Have the routines to get interface lists take a pointer to a "gchar *"

as an argument, and, on an error, if they have an error message, have
them set that "gchar *" to point to a g_malloc()ed string containing the
error message, rather than taking a pointer to a buffer for that message
as an argument.  That's more like what's done in Wiretap, and doesn't
impose an upper limit on the lengths of those error messages.  If that
pointer is null, don't allocate the message string and return it.

Have that error message already have the "cant_get" processing applied
to it, so nobody other than those routines need to call the "cant_get"
routines to process the error messages.

Have get_airpcap_interface_list() explicitly set "*err" to the
appropriate error code.

Clean up indentation.

svn path=/trunk/; revision=20521

1 files changed, 25 insertions, 13 deletions

diff --git a/capture-pcap-util-unix.c b/capture-pcap-util-unix.c
index bfb124c538..ea8968b7d0 100644
--- a/capture-pcap-util-unix.c
+++ b/capture-pcap-util-unix.c
@@ -74,7 +74,7 @@ search_for_if_cb(gpointer data, gpointer user_data);
 #endif
 
 GList *
-get_interface_list(int *err, char *err_str)
+get_interface_list(int *err, char **err_str)
 {
 #ifdef HAVE_PCAP_FINDALLDEVS
 	return get_interface_list_findalldevs(err, err_str);
@@ -90,11 +90,15 @@ get_interface_list(int *err, char *err_str)
 	int len, lastlen;
 	char *buf;
 	if_info_t *if_info;
+	char errbuf[PCAP_ERRBUF_SIZE];
 
 	if (sock < 0) {
 		*err = CANT_GET_INTERFACE_LIST;
-		g_snprintf(err_str, PCAP_ERRBUF_SIZE, "Error opening socket: %s",
-		    strerror(errno));
+		if (err_str != NULL) {
+			*err_str = g_strdup_printf(
+			    "Can't get list of interfaces: error opening socket: %s",
+			    strerror(errno));
+		}
 		return NULL;
 	}
 
@@ -111,15 +115,19 @@ get_interface_list(int *err, char *err_str)
 		memset (buf, 0, len);
 		if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) {
 			if (errno != EINVAL || lastlen != 0) {
-				g_snprintf(err_str, PCAP_ERRBUF_SIZE,
-					"SIOCGIFCONF ioctl error getting list of interfaces: %s",
-					strerror(errno));
+				if (err_str != NULL) {
+					*err_str = g_strdup_printf(
+					    "Can't get list of interfaces: SIOCGIFCONF ioctl error: %s",
+					    strerror(errno));
+				}
 				goto fail;
 			}
 		} else {
 			if ((unsigned) ifc.ifc_len < sizeof(struct ifreq)) {
-				g_snprintf(err_str, PCAP_ERRBUF_SIZE,
-					"SIOCGIFCONF ioctl gave too small return buffer");
+				if (err_str != NULL) {
+					*err_str = g_strdup(
+					    "Can't get list of interfaces: SIOCGIFCONF ioctl gave too small return buffer");
+				}
 				goto fail;
 			}
 			if (ifc.ifc_len == lastlen)
@@ -165,9 +173,11 @@ get_interface_list(int *err, char *err_str)
 		if (ioctl(sock, SIOCGIFFLAGS, (char *)&ifrflags) < 0) {
 			if (errno == ENXIO)
 				goto next;
-			g_snprintf(err_str, PCAP_ERRBUF_SIZE,
-				"SIOCGIFFLAGS error getting flags for interface %s: %s",
-			    ifr->ifr_name, strerror(errno));
+			if (err_str != NULL) {
+				*err_str = g_strdup_printf(
+				    "Can't get list of interfaces: SIOCGIFFLAGS error getting flags for interface %s: %s",
+				    ifr->ifr_name, strerror(errno));
+			}
 			goto fail;
 		}
 
@@ -184,7 +194,7 @@ get_interface_list(int *err, char *err_str)
 		 * supplied is too large, rather than just truncating it.
 		 */
 		pch = pcap_open_live(ifr->ifr_name, MIN_PACKET_SIZE, 0, 0,
-		    err_str);
+		    errbuf);
 		if (pch == NULL)
 			goto next;
 		pcap_close(pch);
@@ -230,7 +240,7 @@ get_interface_list(int *err, char *err_str)
 	 * Try opening it and, if that succeeds, add it to the end of
 	 * the list of interfaces.
 	 */
-	pch = pcap_open_live("any", MIN_PACKET_SIZE, 0, 0, err_str);
+	pch = pcap_open_live("any", MIN_PACKET_SIZE, 0, 0, errbuf);
 	if (pch != NULL) {
 		/*
 		 * It worked; we can use the "any" device.
@@ -250,6 +260,8 @@ get_interface_list(int *err, char *err_str)
 		 * No interfaces found.
 		 */
 		*err = NO_INTERFACES_FOUND;
+		if (err_str != NULL)
+			*err_str = NULL;
 	}
 	return il;