redir.c

android-w.song.android.widget

/* redir.c -- Functions to perform input and output redirection. */

/* Copyright (C) 1997-2009 Free Software Foundation, Inc.

   This file is part of GNU Bash, the Bourne Again SHell.

   Bash 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 3 of the License, or
   (at your option) any later version.

   Bash 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 Bash.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "config.h"

#if !defined (__GNUC__) && !defined (HAVE_ALLOCA_H) && defined (_AIX)
  #pragma alloca
#endif /* _AIX && RISC6000 && !__GNUC__ */

#include <stdio.h>
#include "bashtypes.h"
#if !defined (_MINIX) && defined (HAVE_SYS_FILE_H)
#  include <sys/file.h>
#endif
#include "filecntl.h"
#include "posixstat.h"

#if defined (HAVE_UNISTD_H)
#  include <unistd.h>
#endif

#include <errno.h>

#if !defined (errno)
extern int errno;
#endif

#include "bashansi.h"
#include "bashintl.h"
#include "memalloc.h"

#define NEED_FPURGE_DECL

#include "shell.h"
#include "flags.h"
#include "execute_cmd.h"
#include "redir.h"

#if defined (BUFFERED_INPUT)
#  include "input.h"
#endif

#define SHELL_FD_BASE	10

int expanding_redir;

extern int posixly_correct;
extern int last_command_exit_value;
extern REDIRECT *redirection_undo_list;
extern REDIRECT *exec_redirection_undo_list;

/* Static functions defined and used in this file. */
static void add_exec_redirect __P((REDIRECT *));
static int add_undo_redirect __P((int, enum r_instruction, int));
static int add_undo_close_redirect __P((int));
static int expandable_redirection_filename __P((REDIRECT *));
static int stdin_redirection __P((enum r_instruction, int));
static int undoablefd __P((int));
static int do_redirection_internal __P((REDIRECT *, int));

static int write_here_document __P((int, WORD_DESC *));
static int write_here_string __P((int, WORD_DESC *));
static int here_document_to_fd __P((WORD_DESC *, enum r_instruction));

static int redir_special_open __P((int, char *, int, int, enum r_instruction));
static int noclobber_open __P((char *, int, int, enum r_instruction));
static int redir_open __P((char *, int, int, enum r_instruction));

static int redir_varassign __P((REDIRECT *, int));
static int redir_varvalue __P((REDIRECT *));

/* Spare redirector used when translating [N]>&WORD[-] or [N]<&WORD[-] to
   a new redirection and when creating the redirection undo list. */
static REDIRECTEE rd;

/* Set to errno when a here document cannot be created for some reason.
   Used to print a reasonable error message. */
static int heredoc_errno;

#define REDIRECTION_ERROR(r, e, fd) \
do { \
  if ((r) < 0) \
    { \
      if (fd >= 0) \
	close (fd); \
      last_command_exit_value = EXECUTION_FAILURE;\
      return ((e) == 0 ? EINVAL : (e));\
    } \
} while (0)

void
redirection_error (temp, error)
     REDIRECT *temp;
     int error;
{
  char *filename, *allocname;
  int oflags;

