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#define _GNU_SOURCE 1
#include <errno.h>
#include <fcntl.h>
#include <pty.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <utmp.h>
#include <utmpx.h>
#include <unistd.h>
static void usage(void) {
fprintf(stderr, "Usage: -a <slave-device-name> <host>\n"
" -d <slave-device-name>\n");
exit(1);
}
static void checkDevice(const char * device) {
struct stat sb1, sb2;
int flags;
if (strstr(device, "/../") || strstr(device, "/./") ||
strstr(device, "//")) {
fprintf(stderr, "a simple path is required\n");
exit(1);
}
if (strncmp(device, "/dev/", 5)) {
fprintf(stderr, "the device must begin with /dev/\n");
exit(1);
}
if (fstat(3, &sb1)) {
fprintf(stderr, "error stat'ing fd 3: %s\n", strerror(errno));
exit(1);
}
if (major(sb1.st_rdev) == 2) {
if (lstat(device, &sb2)) {
fprintf(stderr, "error stat'ing %s: %s\n", device, strerror(errno));
exit(1);
}
if (major(sb2.st_rdev) != 3) {
fprintf(stderr, "%s is not the slave for the master pty on fd 3\n",
device);
exit(1);
}
if (minor(sb1.st_rdev) != minor(sb2.st_rdev)) {
fprintf(stderr, "fd 3 and %s are not the same device\n",
device);
exit(1);
}
} else if (major(sb1.st_rdev) == 5 && minor(sb1.st_rdev) == 2) {
char * dev2 = ptsname(3);
if (!dev2 || strcmp(dev2, device)) {
fprintf(stderr, "passed master doesn't match slave name\n");
exit(1);
}
} else {
fprintf(stderr, "fd 3 is not a master pty device (it is %d, %d)\n",
major(sb1.st_rdev), minor(sb1.st_rdev));
exit(1);
}
if ((flags = fcntl(3, F_GETFL, 0)) < 0) {
fprintf(stderr, "error getting flags for fd 3: %s\n", strerror(errno));
exit(1);
}
if ((flags & O_RDWR) != O_RDWR) {
fprintf(stderr, "fd 3 is not read/writeable\n");
exit(1);
}
}
int main(int argc, const char ** argv) {
struct utmpx utx;
int add;
const char * device, * host;
struct passwd * pw;
int i;
struct stat sb;
char * id;
if (argc < 3) usage();
for (i = 0; i < 3; i++) {
if (fstat(i, &sb)) {
fprintf(stderr, "error: failed to stat %d\n", i);
exit(1);
}
}
if (!strcmp(argv[1], "-a")) {
if (argc > 4) usage();
add = 1;
} else if (!strcmp(argv[1], "-d")) {
if (argc != 3) usage();
add = 0;
} else
usage();
device = argv[2];
if (!getuid()) {
host = argv[3]; /* either NULL or something real */
} else {
host = NULL;
}
memset(&utx, 0, sizeof(utx));
if (add)
utx.ut_type = USER_PROCESS;
else
utx.ut_type = DEAD_PROCESS;
utx.ut_pid = getppid();
if (utx.ut_pid == 1) {
fprintf(stderr, "error: parent pid should not be init\n");
exit(1);
}
checkDevice(device);
strncpy(utx.ut_line, device + 5, sizeof(utx.ut_line));
pw = getpwuid(getuid());
if (!pw) {
fprintf(stderr, "cannot find user w/ uid %d\n", getuid());
exit(1);
}
strncpy(utx.ut_user, pw->pw_name, sizeof(utx.ut_user));
if (host)
strncpy(utx.ut_host, host, sizeof(utx.ut_host));
if (!strncmp("pts/", utx.ut_line, 4)) {
id = utx.ut_line + 3;
if (strlen(id) > 4) id++;
} else {
id = utx.ut_line + 2;
}
strncpy(utx.ut_id, id, sizeof(utx.ut_id));
gettimeofday(&utx.ut_tv, NULL);
pututxline(&utx);
updwtmpx(_PATH_WTMP, &utx);
return 0;
}
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