Add the get command line path from PID fct

Signed-off-by: David Goulet <david.goulet@polymtl.ca>

diff --git a/lttng/lttng.c b/lttng/lttng.c
index 3878fb8367614654d1e837951c121024803e8366..52c3e3873d27ce967f6cb3294126b64d269144b8 100644 (file)
--- a/lttng/lttng.c
+++ b/lttng/lttng.c
@@ -45,6 +45,7 @@ static int process_opt_list_sessions(void);
 static int process_opt_create_session(void);
 static void sighandler(int sig);
 static int set_signal_handler(void);
+static int get_cmdline_by_pid(pid_t pid, char **cmdline);
 
 /*
  *  start_client
@@ -180,9 +181,7 @@ static int process_opt_list_apps(void)
 {
        int i, ret, count;
        pid_t *pids;
-       FILE *fp;
-       char path[24];  /* Can't go bigger than /proc/65535/cmdline */
-       char cmdline[PATH_MAX];
+       char *cmdline;
 
        count = lttng_ust_list_apps(&pids);
        if (count < 0) {
@@ -192,15 +191,13 @@ static int process_opt_list_apps(void)
 
        MSG("LTTng UST traceable application [name (pid)]:");
        for (i=0; i < count; i++) {
-               snprintf(path, sizeof(path), "/proc/%d/cmdline", pids[i]);
-               fp = fopen(path, "r");
-               if (fp == NULL) {
+               ret = get_cmdline_by_pid(pids[i], &cmdline);
+               if (!ret) {
                        MSG("\t(not running) (%d)", pids[i]);
                        continue;
                }
-               ret = fread(cmdline, 1, sizeof(cmdline), fp);
                MSG("\t%s (%d)", cmdline, pids[i]);
-               fclose(fp);
+               free(cmdline);
        }
 
        /* Allocated by lttng_ust_list_apps() */
@@ -212,6 +209,39 @@ error:
        return ret;
 }
 
+/*
+ *  get_cmdline_by_pid
+ *
+ *  Get command line from /proc for a
+ *  specific pid. Allocate cmdline so the
+ *  user must free() that pointer.
+ *
+ *  On success, return 1
+ *  On error (not found), return 0
+ */
+static int get_cmdline_by_pid(pid_t pid, char **cmdline)
+{
+       int ret;
+       FILE *fp;
+       char path[24];  /* Can't go bigger than /proc/65535/cmdline */
+
+       snprintf(path, sizeof(path), "/proc/%d/cmdline", pid);
+       fp = fopen(path, "r");
+       if (fp == NULL) {
+               goto not_running;
+       }
+
+       /* Caller must free() *cmdline */
+       *cmdline = malloc(PATH_MAX);
+       ret = fread(*cmdline, 1, PATH_MAX, fp);
+       fclose(fp);
+
+       return 1;
+
+not_running:
+       return 0;
+}
+
 /*
  *  spawn_sessiond
  *