error.c

/* Error handler for noninteractive utilities
   Copyright (C) 1990-2016 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C 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.

   The GNU C 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 the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

/* Written by David MacKenzie <djm@gnu.ai.mit.edu>.  */

#if !_LIBC
# include <config.h>
#endif

#include "error.h"

#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#if !_LIBC && ENABLE_NLS
# include "gettext.h"
# define _(msgid) gettext (msgid)
#endif

#ifdef _LIBC
# include <libintl.h>
# include <stdbool.h>
# include <stdint.h>
# include <wchar.h>
# define mbsrtowcs __mbsrtowcs
# define USE_UNLOCKED_IO 0
# define _GL_ATTRIBUTE_FORMAT_PRINTF(a, b)
# define _GL_ARG_NONNULL(a)
#endif

#if USE_UNLOCKED_IO
# include "unlocked-io.h"
#endif

#ifndef _
# define _(String) String
#endif

/* If NULL, error will flush stdout, then print on stderr the program
   name, a colon and a space.  Otherwise, error will call this
   function without parameters instead.  */
void (*error_print_progname) (void);

/* This variable is incremented each time 'error' is called.  */
unsigned int error_message_count;

#ifdef _LIBC
/* In the GNU C library, there is a predefined variable for this.  */

# define program_name program_invocation_name
# include <errno.h>
# include <limits.h>
# include <libio/libioP.h>

/* In GNU libc we want do not want to use the common name 'error' directly.
   Instead make it a weak alias.  */
extern void __error (int status, int errnum, const char *message, ...)
     __attribute__ ((__format__ (__printf__, 3, 4)));
extern void __error_at_line (int status, int errnum, const char *file_name,
			     unsigned int line_number, const char *message,
			     ...)
     __attribute__ ((__format__ (__printf__, 5, 6)));;
# define error __error
# define error_at_line __error_at_line

# include <libio/iolibio.h>
# define fflush(s) _IO_fflush (s)
# undef putc
# define putc(c, fp) _IO_putc (c, fp)

# include <libc-lock.h>

#else /* not _LIBC */

# include <fcntl.h>
# include <unistd.h>

# if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
/* Get declarations of the native Windows API functions.  */
#  define WIN32_LEAN_AND_MEAN
#  include <windows.h>
/* Get _get_osfhandle.  */
#  include "msvc-nothrow.h"
# endif

/* The gnulib override of fcntl is not needed in this file.  */
# undef fcntl

# if !HAVE_DECL_STRERROR_R
#  ifndef HAVE_DECL_STRERROR_R
"this configure-time declaration test was not run"
#  endif
#  if STRERROR_R_CHAR_P
char *strerror_r ();
#  else
int strerror_r ();
#  endif
# endif

/* The calling program should define program_name and set it to the
   name of the executing program.  */
extern char *program_name;

# if HAVE_STRERROR_R || defined strerror_r
#  define __strerror_r strerror_r
# endif	/* HAVE_STRERROR_R || defined strerror_r */
#endif	/* not _LIBC */

#if !_LIBC
/* Return non-zero if FD is open.  */
static int
is_open (int fd)
{
# if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  /* On native Windows: The initial state of unassigned standard file
     descriptors is that they are open but point to an INVALID_HANDLE_VALUE.
     There is no fcntl, and the gnulib replacement fcntl does not support
     F_GETFL.  */
  return (HANDLE) _get_osfhandle (fd) != INVALID_HANDLE_VALUE;
# else
#  ifndef F_GETFL
#   error Please port fcntl to your platform
#  endif
  return 0 <= fcntl (fd, F_GETFL);
# endif
}
#endif

static void
flush_stdout (void)
{
#if !_LIBC
  int stdout_fd;

# if GNULIB_FREOPEN_SAFER
  /* Use of gnulib's freopen-safer module normally ensures that
       fileno (stdout) == 1
     whenever stdout is open.  */
  stdout_fd = STDOUT_FILENO;
# else
  /* POSIX states that fileno (stdout) after fclose is unspecified.  But in
     practice it is not a problem, because stdout is statically allocated and
     the fd of a FILE stream is stored as a field in its allocated memory.  */
  stdout_fd = fileno (stdout);
# endif
  /* POSIX states that fflush (stdout) after fclose is unspecified; it
     is safe in glibc, but not on all other platforms.  fflush (NULL)
     is always defined, but too draconian.  */
  if (0 <= stdout_fd && is_open (stdout_fd))
#endif
    fflush (stdout);
}

static void
print_errno_message (int errnum)
{
  char const *s;

#if defined HAVE_STRERROR_R || _LIBC
  char errbuf[1024];
# if _LIBC || STRERROR_R_CHAR_P
  s = __strerror_r (errnum, errbuf, sizeof errbuf);
# else
  if (__strerror_r (errnum, errbuf, sizeof errbuf) == 0)
    s = errbuf;
  else
    s = 0;
# endif
#else
  s = strerror (errnum);
#endif

