text: /* tilde.c -- Tilde expansion code (~/foo := $HOME/foo). */
  
  /* Copyright (C) 1988,1989 Free Software Foundation, Inc.
  
     This file is part of GNU Readline, a library for reading lines
     of text with interactive input and history editing.
  
     Readline is free software; you can redistribute it and/or modify it
     under the terms of the GNU General Public License as published by the
     Free Software Foundation; either version 1, or (at your option) any
     later version.
  
     Readline 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
     General Public License for more details.
  
     You should have received a copy of the GNU General Public License
     along with Readline; see the file COPYING.  If not, write to the Free
     Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
  
  #if defined (HAVE_CONFIG_H)
  #  include <config.h>
  #endif
  
  #if defined (HAVE_UNISTD_H)
  #  ifdef _MINIX
  #    include <sys/types.h>
  #  endif
  #  include <unistd.h>
  #endif
  
  #if defined (HAVE_STRING_H)
  #  include <string.h>
  #else /* !HAVE_STRING_H */
  #  include <strings.h>
  #endif /* !HAVE_STRING_H */  
  
  #if defined (HAVE_STDLIB_H)
  #  include <stdlib.h>
  #else
  #  include "ansi_stdlib.h"
  #endif /* HAVE_STDLIB_H */
  
  #include <sys/types.h>
  #include <pwd.h>
  
  #include "tilde.h"
  
  #if !defined (HAVE_GETPW_DECLS)
  extern struct passwd *getpwuid (), *getpwnam ();
  #endif /* !HAVE_GETPW_DECLS */
  
  #if !defined (savestring)
  extern char *xmalloc ();
  #  ifndef strcpy
  extern char *strcpy ();
  #  endif
  #define savestring(x) strcpy (xmalloc (1 + strlen (x)), (x))
  #endif /* !savestring */
  
  #if !defined (NULL)
  #  if defined (__STDC__)
  #    define NULL ((void *) 0)
  #  else
  #    define NULL 0x0
  #  endif /* !__STDC__ */
  #endif /* !NULL */
  
  #if defined (TEST) || defined (STATIC_MALLOC)
  static char *xmalloc (), *xrealloc ();
  #else
  extern char *xmalloc (), *xrealloc ();
  #endif /* TEST || STATIC_MALLOC */
  
  /* If being compiled as part of bash, these will be satisfied from
     variables.o.  If being compiled as part of readline, they will
     be satisfied from shell.o. */
  extern char *get_home_dir ();
  extern char *get_env_value ();
  
  /* The default value of tilde_additional_prefixes.  This is set to
     whitespace preceding a tilde so that simple programs which do not
     perform any word separation get desired behaviour. */
  static char *default_prefixes[] =
    { " ~", "\t~", (char *)NULL };
  
  /* The default value of tilde_additional_suffixes.  This is set to
     whitespace or newline so that simple programs which do not
     perform any word separation get desired behaviour. */
  static char *default_suffixes[] =
    { " ", "\n", (char *)NULL };
  
  /* If non-null, this contains the address of a function that the application
     wants called before trying the standard tilde expansions.  The function
     is called with the text sans tilde, and returns a malloc()'ed string
     which is the expansion, or a NULL pointer if the expansion fails. */
  CPFunction *tilde_expansion_preexpansion_hook = (CPFunction *)NULL;
  
  /* If non-null, this contains the address of a function to call if the
     standard meaning for expanding a tilde fails.  The function is called
     with the text (sans tilde, as in "foo"), and returns a malloc()'ed string
     which is the expansion, or a NULL pointer if there is no expansion. */
  CPFunction *tilde_expansion_failure_hook = (CPFunction *)NULL;
  
  /* When non-null, this is a NULL terminated array of strings which
     are duplicates for a tilde prefix.  Bash uses this to expand
     `=~' and `:~'. */
  char **tilde_additional_prefixes = default_prefixes;
  
  /* When non-null, this is a NULL terminated array of strings which match
     the end of a username, instead of just "/".  Bash sets this to
     `:' and `=~'. */
  char **tilde_additional_suffixes = default_suffixes;
  
