utils.c

wget讓你可以在console介面下

/* Various utility functions.
   Copyright (C) 2005 Free Software Foundation, Inc.

This file is part of GNU Wget.

GNU Wget 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 2 of the License, or
(at your option) any later version.

GNU Wget 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 Wget; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

In addition, as a special exception, the Free Software Foundation
gives permission to link the code of its release of Wget with the
OpenSSL project's "OpenSSL" library (or with modified versions of it
that use the same license as the "OpenSSL" library), and distribute
the linked executables.  You must obey the GNU General Public License
in all respects for all of the code used other than "OpenSSL".  If you
modify this file, you may extend this exception to your version of the
file, but you are not obligated to do so.  If you do not wish to do
so, delete this exception statement from your version.  */

#include <config.h>

#include <stdio.h>
#include <stdlib.h>
#ifdef HAVE_STRING_H
# include <string.h>
#else  /* not HAVE_STRING_H */
# include <strings.h>
#endif /* not HAVE_STRING_H */
#include <sys/types.h>
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#ifdef HAVE_MMAP
# include <sys/mman.h>
#endif
#ifdef HAVE_PWD_H
# include <pwd.h>
#endif
#ifdef HAVE_LIMITS_H
# include <limits.h>
#endif
#ifdef HAVE_UTIME_H
# include <utime.h>
#endif
#ifdef HAVE_SYS_UTIME_H
# include <sys/utime.h>
#endif
#include <errno.h>
#ifdef NeXT
# include <libc.h>		/* for access() */
#endif
#include <fcntl.h>
#include <assert.h>
#ifdef WGET_USE_STDARG
# include <stdarg.h>
#else
# include <varargs.h>
#endif
#ifdef HAVE_LOCALE_H
# include <locale.h>
#endif

/* For TIOCGWINSZ and friends: */
#ifdef HAVE_SYS_IOCTL_H
# include <sys/ioctl.h>
#endif
#ifdef HAVE_TERMIOS_H
# include <termios.h>
#endif

/* Needed for run_with_timeout. */
#undef USE_SIGNAL_TIMEOUT
#ifdef HAVE_SIGNAL_H
# include <signal.h>
#endif
#ifdef HAVE_SETJMP_H
# include <setjmp.h>
#endif

#ifndef HAVE_SIGSETJMP
/* If sigsetjmp is a macro, configure won't pick it up. */
# ifdef sigsetjmp
#  define HAVE_SIGSETJMP
# endif
#endif

#ifdef HAVE_SIGNAL
# ifdef HAVE_SIGSETJMP
#  define USE_SIGNAL_TIMEOUT
# endif
# ifdef HAVE_SIGBLOCK
#  define USE_SIGNAL_TIMEOUT
# endif
#endif

#include "wget.h"
#include "utils.h"
#include "hash.h"

#ifndef errno
extern int errno;
#endif

/* Utility function: like xstrdup(), but also lowercases S.  */

char *
xstrdup_lower (const char *s)
{
  char *copy = xstrdup (s);
  char *p = copy;
  for (; *p; p++)
    *p = TOLOWER (*p);
  return copy;
}

/* Copy the string formed by two pointers (one on the beginning, other
   on the char after the last char) to a new, malloc-ed location.
   0-terminate it.  */
char *
strdupdelim (const char *beg, const char *end)
{
  char *res = (char *)xmalloc (end - beg + 1);
  memcpy (res, beg, end - beg);
  res[end - beg] = '\0';
  return res;
}

/* Parse a string containing comma-separated elements, and return a
   vector of char pointers with the elements.  Spaces following the
   commas are ignored.  */
char **
sepstring (const char *s)
{
  char **res;
  const char *p;
  int i = 0;

  if (!s || !*s)
    return NULL;
  res = NULL;
  p = s;
  while (*s)
    {
      if (*s == ',')
	{
	  res = (char **)xrealloc (res, (i + 2) * sizeof (char *));
	  res[i] = strdupdelim (p, s);
	  res[++i] = NULL;
	  ++s;
	  /* Skip the blanks following the ','.  */
	  while (ISSPACE (*s))
	    ++s;
	  p = s;
	}
      else
	++s;
    }
  res = (char **)xrealloc (res, (i + 2) * sizeof (char *));
  res[i] = strdupdelim (p, s);
  res[i + 1] = NULL;
  return res;
}

#ifdef WGET_USE_STDARG
# define VA_START(args, arg1) va_start (args, arg1)
#else
# define VA_START(args, ignored) va_start (args)
#endif

/* Like sprintf, but allocates a string of sufficient size with malloc
   and returns it.  GNU libc has a similar function named asprintf,
   which requires the pointer to the string to be passed.  */

char *
aprintf (const char *fmt, ...)
{
  /* This function is implemented using vsnprintf, which we provide
     for the systems that don't have it.  Therefore, it should be 100%
     portable.  */

  int size = 32;
  char *str = xmalloc (size);

  while (1)
    {
      int n;
      va_list args;

