path: root/src/grep.c

/* grep.c - main driver file for grep.
   Copyright 1992, 1997-1999, 2000 Free Software Foundation, Inc.

   This program 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, or (at your option)
   any later version.

   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 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., 59 Temple Place - Suite 330, Boston, MA
   02111-1307, USA.  */

/* Written July 1992 by Mike Haertel.  */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <sys/types.h>
#include <sys/stat.h>
#if defined(HAVE_MMAP)
# include <sys/mman.h>
#endif
#if defined(HAVE_SETRLIMIT)
# include <sys/time.h>
# include <sys/resource.h>
#endif
#include <stdio.h>
#include "system.h"
#include "getopt.h"
#include "getpagesize.h"
#include "grep.h"
#include "savedir.h"
#include "xstrtol.h"

#undef MAX
#define MAX(A,B) ((A) > (B) ? (A) : (B))

struct stats
{
  struct stats const *parent;
  struct stat stat;
};

/* base of chain of stat buffers, used to detect directory loops */
static struct stats stats_base;

/* if non-zero, display usage information and exit */
static int show_help;

/* If non-zero, print the version on standard output and exit.  */
static int show_version;

/* If nonzero, use mmap if possible.  */
static int mmap_option;

/* Short options.  */
static char const short_options[] =
"0123456789A:B:C:EFGHIPUVX:abcd:e:f:hiLlm:nqrsuvwxyZz";

/* Non-boolean long options that have no corresponding short equivalents.  */
enum
{
  BINARY_FILES_OPTION = CHAR_MAX + 1
};

/* Long options equivalences. */
static struct option const long_options[] =
{
  {"after-context", required_argument, NULL, 'A'},
  {"basic-regexp", no_argument, NULL, 'G'},
  {"before-context", required_argument, NULL, 'B'},
  {"binary-files", required_argument, NULL, BINARY_FILES_OPTION},
  {"byte-offset", no_argument, NULL, 'b'},
  {"context", required_argument, NULL, 'C'},
  {"count", no_argument, NULL, 'c'},
  {"directories", required_argument, NULL, 'd'},
  {"extended-regexp", no_argument, NULL, 'E'},
  {"file", required_argument, NULL, 'f'},
  {"files-with-matches", no_argument, NULL, 'l'},
  {"files-without-match", no_argument, NULL, 'L'},
  {"fixed-regexp", no_argument, NULL, 'F'},
  {"fixed-strings", no_argument, NULL, 'F'},
  {"help", no_argument, &show_help, 1},
  {"ignore-case", no_argument, NULL, 'i'},
  {"line-number", no_argument, NULL, 'n'},
  {"line-regexp", no_argument, NULL, 'x'},
  {"max-count", required_argument, NULL, 'm'},
  {"mmap", no_argument, &mmap_option, 1},
  {"no-filename", no_argument, NULL, 'h'},
  {"no-messages", no_argument, NULL, 's'},
  {"null", no_argument, NULL, 'Z'},
  {"null-data", no_argument, NULL, 'z'},
  {"perl-regexp", no_argument, NULL, 'P'},
  {"quiet", no_argument, NULL, 'q'},
  {"recursive", no_argument, NULL, 'r'},
  {"regexp", required_argument, NULL, 'e'},
  {"invert-match", no_argument, NULL, 'v'},
  {"silent", no_argument, NULL, 'q'},
  {"text", no_argument, NULL, 'a'},
  {"binary", no_argument, NULL, 'U'},
  {"unix-byte-offsets", no_argument, NULL, 'u'},
  {"version", no_argument, NULL, 'V'},
  {"with-filename", no_argument, NULL, 'H'},
  {"word-regexp", no_argument, NULL, 'w'},
  {0, 0, 0, 0}
};

/* Define flags declared in grep.h. */
int match_icase;
int match_words;
int match_lines;
unsigned char eolbyte;

/* For error messages. */
static char *prog;
static char const *filename;
static int errseen;

/* How to handle directories.  */
static enum
  {
    READ_DIRECTORIES,
    RECURSE_DIRECTORIES,
    SKIP_DIRECTORIES
  } directories;

static int grepdir PARAMS ((char const *, struct stats const *));
#if HAVE_DOS_FILE_CONTENTS
static inline int undossify_input PARAMS ((register char *, size_t));
#endif

/* Functions we'll use to search. */
static void (*compile) PARAMS ((char const *, size_t));
static size_t (*execute) PARAMS ((char const *, size_t, size_t *));

/* Print a message and possibly an error string.  Remember
   that something awful happened. */
static void
error (const char *mesg, int errnum)
{
  if (errnum)
    fprintf (stderr, "%s: %s: %s\n", prog, mesg, strerror (errnum));
  else
    fprintf (stderr, "%s: %s\n", prog, mesg);
  errseen = 1;
}

/* Like error (), but die horribly after printing. */
void
fatal (const char *mesg, int errnum)
{
  error (mesg, errnum);
  exit (2);
}

/* Interface to handle errors and fix library lossage. */
char *
xmalloc (size_t size)
{
  char *result;

  result = malloc (size);
  if (size && !result)
    fatal (_("memory exhausted"), 0);
  return result;
}

/* Interface to handle errors and fix some library lossage. */
char *
xrealloc (char *ptr, size_t size)
{
  char *result;

  if (ptr)
    result = realloc (ptr, size);
  else
    result = malloc (size);
  if (size && !result)
    fatal (_("memory exhausted"), 0);
  return result;
}

