[settings] Explicitly separate the concept of a completed fetched setting

The fetch_setting() family of functions may currently modify the
definition of the specified setting (e.g. to add missing type
information).  Clean up this interface by requiring callers to provide
an explicit buffer to contain the completed definition of the fetched
setting, if required.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

4 files changed, 33 insertions, 39 deletions

diff --git a/src/net/udp/dhcp.c b/src/net/udp/dhcp.c
index 66bcc83a..3163f39c 100644
--- a/src/net/udp/dhcp.c
+++ b/src/net/udp/dhcp.c
@@ -92,7 +92,7 @@ static uint8_t dhcp_request_options_data[] = {
 };
 
 /** DHCP server address setting */
-struct setting dhcp_server_setting __setting ( SETTING_MISC ) = {
+const struct setting dhcp_server_setting __setting ( SETTING_MISC ) = {
 	.name = "dhcp-server",
 	.description = "DHCP server",
 	.tag = DHCP_SERVER_IDENTIFIER,
@@ -975,6 +975,7 @@ int dhcp_create_request ( struct dhcp_packet *dhcppkt,
 	uint8_t *dhcp_features;
 	size_t dhcp_features_len;
 	size_t ll_addr_len;
+	void *user_class;
 	ssize_t len;
 	int rc;
 
@@ -985,7 +986,7 @@ int dhcp_create_request ( struct dhcp_packet *dhcppkt,
 					 data, max_len ) ) != 0 ) {
 		DBG ( "DHCP could not create DHCP packet: %s\n",
 		      strerror ( rc ) );
-		return rc;
+		goto err_create_packet;
 	}
 
 	/* Set client IP address */
@@ -998,17 +999,17 @@ int dhcp_create_request ( struct dhcp_packet *dhcppkt,
 				    dhcp_features_len ) ) != 0 ) {
 		DBG ( "DHCP could not set features list option: %s\n",
 		      strerror ( rc ) );
-		return rc;
+		goto err_store_features;
 	}
 
 	/* Add options to identify the network device */
-	fetch_setting ( &netdev->settings.settings, &busid_setting, &dhcp_desc,
-		sizeof ( dhcp_desc ) );
+	fetch_raw_setting ( netdev_settings ( netdev ), &busid_setting,
+			    &dhcp_desc, sizeof ( dhcp_desc ) );
 	if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_EB_BUS_ID, &dhcp_desc,
 				    sizeof ( dhcp_desc ) ) ) != 0 ) {
 		DBG ( "DHCP could not set bus ID option: %s\n",
 		      strerror ( rc ) );
-		return rc;
+		goto err_store_busid;
 	}
 
 	/* Add DHCP client identifier.  Required for Infiniband, and
@@ -1022,7 +1023,7 @@ int dhcp_create_request ( struct dhcp_packet *dhcppkt,
 				    ( ll_addr_len + 1 ) ) ) != 0 ) {
 		DBG ( "DHCP could not set client ID: %s\n",
 		      strerror ( rc ) );
-		return rc;
+		goto err_store_client_id;
 	}
 
 	/* Add client UUID, if we have one.  Required for PXE.  The
@@ -1039,25 +1040,29 @@ int dhcp_create_request ( struct dhcp_packet *dhcppkt,
 					    sizeof ( client_uuid ) ) ) != 0 ) {
 			DBG ( "DHCP could not set client UUID: %s\n",
 			      strerror ( rc ) );
-			return rc;
+			goto err_store_client_uuid;
 		}
 	}
 
 	/* Add user class, if we have one. */
-	if ( ( len = fetch_setting_len ( NULL, &user_class_setting ) ) >= 0 ) {
-		char user_class[len];
-		fetch_setting ( NULL, &user_class_setting, user_class,
-				sizeof ( user_class ) );
+	if ( ( len = fetch_raw_setting_copy ( NULL, &user_class_setting,
+					      &user_class ) ) >= 0 ) {
 		if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_USER_CLASS_ID,
-					    &user_class,
-					    sizeof ( user_class ) ) ) != 0 ) {
+					    user_class, len ) ) != 0 ) {
 			DBG ( "DHCP could not set user class: %s\n",
 			      strerror ( rc ) );
-			return rc;
+			goto err_store_user_class;
 		}
 	}
 
-	return 0;
+ err_store_user_class:
+	free ( user_class );
+ err_store_client_uuid:
+ err_store_client_id:
+ err_store_busid:
+ err_store_features:
+ err_create_packet:
+	return rc;
 }
 
 /****************************************************************************
@@ -1384,7 +1389,8 @@ int start_pxebs ( struct interface *job, struct net_device *netdev,
 	int rc;
 
 	/* Get upper bound for PXE boot server IP address list */
-	pxebs_list_len = fetch_setting_len ( NULL, &pxe_boot_servers_setting );
+	pxebs_list_len = fetch_raw_setting ( NULL, &pxe_boot_servers_setting,
+					     NULL, 0 );
 	if ( pxebs_list_len < 0 )
 		pxebs_list_len = 0;
 