      /* See log_vprintf_internal for explanation why it's OK to rely
	 on the return value of vsnprintf.  */

      VA_START (args, fmt);
      n = vsnprintf (str, size, fmt, args);
      va_end (args);

      /* If the printing worked, return the string. */
      if (n > -1 && n < size)
	return str;

      /* Else try again with a larger buffer. */
      if (n > -1)		/* C99 */
	size = n + 1;		/* precisely what is needed */
      else
	size <<= 1;		/* twice the old size */
      str = xrealloc (str, size);
    }
}

/* Concatenate the NULL-terminated list of string arguments into
   freshly allocated space.  */

char *
concat_strings (const char *str0, ...)
{
  va_list args;
  int saved_lengths[5];		/* inspired by Apache's apr_pstrcat */
  char *ret, *p;

  const char *next_str;
  int total_length = 0;
  int argcount;

  /* Calculate the length of and allocate the resulting string. */

  argcount = 0;
  VA_START (args, str0);
  for (next_str = str0; next_str != NULL; next_str = va_arg (args, char *))
    {
      int len = strlen (next_str);
      if (argcount < countof (saved_lengths))
	saved_lengths[argcount++] = len;
      total_length += len;
    }
  va_end (args);
  p = ret = xmalloc (total_length + 1);

  /* Copy the strings into the allocated space. */

  argcount = 0;
  VA_START (args, str0);
  for (next_str = str0; next_str != NULL; next_str = va_arg (args, char *))
    {
      int len;
      if (argcount < countof (saved_lengths))
	len = saved_lengths[argcount++];
      else
	len = strlen (next_str);
      memcpy (p, next_str, len);
      p += len;
    }
  va_end (args);
  *p = '\0';

  return ret;
}

/* Return pointer to a static char[] buffer in which zero-terminated
   string-representation of TM (in form hh:mm:ss) is printed.

   If TM is NULL, the current time will be used.  */

char *
time_str (time_t *tm)
{
  static char output[15];
  struct tm *ptm;
  time_t secs = tm ? *tm : time (NULL);

  if (secs == -1)
    {
      /* In case of error, return the empty string.  Maybe we should
	 just abort if this happens?  */
      *output = '\0';
      return output;
    }
  ptm = localtime (&secs);
  sprintf (output, "%02d:%02d:%02d", ptm->tm_hour, ptm->tm_min, ptm->tm_sec);
  return output;
}

/* Like the above, but include the date: YYYY-MM-DD hh:mm:ss.  */

char *
datetime_str (time_t *tm)
{
  static char output[20];	/* "YYYY-MM-DD hh:mm:ss" + \0 */
  struct tm *ptm;
  time_t secs = tm ? *tm : time (NULL);

  if (secs == -1)
    {
      /* In case of error, return the empty string.  Maybe we should
	 just abort if this happens?  */
      *output = '\0';
      return output;
    }
  ptm = localtime (&secs);
  sprintf (output, "%04d-%02d-%02d %02d:%02d:%02d",
	   ptm->tm_year + 1900, ptm->tm_mon + 1, ptm->tm_mday,
	   ptm->tm_hour, ptm->tm_min, ptm->tm_sec);
  return output;
}

/* The Windows versions of the following two functions are defined in
   mswindows.c.  */

#ifndef WINDOWS
void
fork_to_background (void)
{
  pid_t pid;
  /* Whether we arrange our own version of opt.lfilename here.  */
  int logfile_changed = 0;

  if (!opt.lfilename)
    {
      /* We must create the file immediately to avoid either a race
	 condition (which arises from using unique_name and failing to
	 use fopen_excl) or lying to the user about the log file name
	 (which arises from using unique_name, printing the name, and
	 using fopen_excl later on.)  */
      FILE *new_log_fp = unique_create (DEFAULT_LOGFILE, 0, &opt.lfilename);
      if (new_log_fp)
	{
	  logfile_changed = 1;
	  fclose (new_log_fp);
	}
    }
  pid = fork ();
  if (pid < 0)
    {
      /* parent, error */
      perror ("fork");
      exit (1);
    }
  else if (pid != 0)
    {
      /* parent, no error */
      printf (_("Continuing in background, pid %d.\n"), (int)pid);
      if (logfile_changed)
	printf (_("Output will be written to `%s'.\n"), opt.lfilename);
      exit (0);			/* #### should we use _exit()? */
    }

  /* child: give up the privileges and keep running. */
  setsid ();
  freopen ("/dev/null", "r", stdin);
  freopen ("/dev/null", "w", stdout);
  freopen ("/dev/null", "w", stderr);
}
#endif /* not WINDOWS */