/* Convert STR to a positive integer, storing the result in *OUT.
   STR must be a valid context length argument; report an error if it
   isn't.  */
static void
context_length_arg (char const *str, int *out)
{
  uintmax_t value;
  if (! (xstrtoumax (str, 0, 10, &value, "") == LONGINT_OK
	 && 0 <= (*out = value)
	 && *out == value))
    {
      fprintf (stderr, "%s: %s: %s\n", prog, str,
	       _("invalid context length argument"));
      exit (2);
    }
}


/* Hairy buffering mechanism for grep.  The intent is to keep
   all reads aligned on a page boundary and multiples of the
   page size. */

static char *ubuffer;		/* Unaligned base of buffer. */
static char *buffer;		/* Base of buffer. */
static size_t bufsalloc;	/* Allocated size of buffer save region. */
static size_t bufalloc;		/* Total buffer size. */
#define PREFERRED_SAVE_FACTOR 5	/* Preferred value of bufalloc / bufsalloc.  */
static int bufdesc;		/* File descriptor. */
static char *bufbeg;		/* Beginning of user-visible stuff. */
static char *buflim;		/* Limit of user-visible stuff. */
static size_t pagesize;		/* alignment of memory pages */
static off_t bufoffset;		/* Read offset; defined on regular files.  */
static off_t after_last_match;	/* Pointer after last matching line that
				   would have been output if we were
				   outputting characters. */

#if defined(HAVE_MMAP)
static int bufmapped;		/* True if buffer is memory-mapped.  */
static off_t initial_bufoffset;	/* Initial value of bufoffset. */
#else
# define bufmapped 0
#endif

/* Return VAL aligned to the next multiple of ALIGNMENT.  VAL can be
   an integer or a pointer.  Both args must be free of side effects.  */
#define ALIGN_TO(val, alignment) \
  ((size_t) (val) % (alignment) == 0 \
   ? (val) \
   : (val) + ((alignment) - (size_t) (val) % (alignment)))

/* Return the address of a page-aligned buffer of size SIZE,
   reallocating it from *UP.  Set *UP to the newly allocated (but
   possibly unaligned) buffer used to build the aligned buffer.  To
   free the buffer, free (*UP).  */
static char *
page_alloc (size_t size, char **up)
{
  size_t asize = size + pagesize - 1;
  if (size <= asize)
    {
      char *p = *up ? realloc (*up, asize) : malloc (asize);
      if (p)
	{
	  *up = p;
	  return ALIGN_TO (p, pagesize);
	}
    }
  return NULL;
}

/* Reset the buffer for a new file, returning zero if we should skip it.
   Initialize on the first time through. */
static int
reset (int fd, char const *file, struct stats *stats)
{
  if (pagesize)
    bufsalloc = ALIGN_TO (bufalloc / PREFERRED_SAVE_FACTOR, pagesize);
  else
    {
      size_t ubufsalloc;
      pagesize = getpagesize ();
      if (pagesize == 0)
	abort ();
#ifndef BUFSALLOC
      ubufsalloc = MAX (8192, pagesize);
#else
      ubufsalloc = BUFSALLOC;
#endif
      bufsalloc = ALIGN_TO (ubufsalloc, pagesize);
      bufalloc = PREFERRED_SAVE_FACTOR * bufsalloc;
      if (bufsalloc < ubufsalloc
	  || bufalloc / PREFERRED_SAVE_FACTOR != bufsalloc
	  || ! (buffer = page_alloc (bufalloc, &ubuffer)))
	fatal (_("memory exhausted"), 0);
    }

  buflim = buffer;
  bufdesc = fd;

  if (fstat (fd, &stats->stat) != 0)
    {
      error ("fstat", errno);
      return 0;
    }
  if (directories == SKIP_DIRECTORIES && S_ISDIR (stats->stat.st_mode))
    return 0;
  if (S_ISREG (stats->stat.st_mode))
    {
      if (file)
	bufoffset = 0;
      else
	{
	  bufoffset = lseek (fd, 0, SEEK_CUR);
	  if (bufoffset < 0)
	    {
	      error ("lseek", errno);
	      return 0;
	    }
	}
#ifdef HAVE_MMAP
      initial_bufoffset = bufoffset;
      bufmapped = mmap_option && bufoffset % pagesize == 0;
#endif
    }
  else
    {
#ifdef HAVE_MMAP
      bufmapped = 0;
#endif
    }
  return 1;
}

/* Read new stuff into the buffer, saving the specified
   amount of old stuff.  When we're done, 'bufbeg' points
   to the beginning of the buffer contents, and 'buflim'
   points just after the end.  Return zero if there's an error.  */
static int
fillbuf (size_t save, struct stats const *stats)
{
  size_t fillsize = 0;
  int cc = 1;
  size_t readsize;

  /* Offset from start of unaligned buffer to start of old stuff
     that we want to save.  */
  size_t saved_offset = buflim - ubuffer - save;

  if (bufsalloc < save)
    {
      size_t aligned_save = ALIGN_TO (save, pagesize);
      size_t maxalloc = (size_t) -1;
      size_t newalloc;

      if (S_ISREG (stats->stat.st_mode))
	{
	  /* Calculate an upper bound on how much memory we should allocate.
	     We can't use ALIGN_TO here, since off_t might be longer than
	     size_t.  Watch out for arithmetic overflow.  */
	  off_t to_be_read = stats->stat.st_size - bufoffset;
	  size_t slop = to_be_read % pagesize;
	  off_t aligned_to_be_read = to_be_read + (slop ? pagesize - slop : 0);
	  off_t maxalloc_off = aligned_save + aligned_to_be_read;
	  if (0 <= maxalloc_off && maxalloc_off == (size_t) maxalloc_off)
	    maxalloc = maxalloc_off;
	}

