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// https://github.com/sergev/bkunix/blob/master/src/bin/pwd.c
void
cat(name)
char *name;
{
register int i, j;
i = -1;
while (name[++i] != 0);
if ((off+i+2) > 511) {
write(2, "pwd: too long path\n", 19);
exit(1);
}
for (j=off+1; j>=0; --j)
path[j+i+1] = path[j];
off=i+off+1;
path[i] = '/';
for (--i; i>=0; --i)
path[i] = name[i];
}
char * ckroot(dev, ino)
int dev, ino;
{
DIR * dir;
struct stat st;
register struct dirent * d;
chdir("/");
dir = opendir("/");
do {
d = readdir(dir);
if (! d) {
return "[mount point]";
}
stat(d->d_name, &st);
} while (st.st_dev != dev || st.st_ino != ino);
closedir(dir);
return d->d_name;
}
int
main()
{
int rdev, rino;
DIR *dir;
struct stat dot, dotdot;
register struct dirent *d;
stat("/", &dot);
rdev = dot.st_dev;
rino = dot.st_ino;
/*printf ("/ dev=%d ino=%d\n", rdev, (int) rino);*/
for (;;) {
stat(".", &dot);
/*printf (". dev=%d ino=%d\n", (int) dot.st_dev, (int) dot.st_ino);*/
if (dot.st_ino == rino && dot.st_dev == rdev)
break;
dir = opendir("..");
if (! dir) {
write(2, "pwd: cannot open ..\n", 20);
return 1;
}
stat("..", &dotdot);
/*printf (".. dev=%d ino=%d\n", (int) dotdot.st_dev, (int) dotdot.st_ino);*/
chdir("..");
if (dot.st_dev == dotdot.st_dev) {
if (dot.st_ino == dotdot.st_ino) {
cat(ckroot(dot.st_dev, dot.st_ino));
break;
}
do {
d = readdir(dir);
if (! d) {
write(2, "read error in ..\n", 17);
return 1;
}
} while (d->d_ino != dot.st_ino);
} else {
do {
d = readdir(dir);
if (! d) {
write(2, "read error in ..\n", 17);
return 1;
}
stat(d->d_name, &dotdot);
/*printf ("%.14s dev=%d ino=%d\n", d->d_name, (int) dotdot.st_dev, (int) dotdot.st_ino);*/
} while (dotdot.st_ino != dot.st_ino ||
dotdot.st_dev != dot.st_dev);
}
closedir(dir);
cat(d->d_name);
/*path[off] = 0; printf ("pwd %s\n", path);*/
}
write(1, "/", 1);
if (off < 0)
off = 0;
path[off] = '\n';
write(1, path, off + 1);
return 0;
}