PERFORCE change 131558 for review

[Robert Watson]

http://perforce.freebsd.org/chv.cgi?CH=131558

Change 131558 by rwatson at rwatson_cinnamon on 2007/12/24 23:04:49

	Fix up commenting, ifdef'ing, and indentation a bit.

Affected files ...

.. //depot/projects/zcopybpf/src/contrib/libpcap/pcap-bpf.c#18 edit

Differences ...

==== //depot/projects/zcopybpf/src/contrib/libpcap/pcap-bpf.c#18 (text+ko) ====

@@ -39,8 +39,6 @@
 #include <sys/ioctl.h>
 #include <sys/utsname.h>
 
-#include <machine/atomic.h>
-
 #include <net/if.h>
 
 #ifdef _AIX
@@ -90,6 +88,10 @@
 
 #endif /* _AIX */
 
+#ifdef BIOCSETBUFMODE
+#include <machine/atomic.h>
+#endif
+
 #include <ctype.h>
 #include <errno.h>
 #include <netdb.h>
@@ -156,10 +158,6 @@
 {
 	struct bpf_zbuf_header *bzh;
 
-	/*
-	 * If we've never used a buffer before, or if the last buffer was
-	 * zbuf2, try zbuf1.
-	 */
 	if (p->zbuffer == p->zbuf2 || p->zbuffer == NULL) {
 		bzh = (struct bpf_zbuf_header *)p->zbuf1;
 		if (bzh->bzh_user_gen !=
@@ -243,13 +241,13 @@
 		    "BIOCROTZBUF: %s", strerror(errno));
 		return (-1);
 	}
-
-	/*
-	 * Last chance for data.
-	 */
 	return (pcap_next_zbuf_shm(p, cc));
 }
 
+/*
+ * Notify kernel that we are done with the buffer.  We don't reset zbuffer so
+ * that we know which buffer to use next time around.
+ */
 static int
 pcap_ack_zbuf(pcap_t *p)
 {
@@ -795,15 +793,12 @@
 		goto bad;
 	}
 
+#ifdef BIOCSETBUFMODE
 	/*
-	 * XXXRW: Depending on the availability of zero-copy BPF, we take one
-	 * of two strategies here: if it is available and usable, we go ahead
-	 * and set it up; otherwise we play the song-and-dance to try to
-	 * probe an acceptable read buffer size.  Zero-copy BPF requires that
-	 * buffers be mapped into memory before selecting the interface to
-	 * attach to, so we do that here also.
+	 * If the BPF extension to set buffer mode is present, try setting
+	 * the mode to zero-copy.  If that fails, use regular buffering.  If
+	 * it succeeds but other setup fails, return an error to the user.
 	 */
-#ifdef BIOCSETBUFMODE
 	bufmode = BPF_BUFMODE_ZBUF;
 	if (ioctl(fd, BIOCSETBUFMODE, (caddr_t)&bufmode) == 0) {
 		p->zerocopy = 1;
@@ -812,14 +807,9 @@
 			    pcap_strerror(errno));
 			goto bad;
 		}
-
-		/*
-		 * XXXRW: This logic should be revisited.
-		 */
 		p->zbufsize = 32768;
 		if (p->zbufsize > zbufmax)
 			p->zbufsize = zbufmax;
-
 		p->zbuf1 = mmap(NULL, p->zbufsize, PROT_READ | PROT_WRITE,
 		    MAP_ANON, -1, 0);
 		p->zbuf2 = mmap(NULL, p->zbufsize, PROT_READ | PROT_WRITE,
@@ -829,18 +819,15 @@
 			    pcap_strerror(errno));
 			goto bad;
 		}
-
 		bzero(&bz, sizeof(bz));
 		bz.bz_bufa = p->zbuf1;
 		bz.bz_bufb = p->zbuf2;
 		bz.bz_buflen = p->zbufsize;
-
 		if (ioctl(fd, BIOCSETZBUF, (caddr_t)&bz) < 0) {
 			snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCSETZBUF: %s",
 			    pcap_strerror(errno));
 			goto bad;
 		}
-
 		(void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
 		if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) < 0) {
 			snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCSETIF: %s: %s",
@@ -852,41 +839,43 @@
 	} else {
 #endif
 
-	/*
-	 * Try finding a good size for the buffer; 32768 may be too
-	 * big, so keep cutting it in half until we find a size
-	 * that works, or run out of sizes to try.  If the default
-	 * is larger, don't make it smaller.
-	 *
-	 * XXX - there should be a user-accessible hook to set the
-	 * initial buffer size.
-	 */
-	if ((ioctl(fd, BIOCGBLEN, (caddr_t)&v) < 0) || v < 32768)
-		v = 32768;
-	for ( ; v != 0; v >>= 1) {
-		/* Ignore the return value - this is because the call fails
-		 * on BPF systems that don't have kernel malloc.  And if
-		 * the call fails, it's no big deal, we just continue to
-		 * use the standard buffer size.
+		/*
+		 * Try finding a good size for the buffer; 32768 may be too
+		 * big, so keep cutting it in half until we find a size
+		 * that works, or run out of sizes to try.  If the default
+		 * is larger, don't make it smaller.
+		 *
+		 * XXX - there should be a user-accessible hook to set the
+		 * initial buffer size.
 		 */
-		(void) ioctl(fd, BIOCSBLEN, (caddr_t)&v);
+		if ((ioctl(fd, BIOCGBLEN, (caddr_t)&v) < 0) || v < 32768)
+			v = 32768;
+		for ( ; v != 0; v >>= 1) {
+			/* Ignore the return value - this is because the call
+			 * fails on BPF systems that don't have kernel
+			 * malloc.  And if the call fails, it's no big deal,
+			 * we just continue to use the standard buffer size.
+			 */
+			(void) ioctl(fd, BIOCSBLEN, (caddr_t)&v);
+
+			(void)strncpy(ifr.ifr_name, device,
+			    sizeof(ifr.ifr_name));
+			if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) >= 0)
+				break;	/* that size worked; we're done */
 
-		(void)strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
-		if (ioctl(fd, BIOCSETIF, (caddr_t)&ifr) >= 0)
-			break;	/* that size worked; we're done */
+			if (errno != ENOBUFS) {
+				snprintf(ebuf, PCAP_ERRBUF_SIZE,
+				    "BIOCSETIF: %s: %s",
+				    device, pcap_strerror(errno));
+				goto bad;
+			}
+		}
 
-		if (errno != ENOBUFS) {
-			snprintf(ebuf, PCAP_ERRBUF_SIZE, "BIOCSETIF: %s: %s",
-			    device, pcap_strerror(errno));
+		if (v == 0) {
+			snprintf(ebuf, PCAP_ERRBUF_SIZE,
+			    "BIOCSBLEN: %s: No buffer size worked", device);
 			goto bad;
 		}
-	}
-
-	if (v == 0) {
-		snprintf(ebuf, PCAP_ERRBUF_SIZE,
-			 "BIOCSBLEN: %s: No buffer size worked", device);
-		goto bad;
-	}
 #ifdef BIOCSETBUFMODE
 	}
 #endif