      /* Grow bufsalloc until it is at least as great as `save'; but
	 if there is an overflow, just grow it to the next page boundary.  */
      while (bufsalloc < save)
	if (bufsalloc < bufsalloc * 2)
	  bufsalloc *= 2;
	else
	  {
	    bufsalloc = aligned_save;
	    break;
	  }

      /* Grow the buffer size to be PREFERRED_SAVE_FACTOR times
	 bufsalloc....  */
      newalloc = PREFERRED_SAVE_FACTOR * bufsalloc;
      if (maxalloc < newalloc)
	{
	  /* ... except don't grow it more than a pagesize past the
	     file size, as that might cause unnecessary memory
	     exhaustion if the file is large.  */
	  newalloc = maxalloc;
	  bufsalloc = aligned_save;
	}

      /* Check that the above calculations made progress, which might
         not occur if there is arithmetic overflow.  If there's no
	 progress, or if the new buffer size is larger than the old
	 and buffer reallocation fails, report memory exhaustion.  */
      if (bufsalloc < save || newalloc < save
	  || (newalloc == save && newalloc != maxalloc)
	  || (bufalloc < newalloc
	      && ! (buffer
		    = page_alloc ((bufalloc = newalloc) + 1, &ubuffer))))
	fatal (_("memory exhausted"), 0);
    }

  bufbeg = buffer + bufsalloc - save;
  memmove (bufbeg, ubuffer + saved_offset, save);
  readsize = bufalloc - bufsalloc;

#if defined(HAVE_MMAP)
  if (bufmapped)
    {
      size_t mmapsize = readsize;

      /* Don't mmap past the end of the file; some hosts don't allow this.
	 Use `read' on the last page.  */
      if (stats->stat.st_size - bufoffset < mmapsize)
	{
	  mmapsize = stats->stat.st_size - bufoffset;
	  mmapsize -= mmapsize % pagesize;
	}

      if (mmapsize
	  && (mmap ((caddr_t) (buffer + bufsalloc), mmapsize,
		    PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_FIXED,
		    bufdesc, bufoffset)
	      != (caddr_t) -1))
	{
	  /* Do not bother to use madvise with MADV_SEQUENTIAL or
	     MADV_WILLNEED on the mmapped memory.  One might think it
	     would help, but it slows us down about 30% on SunOS 4.1.  */
	  fillsize = mmapsize;
	}
      else
	{
	  /* Stop using mmap on this file.  Synchronize the file
	     offset.  Do not warn about mmap failures.  On some hosts
	     (e.g. Solaris 2.5) mmap can fail merely because some
	     other process has an advisory read lock on the file.
	     There's no point alarming the user about this misfeature.  */
	  bufmapped = 0;
	  if (bufoffset != initial_bufoffset
	      && lseek (bufdesc, bufoffset, SEEK_SET) < 0)
	    {
	      error ("lseek", errno);
	      cc = 0;
	    }
	}
    }
#endif /*HAVE_MMAP*/

  if (! fillsize)
    {
      ssize_t bytesread;
      while ((bytesread = read (bufdesc, buffer + bufsalloc, readsize)) < 0
	     && errno == EINTR)
	continue;
      if (bytesread < 0)
	cc = 0;
      else
	fillsize = bytesread;
    }

  bufoffset += fillsize;
#if HAVE_DOS_FILE_CONTENTS
  if (fillsize)
    fillsize = undossify_input (buffer + bufsalloc, fillsize);
#endif
  buflim = buffer + bufsalloc + fillsize;
  return cc;
}

/* Flags controlling the style of output. */
static enum
  {
    BINARY_BINARY_FILES,
    TEXT_BINARY_FILES,
    WITHOUT_MATCH_BINARY_FILES
  } binary_files;		/* How to handle binary files.  */
static int filename_mask;	/* If zero, output nulls after filenames.  */
static int out_quiet;		/* Suppress all normal output. */
static int out_invert;		/* Print nonmatching stuff. */
static int out_file;		/* Print filenames. */
static int out_line;		/* Print line numbers. */
static int out_byte;		/* Print byte offsets. */
static int out_before;		/* Lines of leading context. */
static int out_after;		/* Lines of trailing context. */
static int count_matches;	/* Count matching lines.  */
static int list_files;		/* List matching files.  */
static int no_filenames;	/* Suppress file names.  */
static int suppress_errors;	/* Suppress diagnostics.  */
static off_t max_count;		/* Stop after outputting this many
				   lines from an input file.  */

/* Internal variables to keep track of byte count, context, etc. */
static off_t totalcc;		/* Total character count before bufbeg. */
static char const *lastnl;	/* Pointer after last newline counted. */
static char const *lastout;	/* Pointer after last character output;
				   NULL if no character has been output
				   or if it's conceptually before bufbeg. */
static off_t totalnl;		/* Total newline count before lastnl. */
static off_t outleft;		/* Maximum number of lines to be output.  */
static int pending;		/* Pending lines of output.
				   Always kept 0 if out_quiet is true.  */
static int done_on_match;	/* Stop scanning file on first match */

#if HAVE_DOS_FILE_CONTENTS
# include "dosbuf.c"
#endif

static void
nlscan (char const *lim)
{
  char const *beg;
  for (beg = lastnl;
       beg != lim;
       beg = memchr (beg, eolbyte, lim - beg), beg++)
    totalnl++;
  lastnl = lim;
}

static void
print_offset_sep (off_t pos, int sep)
{
  /* Do not rely on printf to print pos, since off_t may be longer than long,
     and long long is not portable.  */

  char buf[sizeof pos * CHAR_BIT];
  char *p = buf + sizeof buf - 1;
  *p = sep;

  do
    *--p = '0' + pos % 10;
  while ((pos /= 10) != 0);

  fwrite (p, 1, buf + sizeof buf - p, stdout);
}

static void
prline (char const *beg, char const *lim, int sep)
{
  if (out_file)
    printf ("%s%c", filename, sep & filename_mask);
  if (out_line)
    {
      nlscan (beg);
      print_offset_sep (++totalnl, sep);
      lastnl = lim;
    }
  if (out_byte)
    {
      off_t pos = totalcc + (beg - bufbeg);
#if HAVE_DOS_FILE_CONTENTS
      pos = dossified_pos (pos);
#endif
      print_offset_sep (pos, sep);
    }
  fwrite (beg, 1, lim - beg, stdout);
  if (ferror (stdout))
    error (_("writing output"), errno);
  lastout = lim;
}