  allocname = 0;
  if (temp->rflags & REDIR_VARASSIGN)
    filename = savestring (temp->redirector.filename->word);
  else if (temp->redirector.dest < 0)
    /* This can happen when read_token_word encounters overflow, like in
       exec 4294967297>x */
    filename = _("file descriptor out of range");
#ifdef EBADF
  /* This error can never involve NOCLOBBER */
  else if (error != NOCLOBBER_REDIRECT && temp->redirector.dest >= 0 && error == EBADF)
    {
      /* If we're dealing with two file descriptors, we have to guess about
         which one is invalid; in the cases of r_{duplicating,move}_input and
         r_{duplicating,move}_output we're here because dup2() failed. */
      switch (temp->instruction)
        {
        case r_duplicating_input:
        case r_duplicating_output:
        case r_move_input:
        case r_move_output:
	  filename = allocname = itos (temp->redirectee.dest);
	  break;
	case r_duplicating_input_word:
	  if (temp->redirector.dest == 0)	/* Guess */
	    filename = temp->redirectee.filename->word;	/* XXX */
	  else
	    filename = allocname = itos (temp->redirector.dest);
	  break;
	case r_duplicating_output_word:
	  if (temp->redirector.dest == 1)	/* Guess */
	    filename = temp->redirectee.filename->word;	/* XXX */
	  else
	    filename = allocname = itos (temp->redirector.dest);
	  break;
	default:
	  filename = allocname = itos (temp->redirector.dest);
	  break;
        }
    }
#endif
  else if (expandable_redirection_filename (temp))
    {
expandable_filename:
      if (posixly_correct && interactive_shell == 0)
	{
	  oflags = temp->redirectee.filename->flags;
	  temp->redirectee.filename->flags |= W_NOGLOB;
	}
      filename = allocname = redirection_expand (temp->redirectee.filename);
      if (posixly_correct && interactive_shell == 0)
	temp->redirectee.filename->flags = oflags;
      if (filename == 0)
	filename = temp->redirectee.filename->word;
    }
  else if (temp->redirectee.dest < 0)
    filename = "file descriptor out of range";
  else
    filename = allocname = itos (temp->redirectee.dest);

  switch (error)
    {
    case AMBIGUOUS_REDIRECT:
      internal_error (_("%s: ambiguous redirect"), filename);
      break;

    case NOCLOBBER_REDIRECT:
      internal_error (_("%s: cannot overwrite existing file"), filename);
      break;

#if defined (RESTRICTED_SHELL)
    case RESTRICTED_REDIRECT:
      internal_error (_("%s: restricted: cannot redirect output"), filename);
      break;
#endif /* RESTRICTED_SHELL */

    case HEREDOC_REDIRECT:
      internal_error (_("cannot create temp file for here-document: %s"), strerror (heredoc_errno));
      break;

    case BADVAR_REDIRECT:
      internal_error (_("%s: cannot assign fd to variable"), filename);
      break;

    default:
      internal_error ("%s: %s", filename, strerror (error));
      break;
    }

  FREE (allocname);
}

/* Perform the redirections on LIST.  If flags & RX_ACTIVE, then actually
   make input and output file descriptors, otherwise just do whatever is
   neccessary for side effecting.  flags & RX_UNDOABLE says to remember
   how to undo the redirections later, if non-zero.  If flags & RX_CLEXEC
   is non-zero, file descriptors opened in do_redirection () have their
   close-on-exec flag set. */
int
do_redirections (list, flags)
     REDIRECT *list;
     int flags;
{
  int error;
  REDIRECT *temp;

  if (flags & RX_UNDOABLE)
    {
      if (redirection_undo_list)
	{
	  dispose_redirects (redirection_undo_list);
	  redirection_undo_list = (REDIRECT *)NULL;
	}
      if (exec_redirection_undo_list)
	dispose_exec_redirects ();
    }

  for (temp = list; temp; temp = temp->next)
    {
      error = do_redirection_internal (temp, flags);
      if (error)
	{
	  redirection_error (temp, error);
	  return (error);
	}
    }
  return (0);
}

/* Return non-zero if the redirection pointed to by REDIRECT has a
   redirectee.filename that can be expanded. */
static int
expandable_redirection_filename (redirect)
     REDIRECT *redirect;
{
  switch (redirect->instruction)
    {
    case r_output_direction:
    case r_appending_to:
    case r_input_direction:
    case r_inputa_direction:
    case r_err_and_out:
    case r_append_err_and_out:
    case r_input_output:
    case r_output_force:
    case r_duplicating_input_word:
    case r_duplicating_output_word:
    case r_move_input_word:
    case r_move_output_word:
      return 1;

    default:
      return 0;
    }
}

/* Expand the word in WORD returning a string.  If WORD expands to
   multiple words (or no words), then return NULL. */
char *
redirection_expand (word)
     WORD_DESC *word;
{
  char *result;
  WORD_LIST *tlist1, *tlist2;
  WORD_DESC *w;

  w = copy_word (word);
  if (posixly_correct)
    w->flags |= W_NOSPLIT;

  tlist1 = make_word_list (w, (WORD_LIST *)NULL);
  expanding_redir = 1;
  tlist2 = expand_words_no_vars (tlist1);
  expanding_redir = 0;
  dispose_words (tlist1);

