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/* fgrep.c - grep program built around matcher.
   Copyright 1989 Free Software Foundation
		  Written August 1989 by Mike Haertel.

   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 1, 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., 675 Mass Ave, Cambridge, MA 02139, USA.

   The author may be reached (Email) at the address mike@ai.mit.edu,
   or (US mail) as Mike Haertel c/o Free Software Foundation. */

#include "std.h"
#include "unix.h"

#include <errno.h>
#include <stdio.h>
#include <string.h>

#include "kwset.h"

#define NCHAR (UCHAR_MAX + 1)

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

/* Flags controlling the style of output. */
static int out_silent;		/* 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. */

/* Print MESG and possibly the error string for ERRNUM.  Remember
   that something awful happened. */
static void
DEFUN(error, (mesg, errnum), const char *mesg AND int errnum)
{
  if (errnum)
    fprintf(stderr, "%s: %s: %s\n", prog, mesg, strerror(errnum));
  else
    fprintf(stderr, "%s: %s\n", prog, mesg);
  error_seen = 1;
}

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

/* Interface to handle errors and fix library lossage. */
static PTR
DEFUN(xmalloc, (size), size_t size)
{
  PTR result;

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

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

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

/* Compiled search pattern. */
kwset_t kwset;

/* Flags controlling how pattern matching is performed. */
static int match_fold;		/* Fold all letters to one case. */
static int match_words;		/* Match only whole words. */
static int match_lines;		/* Match only whole lines. */

static void
DEFUN(compile, (pattern, size), const char *pattern AND size_t size)
{
  const char *beg, *lim, *err;
  static char trans[NCHAR];
  int i;

  if (match_fold)
    for (i = 0; i < NCHAR; ++i)
      trans[i] = TOLOWER(i);

  if (!(kwset = kwsalloc(match_fold ? trans : (const char *) NULL)))
    fatal("memory exhausted", 0);

  beg = pattern;
  do
    {
      for (lim = beg; lim < pattern + size && *lim != '\n'; ++lim)
	;
      if (err = kwsincr(kwset, beg, lim - beg))
	fatal(err, 0);
      if (lim < pattern + size)
	++lim;
      beg = lim;
    }
  while (beg < pattern + size);

  if (err = kwsprep(kwset))
    fatal(err, 0);
}

static char *
DEFUN(execute, (buf, size), char *buf AND size_t size)
{
  register char *beg, *try;
  register size_t len;
  struct kwsmatch kwsmatch;

  beg = buf;
  for (;beg <= buf + size; ++beg)
    {
      if (!(beg = kwsexec(kwset, beg, buf + size - beg, &kwsmatch)))
	return NULL;;
      len = kwsmatch.size[0];
      if (match_lines)
	{
	  if (beg > buf && beg[-1] != '\n')
	    continue;
	  if (beg + len < buf + size && *(beg + len) != '\n')
	    continue;
	  return beg;
	}
      else if (match_words)
	for (try = beg; len && try;)
	  {
	    if (try > buf && (ISALNUM((unsigned char) try[-1])
			      || !ISALNUM((unsigned char) *try)))
	      goto retry;
	    if (try + len < buf + size
		&& (ISALNUM((unsigned char) *(try + len))
		    || !ISALNUM((unsigned char) (try + len)[-1])))
	      goto retry;
	    return try;
	  retry:
	    if (--len)
	      try = kwsexec(kwset, beg, len, &kwsmatch);
	    else
	      break;
	    len = kwsmatch.size[0];
	  }
      else
	return beg;
    }

  return NULL;
}

/* Hairy buffering mechanism to efficiently support all the options. */
static char *bufbeg;		/* Beginning of user-visible portion. */
static char *buflim;		/* Limit of user-visible portion. */
static char *buf;		/* Pointer to base of buffer. */
static size_t bufalloc;		/* Allocated size of buffer. */
static size_t bufcc;		/* Count of characters in buffer. */
static unsigned long int buftotalcc;
				/* Total character count since reset. */
static char *buflast;		/* Pointer after last character printed. */
static int bufgap;		/* Weird flag indicating buflast is a lie. */
static unsigned long int buftotalnl;
				/* Count of newlines before last character. */
static int bufpending;		/* Lines of pending output at buflast. */
static int bufdesc;		/* File descriptor to read from. */
static int bufeof;		/* Flag indicating EOF reached. */
static const char *buffile;	/* File name for messages. */

/* Scan and count the newlines prior to LIM in the buffer. */
static void
DEFUN(nlscan, (lim), register char *lim)
{
  register char *p;

  for (p = buflast; p < lim; ++p)
    if (*p == '\n')
      ++buftotalnl;
  buflast = lim;
}

