X-Git-Url: https://git.tcpdump.org/libpcap/blobdiff_plain/a94d5a3f5426b1e91c9ba1851d35d4fee55e80df..09b51d326c38ea8e10ce4da09c09d50e08c5aeb8:/pcap-dag.c

diff --git a/pcap-dag.c b/pcap-dag.c
index b3949d53..f261ead0 100644
--- a/pcap-dag.c
+++ b/pcap-dag.c
@@ -213,7 +213,7 @@ static int dag_get_datalink(pcap_t *p);
 static int dag_setnonblock(pcap_t *p, int nonblock);
 
 static void
-delete_pcap_dag(pcap_t *p)
+delete_pcap_dag(const pcap_t *p)
 {
 	pcap_dag_node_t *curr = NULL, *prev = NULL;
 
@@ -299,7 +299,7 @@ new_pcap_dag(pcap_t *p)
 }
 
 static unsigned int
-dag_erf_ext_header_count(uint8_t * erf, size_t len)
+dag_erf_ext_header_count(const uint8_t *erf, size_t len)
 {
 	uint32_t hdr_num = 0;
 	uint8_t  hdr_type;
@@ -736,7 +736,7 @@ dag_inject(pcap_t *p, const void *buf _U_, int size _U_)
  *  API polling parameters.
  *
  *  snaplen is now also ignored, until we get per-stream slen support. Set
- *  slen with approprite DAG tool BEFORE pcap_activate().
+ *  slen with appropriate DAG tool BEFORE pcap_activate().
  *
  *  See also pcap(3).
  */
@@ -793,14 +793,23 @@ static int dag_activate(pcap_t* p)
 		/*
 		 * XXX - does this reliably set errno?
 		 */
-		if (errno == ENOENT)
+		if (errno == ENOENT) {
+			/*
+			 * There's nothing more to say, so clear
+			 * the error message.
+			 */
 			ret = PCAP_ERROR_NO_SUCH_DEVICE;
-		else if (errno == EPERM || errno == EACCES)
+			p->errbuf[0] = '\0';
+		} else if (errno == EPERM || errno == EACCES) {
 			ret = PCAP_ERROR_PERM_DENIED;
-		else
+			snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
+			    "Attempt to open %s failed with %s - additional privileges may be required",
+			    device, (errno == EPERM) ? "EPERM" : "EACCES");
+		} else {
 			ret = PCAP_ERROR;
-		pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
-		    errno, "dag_config_init %s", device);
+			pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
+			    errno, "dag_config_init %s", device);
+		}
 		goto fail;
 	}
 
@@ -950,7 +959,7 @@ static int dag_activate(pcap_t* p)
 		 * Did the user request that they not be stripped?
 		 */
 		if ((s = getenv("ERF_DONT_STRIP_FCS")) != NULL) {
-			/* Yes.  Note the number of bytes that will be
+			/* Yes.  Note the number of 16-bit words that will be
 			   supplied. */
 			p->linktype_ext = LT_FCS_DATALINK_EXT(pd->dag_fcs_bits/16);