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#include <dirent.h>
#include <stdio.h>
#include <stdlib.h>

unsigned int getProcessID( char *process )
{
  int target_link;
  DIR *dir_p;
  DIR *dir_proc;
  struct dirent *dir_entry_p;
  struct dirent *dir_proc_p;
  char dir_name[35];
  char target_name[235];
  char exe_link[235];
  char process_id[20];
  int i;

  dir_p = opendir( "/proc/" ); /* Open /proc/ directory */

  while( NULL != (dir_entry_p = readdir(dir_p))) /* Reading /proc/ entries */
    {
      if ( strspn( dir_entry_p->d_name, "0123456789" ) == strlen( dir_entry_p->d_name ) ) /* Checking for numbered directories */
	{
	  strcpy( process_id, dir_entry_p->d_name ); /* Saving the numbered directory i.e process-id */

	  strcpy( dir_name, "/proc/" );
	  strcat( dir_name, dir_entry_p->d_name );
	  strcat( dir_name, "/" ); /* Obtaining the full-path eg: /proc/24657/ */

	  if ( ( dir_proc = opendir( dir_name ) ) ) /* Open that numbered directory */
	    {
	      while ( ( dir_proc_p = readdir( dir_proc ) ) ) /* Reading its entries */
		{
		  if ( strcmp( dir_proc_p->d_name, "exe" ) == 0 ) /* Check for that exe link file */
		    {
		      strcat( exe_link, dir_name );
		      strcat( exe_link, dir_proc_p->d_name ); /* Getting the full-path of that exe link */

		      /* Getting the target of the exe ie to which binary it points to */
		      target_link = readlink( exe_link, target_name, sizeof( target_name ) ); 
		      target_name[ target_link ] = '\0';

		      if ( strstr( target_name, process ) != NULL ) /* Searching for process name in the target name */
			{
			  printf( "\n\n%s FOUND --- PROCESS_ID %s \n\n\n", process, process_id );
			  return atoi(process_id); /* GOT IT: return the process-id */
			}

		      strcpy( exe_link ,"" );
		    }
		}
	    }
	  else
	    printf( "Dir %s opening failed \n", dir_name );
	}
    }

  closedir(dir_p);
  return 0;
}


int main()
{
  system( "emacs &" );
  printf( " %u ", getProcessID( "emacs" ) );
  return 0;
}

unsigned int getProcessID(char *p_processname) {
	DIR *dir_p;
	struct dirent *dir_entry_p;
	char dir_name[40];										// ??? buffer overrun potential
	char target_name[252];									// ??? buffer overrun potential
	int target_result;
	char exe_link[252];
	int errorcount;
	int result;

	errorcount=0;
	result=0;
	dir_p = opendir("/proc/"); 																// Open /proc/ directory
	while(NULL != (dir_entry_p = readdir(dir_p))) {											// Reading /proc/ entries
		if (strspn(dir_entry_p->d_name, "0123456789") == strlen(dir_entry_p->d_name)) {		// Checking for numbered directories 
			strcpy(dir_name, "/proc/");
			strcat(dir_name, dir_entry_p->d_name);
			strcat(dir_name, "/"); 															// Obtaining the full-path eg: /proc/24657/ 
			exe_link[0] = 0;
			strcat(exe_link, dir_name);
			strcat(exe_link, "exe");													 	// Getting the full-path of that exe link
			target_result = readlink(exe_link, target_name, sizeof(target_name)-1);			// Getting the target of the exe ie to which binary it points to
			if (target_result > 0) {
				target_name[target_result] = 0;
				if (strstr(target_name, p_processname) != NULL) {							// Searching for process name in the target name -- ??? could be a better search !!!
					result = atoi(dir_entry_p->d_name);
					printf("getProcessID(%s) :Found. id = %d\n", p_processname, result);
					closedir(dir_p);
					return result;
				}
			}
		}
	}
	closedir(dir_p);
	printf("getProcessID(%s) : id = 0 (could not find process)\n", p_processname);
	return result;
}