  /* Find the start of a tilde expansion in STRING, and return the index of
     the tilde which starts the expansion.  Place the length of the text
     which identified this tilde starter in LEN, excluding the tilde itself. */
  static int
  tilde_find_prefix (string, len)
       char *string;
       int *len;
  {
    register int i, j, string_len;
    register char **prefixes = tilde_additional_prefixes;
  
    string_len = strlen (string);
    *len = 0;
  
    if (*string == '\0' || *string == '~')
      return (0);
  
    if (prefixes)
      {
        for (i = 0; i < string_len; i++)
  	{
  	  for (j = 0; prefixes[j]; j++)
  	    {
  	      if (strncmp (string + i, prefixes[j], strlen (prefixes[j])) == 0)
  		{
  		  *len = strlen (prefixes[j]) - 1;
  		  return (i + *len);
  		}
  	    }
  	}
      }
    return (string_len);
  }
  
  /* Find the end of a tilde expansion in STRING, and return the index of
     the character which ends the tilde definition.  */
  static int
  tilde_find_suffix (string)
       char *string;
  {
    register int i, j, string_len;
    register char **suffixes;
  
    suffixes = tilde_additional_suffixes;
    string_len = strlen (string);
  
    for (i = 0; i < string_len; i++)
      {
        if (string[i] == '/' /* || !string[i] */)
  	break;
  
        for (j = 0; suffixes && suffixes[j]; j++)
  	{
  	  if (strncmp (string + i, suffixes[j], strlen (suffixes[j])) == 0)
  	    return (i);
  	}
      }
    return (i);
  }
  
  /* Return a new string which is the result of tilde expanding STRING. */
  char *
  tilde_expand (string)
       char *string;
  {
    char *result;
    int result_size, result_index;
  
    result_index = result_size = 0;
    if (result = strchr (string, '~'))
      result = xmalloc (result_size = (strlen (string) + 16));
    else
      result = xmalloc (result_size = (strlen (string) + 1));
  
    /* Scan through STRING expanding tildes as we come to them. */
    while (1)
      {
        register int start, end;
        char *tilde_word, *expansion;
        int len;
  
        /* Make START point to the tilde which starts the expansion. */
        start = tilde_find_prefix (string, &len);
  
        /* Copy the skipped text into the result. */
        if ((result_index + start + 1) > result_size)
  	result = xrealloc (result, 1 + (result_size += (start + 20)));
  
        strncpy (result + result_index, string, start);
        result_index += start;
  
        /* Advance STRING to the starting tilde. */
        string += start;
  
        /* Make END be the index of one after the last character of the
  	 username. */
        end = tilde_find_suffix (string);
  
        /* If both START and END are zero, we are all done. */
        if (!start && !end)
  	break;
  
        /* Expand the entire tilde word, and copy it into RESULT. */
        tilde_word = xmalloc (1 + end);
        strncpy (tilde_word, string, end);
        tilde_word[end] = '\0';
        string += end;
  
        expansion = tilde_expand_word (tilde_word);
        free (tilde_word);
  
        len = strlen (expansion);
        if ((result_index + len + 1) > result_size)
  	result = xrealloc (result, 1 + (result_size += (len + 20)));
  
        strcpy (result + result_index, expansion);
        result_index += len;
        free (expansion);
      }
  
    result[result_index] = '\0';
  
    return (result);
  }
  
  /* Take FNAME and return the tilde prefix we want expanded.  If LENP is
     non-null, the index of the end of the prefix into FNAME is returned in
     the location it points to. */
  static char *
  isolate_tilde_prefix (fname, lenp)
       char *fname;
       int *lenp;
  {
    char *ret;
    int i;
  
    ret = xmalloc (strlen (fname));
    for (i = 1; fname[i] && fname[i] != '/'; i++)
      ret[i - 1] = fname[i];
    ret[i - 1] = '\0';
    if (lenp)
      *lenp = i;
    return ret;
  }
  
  /* Return a string that is PREFIX concatenated with SUFFIX starting at
     SUFFIND. */
  static char *
  glue_prefix_and_suffix (prefix, suffix, suffind)
       char *prefix, *suffix;
       int suffind;
  {
    char *ret;
    int plen, slen;
  
    plen = (prefix && *prefix) ? strlen (prefix) : 0;
    slen = strlen (suffix + suffind);
    ret = xmalloc (plen + slen + 1);
    if (prefix && *prefix)
      strcpy (ret, prefix);
    strcpy (ret + plen, suffix + suffind);
    return ret;
  }
  
