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/* 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 */