- Teach pmcstat(8) to log over the network; the -O option now

  takes a host:port specification.
- Update the manual page and add an example showing how log
  over the network using pmcstat(8) and nc(1).  Document the
  current inability to process logs in cross-platform manner.
- Have pmcstat_open_log() call err(3) directly in case
  of an error; this simplifies error handling in its caller.

MFC after:	1 week

1 files changed, 67 insertions, 6 deletions

diff --git a/usr.sbin/pmcstat/pmcstat_log.c b/usr.sbin/pmcstat/pmcstat_log.c
index 8cf3087..0beb7c7 100644
--- a/usr.sbin/pmcstat/pmcstat_log.c
+++ b/usr.sbin/pmcstat/pmcstat_log.c
@@ -40,6 +40,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/mman.h>
 #include <sys/pmc.h>
 #include <sys/queue.h>
+#include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/wait.h>
 
@@ -47,9 +48,11 @@ __FBSDID("$FreeBSD$");
 
 #include <assert.h>
 #include <err.h>
+#include <errno.h>
 #include <fcntl.h>
 #include <libgen.h>
 #include <limits.h>
+#include <netdb.h>
 #include <pmc.h>
 #include <pmclog.h>
 #include <sysexits.h>
@@ -1639,19 +1642,77 @@ pmcstat_close_log(struct pmcstat_args *a)
 int
 pmcstat_open_log(const char *path, int mode)
 {
-	int fd;
+	int error, fd;
+	size_t hlen;
+	const char *p, *errstr;
+	struct addrinfo hints, *res, *res0;
+	char hostname[MAXHOSTNAMELEN];
+
+	errstr = NULL;
+	fd = -1;
 
 	/*
 	 * If 'path' is "-" then open one of stdin or stdout depending
-	 * on the value of 'mode'.  Otherwise, treat 'path' as a file
-	 * name and open that.
+	 * on the value of 'mode'.
+	 * 
+	 * If 'path' contains a ':' and does not start with a '/' or '.',
+	 * and is being opened for writing, treat it as a "host:port"
+	 * specification and open a network socket.
+	 *
+	 * Otherwise, treat 'path' as a file name and open that.
 	 */
 	if (path[0] == '-' && path[1] == '\0')
 		fd = (mode == PMCSTAT_OPEN_FOR_READ) ? 0 : 1;
-	else
-		fd = open(path, mode == PMCSTAT_OPEN_FOR_READ ?
+	else if (mode == PMCSTAT_OPEN_FOR_WRITE && path[0] != '/' &&
+	    path[0] != '.' && strchr(path, ':') != NULL) {
+
+		p = strrchr(path, ':');
+		hlen = p - path;
+		if (p == path || hlen >= sizeof(hostname)) {
+			errstr = strerror(EINVAL);
+			goto done;
+		}
+
+		assert(hlen < sizeof(hostname));
+		(void) strncpy(hostname, path, hlen);
+		hostname[hlen] = '\0';
+
+		(void) memset(&hints, 0, sizeof(hints));
+		hints.ai_family = AF_UNSPEC;
+		hints.ai_socktype = SOCK_STREAM;
+		if ((error = getaddrinfo(hostname, p+1, &hints, &res0)) != 0) {
+			errstr = gai_strerror(error);
+			goto done;
+		}
+
+		fd = -1;
+		for (res = res0; res; res = res->ai_next) {
+			if ((fd = socket(res->ai_family, res->ai_socktype,
+			    res->ai_protocol)) < 0) {
+				errstr = strerror(errno);
+				continue;
+			}
+			if (connect(fd, res->ai_addr, res->ai_addrlen) < 0) {
+				errstr = strerror(errno);
+				(void) close(fd);
+				fd = -1;
+				continue;
+			}
+			errstr = NULL;
+			break;
+		}
+		freeaddrinfo(res0);
+
+	} else if ((fd = open(path, mode == PMCSTAT_OPEN_FOR_READ ?
 		    O_RDONLY : (O_WRONLY|O_CREAT|O_TRUNC),
-		    S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
+		    S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH)) < 0)
+			errstr = strerror(errno);
+
+  done: 
+	if (errstr)
+		errx(EX_OSERR, "ERROR: Cannot open \"%s\" for %s: %s.", path,
+		    (mode == PMCSTAT_OPEN_FOR_READ ? "reading" : "writing"),
+		    errstr);
 
 	return (fd);
 }