/* Print pending lines of trailing context prior to LIM. Trailing context ends
   at the next matching line when OUTLEFT is 0.  */
static void
prpending (char const *lim)
{
  if (!lastout)
    lastout = bufbeg;
  while (pending > 0 && lastout < lim)
    {
      char const *nl = memchr (lastout, eolbyte, lim - lastout);
      size_t match_size;
      --pending;
      if (outleft
	  || (((*execute) (lastout, nl - lastout, &match_size) == (size_t) -1)
	      == !out_invert))
	prline (lastout, nl + 1, '-');
      else
	pending = 0;
    }
}

/* Print the lines between BEG and LIM.  Deal with context crap.
   If NLINESP is non-null, store a count of lines between BEG and LIM.  */
static void
prtext (char const *beg, char const *lim, int *nlinesp)
{
  static int used;		/* avoid printing "--" before any output */
  char const *bp, *p;
  char eol = eolbyte;
  int i, n;

  if (!out_quiet && pending > 0)
    prpending (beg);

  p = beg;

  if (!out_quiet)
    {
      /* Deal with leading context crap. */

      bp = lastout ? lastout : bufbeg;
      for (i = 0; i < out_before; ++i)
	if (p > bp)
	  do
	    --p;
	  while (p > bp && p[-1] != eol);

      /* We only print the "--" separator if our output is
	 discontiguous from the last output in the file. */
      if ((out_before || out_after) && used && p != lastout)
	puts ("--");

      while (p < beg)
	{
	  char const *nl = memchr (p, eol, beg - p);
	  nl++;
	  prline (p, nl, '-');
	  p = nl;
	}
    }

  if (nlinesp)
    {
      /* Caller wants a line count. */
      for (n = 0; p < lim && n < outleft; n++)
	{
	  char const *nl = memchr (p, eol, lim - p);
	  nl++;
	  if (!out_quiet)
	    prline (p, nl, ':');
	  p = nl;
	}
      *nlinesp = n;

      /* relying on it that this function is never called when outleft = 0.  */
      after_last_match = bufoffset - (buflim - p);
    }
  else
    if (!out_quiet)
      prline (beg, lim, ':');

  pending = out_quiet ? 0 : out_after;
  used = 1;
}

/* Scan the specified portion of the buffer, matching lines (or
   between matching lines if OUT_INVERT is true).  Return a count of
   lines printed. */
static int
grepbuf (char const *beg, char const *lim)
{
  int nlines, n;
  register char const *p;
  size_t match_offset;
  size_t match_size;

  nlines = 0;
  p = beg;
  while ((match_offset = (*execute) (p, lim - p, &match_size)) != (size_t) -1)
    {
      char const *b = p + match_offset;
      char const *endp = b + match_size;
      /* Avoid matching the empty line at the end of the buffer. */
      if (b == lim)
	break;
      if (!out_invert)
	{
	  prtext (b, endp, (int *) 0);
	  nlines++;
          outleft--;
	  if (!outleft || done_on_match)
	    {
	      after_last_match = bufoffset - (buflim - endp);
	      return nlines;
	    }
	}
      else if (p < b)
	{
	  prtext (p, b, &n);
	  nlines += n;
          outleft -= n;
	  if (!outleft)
	    return nlines;
	}
      p = endp;
    }
  if (out_invert && p < lim)
    {
      prtext (p, lim, &n);
      nlines += n;
      outleft -= n;
    }
  return nlines;
}

/* Search a given file.  Normally, return a count of lines printed;
   but if the file is a directory and we search it recursively, then
   return -2 if there was a match, and -1 otherwise.  */
static int
grep (int fd, char const *file, struct stats *stats)
{
  int nlines, i;
  int not_text;
  size_t residue, save;
  char const *beg, *lim;
  char eol = eolbyte;

  if (!reset (fd, file, stats))
    return 0;

  if (file && directories == RECURSE_DIRECTORIES
      && S_ISDIR (stats->stat.st_mode))
    {
      /* Close fd now, so that we don't open a lot of file descriptors
	 when we recurse deeply.  */
      if (close (fd) != 0)
	error (file, errno);
      return grepdir (file, stats) - 2;
    }

  totalcc = 0;
  lastout = 0;
  totalnl = 0;
  outleft = max_count;
  after_last_match = 0;
  pending = 0;

  nlines = 0;
  residue = 0;
  save = 0;

  if (! fillbuf (save, stats))
    {
      if (! (is_EISDIR (errno, file) && suppress_errors))
	error (filename, errno);
      return 0;
    }

  not_text = (((binary_files == BINARY_BINARY_FILES && !out_quiet)
	       || binary_files == WITHOUT_MATCH_BINARY_FILES)
	      && memchr (bufbeg, eol ? '\0' : '\200', buflim - bufbeg));
  if (not_text && binary_files == WITHOUT_MATCH_BINARY_FILES)
    return 0;
  done_on_match += not_text;
  out_quiet += not_text;

  for (;;)
    {
      lastnl = bufbeg;
      if (lastout)
	lastout = bufbeg;

