/* grep.c - main driver file for grep.
   Copyright (C) 1992 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., 675 Mass Ave, Cambridge, MA 02139, USA.

   Written July 1992 by Mike Haertel.  */

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

#ifndef errno
extern int errno;
#endif

#ifdef STDC_HEADERS
#include <stdlib.h>
#else
#include <sys/types.h>
extern char *malloc(), *realloc();
extern void free();
#endif

#if defined(STDC_HEADERS) || defined(HAVE_STRING_H)
#include <string.h>
#ifdef NEED_MEMORY_H
#include <memory.h>
#endif
#else
#include <strings.h>
#ifdef __STDC__
extern void *memchr();
#else
extern char *memchr();
#endif
#define strrchr rindex
#endif

#ifdef HAVE_UNISTD_H
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#else
#define O_RDONLY 0
extern int open(), read(), close();
#endif

#include "getpagesize.h"
#include "grep.h"

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

/* Provide missing ANSI features if necessary. */

#ifndef HAVE_STRERROR
extern int sys_nerr;
extern char *sys_errlist[];
#define strerror(E) ((E) < sys_nerr ? sys_errlist[(E)] : "bogus error number")
#endif

#ifndef HAVE_MEMCHR
#ifdef __STDC__
#define VOID void
#else
#define VOID char
#endif
VOID *
memchr(vp, c, n)
     VOID *vp;
     int c;
     size_t n;
{
  unsigned char *p;

  for (p = (unsigned char *) vp; n--; ++p)
    if (*p == c)
      return (VOID *) p;
  return 0;
}
#endif

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

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

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

/* Print a message and possibly an error string.  Remember
   that something awful happened. */
static void
error(mesg, errnum)
#ifdef __STDC__
     const
#endif
     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(mesg, errnum)
#ifdef __STDC__
     const
#endif
     char *mesg;
     int errnum;
{
  error(mesg, errnum);
  exit(2);
}

/* Interface to handle errors and fix library lossage. */
char *
xmalloc(size)
     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(ptr, size)
     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;
}

#if !defined(HAVE_VALLOC)
#define valloc malloc
#else
#ifdef __STDC__
extern void *valloc(size_t);
#else
extern char *valloc();
#endif
#endif

/* 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 *buffer;		/* Base of buffer. */
static size_t bufsalloc;	/* Allocated size of buffer save region. */
static size_t bufalloc;		/* Total buffer size. */
static int bufdesc;		/* File descriptor. */
static char *bufbeg;		/* Beginning of user-visible stuff. */
static char *buflim;		/* Limit of user-visible stuff. */

#if defined(HAVE_WORKING_MMAP)
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>

static int bufmapped;		/* True for ordinary files. */
static struct stat bufstat;	/* From fstat(). */
static off_t bufoffset;		/* What read() normally remembers. */
#endif

/* Reset the buffer for a new file.  Initialize
   on the first time through. */
void
reset(fd)
     int fd;
{
  static int initialized;

  if (!initialized)
    {
      initialized = 1;
#ifndef BUFSALLOC
      bufsalloc = MAX(8192, getpagesize());
#else
      bufsalloc = BUFSALLOC;
#endif
      bufalloc = 5 * bufsalloc;
      /* The 1 byte of overflow is a kludge for dfaexec(), which
	 inserts a sentinel newline at the end of the buffer
	 being searched.  There's gotta be a better way... */
      buffer = valloc(bufalloc + 1);
      if (!buffer)
	fatal("memory exhausted", 0);
      bufbeg = buffer;
      buflim = buffer;
    }
  bufdesc = fd;
#if defined(HAVE_WORKING_MMAP)
  if (fstat(fd, &bufstat) < 0 || !S_ISREG(bufstat.st_mode))
    bufmapped = 0;
  else
    {
      bufmapped = 1;
      bufoffset = lseek(fd, 0, 1);
    }
#endif
}

/* 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 count of new stuff. */
static int
fillbuf(save)
     size_t save;
{
  char *nbuffer, *dp, *sp;
  int cc;
#if defined(HAVE_WORKING_MMAP)
  caddr_t maddr;
#endif
  static int pagesize;

  if (pagesize == 0 && (pagesize = getpagesize()) == 0)
    abort();

  if (save > bufsalloc)
    {
      while (save > bufsalloc)
	bufsalloc *= 2;
      bufalloc = 5 * bufsalloc;
      nbuffer = valloc(bufalloc + 1);
      if (!nbuffer)
	fatal("memory exhausted", 0);
    }
  else
    nbuffer = buffer;

  sp = buflim - save;
  dp = nbuffer + bufsalloc - save;
  bufbeg = dp;
  while (save--)
    *dp++ = *sp++;

  /* We may have allocated a new, larger buffer.  Since
     there is no portable vfree(), we just have to forget
     about the old one.  Sorry. */
  buffer = nbuffer;

