Re: [PATCH iproute2] ip vrf: Add command name next to pid

[David Ahern]

On 4/14/17 4:57 PM, Stephen Hemminger wrote:
> Overall, this looks like a good idea.
> 
>> +
>> +int get_comm(char *pid, char *comm, int len)
> 
> 
> Please use more glibc style function signature, like:
> 
> int get_comm(const char *pid, char *comm, size_t len)
> 
> And maybe even
> int get_command_name(pid_t pid, char *comm, size_t len)
> 

I'd pref to keep as char *. No sense converting from string to pid_t to
string. The vrf code is reading a cgroups file; the other potential user
is netns which is also reading pid from a file.

Re: [PATCH iproute2] ip vrf: Add command name next to pid

[Stephen Hemminger]

Overall, this looks like a good idea.

> +
> +int get_comm(char *pid, char *comm, int len)


Please use more glibc style function signature, like:

int get_comm(const char *pid, char *comm, size_t len)

And maybe even
int get_command_name(pid_t pid, char *comm, size_t len)

[PATCH iproute2] ip vrf: Add command name next to pid

[David Ahern]

'ip vrf pids' is used to list processes bound to a vrf, but it only
shows the pid leaving a lot of work for the user. Add the command
name to the output. With this patch you get the more user friendly:

$ ip vrf pids mgmt
 1121  ntpd
 1418  gdm-session-wor
 1488  gnome-session
 1491  dbus-launch
 1492  dbus-daemon
 1565  sshd
 ...

Signed-off-by: David Ahern 
---
 include/utils.h |  1 +
 ip/ipvrf.c  | 24 ++--
 lib/fs.c| 42 ++
 3 files changed, 57 insertions(+), 10 deletions(-)

diff --git a/include/utils.h b/include/utils.h
index 22369e0b4e03..d66784674633 100644
--- a/include/utils.h
+++ b/include/utils.h
@@ -260,5 +260,6 @@ int get_real_family(int rtm_type, int rtm_family);
 int cmd_exec(const char *cmd, char **argv, bool do_fork);
 int make_path(const char *path, mode_t mode);
 char *find_cgroup2_mount(void);
+int get_comm(char *pid, char *comm, int len);
 
 #endif /* __UTILS_H__ */
diff --git a/ip/ipvrf.c b/ip/ipvrf.c
index 5e204a9ebbb1..6d4bd6206cc8 100644
--- a/ip/ipvrf.c
+++ b/ip/ipvrf.c
@@ -111,27 +111,31 @@ static void read_cgroup_pids(const char *base_path, char 
*name)
 {
char path[PATH_MAX];
char buf[4096];
-   ssize_t n;
-   int fd;
+   FILE *fp;
 
if (snprintf(path, sizeof(path), "%s/vrf/%s%s",
 base_path, name, CGRP_PROC_FILE) >= sizeof(path))
return;
 
-   fd = open(path, O_RDONLY);
-   if (fd < 0)
+   fp = fopen(path, "r");
+   if (!fp)
return; /* no cgroup file, nothing to show */
 
/* dump contents (pids) of cgroup.procs */
-   while (1) {
-   n = read(fd, buf, sizeof(buf) - 1);
-   if (n <= 0)
-   break;
+   while (fgets(buf, sizeof(buf), fp)) {
+   char *nl, comm[32];
 
-   printf("%s", buf);
+   nl = strchr(buf, '\n');
+   if (nl)
+   *nl = '\0';
+
+   if (get_comm(buf, comm, sizeof(comm)))
+   strcpy(comm, "");
+
+   printf("%5s  %s\n", buf, comm);
}
 
-   close(fd);
+   fclose(fp);
 }
 
 /* recurse path looking for PATH[/NETNS]/vrf/NAME */
diff --git a/lib/fs.c b/lib/fs.c
index 12a4657a0bc9..81298f0ad91a 100644
--- a/lib/fs.c
+++ b/lib/fs.c
@@ -14,6 +14,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
 #include 
@@ -149,3 +150,44 @@ int make_path(const char *path, mode_t mode)
 
return rc;
 }
+
+int get_comm(char *pid, char *comm, int len)
+{
+   char path[PATH_MAX];
+   char line[128];
+   FILE *fp;
+
+   if (snprintf(path, sizeof(path),
+"/proc/%s/status", pid) >= sizeof(path)) {
+   return -1;
+   }
+
+   fp = fopen(path, "r");
+   if (!fp)
+   return -1;
+
+   comm[0] = '\0';
+   while (fgets(line, sizeof(line), fp)) {
+   char *nl, *name;
+
+   name = strstr(line, "Name:");
+   if (!name)
+   continue;
+
+   name += 5;
+   while (isspace(*name))
+   name++;
+
+   nl = strchr(name, '\n');
+   if (nl)
+   *nl = '\0';
+
+   strncpy(comm, name, len - 1);
+   comm[len - 1] = '\0';
+   break;
+   }
+
+   fclose(fp);
+
+   return 0;
+}
-- 
2.1.4