/* Copyright (c) 2000, 2023, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   Without limiting anything contained in the foregoing, this file,
   which is part of C Driver for MySQL (Connector/C), is also subject to the
   Universal FOSS Exception, version 1.0, a copy of which can be found at
   http://oss.oracle.com/licenses/universal-foss-exception.

   This program 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, version 2.0, for more details.

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

#include "mysys_priv.h"
#include "my_sys.h"
#include <m_string.h>
#ifdef HAVE_PWD_H
#include <pwd.h>
#endif

static char * expand_tilde(char **path);

	/* Pack a dirname ; Changes HOME to ~/ and current dev to ./ */
	/* from is a dirname (from dirname() ?) ending with FN_LIBCHAR */
	/* to may be == from */

void pack_dirname(char * to, const char *from)
{
  int cwd_err;
  size_t d_length, length, buff_length= 0;
  char * start;
  char buff[FN_REFLEN];
  DBUG_ENTER("pack_dirname");

  (void) intern_filename(to,from);		/* Change to intern name */

#ifdef FN_DEVCHAR
  if ((start=strrchr(to,FN_DEVCHAR)) != 0)	/* Skip device part */
    start++;
  else
#endif
    start=to;

  if (!(cwd_err= my_getwd(buff,FN_REFLEN,MYF(0))))
  {
    buff_length= strlen(buff);
    d_length= (size_t) (start-to);
    if ((start == to ||
	 (buff_length == d_length && !memcmp(buff,start,d_length))) &&
	*start != FN_LIBCHAR && *start)
    {						/* Put current dir before */
      bchange((uchar*) to, d_length, (uchar*) buff, buff_length, strlen(to)+1);
    }
  }

  if ((d_length= cleanup_dirname(to,to)) != 0)
  {
    length=0;
    if (home_dir)
    {
      length= strlen(home_dir);
      if (home_dir[length-1] == FN_LIBCHAR)
	length--;				/* Don't test last '/' */
    }
    if (length > 1 && length < d_length)
    {						/* test if /xx/yy -> ~/yy */
      if (memcmp(to,home_dir,length) == 0 && to[length] == FN_LIBCHAR)
      {
	to[0]=FN_HOMELIB;			/* Filename begins with ~ */
	(void) my_stpmov(to+1,to+length);
      }
    }
    if (! cwd_err)
    {						/* Test if cwd is ~/... */
      if (length > 1 && length < buff_length)
      {
	if (memcmp(buff,home_dir,length) == 0 && buff[length] == FN_LIBCHAR)
	{
	  buff[0]=FN_HOMELIB;
	  (void) my_stpmov(buff+1,buff+length);
	}
      }
      if (is_prefix(to,buff))
      {
	length= strlen(buff);
	if (to[length])
	  (void) my_stpmov(to,to+length);	/* Remove everything before */
	else
	{
	  to[0]= FN_CURLIB;			/* Put ./ instead of cwd */
	  to[1]= FN_LIBCHAR;
	  to[2]= '\0';
	}
      }
    }
  }
  DBUG_PRINT("exit",("to: '%s'",to));
  DBUG_VOID_RETURN;
} /* pack_dirname */


/*
  remove unwanted chars from dirname

  SYNOPSIS
     cleanup_dirname()
     to		Store result here
     from	Dirname to fix.  May be same as to

  IMPLEMENTATION
  "/../" removes prev dir
  "/~/" removes all before ~
  //" is same as "/", except on Win32 at start of a file
  "/./" is removed
  Unpacks home_dir if "~/.." used
  Unpacks current dir if if "./.." used

  RETURN
    #  length of new name   
*/

size_t cleanup_dirname(char *to, const char *from)
{
  size_t length;
  char *pos;
  char *from_ptr;
  char *start;
  char parent[5],				/* for "FN_PARENTDIR" */
       buff[FN_REFLEN+1],*end_parentdir;
#ifdef _WIN32
  CHARSET_INFO *fs= fs_character_set();
#endif
  DBUG_ENTER("cleanup_dirname");
  DBUG_PRINT("enter",("from: '%s'",from));

  start=buff;
  from_ptr=(char *) from;
#ifdef FN_DEVCHAR
  if ((pos=strrchr(from_ptr,FN_DEVCHAR)) != 0)
  {						/* Skip device part */
    length=(size_t) (pos-from_ptr)+1;
    start=my_stpnmov(buff,from_ptr,length); from_ptr+=length;
  }
#endif

