src/osdep_linux.c

   1
   2 #include <sys/types.h>
   3 #include <sys/stat.h>
   4
   5 #include <errno.h>
   6 #include <fcntl.h>
   7 #include <limits.h>
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <unistd.h>
  11
  12 #include <WINGs/WUtil.h>
  13
  14 #include "wconfig.h"
  15
  16 #define RETRY( x )      do {                            \
  17                                 x;                      \
  18                         } while (errno == EINTR);
  19
  20 /*
  21  * copy argc and argv for an existing process identified by `pid'
  22  * into suitable storage given in ***argv and *argc.
  23  *
  24  * subsequent calls use the same static area for argv and argc.
  25  *
  26  * returns 0 for failure, in which case argc := 0 and argv := NULL
  27  * returns 1 for success
  28  */
  29 Bool GetCommandForPid(int pid, char ***argv, int *argc)
  30 {
  31         static char buf[_POSIX_ARG_MAX];
  32         int fd, i, j;
  33         ssize_t count;
  34
  35         *argv = NULL;
  36         *argc = 0;
  37
  38         /* cmdline is a flattened series of null-terminated strings */
  39         snprintf(buf, sizeof(buf), "/proc/%d/cmdline", pid);
  40         while (1) {
  41                 /* not switching this to stdio yet, as this does not need
  42                  * to be portable, and i'm lazy */
  43                 if ((fd = open(buf, O_RDONLY)) != -1)
  44                         break;
  45                 if (errno == EINTR)
  46                         continue;
  47                 return False;
  48         }
  49
  50         while (1) {
  51                 if ((count = read(fd, buf, sizeof(buf))) != -1)
  52                         break;
  53                 if (errno == EINTR)
  54                         continue;
  55                 RETRY( close(fd) )
  56                 return False;
  57         }
  58         RETRY( close(fd) )
  59
  60         /* count args */
  61         for (i = 0; i < count; i++)
  62                 if (buf[i] == '\0')
  63                         (*argc)++;
  64
  65         if (*argc == 0)
  66                 return False;
  67
  68         *argv = (char **)wmalloc(sizeof(char *) * (*argc + 1 /* term. null ptr */));
  69         (*argv)[0] = buf;
  70
  71         /* go through buf, set argv[$next] to the beginning of each string */
  72         for (i = 0, j = 1; i < count; i++) {
  73                 if (buf[i] != '\0')
  74                         continue;
  75                 if (i < count - 1)
  76                         (*argv)[j++] = &buf[i + 1];
  77                 if (j == *argc)
  78                         break;
  79         }
  80
  81         /* the list of arguments must be terminated by a null pointer */
  82         (*argv)[j] = NULL;
  83         return True;
  84 }