/* tilde.c: Expand user's home directories.

    Copyright 1997, 98, 2005, Olaf Weber.
    Copyright 1993, 95, 96, 97 Karl Berry.

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

*/

#include <kpathsea/config.h>

#include <kpathsea/c-pathch.h>
#include <kpathsea/tilde.h>

#ifdef HAVE_PWD_H
#include <pwd.h>
#endif


/* If NAME has a leading ~ or ~user, Unix-style, expand it to the user's
   home directory, and return a new malloced string.  If no ~, or no
   <pwd.h>, just return NAME.  */

string
kpse_tilde_expand P1C(const_string, name)
{
  const_string expansion;
  const_string home;
  const_string prefix;
  
  assert (name);

  /* If there is a leading "!!", set prefix to "!!", otherwise use
     the empty string.  After this, we can test whether a prefix was
     found by checking *prefix, and it is safe to unconditionally
     prepend it. */
  if (name[0] == '!' && name[1] == '!') {
    name += 2;
    prefix = "!!";
  } else {
    prefix = "";
  }
  
  /* If no leading tilde, do nothing, and return the original string.  */
  if (*name != '~') {
    if (*prefix)
      name -= 2;
    expansion = name;
  
  /* If a bare tilde, return the home directory or `.'.  (Very unlikely
     that the directory name will do anyone any good, but ...  */
  } else if (name[1] == 0) {
    home = getenv ("HOME");
    if (!home) {
      home = ".";
    }
    expansion = concat (prefix, home);
  
  /* If `~/', remove any trailing / or replace leading // in $HOME.
     Should really check for doubled intermediate slashes, too.  */
  } else if (IS_DIR_SEP (name[1])) {
    unsigned c = 1;
    home = getenv ("HOME");
    if (!home) {
      home = ".";
    }
    if (IS_DIR_SEP (*home) && IS_DIR_SEP (home[1])) {  /* handle leading // */
      home++;
    }
    if (IS_DIR_SEP (home[strlen (home) - 1])) {        /* omit / after ~ */
      c++;
    }
    expansion = concat3 (prefix, home, name + c);
  
  /* If `~user' or `~user/', look up user in the passwd database (but
     OS/2 doesn't have this concept.  */
  } else {
#ifdef HAVE_PWD_H
      struct passwd *p;
      string user;
      unsigned c = 2;
      while (!IS_DIR_SEP (name[c]) && name[c] != 0) /* find user name */
        c++;
      
      user = (string) xmalloc (c);
      strncpy (user, name + 1, c - 1);
      user[c - 1] = 0;
      
      /* We only need the cast here for (deficient) systems
         which do not declare `getpwnam' in <pwd.h>.  */
      p = (struct passwd *) getpwnam (user);
      free (user);

      /* If no such user, just use `.'.  */
      home = p ? p->pw_dir : ".";
      if (IS_DIR_SEP (*home) && IS_DIR_SEP (home[1])) { /* handle leading // */
        home++;
      }
      if (IS_DIR_SEP (home[strlen (home) - 1]) && name[c] != 0)
        c++; /* If HOME ends in /, omit the / after ~user. */

      expansion = concat3 (prefix, home, name + c);
#else /* not HAVE_PWD_H */
      /* Since we don't know how to look up a user name, just return the
         original string. */
      if (*prefix)
        name -= 2;
      expansion = name;
#endif /* not HAVE_PWD_H */
  }
  /* We may return the same thing as the original, and then we might not
     be returning a malloc-ed string.  Callers beware.  Sorry.  */
  return (string) expansion;
}

#ifdef TEST

void
test_expand_tilde (const_string filename)
{
  string answer;
  
  printf ("Tilde expansion of `%s':\t", filename ? filename : "(nil)");
  answer = kpse_tilde_expand (filename);
  puts (answer);
}

int
main ()
{
  string tilde_path = "tilde";

  test_expand_tilde ("");
  test_expand_tilde ("none");
  test_expand_tilde ("~root");
  test_expand_tilde ("~");
  test_expand_tilde ("foo~bar");

  test_expand_tilde ("!!");
  test_expand_tilde ("!!none");
  test_expand_tilde ("!!~root");
  test_expand_tilde ("!!~");
  test_expand_tilde ("!!foo~bar");
  
  return 0;
}

#endif /* TEST */


/*
Local variables:
standalone-compile-command: "gcc -g -I. -I.. -DTEST tilde.c kpathsea.a"
End:
*/