#if !_LIBC
  if (! s)
    s = _("Unknown system error");
#endif

#if _LIBC
  __fxprintf (NULL, ": %s", s);
#else
  fprintf (stderr, ": %s", s);
#endif
}

static void _GL_ATTRIBUTE_FORMAT_PRINTF (3, 0) _GL_ARG_NONNULL ((3))
error_tail (int status, int errnum, const char *message, va_list args)
{
#if _LIBC
  if (_IO_fwide (stderr, 0) > 0)
    {
      size_t len = strlen (message) + 1;
      wchar_t *wmessage = NULL;
      mbstate_t st;
      size_t res;
      const char *tmp;
      bool use_malloc = false;

      while (1)
	{
	  if (__libc_use_alloca (len * sizeof (wchar_t)))
	    wmessage = (wchar_t *) alloca (len * sizeof (wchar_t));
	  else
	    {
	      if (!use_malloc)
		wmessage = NULL;

	      wchar_t *p = (wchar_t *) realloc (wmessage,
						len * sizeof (wchar_t));
	      if (p == NULL)
		{
		  free (wmessage);
		  fputws_unlocked (L"out of memory\n", stderr);
		  return;
		}
	      wmessage = p;
	      use_malloc = true;
	    }

	  memset (&st, '\0', sizeof (st));
	  tmp = message;

	  res = mbsrtowcs (wmessage, &tmp, len, &st);
	  if (res != len)
	    break;

	  if (__builtin_expect (len >= SIZE_MAX / sizeof (wchar_t) / 2, 0))
	    {
	      /* This really should not happen if everything is fine.  */
	      res = (size_t) -1;
	      break;
	    }

	  len *= 2;
	}

      if (res == (size_t) -1)
	{
	  /* The string cannot be converted.  */
	  if (use_malloc)
	    {
	      free (wmessage);
	      use_malloc = false;
	    }
	  wmessage = (wchar_t *) L"???";
	}

      __vfwprintf (stderr, wmessage, args);

      if (use_malloc)
	free (wmessage);
    }
  else
#endif
    vfprintf (stderr, message, args);
  va_end (args);

  ++error_message_count;
  if (errnum)
    print_errno_message (errnum);
#if _LIBC
  __fxprintf (NULL, "\n");
#else
  putc ('\n', stderr);
#endif
  fflush (stderr);
  if (status)
    exit (status);
}


/* Print the program name and error message MESSAGE, which is a printf-style
   format string with optional args.
   If ERRNUM is nonzero, print its corresponding system error message.
   Exit with status STATUS if it is nonzero.  */
void
error (int status, int errnum, const char *message, ...)
{
  va_list args;

#if defined _LIBC && defined __libc_ptf_call
  /* We do not want this call to be cut short by a thread
     cancellation.  Therefore disable cancellation for now.  */
  int state = PTHREAD_CANCEL_ENABLE;
  __libc_ptf_call (__pthread_setcancelstate,
		   (PTHREAD_CANCEL_DISABLE, &state), 0);
#endif

  flush_stdout ();
#ifdef _LIBC
  _IO_flockfile (stderr);
#endif
  if (error_print_progname)
    (*error_print_progname) ();
  else
    {
#if _LIBC
      __fxprintf (NULL, "%s: ", program_name);
#else
      fprintf (stderr, "%s: ", program_name);
#endif
    }

  va_start (args, message);
  error_tail (status, errnum, message, args);

#ifdef _LIBC
  _IO_funlockfile (stderr);
# ifdef __libc_ptf_call
  __libc_ptf_call (__pthread_setcancelstate, (state, NULL), 0);
# endif
#endif
}

/* Sometimes we want to have at most one error per line.  This
   variable controls whether this mode is selected or not.  */
int error_one_per_line;

void
error_at_line (int status, int errnum, const char *file_name,
	       unsigned int line_number, const char *message, ...)
{
  va_list args;

  if (error_one_per_line)
    {
      static const char *old_file_name;
      static unsigned int old_line_number;

      if (old_line_number == line_number
	  && (file_name == old_file_name
	      || (old_file_name != NULL
		  && file_name != NULL
		  && strcmp (old_file_name, file_name) == 0)))

	/* Simply return and print nothing.  */
	return;

      old_file_name = file_name;
      old_line_number = line_number;
    }

#if defined _LIBC && defined __libc_ptf_call
  /* We do not want this call to be cut short by a thread
     cancellation.  Therefore disable cancellation for now.  */
  int state = PTHREAD_CANCEL_ENABLE;
  __libc_ptf_call (__pthread_setcancelstate,
		   (PTHREAD_CANCEL_DISABLE, &state),
		   0);
#endif

  flush_stdout ();
#ifdef _LIBC
  _IO_flockfile (stderr);
#endif
  if (error_print_progname)
    (*error_print_progname) ();
  else
    {
#if _LIBC
      __fxprintf (NULL, "%s:", program_name);
#else
      fprintf (stderr, "%s:", program_name);
#endif
    }

#if _LIBC
  __fxprintf (NULL, file_name != NULL ? "%s:%d: " : " ",
	      file_name, line_number);
#else
  fprintf (stderr, file_name != NULL ? "%s:%d: " : " ",
	   file_name, line_number);
#endif

  va_start (args, message);
  error_tail (status, errnum, message, args);

#ifdef _LIBC
  _IO_funlockfile (stderr);
# ifdef __libc_ptf_call
  __libc_ptf_call (__pthread_setcancelstate, (state, NULL), 0);
# endif
#endif
}

#ifdef _LIBC
/* Make the weak alias.  */
# undef error
# undef error_at_line
weak_alias (__error, error)
weak_alias (__error_at_line, error_at_line)
#endif