patched nALFS to use uid:gid style user info

Categories: LFS

As I got no replies for my mail to alfs mailing list, I have finally decided to get my hands dirtier (They are already dirty). I have made a patch for nALFS that seems to do the job of using <user>uid:gid</user>. the usual at your own risk blah blah... disclaimer.

The format <user>uid:gid</user> has to be strictly followed and it won't check for the format, neither does it have any defaults in case you omit anything. I don't know if I have broken the original functionality. I had to bypass the user not found check and I didn't care to adopt it, instead I removed it. So I suggest either you look into it and modify it further or wait till my exams are over and I'll be more free to work them out.

There is one more catch, there are two files with same function which are exact replicas. But I changed only one that was being used when I traced it in gdb. Be warned, its only a couple of days since I started using gdb. Thanks to Kousik and Sunny.

nALFS-1.2.5-user-UID.patch

diff -Naur nALFS-1.2.5/src/handlers/stage.c nALFS-1.2.5-#/src/handlers/stage.c
--- nALFS-1.2.5/src/handlers/stage.c 2004-07-04 11:21:11.000000000 +0530
+++ nALFS-1.2.5-#/src/handlers/stage.c 2005-11-17 06:18:00.000000000 +0530
@@ -103,8 +103,9 @@
 static INLINE int change_to_user(const char *user)
 {
  struct passwd *pw;
-
-
+ uid_t uid;
+ gid_t gid;
+ 
  setpwent();
 
  /* getpwnam() is failing in chroot() */
@@ -118,20 +119,28 @@
 
  if (pw == NULL) {
   Nprint_h_err("User %s doesn't exist.", user);
-  return -1;
+  // return -1;
+  //check for UID
+  uid = atoi(strtok(user,":"));
+  gid = atoi(strtok(NULL,"\0"));
+ }
+ else
+ {
+  uid = pw->pw_uid;
+  gid = pw->pw_gid;
  }
 
- if (set_supplementary_groups(user, pw->pw_gid)) {
+ if (set_supplementary_groups(user, gid)) {
   return -1;
  }
 
- if (setgid(pw->pw_gid)) {
+ if (setgid(gid)) {
   Nprint_h_err("Unable to set group ID: %s",
    strerror(errno));
   return -1;
  }
 
- if (setuid(pw->pw_uid)) {
+ if (setuid(uid)) {
   Nprint_h_err("Unable to set user ID: %s",
    strerror(errno));
   return -1;