      /* no more data to scan (eof) except for maybe a residue -> break */
      if (buflim - bufbeg == save)
	break;

      beg = bufbeg + save - residue;

      /* Determine new residue (the length of an incomplete line at the end of
         the buffer, 0 means there is no incomplete last line).  */
      for (lim = buflim; lim > beg && lim[-1] != eol; --lim)
	;
      residue = buflim - lim;

      if (beg < lim)
	{
	  if (outleft)
	    nlines += grepbuf (beg, lim);
	  if (pending)
	    prpending (lim);
	  if((!outleft && !pending) || (nlines && done_on_match && !out_invert))
	    goto finish_grep;
	}

      /* The last OUT_BEFORE lines at the end of the buffer will be needed as
	 leading context if there is a matching line at the begin of the
	 next data. Make beg point to their begin.  */
      i = 0;
      beg = lim;
      while (i < out_before && beg > bufbeg && beg != lastout)
	{
	  ++i;
	  do
	    --beg;
	  while (beg > bufbeg && beg[-1] != eol);
	}

      /* detect if leading context is discontinuous from last printed line.  */
      if (beg != lastout)
	lastout = 0;

      /* Handle some details and read more data to scan.  */
      save = residue + lim - beg;
      totalcc += buflim - bufbeg - save;
      if (out_line)
	nlscan (beg);
      if (! fillbuf (save, stats))
	{
	  if (! (is_EISDIR (errno, file) && suppress_errors))
	    error (filename, errno);
	  goto finish_grep;
	}
    }
  if (residue)
    {
      *buflim++ = eol;
      if (outleft)
	nlines += grepbuf (bufbeg + save - residue, buflim);
      if (pending)
        prpending (buflim);
    }

 finish_grep:
  done_on_match -= not_text;
  out_quiet -= not_text;
  if ((not_text & ~out_quiet) && nlines != 0)
    printf (_("Binary file %s matches\n"), filename);
  return nlines;
}

static int
grepfile (char const *file, struct stats *stats)
{
  int desc;
  int count;
  int status;

  if (! file)
    {
      desc = 0;
      filename = _("(standard input)");
    }
  else
    {
      while ((desc = open (file, O_RDONLY)) < 0 && errno == EINTR)
	continue;

      if (desc < 0)
	{
	  int e = errno;

	  if (is_EISDIR (e, file) && directories == RECURSE_DIRECTORIES)
	    {
	      if (stat (file, &stats->stat) != 0)
		{
		  error (file, errno);
		  return 1;
		}

	      return grepdir (file, stats);
	    }

	  if (!suppress_errors)
	    {
	      if (directories == SKIP_DIRECTORIES)
		switch (e)
		  {
#ifdef EISDIR
		  case EISDIR:
		    return 1;
#endif
		  case EACCES:
		    /* When skipping directories, don't worry about
		       directories that can't be opened.  */
		    if (stat (file, &stats->stat) == 0
			&& S_ISDIR (stats->stat.st_mode))
		      return 1;
		    break;
		  }

	      error (file, e);
	    }

	  return 1;
	}

      filename = file;
    }

#ifdef SET_BINARY
  /* Set input to binary mode.  Pipes are simulated with files
     on DOS, so this includes the case of "foo | grep bar".  */
  if (!isatty (desc))
    SET_BINARY (desc);
#endif

  count = grep (desc, file, stats);
  if (count < 0)
    status = count + 2;
  else
    {
      if (count_matches)
	{
	  if (out_file)
	    printf ("%s%c", filename, ':' & filename_mask);
	  printf ("%d\n", count);
	}

      status = !count;
      if (list_files == 1 - 2 * status)
	printf ("%s%c", filename, '\n' & filename_mask);

      if (! file)
	{
	  off_t required_offset = outleft ? bufoffset : after_last_match;
	  if ((bufmapped || required_offset != bufoffset)
	      && lseek (desc, required_offset, SEEK_SET) < 0
	      && S_ISREG (stats->stat.st_mode))
	    error (filename, errno);
	}
      else
	while (close (desc) != 0)
	  if (errno != EINTR)
	    {
	      error (file, errno);
	      break;
	    }
    }

  return status;
}

static int
grepdir (char const *dir, struct stats const *stats)
{
  int status = 1;
  struct stats const *ancestor;
  char *name_space;

  for (ancestor = stats;  (ancestor = ancestor->parent) != 0;  )
    if (ancestor->stat.st_ino == stats->stat.st_ino
	&& ancestor->stat.st_dev == stats->stat.st_dev)
      {
	if (!suppress_errors)
	  fprintf (stderr, _("%s: warning: %s: %s\n"), prog, dir,
		   _("recursive directory loop"));
	return 1;
      }

  name_space = savedir (dir, (unsigned) stats->stat.st_size);

  if (! name_space)
    {
      if (errno)
	{
	  if (!suppress_errors)
	    error (dir, errno);
	}
      else
	fatal (_("Memory exhausted"), 0);
    }
  else
    {
      size_t dirlen = strlen (dir);
      int needs_slash = ! (dirlen == FILESYSTEM_PREFIX_LEN (dir)
			   || IS_SLASH (dir[dirlen - 1]));
      char *file = NULL;
      char const *namep = name_space;
      struct stats child;
      child.parent = stats;
      out_file += !no_filenames;
      while (*namep)
	{
	  size_t namelen = strlen (namep);
	  file = xrealloc (file, dirlen + 1 + namelen + 1);
	  strcpy (file, dir);
	  file[dirlen] = '/';
	  strcpy (file + dirlen + needs_slash, namep);
	  namep += namelen + 1;
	  status &= grepfile (file, &child);
	}
      out_file -= !no_filenames;
      if (file)
        free (file);
      free (name_space);
    }

