processes plugin: Get complete command line for processes on Linux as well.

On Linux, /proc/<pid>/cmdline is now used to determine the complete command
line of a process which may then be used with the "ProcessMatch" configuration
option.

diff --git a/src/processes.c b/src/processes.c
index 3b21990..4fb70ad 100644 (file)
--- a/src/processes.c
+++ b/src/processes.c
@@ -22,6 +22,7 @@
  *   Lyonel Vincent <lyonel at ezix.org>
  *   Florian octo Forster <octo at verplant.org>
  *   Oleg King <king2 at kaluga.ru>
+ *   Sebastian Harl <sh at tokkee.org>
  **/
 
 #include "collectd.h"
@@ -755,6 +756,96 @@ int ps_read_process (int pid, procstat_t *ps, char *state)
        /* success */
        return (0);
 } /* int ps_read_process (...) */
+
+static char *ps_get_cmdline (pid_t pid, char *name, char *buf, size_t buf_len)
+{
+       char  *buf_ptr;
+       size_t len;
+
+       char file[PATH_MAX];
+       int  fd;
+
+       size_t n;
+
+       if ((pid < 1) || (NULL == buf) || (buf_len < 2))
+               return NULL;
+
+       ssnprintf (file, sizeof (file), "/proc/%u/cmdline", pid);
+
+       fd = open (file, O_RDONLY);
+       if (fd < 0) {
+               char errbuf[4096];
+               WARNING ("processes plugin: Failed to open `%s': %s.", file,
+                               sstrerror (errno, errbuf, sizeof (errbuf)));
+               return NULL;
+       }
+
+       buf_ptr = buf;
+       len     = buf_len;
+
+       n = 0;
+
+       while (42) {
+               size_t status;
+
+               status = read (fd, (void *)buf_ptr, len);
+
+               if (status < 0) {
+                       char errbuf[4096];
+
+                       if ((EAGAIN == errno) || (EINTR == errno))
+                               continue;
+
+                       WARNING ("processes plugin: Failed to read from `%s': %s.", file,
+                                       sstrerror (errno, errbuf, sizeof (errbuf)));
+                       close (fd);
+                       return NULL;
+               }
+
+               n += status;
+
+               if (status == 0)
+                       break;
+
+               buf_ptr += status;
+               len     -= status;
+
+               if (len <= 0)
+                       break;
+       }
+
+       close (fd);
+
+       if (0 == n) {
+               /* cmdline not available; e.g. kernel thread, zombie */
+               if (NULL == name)
+                       return NULL;
+
+               ssnprintf (buf, buf_len, "[%s]", name);
+               return buf;
+       }
+
+       assert (n <= buf_len);
+
+       if (n == buf_len)
+               --n;
+       buf[n] = '\0';
+
+       --n;
+       /* remove trailing whitespace */
+       while ((n > 0) && (isspace (buf[n]) || ('\0' == buf[n]))) {
+               buf[n] = '\0';
+               --n;
+       }
+
+       /* arguments are separated by '\0' in /proc/<pid>/cmdline */
+       while (n > 0) {
+               if ('\0' == buf[n])
+                       buf[n] = ' ';
+               --n;
+       }
+       return buf;
+} /* char *ps_get_cmdline (...) */
 #endif /* KERNEL_LINUX */
 
 #if HAVE_THREAD_INFO
@@ -1070,6 +1161,8 @@ static int ps_read (void)
        DIR           *proc;
        int            pid;
 
+       char cmdline[ARG_MAX];
+
        int        status;
        procstat_t ps;
        procstat_entry_t pse;
@@ -1130,8 +1223,9 @@ static int ps_read (void)
                        case 'W': paging++;   break;
                }
 
-               /* FIXME: cmdline should be here instead of NULL */
-               ps_list_add (ps.name, NULL, &pse);
+               ps_list_add (ps.name,
+                               ps_get_cmdline (pid, ps.name, cmdline, sizeof (cmdline)),
+                               &pse);
        }
 
        closedir (proc);