/* Print the line beginning at BEG, using SEP to separate optional label
   fields from the text of the line.  Return the size of the line. */
static size_t
DEFUN(prline, (beg, sep), register char *beg AND register char sep)
{
  register size_t cc;
  register char c;
  static int err;
  
  cc = 0;

  if (out_silent || err)
    while (beg < buflim)
      {
	++cc;
	if (*beg++ == '\n')
	  break;
      }
  else
    {
      if (out_file)
	printf("%s%c", buffile, sep);
      if (out_line)
	{
	  nlscan(beg);
	  printf("%d%c", buftotalnl + 1, sep);
	}
      if (out_byte)
	printf("%lu%c", buftotalcc + (beg - buf), sep);
      while (beg < buflim)
	{
	  ++cc;
	  c = *beg++;
	  putchar(c);
	  if (c == '\n')
	    break;
	}
      if (ferror(stdout))
	{
	  error("output error", errno);
	  err = 1;
	}
    }

  if (out_line)
    nlscan(beg);
  else
    buflast = beg;
  bufgap = 0;

  return cc;
}

/* Print pending bytes of last trailing context prior to LIM. */
static void
DEFUN(prpending, (lim), register char *lim)
{
  while (buflast < lim && bufpending)
    {
      --bufpending;
      prline(buflast, '-');
    }
}

/* Print the lines between BEG and LIM.  Deal with context crap.
   Return the count of lines between BEG and LIM. */
static int
DEFUN(prtext, (beg, lim), char *beg AND char *lim)
{
  static int used;
  register char *p;
  int i, n;

  prpending(beg);

  p = beg;
  for (i = 0; i < out_before; ++i)
    if (p > buflast)
      do
	--p;
      while (p > buflast && p[-1] != '\n');

  if ((out_before || out_after) && used && (p > buflast || bufgap))
    puts("--");

  while (p < beg)
    p += prline(p, '-');

  n = 0;
  while (p < lim)
    {
      ++n;
      p += prline(p, ':');
    }

  bufpending = out_after;
  used = 1;

  return n;
}

/* Fill the user-visible portion of the buffer, returning a byte count. */
static int
fillbuf()
{
  register char *b, *d, *l;
  int i, cc;
  size_t discard, save;

  prpending(buflim);

  b = buflim;
  for (i = 0; i < out_before; ++i)
    if (b > buflast)
      do
	--b;
      while (b > buflast && b[-1] != '\n');

  if (buflast < b)
    bufgap = 1;
  if (out_line)
    nlscan(b);

  discard = b - buf;
  save = buflim - b;

  if (b > buf)
    {
      d = buf;
      l = buf + bufcc;
      while (b < l)
	*d++ = *b++;
    }

  bufcc -= discard;
  buftotalcc += discard;

  do
    {
      if (!bufeof)
	{
	  if (bufcc > bufalloc / 2)
	    buf = xrealloc(buf, bufalloc *= 2);
	  cc = read(bufdesc, buf + bufcc, bufalloc - bufcc);
	  if (cc < 0)
	    {
	      error(buffile, errno);
	      bufeof = 1;
	    }
	  else
	    {
	      bufeof = !cc;
	      bufcc += cc;
	    }
	}
      bufbeg = buf + save;
      for (l = buf + bufcc; l > bufbeg && l[-1] != '\n'; --l)
	;
      buflim = l;
      buflast = buf;
    }
  while (!bufeof && bufbeg == buflim);

  if (bufeof)
    buflim = buf + bufcc;

  return buflim - bufbeg;
}

/* One-time initialization. */
static void
initbuf()
{
  bufalloc = 8192;
  buf = xmalloc(bufalloc);
}

/* Reset the buffer for a new file. */
static void
DEFUN(resetbuf, (desc, file), int desc AND const char *file)
{
  bufbeg = buf;
  buflim = buf;
  bufcc = 0;
  buftotalcc = 0;
  buflast = buf;
  bufgap = 0;
  buftotalnl = 0;
  bufpending = 0;
  bufdesc = desc;
  bufeof = 0;
  buffile = file;
}

