trace-cmd: Add -l option to trace-cmd listen for log file output

Add a way to pipe log info to another file, especially useful in
daemon mode.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

3 files changed, 83 insertions, 21 deletions

diff --git a/Documentation/trace-cmd-listen.1.txt b/Documentation/trace-cmd-listen.1.txt
index 15014e6..c9bafcd 100644
--- a/Documentation/trace-cmd-listen.1.txt
+++ b/Documentation/trace-cmd-listen.1.txt
@@ -33,6 +33,9 @@ OPTIONS
     This option overrides the default 'trace' in the 'trace.HOST:PORT.dat' that
     is created when a remote host connects.
 
+*-l* 'filename'::
+    This option writes the output messages to a log file instead of standard output.
+
 
 SEE ALSO
 --------
diff --git a/trace-listen.c b/trace-listen.c
index e12431c..9564620 100644
--- a/trace-listen.c
+++ b/trace-listen.c
@@ -43,6 +43,8 @@ static char *output_dir;
 static char *default_output_file = "trace";
 static char *output_file;
 
+static FILE *logfp;
+
 static int debug;
 
 static int use_tcp;
@@ -107,6 +109,51 @@ static void finish(int sig)
         done = 1;
 }
 
+#define LOG_BUF_SIZE 1024
+static void __plog(const char *prefix, const char *fmt, va_list ap,
+                   FILE *fp)
+{
+        static int newline = 1;
+        char buf[LOG_BUF_SIZE];
+        int r;
+
+        r = vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);
+
+        if (r > LOG_BUF_SIZE)
+                r = LOG_BUF_SIZE;
+
+        if (logfp) {
+                if (newline)
+                        fprintf(logfp, "[%d]%s%.*s", getpid(), prefix, r, buf);
+                else
+                        fprintf(logfp, "[%d]%s%.*s", getpid(), prefix, r, buf);
+                newline = buf[r - 1] == '\n';
+                fflush(logfp);
+                return;
+        }
+
+        fprintf(fp, "%.*s", r, buf);
+}
+
+static void plog(const char *fmt, ...)
+{
+        va_list ap;
+
+        va_start(ap, fmt);
+        __plog("", fmt, ap, stdout);
+        va_end(ap);
+}
+
+static void pdie(const char *fmt, ...)
+{
+        va_list ap;
+
+        va_start(ap, fmt);
+        __plog("Error: ", fmt, ap, stderr);
+        va_end(ap);
+        exit(-1);
+}
+
 static void process_udp_child(int sfd, const char *host, const char *port,
                               int cpu, int page_size)
 {
@@ -124,15 +171,15 @@ static void process_udp_child(int sfd, const char *host, const char *port,
         tempfile = get_temp_file(host, port, cpu);
         fd = open(tempfile, O_WRONLY | O_TRUNC | O_CREAT, 0644);
         if (fd < 0)
-                die("creating %s", tempfile);
+                pdie("creating %s", tempfile);
 
         if (use_tcp) {
                 if (listen(sfd, backlog) < 0)
-                        die("listen");
+                        pdie("listen");
                 peer_addr_len = sizeof(peer_addr);
                 cfd = accept(sfd, (struct sockaddr *)&peer_addr, &peer_addr_len);
                 if (cfd < 0)
-                        die("accept");
+                        pdie("accept");
                 close(sfd);
                 sfd = cfd;
         }
@@ -141,7 +188,7 @@ static void process_udp_child(int sfd, const char *host, const char *port,
                 /* TODO, make this copyless! */
                 n = read(sfd, buf, page_size);
                 if (n < 0)
-                        die("reading client");
+                        pdie("reading client");
                 if (!n)
                         break;
                 /* UDP requires that we get the full size in one go */
@@ -178,7 +225,7 @@ static int open_udp(const char *node, const char *port, int *pid,
 
         s = getaddrinfo(NULL, buf, &hints, &result);
         if (s != 0)
-                die("getaddrinfo: error opening udp socket");
+                pdie("getaddrinfo: error opening udp socket");
 
         for (rp = result; rp != NULL; rp = rp->ai_next) {
                 sfd = socket(rp->ai_family, rp->ai_socktype,
@@ -195,7 +242,7 @@ static int open_udp(const char *node, const char *port, int *pid,
         if (rp == NULL) {
                 freeaddrinfo(result);
                 if (++num_port > MAX_PORT_SEARCH)
-                        die("No available ports to bind");
+                        pdie("No available ports to bind");
                 goto again;
         }
 
@@ -204,7 +251,7 @@ static int open_udp(const char *node, const char *port, int *pid,
         *pid = fork();
 
         if (*pid < 0)
-                die("creating udp reader");
+                pdie("creating udp reader");
 
         if (!*pid)
                 process_udp_child(sfd, node, port, cpu, pagesize);
@@ -242,7 +289,7 @@ static void process_client(const char *node, const char *port, int fd)
 
         cpus = atoi(buf);
 
-        printf("cpus=%d\n", cpus);
+        plog("cpus=%d\n", cpus);
         if (cpus < 0)
                 return;
 
@@ -254,7 +301,7 @@ static void process_client(const char *node, const char *port, int fd)
 
         pagesize = atoi(buf);
 