@@ -1422,8 +1428,8 @@ int start_pxebs ( struct interface *job, struct net_device *netdev,
 	if ( pxebs_list_len ) {
 		uint8_t buf[pxebs_list_len];
 
-		fetch_setting ( NULL, &pxe_boot_servers_setting,
-				buf, sizeof ( buf ) );
+		fetch_raw_setting ( NULL, &pxe_boot_servers_setting,
+				    buf, sizeof ( buf ) );
 		pxebs_list ( dhcp, buf, sizeof ( buf ), ip );
 	}
 	if ( ! dhcp->pxe_attempt->s_addr ) {
diff --git a/src/net/udp/dhcpv6.c b/src/net/udp/dhcpv6.c
index 42d11194..7bed83d9 100644
--- a/src/net/udp/dhcpv6.c
+++ b/src/net/udp/dhcpv6.c
@@ -256,7 +256,7 @@ static int dhcpv6_iaaddr ( struct dhcpv6_option_list *options, uint32_t iaid,
  */
 
 /** DHCPv6 settings scope */
-static struct settings_scope dhcpv6_settings_scope;
+static const struct settings_scope dhcpv6_settings_scope;
 
 /** A DHCPv6 settings block */
 struct dhcpv6_settings {
@@ -276,7 +276,7 @@ struct dhcpv6_settings {
  * @ret applies		Setting applies within this settings block
  */
 static int dhcpv6_applies ( struct settings *settings __unused,
-			    struct setting *setting ) {
+			    const struct setting *setting ) {
 
 	return ( setting->scope == &dhcpv6_settings_scope );
 }
@@ -543,7 +543,7 @@ static size_t dhcpv6_user_class ( void *data, size_t len ) {
 	int actual_len;
 
 	/* Fetch user-class setting, if defined */
-	actual_len = fetch_setting ( NULL, &user_class_setting, data, len );
+	actual_len = fetch_raw_setting ( NULL, &user_class_setting, data, len );
 	if ( actual_len >= 0 )
 		return actual_len;
 
diff --git a/src/net/udp/dns.c b/src/net/udp/dns.c
index 45f0f07c..447da8af 100644
--- a/src/net/udp/dns.c
+++ b/src/net/udp/dns.c
@@ -594,7 +594,7 @@ struct resolver dns_resolver __resolver ( RESOLV_NORMAL ) = {
  */
 
 /** DNS server setting */
-struct setting dns_setting __setting ( SETTING_IPv4_EXTRA ) = {
+const struct setting dns_setting __setting ( SETTING_IPv4_EXTRA ) = {
 	.name = "dns",
 	.description = "DNS server",
 	.tag = DHCP_DNS_SERVERS,
@@ -622,11 +622,7 @@ static int apply_dns_settings ( void ) {
 
 	/* Get local domain DHCP option */
 	free ( localdomain );
-	if ( ( len = fetch_string_setting_copy ( NULL, &domain_setting,
-						 &localdomain ) ) < 0 ) {
-		DBG ( "DNS could not fetch local domain: %s\n",
-		      strerror ( len ) );
-	}
+	fetch_string_setting_copy ( NULL, &domain_setting, &localdomain );
 	if ( localdomain )
 		DBG ( "DNS local domain %s\n", localdomain );
 
diff --git a/src/net/udp/syslog.c b/src/net/udp/syslog.c
index 4210083d..6554ab9b 100644
--- a/src/net/udp/syslog.c
+++ b/src/net/udp/syslog.c
@@ -188,7 +188,7 @@ struct console_driver syslog_console __console_driver = {
  */
 
 /** Syslog server setting */
-struct setting syslog_setting __setting ( SETTING_MISC ) = {
+const struct setting syslog_setting __setting ( SETTING_MISC ) = {
 	.name = "syslog",
 	.description = "Syslog server",
 	.tag = DHCP_LOG_SERVERS,
@@ -209,17 +209,9 @@ static int apply_syslog_settings ( void ) {
 
 	/* Fetch hostname and domain name */
 	free ( syslog_hostname );
-	if ( ( len = fetch_string_setting_copy ( NULL, &hostname_setting,
-						 &syslog_hostname ) ) < 0 ) {
-		rc = len;
-		DBG ( "SYSLOG could not fetch hostname: %s\n", strerror ( rc ));
-	}
+	fetch_string_setting_copy ( NULL, &hostname_setting, &syslog_hostname );
 	free ( syslog_domain );
-	if ( ( len = fetch_string_setting_copy ( NULL, &domain_setting,
-						 &syslog_domain ) ) < 0 ) {
-		rc = len;
-		DBG ( "SYSLOG could not fetch domain: %s\n", strerror ( rc ) );
-	}
+	fetch_string_setting_copy ( NULL, &domain_setting, &syslog_domain );
 
 	/* Fetch log server */
 	syslog_console.disabled = CONSOLE_DISABLED;