#include <glob.h>

// Returns pid of pppd (must be /usr/sbin/pppd) process that has

// "linkname device" in its command line. 0 if not found, -1 on error.

static int

get_pppd_pid(char *device) {

    int i;

    glob_t globbuf;

    int ge = glob("/proc/*/cmdline", 0, NULL, &globbuf);

    if (!ge) {

	for (i = 0; i < globbuf.gl_pathc; ++i) {	    

	    FILE *fcmdline;

	    char cmdline[1024]; // hope this will be enough

	    if (fcmdline = fopen(globbuf.gl_pathv[i], "r")) {

		int num_read;

		num_read = fread(cmdline, 1, 1024, fcmdline);

		if (num_read > 0 && !strcmp(cmdline, "/usr/sbin/pppd")) {

		    int prev_linkname = 0;

		    char *p = cmdline;

		    while (*p && p - cmdline < 1024) {

			if (prev_linkname && !strcmp(p, device)) {

			    int retval;

			    globbuf.gl_pathv[i][strlen(globbuf.gl_pathv[i])-8] = 0;

			    retval = atoi(globbuf.gl_pathv[i]+6);

			    globfree(&globbuf);

			    fclose(fcmdline);

			    return retval;

			}

			prev_linkname = !strcmp(p, "linkname");

			p += strlen(p) + 1;

		    }		    

		}

		fclose(fcmdline);

	    }

	}

	globfree(&globbuf);

	return 0;

    }

    else

	return -1;

}

// If there exists only one child of specified process, returns its pid.

// Otherwise (if no children or more than 1) returns 0. -1 on error.

static int get_only_child(int parent_pid) {

    int i;

    glob_t globbuf;

    int ge = glob("/proc/*/status", 0, NULL, &globbuf);

    if (!ge) {

        int result_pid = 0;

	for (i = 0; i < globbuf.gl_pathc; ++i) {	    

	    FILE *fstatus;

	    char status[1024]; // hope this will be enough

	    if (fstatus = fopen(globbuf.gl_pathv[i], "r")) {

		int num_read;

		num_read = fread(status, 1, 1023, fstatus);

		if (num_read > 0) {			

		    char *ppid_pos;

		    status[num_read] = 0;

		    ppid_pos = strstr(status, "PPid:\t");

		    if (ppid_pos)

		    {

			int cur_ppid = atoi(ppid_pos+6);

			if (cur_ppid == parent_pid)

			{

			    // Heuristics: we look only for those chldren

			    // which have non-empty commandline

			    char cmdline[256], *p;

			    FILE *fcmdline;

			    strcpy(cmdline, globbuf.gl_pathv[i]);

			    for(p=cmdline+strlen(cmdline); *p!='/' && p>=cmdline; --p);

			    ++p;

			    strcpy(p, "cmdline");			    

			    if (!(fcmdline = fopen(cmdline, "r")) 

			        || !fread(cmdline, 1, 256, fcmdline))

			    {

				fclose(fstatus);

				continue;

			    }

			    fclose(fcmdline);

			    if (result_pid)

			    {

				globfree(&globbuf);

				fclose(fstatus);

				return 0;

			    }

			    else

				result_pid = atoi(globbuf.gl_pathv[i]+6);

			}

		    }

		}

		fclose(fstatus);

	    }

	}

	globfree(&globbuf);

	return result_pid;

    }

    else

	return -1;

}

	    int proc_pppd_pid, chat_pid, i;

	    // We suspect that pppd is running, but haven't created

	    // .pid file yet. Keep waiting for .pid file and try 

	    // to find chat or whatever pppd uses

	    // to establish connection.

	    for (i=0; !pppdPid && (proc_pppd_pid = get_pppd_pid(device))

	              && !(chat_pid = get_only_child(proc_pppd_pid))

	              && i<60000;

	         ++i)

	    {

		physicalDevice = pppLogicalToPhysical(&pppdPid, real_device);

		if (physicalDevice) { free(physicalDevice); physicalDevice = NULL; }

		usleep(1000);

	    }

	    if (pppdPid)

		sleep(2); // Else pppd may hangup, seems there's a bug in it

	    else

		if (chat_pid)

		{

		    // Found chat or whatever. 

		    // Let's kill it instead of pppd.

		    pppdPid = chat_pid;

		}