Research V6 development

[unix-history] / usr / source / s2 / pwd.c

char dot[] ".";
char dotdot[] "..";
char root[] "/";
char name[512];
int file, off -1;
struct statb {int devn, inum, i[18];}x;
struct entry { int jnum; char name[16];}y;

main() {
       int n;

loop0:
       stat(dot, &x);
       if((file = open(dotdot,0)) < 0) prname();
loop1:
       if((n = read(file,&y,16)) < 16) prname();
       if(y.jnum != x.inum)goto loop1;
       close(file);
       if(y.jnum == 1) ckroot();
       cat();
       chdir(dotdot);
       goto loop0;
}
ckroot() {
       int i, n;

       if((n = stat(y.name,&x)) < 0) prname();
       i = x.devn;
       if((n = chdir(root)) < 0) prname();
       if((file = open(root,0)) < 0) prname();
loop:
       if((n = read(file,&y,16)) < 16) prname();
       if(y.jnum == 0) goto loop;
       if((n = stat(y.name,&x)) < 0) prname();
       if(x.devn != i) goto loop;
       x.i[0] =& 060000;
       if(x.i[0] != 040000) goto loop;
       if(y.name[0]=='.')if(((y.name[1]=='.') && (y.name[2]==0)) ||
                               (y.name[1] == 0)) goto pr;
       cat();
pr:
       write(1,root,1);
       prname();
}
prname() {
       if(off<0)off=0;
       name[off] = '\n';
       write(1,name,off+1);
       exit();
}
cat() {
       int i, j;

       i = -1;
       while(y.name[++i] != 0);
       if((off+i+2) > 511) prname();
       for(j=off+1; j>=0; --j) name[j+i+1] = name[j];
       off=i+off+1;
       name[i] = root[0];
       for(--i; i>=0; --i) name[i] = y.name[i];
}