  parent[0]=FN_LIBCHAR;
  length=(size_t) (my_stpcpy(parent+1,FN_PARENTDIR)-parent);
  for (pos=start ; (*pos= *from_ptr++) != 0 ; pos++)
  {
#ifdef _WIN32
    uint l;
    if (use_mb(fs) && (l= my_ismbchar(fs, from_ptr - 1, from_ptr + 2)))
    {
      for (l-- ; l ; *++pos= *from_ptr++, l--);
      start= pos + 1; /* Don't look inside multi-byte char */
      continue;
    }
#endif
    if (*pos == '/')
      *pos = FN_LIBCHAR;
    if (*pos == FN_LIBCHAR)
    {
      if ((size_t) (pos-start) > length && memcmp(pos-length,parent,length) == 0)
      {						/* If .../../; skip prev */
	pos-=length;
	if (pos != start)
	{					 /* not /../ */
	  pos--;
	  if (*pos == FN_HOMELIB && (pos == start || pos[-1] == FN_LIBCHAR))
	  {
	    if (!home_dir)
	    {
	      pos+=length+1;			/* Don't unpack ~/.. */
	      continue;
	    }
	    pos=my_stpcpy(buff,home_dir)-1;	/* Unpacks ~/.. */
	    if (*pos == FN_LIBCHAR)
	      pos--;				/* home ended with '/' */
	  }
	  if (*pos == FN_CURLIB && (pos == start || pos[-1] == FN_LIBCHAR))
	  {
	    if (my_getwd(curr_dir,FN_REFLEN,MYF(0)))
	    {
	      pos+=length+1;			/* Don't unpack ./.. */
	      continue;
	    }
	    pos=my_stpcpy(buff,curr_dir)-1;	/* Unpacks ./.. */
	    if (*pos == FN_LIBCHAR)
	      pos--;				/* home ended with '/' */
	  }
	  end_parentdir=pos;
	  while (pos >= start && *pos != FN_LIBCHAR)	/* remove prev dir */
	    pos--;
          if (pos[1] == FN_HOMELIB ||
              (pos >= start && memcmp(pos, parent, length) == 0))
	  {					/* Don't remove ~user/ */
	    pos=my_stpcpy(end_parentdir+1,parent);
	    *pos=FN_LIBCHAR;
	    continue;
	  }
	}
      }
      else if ((size_t) (pos-start) == length-1 &&
	       !memcmp(start,parent+1,length-1))
	start=pos;				/* Starts with "../" */
      else if (pos-start > 0 && pos[-1] == FN_LIBCHAR)
      {
#ifdef FN_NETWORK_DRIVES
	if (pos-start != 1)
#endif
	  pos--;			/* Remove dupplicate '/' */
      }
      else if (pos-start > 1 && pos[-1] == FN_CURLIB && pos[-2] == FN_LIBCHAR)
	pos-=2;					/* Skip /./ */
      else if (pos > buff+1 && pos[-1] == FN_HOMELIB && pos[-2] == FN_LIBCHAR)
      {					/* Found ..../~/  */
	buff[0]=FN_HOMELIB;
	buff[1]=FN_LIBCHAR;
	start=buff; pos=buff+1;
      }
    }
  }
  (void) my_stpcpy(to,buff);
  DBUG_PRINT("exit",("to: '%s'",to));
  DBUG_RETURN((size_t) (pos-buff));
} /* cleanup_dirname */


/**
  Convert a directory name to a format which can be compared as strings

  @param to     result buffer, FN_REFLEN chars in length; may be == from
  @param from   'packed' directory name, in whatever format
  @returns      size of the normalized name

  @details
  - Ensures that last char is FN_LIBCHAR, unless it is FN_DEVCHAR
  - Uses cleanup_dirname

  It does *not* expand ~/ (although, see cleanup_dirname).  Nor does it do
  any case folding.  All case-insensitive normalization should be done by
  the caller.
*/

size_t normalize_dirname(char *to, const char *from)
{
  size_t length;
  char buff[FN_REFLEN];
  DBUG_ENTER("normalize_dirname");