  return status;
}

static void
usage (int status)
{
  if (status != 0)
    {
      fprintf (stderr, _("Usage: %s [OPTION]... PATTERN [FILE]...\n"), prog);
      fprintf (stderr, _("Try `%s --help' for more information.\n"), prog);
    }
  else
    {
      printf (_("Usage: %s [OPTION]... PATTERN [FILE] ...\n"), prog);
      printf (_("\
Search for PATTERN in each FILE or standard input.\n\
Example: %s -i 'hello world' menu.h main.c\n\
\n\
Regexp selection and interpretation:\n"), prog);
      printf (_("\
  -E, --extended-regexp     PATTERN is an extended regular expression\n\
  -F, --fixed-strings       PATTERN is a set of newline-separated strings\n\
  -G, --basic-regexp        PATTERN is a basic regular expression\n\
  -P, --perl-regexp         PATTERN is a Perl regular expression\n"));
      printf (_("\
  -e, --regexp=PATTERN      use PATTERN as a regular expression\n\
  -f, --file=FILE           obtain PATTERN from FILE\n\
  -i, --ignore-case         ignore case distinctions\n\
  -w, --word-regexp         force PATTERN to match only whole words\n\
  -x, --line-regexp         force PATTERN to match only whole lines\n\
  -z, --null-data           a data line ends in 0 byte, not newline\n"));
      printf (_("\
\n\
Miscellaneous:\n\
  -s, --no-messages         suppress error messages\n\
  -v, --invert-match        select non-matching lines\n\
  -V, --version             print version information and exit\n\
      --help                display this help and exit\n\
      --mmap                use memory-mapped input if possible\n"));
      printf (_("\
\n\
Output control:\n\
  -m, --max-count=NUM       stop after NUM matches\n\
  -b, --byte-offset         print the byte offset with output lines\n\
  -n, --line-number         print line number with output lines\n\
  -H, --with-filename       print the filename for each match\n\
  -h, --no-filename         suppress the prefixing filename on output\n\
  -q, --quiet, --silent     suppress all normal output\n\
      --binary-files=TYPE   assume that binary files are TYPE\n\
                            TYPE is 'binary', 'text', or 'without-match'.\n\
  -a, --text                equivalent to --binary-files=text\n\
  -I                        equivalent to --binary-files=without-match\n\
  -d, --directories=ACTION  how to handle directories\n\
                            ACTION is 'read', 'recurse', or 'skip'.\n\
  -r, --recursive           equivalent to --directories=recurse.\n\
  -L, --files-without-match only print FILE names containing no match\n\
  -l, --files-with-matches  only print FILE names containing matches\n\
  -c, --count               only print a count of matching lines per FILE\n\
  -Z, --null                print 0 byte after FILE name\n"));
      printf (_("\
\n\
Context control:\n\
  -B, --before-context=NUM  print NUM lines of leading context\n\
  -A, --after-context=NUM   print NUM lines of trailing context\n\
  -C, --context=NUM         print NUM lines of output context\n\
  -NUM                      same as --context=NUM\n\
  -U, --binary              do not strip CR characters at EOL (MSDOS)\n\
  -u, --unix-byte-offsets   report offsets as if CRs were not there (MSDOS)\n\
\n\
`egrep' means `grep -E'.  `fgrep' means `grep -F'.\n\
With no FILE, or when FILE is -, read standard input.  If less than\n\
two FILEs given, assume -h.  Exit status is 0 if match, 1 if no match,\n\
and 2 if trouble.\n"));
      printf (_("\nReport bugs to <bug-gnu-utils@gnu.org>.\n"));
    }
  exit (status);
}

/* Set the matcher to M, reporting any conflicts.  */
static void
setmatcher (char const *m)
{
  if (matcher && strcmp (matcher, m) != 0)
    fatal (_("conflicting matchers specified"), 0);
  matcher = m;
}

/* Go through the matchers vector and look for the specified matcher.
   If we find it, install it in compile and execute, and return 1.  */
static int
install_matcher (char const *name)
{
  int i;
#ifdef HAVE_SETRLIMIT
  struct rlimit rlim;
#endif

  for (i = 0; matchers[i].compile; i++)
    if (strcmp (name, matchers[i].name) == 0)
      {
	compile = matchers[i].compile;
	execute = matchers[i].execute;
#if HAVE_SETRLIMIT && defined(RLIMIT_STACK)
	/* I think every platform needs to do this, so that regex.c
	   doesn't oveflow the stack.  The default value of
	   `re_max_failures' is too large for some platforms: it needs
	   more than 3MB-large stack.

	   The test for HAVE_SETRLIMIT should go into `configure'.  */
	if (!getrlimit (RLIMIT_STACK, &rlim))
	  {
	    long newlim;
	    extern long int re_max_failures; /* from regex.c */

	    /* Approximate the amount regex.c needs, plus some more.  */
	    newlim = re_max_failures * 2 * 20 * sizeof (char *);
	    if (newlim > rlim.rlim_max)
	      {
		newlim = rlim.rlim_max;
		re_max_failures = newlim / (2 * 20 * sizeof (char *));
	      }
	    if (rlim.rlim_cur < newlim)
	      {
		rlim.rlim_cur = newlim;
		setrlimit (RLIMIT_STACK, &rlim);
	      }
	  }
#endif
	return 1;
      }
  return 0;
}

