	if (conn->sslsni)
-		free(conn->sslsni);
-	if (conn->requirepeer)
-		free(conn->requirepeer);
-	if (conn->ssl_min_protocol_version)
-		free(conn->ssl_min_protocol_version);
-	if (conn->ssl_max_protocol_version)
-		free(conn->ssl_max_protocol_version);
-	if (conn->gssencmode)
-		free(conn->gssencmode);
-	if (conn->krbsrvname)
-		free(conn->krbsrvname);
-	if (conn->gsslib)
-		free(conn->gsslib);
-	if (conn->connip)
-		free(conn->connip);
+	free(conn->sslrootcert);
+	free(conn->sslcrl);
+	free(conn->sslcrldir);
+	free(conn->sslcompression);
+	free(conn->sslsni);
+	free(conn->requirepeer);
+	free(conn->ssl_min_protocol_version);
+	free(conn->ssl_max_protocol_version);
+	free(conn->gssencmode);
+	free(conn->krbsrvname);
+	free(conn->gsslib);
+	free(conn->connip);
 	/* Note that conn->Pfdebug is not ours to close or free */
-	if (conn->write_err_msg)
-		free(conn->write_err_msg);
-	if (conn->inBuffer)
-		free(conn->inBuffer);
-	if (conn->outBuffer)
-		free(conn->outBuffer);
-	if (conn->rowBuf)
-		free(conn->rowBuf);
-	if (conn->target_session_attrs)
-		free(conn->target_session_attrs);
+	free(conn->write_err_msg);
+	free(conn->inBuffer);
+	free(conn->outBuffer);
+	free(conn->rowBuf);
+	free(conn->target_session_attrs);
 	termPQExpBuffer(&conn->errorMessage);
 	termPQExpBuffer(&conn->workBuffer);
 
@@ -4433,8 +4372,7 @@ fail:
 void
 PQfreeCancel(PGcancel *cancel)
 {
-	if (cancel)
-		free(cancel);
+	free(cancel);
 }
 
 
@@ -5883,8 +5821,7 @@ conninfo_array_parse(const char *const *keywords, const char *const *values,
 						{
 							if (strcmp(options[k].keyword, str_option->keyword) == 0)
 							{
-								if (options[k].val)
-									free(options[k].val);
+								free(options[k].val);
 								options[k].val = strdup(str_option->val);
 								if (!options[k].val)
 								{
@@ -5912,8 +5849,7 @@ conninfo_array_parse(const char *const *keywords, const char *const *values,
 				/*
 				 * Store the value, overriding previous settings
 				 */
-				if (option->val)
-					free(option->val);
+				free(option->val);
 				option->val = strdup(pvalue);
 				if (!option->val)
 				{
@@ -6344,8 +6280,7 @@ conninfo_uri_parse_options(PQconninfoOption *options, const char *uri,
 cleanup:
 	termPQExpBuffer(&hostbuf);
 	termPQExpBuffer(&portbuf);
-	if (buf)
-		free(buf);
+	free(buf);
 	return retval;
 }
 
@@ -6655,8 +6590,7 @@ conninfo_storeval(PQconninfoOption *connOptions,
 		}
 	}
 
-	if (option->val)
-		free(option->val);
+	free(option->val);
 	option->val = value_copy;
 
 	return option;
@@ -6735,16 +6669,11 @@ PQconninfo(PGconn *conn)
 void
 PQconninfoFree(PQconninfoOption *connOptions)
 {
-	PQconninfoOption *option;
-
 	if (connOptions == NULL)
 		return;
 
-	for (option = connOptions; option->keyword != NULL; option++)
-	{
-		if (option->val != NULL)
-			free(option->val);
-	}
+	for (PQconninfoOption *option = connOptions; option->keyword != NULL; option++)
+		free(option->val);
 	free(connOptions);
 }
 
diff --git a/src/interfaces/libpq/fe-exec.c b/src/interfaces/libpq/fe-exec.c
index 919cf5741d4..1750d647a8d 100644
--- a/src/interfaces/libpq/fe-exec.c
+++ b/src/interfaces/libpq/fe-exec.c
@@ -742,8 +742,7 @@ PQclear(PGresult *res)
 		free(res->events[i].name);
 	}
 
-	if (res->events)
-		free(res->events);
+	free(res->events);
 
 	/* Free all the subsidiary blocks */
 	while ((block = res->curBlock) != NULL)
@@ -753,8 +752,7 @@ PQclear(PGresult *res)
 	}
 
 	/* Free the top-level tuple pointer array */
-	if (res->tuples)
-		free(res->tuples);
+	free(res->tuples);
 
 	/* zero out the pointer fields to catch programming errors */
 	res->attDescs = NULL;
diff --git a/src/interfaces/libpq/fe-print.c b/src/interfaces/libpq/fe-print.c
index 82fc592f068..783cd9b756f 100644
--- a/src/interfaces/libpq/fe-print.c
+++ b/src/interfaces/libpq/fe-print.c
@@ -303,26 +303,19 @@ PQprint(FILE *fout, const PGresult *res, const PQprintOpt *po)
 			fputs("</table>\n", fout);
 
 exit:
-		if (fieldMax)
-			free(fieldMax);
-		if (fieldNotNum)
-			free(fieldNotNum);
-		if (border)
-			free(border);
+		free(fieldMax);
+		free(fieldNotNum);
+		free(border);
 		if (fields)
 		{
 			/* if calloc succeeded, this shouldn't overflow size_t */
 			size_t		numfields = ((size_t) nTups + 1) * (size_t) nFields;
 
 			while (numfields-- > 0)
-			{
-				if (fields[numfields])
-					free(fields[numfields]);
-			}
+				free(fields[numfields]);
 			free(fields);
 		}
-		if (fieldNames)
-			free((void *) fieldNames);
+		free(fieldNames);
 		if (usePipe)
 		{
 #ifdef WIN32
@@ -679,8 +672,7 @@ PQdisplayTuples(const PGresult *res,
 
 	fflush(fp);
 
-	if (fLength)
-		free(fLength);
+	free(fLength);
 }
 
 
@@ -763,8 +755,7 @@ PQprintTuples(const PGresult *res,
 		}
 	}
 
-	if (tborder)
-		free(tborder);
+	free(tborder);
 }
 
 
diff --git a/src/interfaces/libpq/fe-secure-common.c b/src/interfaces/libpq/fe-secure-common.c
index 8046fcd884a..cc8a2b85938 100644
--- a/src/interfaces/libpq/fe-secure-common.c
+++ b/src/interfaces/libpq/fe-secure-common.c
@@ -309,8 +309,7 @@ pq_verify_peer_name_matches_certificate(PGconn *conn)
 	}
 
 	/* clean up */
-	if (first_name)
-		free(first_name);
+	free(first_name);
 
 	return (rc == 1);
 }