/* "Touch" FILE, i.e. make its mtime ("modified time") equal the time
   specified with TM.  The atime ("access time") is set to the current
   time.  */

void
touch (const char *file, time_t tm)
{
#ifdef HAVE_STRUCT_UTIMBUF
  struct utimbuf times;
#else
  struct {
    time_t actime;
    time_t modtime;
  } times;
#endif
  times.modtime = tm;
  times.actime = time (NULL);
  if (utime (file, &times) == -1)
    logprintf (LOG_NOTQUIET, "utime(%s): %s\n", file, strerror (errno));
}

/* Checks if FILE is a symbolic link, and removes it if it is.  Does
   nothing under MS-Windows.  */
int
remove_link (const char *file)
{
  int err = 0;
  struct_stat st;

  if (lstat (file, &st) == 0 && S_ISLNK (st.st_mode))
    {
      DEBUGP (("Unlinking %s (symlink).\n", file));
      err = unlink (file);
      if (err != 0)
	logprintf (LOG_VERBOSE, _("Failed to unlink symlink `%s': %s\n"),
		   file, strerror (errno));
    }
  return err;
}

/* Does FILENAME exist?  This is quite a lousy implementation, since
   it supplies no error codes -- only a yes-or-no answer.  Thus it
   will return that a file does not exist if, e.g., the directory is
   unreadable.  I don't mind it too much currently, though.  The
   proper way should, of course, be to have a third, error state,
   other than true/false, but that would introduce uncalled-for
   additional complexity to the callers.  */
int
file_exists_p (const char *filename)
{
#ifdef HAVE_ACCESS
  return access (filename, F_OK) >= 0;
#else
  struct_stat buf;
  return stat (filename, &buf) >= 0;
#endif
}

/* Returns 0 if PATH is a directory, 1 otherwise (any kind of file).
   Returns 0 on error.  */
int
file_non_directory_p (const char *path)
{
  struct_stat buf;
  /* Use lstat() rather than stat() so that symbolic links pointing to
     directories can be identified correctly.  */
  if (lstat (path, &buf) != 0)
    return 0;
  return S_ISDIR (buf.st_mode) ? 0 : 1;
}

/* Return the size of file named by FILENAME, or -1 if it cannot be
   opened or seeked into. */
wgint
file_size (const char *filename)
{
#if defined(HAVE_FSEEKO) && defined(HAVE_FTELLO)
  wgint size;
  /* We use fseek rather than stat to determine the file size because
     that way we can also verify that the file is readable without
     explicitly checking for permissions.  Inspired by the POST patch
     by Arnaud Wylie.  */
  FILE *fp = fopen (filename, "rb");
  if (!fp)
    return -1;
  fseeko (fp, 0, SEEK_END);
  size = ftello (fp);
  fclose (fp);
  return size;
#else
  struct_stat st;
  if (stat (filename, &st) < 0)
    return -1;
  return st.st_size;
#endif
}

/* stat file names named PREFIX.1, PREFIX.2, etc., until one that
   doesn't exist is found.  Return a freshly allocated copy of the
   unused file name.  */

static char *
unique_name_1 (const char *prefix)
{
  int count = 1;
  int plen = strlen (prefix);
  char *template = (char *)alloca (plen + 1 + 24);
  char *template_tail = template + plen;

  memcpy (template, prefix, plen);
  *template_tail++ = '.';

  do
    number_to_string (template_tail, count++);
  while (file_exists_p (template));

  return xstrdup (template);
}

/* Return a unique file name, based on FILE.

   More precisely, if FILE doesn't exist, it is returned unmodified.
   If not, FILE.1 is tried, then FILE.2, etc.  The first FILE.<number>
   file name that doesn't exist is returned.

   The resulting file is not created, only verified that it didn't
   exist at the point in time when the function was called.
   Therefore, where security matters, don't rely that the file created
   by this function exists until you open it with O_EXCL or
   equivalent.

   If ALLOW_PASSTHROUGH is 0, it always returns a freshly allocated
   string.  Otherwise, it may return FILE if the file doesn't exist
   (and therefore doesn't need changing).  */

char *
unique_name (const char *file, int allow_passthrough)
{
  /* If the FILE itself doesn't exist, return it without
     modification. */
  if (!file_exists_p (file))
    return allow_passthrough ? (char *)file : xstrdup (file);

  /* Otherwise, find a numeric suffix that results in unused file name
     and return it.  */
  return unique_name_1 (file);
}

/* Create a file based on NAME, except without overwriting an existing
   file with that name.  Providing O_EXCL is correctly implemented,
   this function does not have the race condition associated with
   opening the file returned by unique_name.  */

FILE *
unique_create (const char *name, int binary, char **opened_name)
{
  /* unique file name, based on NAME */
  char *uname = unique_name (name, 0);
  FILE *fp;
  while ((fp = fopen_excl (uname, binary)) == NULL && errno == EEXIST)
    {