/* Find the white-space-separated options specified by OPTIONS, and
   using BUF to store copies of these options, set ARGV[0], ARGV[1],
   etc. to the option copies.  Return the number N of options found.
   Do not set ARGV[N] to NULL.  If ARGV is NULL, do not store ARGV[0]
   etc.  Backslash can be used to escape whitespace (and backslashes).  */
static int
prepend_args (char const *options, char *buf, char **argv)
{
  char const *o = options;
  char *b = buf;
  int n = 0;

  for (;;)
    {
      while (ISSPACE ((unsigned char) *o))
	o++;
      if (!*o)
	return n;
      if (argv)
	argv[n] = b;
      n++;

      do
	if ((*b++ = *o++) == '\\' && *o)
	  b[-1] = *o++;
      while (*o && ! ISSPACE ((unsigned char) *o));

      *b++ = '\0';
    }
}

/* Prepend the whitespace-separated options in OPTIONS to the argument
   vector of a main program with argument count *PARGC and argument
   vector *PARGV.  */
static void
prepend_default_options (char const *options, int *pargc, char ***pargv)
{
  if (options)
    {
      char *buf = xmalloc (strlen (options) + 1);
      int prepended = prepend_args (options, buf, (char **) NULL);
      int argc = *pargc;
      char * const *argv = *pargv;
      char **pp = (char **) xmalloc ((prepended + argc + 1) * sizeof *pp);
      *pargc = prepended + argc;
      *pargv = pp;
      *pp++ = *argv++;
      pp += prepend_args (options, buf, pp);
      while ((*pp++ = *argv++))
	continue;
    }
}

/* Get the next non-digit option from ARGC and ARGV.
   Return -1 if there are no more options.
   Process any digit options that were encountered on the way,
   and store the resulting integer into *DEFAULT_CONTEXT.  */
static int
get_nondigit_option (int argc, char *const *argv, int *default_context)
{
  int opt;
  char buf[sizeof (uintmax_t) * CHAR_BIT + 4];
  char *p = buf;

  /* Set buf[0] to anything but '0', for the leading-zero test below.  */
  buf[0] = '\0';

  while (opt = getopt_long (argc, argv, short_options, long_options, NULL),
	 '0' <= opt && opt <= '9')
    {
      /* Suppress trivial leading zeros, to avoid incorrect
	 diagnostic on strings like 00000000000.  */
      p -= buf[0] == '0';

      *p++ = opt;
      if (p == buf + sizeof buf - 4)
	{
	  /* Too many digits.  Append "..." to make context_length_arg
	     complain about "X...", where X contains the digits seen
	     so far.  */
	  strcpy (p, "...");
	  p += 3;
	  break;
	}
    }
  if (p != buf)
    {
      *p = '\0';
      context_length_arg (buf, default_context);
    }

  return opt;
}

int
main (int argc, char **argv)
{
  char *keys;
  size_t keycc, oldcc, keyalloc;
  int with_filenames;
  int opt, cc, status;
  int default_context;
  FILE *fp;
  extern char *optarg;
  extern int optind;

  initialize_main (&argc, &argv);
  prog = argv[0];
  if (prog && strrchr (prog, '/'))
    prog = strrchr (prog, '/') + 1;

#if defined(__MSDOS__) || defined(_WIN32)
  /* DOS and MS-Windows use backslashes as directory separators, and usually
     have an .exe suffix.  They also have case-insensitive filesystems.  */
  if (prog)
    {
      char *p = prog;
      char *bslash = strrchr (argv[0], '\\');

      if (bslash && bslash >= prog) /* for mixed forward/backslash case */
	prog = bslash + 1;
      else if (prog == argv[0]
	       && argv[0][0] && argv[0][1] == ':') /* "c:progname" */
	prog = argv[0] + 2;

      /* Collapse the letter-case, so `strcmp' could be used hence.  */
      for ( ; *p; p++)
	if (*p >= 'A' && *p <= 'Z')
	  *p += 'a' - 'A';

      /* Remove the .exe extension, if any.  */
      if ((p = strrchr (prog, '.')) && strcmp (p, ".exe") == 0)
	*p = '\0';
    }
#endif

  keys = NULL;
  keycc = 0;
  with_filenames = 0;
  eolbyte = '\n';
  filename_mask = ~0;

  max_count = TYPE_MAXIMUM (off_t);
  /* The value -1 means to use DEFAULT_CONTEXT. */
  out_after = out_before = -1;
  /* Default before/after context: chaged by -C/-NUM options */
  default_context = 0;

/* Internationalization. */
#if HAVE_SETLOCALE
  setlocale (LC_ALL, "");
#endif
#if ENABLE_NLS
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);
#endif

  prepend_default_options (getenv ("GREP_OPTIONS"), &argc, &argv);