  /*
    Despite the name, this actually converts the name to the system's
    format (TODO: name this properly).
  */
  (void) intern_filename(buff, from);
  length= strlen(buff);			/* Fix that '/' is last */
  if (length &&
#ifdef FN_DEVCHAR
      buff[length - 1] != FN_DEVCHAR &&
#endif
      buff[length - 1] != FN_LIBCHAR && buff[length - 1] != '/')
  {
    /* we need reserve 2 bytes for the trailing slash and the zero */
    if (length >= sizeof (buff) - 1)
      length= sizeof (buff) - 2;
    buff[length]= FN_LIBCHAR;
    buff[length + 1]= '\0';
  }

  length=cleanup_dirname(to, buff);

  DBUG_RETURN(length);
}


/**
  Fixes a directory name so that can be used by open()

  @param to     Result buffer, FN_REFLEN characters. May be == from
  @param from   'Packed' directory name (may contain ~)

  @details
  - Uses normalize_dirname()
  - Expands ~/... to home_dir/...
  - Changes a UNIX filename to system filename (replaces / with \ on windows)

  @returns
   Length of new directory name (= length of to)
*/

size_t unpack_dirname(char * to, const char *from)
{
  size_t length, h_length;
  char buff[FN_REFLEN+1+4],*suffix,*tilde_expansion;
  DBUG_ENTER("unpack_dirname");

  length= normalize_dirname(buff, from);

  if (buff[0] == FN_HOMELIB)
  {
    suffix=buff+1; tilde_expansion=expand_tilde(&suffix);
    if (tilde_expansion)
    {
      length-= (size_t) (suffix-buff)-1;
      if (length+(h_length= strlen(tilde_expansion)) <= FN_REFLEN)
      {
	if ((h_length > 0) && (tilde_expansion[h_length-1] == FN_LIBCHAR))
	  h_length--;
        memmove(buff + h_length, suffix, length);
	memmove(buff, tilde_expansion, h_length);
      }
    }
  }
  DBUG_RETURN(system_filename(to,buff));	/* Fix for open */
} /* unpack_dirname */


	/* Expand tilde to home or user-directory */
	/* Path is reset to point at FN_LIBCHAR after ~xxx */

static char * expand_tilde(char **path)
{
  if (path[0][0] == FN_LIBCHAR)
    return home_dir;			/* ~/ expanded to home */
#ifdef HAVE_GETPWNAM
  {
    char *str,save;
    struct passwd *user_entry;

    if (!(str=strchr(*path,FN_LIBCHAR)))
      str=strend(*path);
    save= *str; *str= '\0';
    user_entry=getpwnam(*path);
    *str=save;
    endpwent();
    if (user_entry)
    {
      *path=str;
      return user_entry->pw_dir;
    }
  }
#endif
  return (char *) 0;
}


/*
  Fix filename so it can be used by open, create

  SYNOPSIS
    unpack_filename()
    to		Store result here. Must be at least of size FN_REFLEN.
    from	Filename in unix format (with ~)

  RETURN
    # length of to

  NOTES
    to may be == from
    ~ will only be expanded if total length < FN_REFLEN
*/


size_t unpack_filename(char * to, const char *from)
{
  size_t length, n_length, buff_length;
  char buff[FN_REFLEN];
  DBUG_ENTER("unpack_filename");

  length=dirname_part(buff, from, &buff_length);/* copy & convert dirname */
  n_length=unpack_dirname(buff,buff);
  if (n_length+strlen(from+length) < FN_REFLEN)
  {
    (void) my_stpcpy(buff+n_length,from+length);
    length= system_filename(to,buff);		/* Fix to usably filename */
  }
  else
    length= system_filename(to,from);		/* Fix to usably filename */
  DBUG_RETURN(length);
} /* unpack_filename */


	/* Convert filename (unix standard) to system standard */
	/* Used before system command's like open(), create() .. */
	/* Returns used length of to; total length should be FN_REFLEN */

size_t system_filename(char *to, const char *from)
{
  return (size_t) (strmake(to,from,FN_REFLEN-1)-to);
}

	/* Fix a filename to intern (UNIX format) */

char *intern_filename(char *to, const char *from)
{
  size_t length, to_length;
  char buff[FN_REFLEN];
  if (from == to)
  {						/* Dirname may destroy from */
    (void) my_stpnmov(buff, from, FN_REFLEN);
    from=buff;
  }
  length= dirname_part(to, from, &to_length);	/* Copy dirname & fix chars */
  (void) my_stpnmov(to + to_length, from + length, FN_REFLEN - to_length);
  return (to);
} /* intern_filename */