/* Scan the user-visible portion of the buffer, calling prtext() for
   matching lines (or between matching lines if OUT_INVERT is true).
   Return a count of lines printed. */
static int
grepbuf()
{
  int total;
  register char *p, *b, *l;

  total = 0;
  p = bufbeg;
  while (b = execute(p, buflim - p))
    {
      if (b == buflim && (b > bufbeg && b[-1] == '\n' || b == bufbeg))
	break;
      while (b > bufbeg && b[-1] != '\n')
	--b;
      l = b + 1;
      while (l < buflim && l[-1] != '\n')
	++l;
      if (!out_invert)
	total += prtext(b, l);
      else if (p < b)
	total += prtext(p, b);
      p = l;
    }
  if (out_invert && p < buflim)
    total += prtext(p, buflim);
  return total;
}

/* Scan the given file, returning a count of lines printed. */
static int
DEFUN(grep, (desc, file), int desc AND const char *file)
{
  int total;

  total = 0;
  resetbuf(desc, file);
  while (fillbuf())
    total += grepbuf();
  return total;
}

static const char version[] = "GNU fgrep, version 1.0";

#define USAGE \
  "usage: %s [-[[AB] ]<num>] [-[CVchilnsvwx]] [-[ef]] <expr> [<files...>]\n"

static void
usage()
{
  fprintf(stderr, USAGE, prog);
  exit(2);
}

int
DEFUN(main, (argc, argv), int argc AND char *argv[])
{
  char *keys;
  size_t keycc, keyalloc;
  int count_matches, no_filenames, list_files;
  int opt, cc, desc, count, status;
  FILE *fp;

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

  keys = NULL;
  count_matches = 0;
  no_filenames = 0;
  list_files = 0;

  while ((opt = getopt(argc, argv, "0123456789A:B:CVbce:f:hilnsvwxy")) != EOF)
    switch (opt)
      {
      case '0':
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
      case '8':
      case '9':
	out_before = 10 * out_before + opt - '0';
	out_after = 10 * out_after + opt - '0';
	break;
      case 'A':
	out_after = atoi(optarg);
	if (out_after < 0)
	  usage();
	break;
      case 'B':
	out_before = atoi(optarg);
	if (out_before < 0)
	  usage();
	break;
      case 'C':
	out_before = out_after = 2;
	break;
      case 'V':
	fprintf(stderr, "%s\n", version);
	break;
      case 'b':
	out_byte = 1;
	break;
      case 'c':
	out_silent = 1;
	count_matches = 1;
	break;
      case 'e':
	if (keys)
	  usage();
	keys = optarg;
	keycc = strlen(keys);
	break;
      case 'f':
	if (keys)
	  usage();
	fp = strcmp(optarg, "-") ? fopen(optarg, "r") : stdin;
	if (!fp)
	  fatal(optarg, errno);
	keyalloc = 1024;
	keys = xmalloc(keyalloc);
	keycc = 0;
	while (!feof(fp)
	       && (cc = fread(keys + keycc, 1, keyalloc - keycc, fp)) > 0)
	  {
	    keycc += cc;
	    if (keycc == keyalloc)
	      keys = xrealloc(keys, keyalloc *= 2);
	  }
	if (fp != stdin)
	  fclose(fp);
	break;
      case 'h':
	no_filenames = 1;
	break;
      case 'i':
      case 'y':			/* For old-timers . . . */
	match_fold = 1;
	break;
      case 'l':
	out_silent = 1;
	list_files = 1;
	break;
      case 'n':
	out_line = 1;
	break;
      case 's':
	out_silent = 1;
	break;
      case 'v':
	out_invert = 1;
	break;
      case 'w':
	match_words = 1;
	break;
      case 'x':
	match_lines = 1;
	break;
      default:
	usage();
	break;
      }

  if (!keys)
    if (optind < argc)
      {
	keys = argv[optind++];
	keycc = strlen(keys);
      }
    else
      usage();

  compile(keys, keycc);

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

  status = 1;
  initbuf();

  if (optind < argc)
    while (optind < argc)
      {
	desc = strcmp(argv[optind], "-") ? open(argv[optind], 0) : 0;
	if (desc < 0)
	  error(argv[optind], errno);
	else
	  {
	    count = grep(desc, argv[optind]);
	    if (count_matches)
	      {
		if (out_file)
		  printf("%s:", argv[optind]);
		printf("%d\n", count);
	      }
	    if (count)
	      {
		status = 0;
		if (list_files)
		  printf("%s\n", argv[optind]);
	      }
	  }
	if (desc)
	  close(desc);
	++optind;
      }
  else
    {
      count = grep(0, "<stdin>");
      if (count_matches)
	printf("%d\n", count);
      if (count)
	{
	  status = 0;
	  if (list_files)
	    printf("%s\n", argv[optind]);
	}
    }

  return error_seen ? 2 : status;
}
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