compiled-tools/grandparentexe.c

   1
   2 #include <stdlib.h>
   3 #include <sys/types.h>
   4 #include <unistd.h>
   5 #include <stdio.h>
   6 #include <string.h>
   7 #include <errno.h>
   8 #include <err.h>
   9
  10 #define ARRAYSIZE(x) (sizeof(x)/sizeof(x[0]))
  11
  12 int main()
  13 {
  14         char *path;
  15         FILE *fh;
  16         char lbuf[32];
  17         pid_t gppid = 0;
  18         char linktarget[256];
  19         size_t len;
  20
  21         if(asprintf(&path, "/proc/%d/status", getppid()) == -1) return(EXIT_FAILURE);
  22         fh = fopen(path, "r");
  23         if(!fh) { perror("fopen"); return(EXIT_FAILURE); }
  24         while(fgets(lbuf, ARRAYSIZE(lbuf), fh) != NULL)
  25         {
  26                 if(sscanf(lbuf, "PPid: %d", &gppid) == 1)
  27                 {
  28                         break;
  29                 }
  30         }
  31         fclose(fh);
  32
  33         if(gppid == 0) { errx(EXIT_FAILURE, "Grandparent Pid not found"); }
  34
  35         if(asprintf(&path, "/proc/%d/exe", gppid) == -1) return(EXIT_FAILURE);
  36         len = readlink(path, linktarget, ARRAYSIZE(linktarget));
  37         if(len == -1) { perror("readlink"); return(EXIT_FAILURE); }
  38         printf("%.*s\n", len, linktarget);
  39
  40         return 0;
  41 }