  while ((opt = get_nondigit_option (argc, argv, &default_context)) != -1)
    switch (opt)
      {
      case 'A':
	context_length_arg (optarg, &out_after);
	break;
      case 'B':
	context_length_arg (optarg, &out_before);
	break;
      case 'C':
	/* Set output match context, but let any explicit leading or
	   trailing amount specified with -A or -B stand. */
	context_length_arg (optarg, &default_context);
	break;
      case 'E':
	setmatcher ("egrep");
	break;
      case 'F':
	setmatcher ("fgrep");
	break;
      case 'P':
	setmatcher ("perl");
	break;
      case 'G':
	setmatcher ("grep");
	break;
      case 'H':
	with_filenames = 1;
	break;
      case 'I':
	binary_files = WITHOUT_MATCH_BINARY_FILES;
	break;
      case 'U':
#if HAVE_DOS_FILE_CONTENTS
	dos_use_file_type = DOS_BINARY;
#endif
	break;
      case 'u':
#if HAVE_DOS_FILE_CONTENTS
	dos_report_unix_offset = 1;
#endif
	break;
      case 'V':
	show_version = 1;
	break;
      case 'X':
	setmatcher (optarg);
	break;
      case 'a':
	binary_files = TEXT_BINARY_FILES;
	break;
      case 'b':
	out_byte = 1;
	break;
      case 'c':
	out_quiet = 1;
	count_matches = 1;
	break;
      case 'd':
	if (strcmp (optarg, "read") == 0)
	  directories = READ_DIRECTORIES;
	else if (strcmp (optarg, "skip") == 0)
	  directories = SKIP_DIRECTORIES;
	else if (strcmp (optarg, "recurse") == 0)
	  directories = RECURSE_DIRECTORIES;
	else
	  fatal (_("unknown directories method"), 0);
	break;
      case 'e':
	cc = strlen (optarg);
	keys = xrealloc (keys, keycc + cc + 1);
	strcpy (&keys[keycc], optarg);
	keycc += cc;
	keys[keycc++] = '\n';
	break;
      case 'f':
	fp = strcmp (optarg, "-") != 0 ? fopen (optarg, "r") : stdin;
	if (!fp)
	  fatal (optarg, errno);
	for (keyalloc = 1; keyalloc <= keycc + 1; keyalloc *= 2)
	  ;
	keys = xrealloc (keys, keyalloc);
	oldcc = keycc;
	while (!feof (fp)
	       && (cc = fread (keys + keycc, 1, keyalloc - 1 - keycc, fp)) > 0)
	  {
	    keycc += cc;
	    if (keycc == keyalloc - 1)
	      keys = xrealloc (keys, keyalloc *= 2);
	  }
	if (fp != stdin)
	  fclose(fp);
	/* Append final newline if file ended in non-newline. */
	if (oldcc != keycc && keys[keycc - 1] != '\n')
	  keys[keycc++] = '\n';
	break;
      case 'h':
	no_filenames = 1;
	break;
      case 'i':
      case 'y':			/* For old-timers . . . */
	match_icase = 1;
	break;
      case 'L':
	/* Like -l, except list files that don't contain matches.
	   Inspired by the same option in Hume's gre. */
	out_quiet = 1;
	list_files = -1;
	done_on_match = 1;
	break;
      case 'l':
	out_quiet = 1;
	list_files = 1;
	done_on_match = 1;
	break;
      case 'm':
	{
	  uintmax_t value;
	  switch (xstrtoumax (optarg, 0, 10, &value, ""))
	    {
	    case LONGINT_OK:
	      max_count = value;
	      if (0 <= max_count && max_count == value)
		break;
	      /* Fall through.  */
	    case LONGINT_OVERFLOW:
	      max_count = TYPE_MAXIMUM (off_t);
	      break;

	    default:
	      fatal (_("invalid max count"), 0);
	    }
	}
	break;
      case 'n':
	out_line = 1;
	break;
      case 'q':
	done_on_match = 1;
	out_quiet = 1;
	break;
      case 'r':
	directories = RECURSE_DIRECTORIES;
	break;
      case 's':
	suppress_errors = 1;
	break;
      case 'v':
	out_invert = 1;
	break;
      case 'w':
	match_words = 1;
	break;
      case 'x':
	match_lines = 1;
	break;
      case 'Z':
	filename_mask = 0;
	break;
      case 'z':
	eolbyte = '\0';
	break;
      case BINARY_FILES_OPTION:
	if (strcmp (optarg, "binary") == 0)
	  binary_files = BINARY_BINARY_FILES;
	else if (strcmp (optarg, "text") == 0)
	  binary_files = TEXT_BINARY_FILES;
	else if (strcmp (optarg, "without-match") == 0)
	  binary_files = WITHOUT_MATCH_BINARY_FILES;
	else
	  fatal (_("unknown binary-files type"), 0);
	break;
      case 0:
	/* long options */
	break;
      default:
	usage (2);
	break;
      }

  if (out_after < 0)
    out_after = default_context;
  if (out_before < 0)
    out_before = default_context;

  if (! matcher)
    matcher = "grep";

  if (show_version)
    {
      printf (_("%s (GNU grep) %s\n"), matcher, VERSION);
      printf ("\n");
      printf (_("\
Copyright 1988, 1992-1999, 2000 Free Software Foundation, Inc.\n"));
      printf (_("\
This is free software; see the source for copying conditions. There is NO\n\
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n"));
      printf ("\n");
      exit (0);
    }

  if (show_help)
    usage (0);

  if (keys)
    {
      if (keycc == 0)
	/* No keys were specified (e.g. -f /dev/null).  Match nothing.  */
        out_invert ^= 1;
      else
	/* Strip trailing newline. */
        --keycc;
    }
  else
    if (optind < argc)
      {
	keys = argv[optind++];
	keycc = strlen (keys);
      }
    else
      usage (2);

  if (!install_matcher (matcher) && !install_matcher ("default"))
    abort ();

  (*compile)(keys, keycc);

  if ((argc - optind > 1 && !no_filenames) || with_filenames)
    out_file = 1;

#ifdef SET_BINARY
  /* Output is set to binary mode because we shouldn't convert
     NL to CR-LF pairs, especially when grepping binary files.  */
  if (!isatty (1))
    SET_BINARY (1);
#endif

  if (max_count == 0)
    exit (1);

  if (optind < argc)
    {
	status = 1;
	do
	{
	  char *file = argv[optind];
	  status &= grepfile (strcmp (file, "-") == 0 ? (char *) NULL : file,
			      &stats_base);
	}
	while ( ++optind < argc);
    }
  else
    status = grepfile ((char *) NULL, &stats_base);

  if (fclose (stdout) == EOF)
    error (_("writing output"), errno);

  exit (errseen ? 2 : status);
}