:: [DNG] issue with procps, any hints?
Startseite
Nachricht löschen
Nachricht beantworten
Autor: aitor
Datum:  
To: dng
Betreff: [DNG] issue with procps, any hints?
Hi,

In order to simplify the code of simple-netaid i'm trying to get the tty of a running process
using the struct `proc_t` declared the `procps` project:

https://salsa.debian.org/debian/procps/-/blob/master/library/include/readproc.h

Pay attention to the integer defined in the line nº 155:

    int tty; // stat- full device number of controlling terminal

This is indeed the value i'm trying to request, and a|ccording to the
comment done at the right of the variable ||containing the word *stat*, this is supposedly the flag to be passed to
openproc():|

|https://manpages.debian.org/testing/procps/openproc.3.en.html
|

|i.e. the flag PROC_FILLSTAT, as shown in the following C program:|

|
|

|______ MAIN.C _______
|

|#include <stdio.h>
#include <stdlib.h>
#include <proc/readproc.h>

int main(int argc, char **argv)
{
  proc_t *proc_info;|

|PROCTAB *proc = openproc(PROC_FILLSTAT);

  while(proc_info = readproc(proc, NULL)) {

    if(proc_info->tgid == atoi(argv[1])) {

       printf("/dev/pts/%d\n", proc_info->tty);
    }

    freeproc(proc_info);
 }

  closeproc(proc);|

|return 0;
}
|

|_______ END ________|

|
|

|You need to install libprocps-dev. Then, compile the program as follows:|

|$ gcc main.c -o main -lprocps|

|If you open a terminal and try to run the program passing the pid of
the process as argument in the command line, that is:|

|$ ./main $(echo $$)|

|It should print the tty of the current terminal, in the same way as tty
does:|

|$ tty
/dev/pts/4
|

|But this is what i'm getting instead:|

|$ ./main $(echo $$)
/dev/pts/34820|

|As you can see, a very high number. Whereas the printed value should be
equal to 4. If you try passing the pid of another running process,
you'll get similar results or zero. Any thoughts on what's wrong in the
program? |||May this be a bug in procps?| |

|Thanks in advance,|

|Aitor.|

|
|