-        printf("pagesize=%d\n", pagesize);
+        plog("pagesize=%d\n", pagesize);
         if (pagesize <= 0)
                 return;
 
@@ -295,14 +342,14 @@ static void process_client(const char *node, const char *port, int fd)
         }
 
         if (use_tcp)
-                printf("Using TCP for live connection\n");
+                plog("Using TCP for live connection\n");
 
         /* Create the client file */
         snprintf(buf, BUFSIZ, "%s.%s:%s.dat", output_file, node, port);
 
         ofd = open(buf, O_RDWR | O_CREAT | O_TRUNC, 0644);
         if (ofd < 0)
-                die("Can not create file %s", buf);
+                pdie("Can not create file %s", buf);
 
         port_array = malloc_or_die(sizeof(int) * cpus);
         pid_array = malloc_or_die(sizeof(int) * cpus);
@@ -334,7 +381,7 @@ static void process_client(const char *node, const char *port, int fd)
                 do {
                         s = write(ofd, buf+s, t);
                         if (s < 0)
-                                die("writing to file");
+                                pdie("writing to file");
                         t -= s;
                         s = n - t;
                 } while (t);
@@ -410,10 +457,10 @@ static void do_connection(int cfd, struct sockaddr_storage *peer_addr,
                         service, NI_MAXSERV, NI_NUMERICSERV);
 
         if (s == 0)
-                printf("Connected with %s:%s\n",
+                plog("Connected with %s:%s\n",
                        host, service);
         else {
-                printf("Error with getnameinfo: %s\n",
+                plog("Error with getnameinfo: %s\n",
                        gai_strerror(s));
                 close(cfd);
                 return;
@@ -425,7 +472,7 @@ static void do_connection(int cfd, struct sockaddr_storage *peer_addr,
                 if (nread > 0)
                         nread = read(cfd, buf, BUFSIZ);
                 if (cfd < 0)
-                        die("client");
+                        pdie("client");
                 if (nread > 0)
                         write(1, buf, nread);
         } while (nread);
@@ -465,7 +512,7 @@ static void do_listen(char *port)
 
         s = getaddrinfo(NULL, port, &hints, &result);
         if (s != 0)
-                die("getaddrinfo: error opening %s", port);
+                pdie("getaddrinfo: error opening %s", port);
 
         for (rp = result; rp != NULL; rp = rp->ai_next) {
                 sfd = socket(rp->ai_family, rp->ai_socktype,
@@ -480,19 +527,19 @@ static void do_listen(char *port)
         }
 
         if (rp == NULL)
-                die("Could not bind");
+                pdie("Could not bind");
 
         freeaddrinfo(result);
 
         if (listen(sfd, backlog) < 0)
-                die("listen");
+                pdie("listen");
 
         peer_addr_len = sizeof(peer_addr);
 
         do {
                 cfd = accept(sfd, (struct sockaddr *)&peer_addr, &peer_addr_len);
                 if (cfd < 0)
-                        die("connecting");
+                        pdie("connecting");
 
                 do_connection(cfd, &peer_addr, peer_addr_len);
 
@@ -507,6 +554,7 @@ static void start_daemon(void)
 
 void trace_listen(int argc, char **argv)
 {
+        char *logfile = NULL;
         char *port = NULL;
         char *iface;
         int daemon = 0;
@@ -527,7 +575,7 @@ void trace_listen(int argc, char **argv)
                         {NULL, 0, NULL, 0}
                 };
 
-                c = getopt_long (argc-1, argv+1, "+hp:o:d:i:D",
+                c = getopt_long (argc-1, argv+1, "+hp:o:d:i:l:D",
                         long_options, &option_index);
                 if (c == -1)
                         break;
@@ -547,6 +595,9 @@ void trace_listen(int argc, char **argv)
                 case 'o':
                         output_file = optarg;
                         break;
+                case 'l':
+                        logfile = optarg;
+                        break;
                 case 'D':
                         daemon = 1;
                         break;
@@ -574,6 +625,13 @@ void trace_listen(int argc, char **argv)
         if (!output_dir)
                 output_dir = default_output_dir;
 
+        if (logfile) {
+                /* set the writes to a logfile instead */
+                logfp = fopen(logfile, "w");
+                if (!logfp)
+                        die("creating log file %s", logfile);
+        }
+
         if (chdir(output_dir) < 0)
                 die("Can't access directory %s", output_dir);
 
diff --git a/trace-usage.c b/trace-usage.c
index 828fdd0..e834d44 100644
--- a/trace-usage.c
+++ b/trace-usage.c
@@ -104,11 +104,12 @@ static struct usage_help usage_help[] = {
         {
                 "listen",
                 "listen on a network socket for trace clients",
-                " %s listen -p port[-D][-o file][-d dir]\n"
+                " %s listen -p port[-D][-o file][-d dir][-l logfile]\n"
                 "          Creates a socket to listen for clients.\n"
                 "          -D create it in daemon mode.\n"
                 "          -o file name to use for clients.\n"
                 "          -d diretory to store client files.\n"
+                "          -l logfile to write messages to.\n"
         },
         {
                 "list",