  /* Do the work of tilde expansion on FILENAME.  FILENAME starts with a
     tilde.  If there is no expansion, call tilde_expansion_failure_hook.
     This always returns a newly-allocated string, never static storage. */
  char *
  tilde_expand_word (filename)
       char *filename;
  {
    char *dirname, *expansion, *username;
    int user_len;
    struct passwd *user_entry;
  
    if (filename == 0)
      return ((char *)NULL);
  
    if (*filename != '~')
      return (savestring (filename));
  
    /* A leading `~/' or a bare `~' is *always* translated to the value of
       $HOME or the home directory of the current user, regardless of any
       preexpansion hook. */
    if (filename[1] == '\0' || filename[1] == '/')
      {
        /* Prefix $HOME to the rest of the string. */
        expansion = get_env_value ("HOME");
  
        /* If there is no HOME variable, look up the directory in
  	 the password database. */
        if (expansion == 0)
  	expansion = get_home_dir ();
  
        return (glue_prefix_and_suffix (expansion, filename, 1));
      }
  
    username = isolate_tilde_prefix (filename, &user_len);
  
    if (tilde_expansion_preexpansion_hook)
      {
        expansion = (*tilde_expansion_preexpansion_hook) (username);
        if (expansion)
  	{
  	  dirname = glue_prefix_and_suffix (expansion, filename, user_len);
  	  free (username);
  	  free (expansion);
  	  return (dirname);
  	}
      }
  
    /* No preexpansion hook, or the preexpansion hook failed.  Look in the
       password database. */
    dirname = (char *)NULL;
    user_entry = getpwnam (username);
    if (user_entry == 0)
      {
        /* If the calling program has a special syntax for expanding tildes,
  	 and we couldn't find a standard expansion, then let them try. */
        if (tilde_expansion_failure_hook)
  	{
  	  expansion = (*tilde_expansion_failure_hook) (username);
  	  if (expansion)
  	    {
  	      dirname = glue_prefix_and_suffix (expansion, filename, user_len);
  	      free (expansion);
  	    }
  	}
        free (username);
        /* If we don't have a failure hook, or if the failure hook did not
  	 expand the tilde, return a copy of what we were passed. */
        if (dirname == 0)
  	dirname = savestring (filename);
      }
    else
      {
        free (username);
        dirname = glue_prefix_and_suffix (user_entry->pw_dir, filename, user_len);
      }
  
    endpwent ();
    return (dirname);
  }
  
  
  #if defined (TEST)
  #undef NULL
  #include <stdio.h>
  
  main (argc, argv)
       int argc;
       char **argv;
  {
    char *result, line[512];
    int done = 0;
  
    while (!done)
      {
        printf ("~expand: ");
        fflush (stdout);
  
        if (!gets (line))
  	strcpy (line, "done");
  
        if ((strcmp (line, "done") == 0) ||
  	  (strcmp (line, "quit") == 0) ||
  	  (strcmp (line, "exit") == 0))
  	{
  	  done = 1;
  	  break;
  	}
  
        result = tilde_expand (line);
        printf ("  --> %s\n", result);
        free (result);
      }
    exit (0);
  }
  
  static void memory_error_and_abort ();
  
  static char *
  xmalloc (bytes)
       int bytes;
  {
    char *temp = (char *)malloc (bytes);
  
    if (!temp)
      memory_error_and_abort ();
    return (temp);
  }
  
  static char *
  xrealloc (pointer, bytes)
       char *pointer;
       int bytes;
  {
    char *temp;
  
    if (!pointer)
      temp = (char *)malloc (bytes);
    else
      temp = (char *)realloc (pointer, bytes);
  
    if (!temp)
      memory_error_and_abort ();
  
    return (temp);
  }
  
  static void
  memory_error_and_abort ()
  {
    fprintf (stderr, "readline: out of virtual memory\n");
    abort ();
  }
  
  /*
   * Local variables:
   * compile-command: "gcc -g -DTEST -o tilde tilde.c"
   * end:
   */
  #endif /* TEST */
  