  if (!tlist2 || tlist2->next)
    {
      /* We expanded to no words, or to more than a single word.
	 Dispose of the word list and return NULL. */
      if (tlist2)
	dispose_words (tlist2);
      return ((char *)NULL);
    }
  result = string_list (tlist2);  /* XXX savestring (tlist2->word->word)? */
  dispose_words (tlist2);
  return (result);
}

static int
write_here_string (fd, redirectee)
     int fd;
     WORD_DESC *redirectee;
{
  char *herestr;
  int herelen, n, e;

  expanding_redir = 1;
  herestr = expand_string_to_string (redirectee->word, 0);
  expanding_redir = 0;
  herelen = STRLEN (herestr);

  n = write (fd, herestr, herelen);
  if (n == herelen)
    {
      n = write (fd, "\n", 1);
      herelen = 1;
    }
  e = errno;
  FREE (herestr);
  if (n != herelen)
    {
      if (e == 0)
	e = ENOSPC;
      return e;
    }
  return 0;
}  

/* Write the text of the here document pointed to by REDIRECTEE to the file
   descriptor FD, which is already open to a temp file.  Return 0 if the
   write is successful, otherwise return errno. */
static int
write_here_document (fd, redirectee)
     int fd;
     WORD_DESC *redirectee;
{
  char *document;
  int document_len, fd2;
  FILE *fp;
  register WORD_LIST *t, *tlist;

  /* Expand the text if the word that was specified had
     no quoting.  The text that we expand is treated
     exactly as if it were surrounded by double quotes. */

  if (redirectee->flags & W_QUOTED)
    {
      document = redirectee->word;
      document_len = strlen (document);
      /* Set errno to something reasonable if the write fails. */
      if (write (fd, document, document_len) < document_len)
	{
	  if (errno == 0)
	    errno = ENOSPC;
	  return (errno);
	}
      else
	return 0;
    }

  expanding_redir = 1;
  tlist = expand_string (redirectee->word, Q_HERE_DOCUMENT);
  expanding_redir = 0;

  if (tlist)
    {
      /* Try using buffered I/O (stdio) and writing a word
	 at a time, letting stdio do the work of buffering
	 for us rather than managing our own strings.  Most
	 stdios are not particularly fast, however -- this
	 may need to be reconsidered later. */
      if ((fd2 = dup (fd)) < 0 || (fp = fdopen (fd2, "w")) == NULL)
	{
	  if (fd2 >= 0)
	    close (fd2);
	  return (errno);
	}
      errno = 0;
      for (t = tlist; t; t = t->next)
	{
	  /* This is essentially the body of
	     string_list_internal expanded inline. */
	  document = t->word->word;
	  document_len = strlen (document);
	  if (t != tlist)
	    putc (' ', fp);	/* separator */
	  fwrite (document, document_len, 1, fp);
	  if (ferror (fp))
	    {
	      if (errno == 0)
		errno = ENOSPC;
	      fd2 = errno;
	      fclose(fp);
	      dispose_words (tlist);
	      return (fd2);
	    }
	}
      dispose_words (tlist);
      if (fclose (fp) != 0)
	{
	  if (errno == 0)
	    errno = ENOSPC;
	  return (errno);
	}
    }
  return 0;
}

/* Create a temporary file holding the text of the here document pointed to
   by REDIRECTEE, and return a file descriptor open for reading to the temp
   file.  Return -1 on any error, and make sure errno is set appropriately. */
static int
here_document_to_fd (redirectee, ri)
     WORD_DESC *redirectee;
     enum r_instruction ri;
{
  char *filename;
  int r, fd, fd2;

  fd = sh_mktmpfd ("sh-thd", MT_USERANDOM|MT_USETMPDIR, &filename);

  /* If we failed for some reason other than the file existing, abort */
  if (fd < 0)
    {
      FREE (filename);
      return (fd);
    }

  errno = r = 0;		/* XXX */
  /* write_here_document returns 0 on success, errno on failure. */
  if (redirectee->word)
    r = (ri != r_reading_string) ? write_here_document (fd, redirectee)
				 : write_here_string (fd, redirectee);