#if defined(HAVE_WORKING_MMAP)
  if (bufmapped && bufoffset % pagesize == 0
      && bufstat.st_size - bufoffset >= bufalloc - bufsalloc)
    {
      maddr = buffer + bufsalloc;
      maddr = mmap(maddr, bufalloc - bufsalloc, PROT_READ | PROT_WRITE,
		   MAP_PRIVATE | MAP_FIXED, bufdesc, bufoffset);
      if (maddr == (caddr_t) -1)
	{
	  fprintf(stderr, "%s: warning: %s: %s\n", filename,
		  strerror(errno));
	  goto tryread;
	}
#if 0
      /* You might thing this (or MADV_WILLNEED) would help,
	 but it doesn't, at least not on a Sun running 4.1.
	 In fact, it actually slows us down about 30%! */
      madvise(maddr, bufalloc - bufsalloc, MADV_SEQUENTIAL);
#endif
      cc = bufalloc - bufsalloc;
      bufoffset += cc;
    }
  else
    {
    tryread:
      /* We come here when we're not going to use mmap() any more.
	 Note that we need to synchronize the file offset the
	 first time through. */
      if (bufmapped)
	{
	  bufmapped = 0;
	  lseek(bufdesc, bufoffset, 0);
	}
      cc = read(bufdesc, buffer + bufsalloc, bufalloc - bufsalloc);
    }
#else
  cc = read(bufdesc, buffer + bufsalloc, bufalloc - bufsalloc);
#endif
  if (cc > 0)
    buflim = buffer + bufsalloc + cc;
  else
    buflim = buffer + bufsalloc;
  return cc;
}

/* Flags controlling the style of output. */
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. */

/* Internal variables to keep track of byte count, context, etc. */
static size_t totalcc;		/* Total character count before bufbeg. */
static char *lastnl;		/* Pointer after last newline counted. */
static char *lastout;		/* Pointer after last character output;
				   NULL if no character has been output
				   or if it's conceptually before bufbeg. */
static size_t totalnl;		/* Total newline count before lastnl. */
static int pending;		/* Pending lines of output. */

static void
nlscan(lim)
     char *lim;
{
  char *beg;

  for (beg = lastnl; beg < lim; ++beg)
    if (*beg == '\n')
      ++totalnl;
  lastnl = beg;
}

static void
prline(beg, lim, sep)
     char *beg;
     char *lim;
     char sep;
{
  if (out_file)
    printf("%s%c", filename, sep);
  if (out_line)
    {
      nlscan(beg);
      printf("%d%c", ++totalnl, sep);
      lastnl = lim;
    }
  if (out_byte)
    printf("%lu%c", totalcc + (beg - bufbeg), 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. */
static void
prpending(lim)
     char *lim;
{
  char *nl;

  if (!lastout)
    lastout = bufbeg;
  while (pending > 0 && lastout < lim)
    {
      --pending;
      if ((nl = memchr(lastout, '\n', lim - lastout)) != 0)
	++nl;
      else
	nl = lim;
      prline(lastout, nl, '-');
    }
}

/* 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(beg, lim, nlinesp)
     char *beg;
     char *lim;
     int *nlinesp;
{
  static int used;		/* avoid printing "--" before any output */
  char *bp, *p, *nl;
  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] != '\n');

      /* 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)
	{
	  nl = memchr(p, '\n', beg - p);
	  prline(p, nl + 1, '-');
	  p = nl + 1;
	}
    }

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

  pending = 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(beg, lim)
     char *beg;
     char *lim;
{
  int nlines, n;
  register char *p, *b;
  char *endp;

  nlines = 0;
  p = beg;
  while ((b = (*execute)(p, lim - p, &endp)) != 0)
    {
      /* Avoid matching the empty line at the end of the buffer. */
      if (b == lim && ((b > beg && b[-1] == '\n') || b == beg))
	break;
      if (!out_invert)
	{
	  prtext(b, endp, (int *) 0);
	  nlines += 1;
	}
      else if (p < b)
	{
	  prtext(p, b, &n);
	  nlines += n;
	}
      p = endp;
    }
  if (out_invert && p < lim)
    {
      prtext(p, lim, &n);
      nlines += n;
    }
  return nlines;
}

/* Search a given file.  Return a count of lines printed. */
static int
grep(fd)
     int fd;
{
  int nlines, i;
  size_t residue, save;
  char *beg, *lim;

  reset(fd);

  totalcc = 0;
  lastout = 0;
  totalnl = 0;
  pending = 0;

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

  for (;;)
    {
      if (fillbuf(save) < 0)
	{
	  error(filename, errno);
	  return nlines;
	}
      lastnl = bufbeg;
      if (lastout)
	lastout = bufbeg;
      if (buflim - bufbeg == save)
	break;
      beg = bufbeg + save - residue;
      for (lim = buflim; lim > beg && lim[-1] != '\n'; --lim)
	;
      residue = buflim - lim;
      if (beg < lim)
	{
	  nlines += grepbuf(beg, lim);
	  if (pending)
	    prpending(lim);
	}
      i = 0;
      beg = lim;
      while (i < out_before && beg > bufbeg && beg != lastout)
	{
	  ++i;
	  do
	    --beg;
	  while (beg > bufbeg && beg[-1] != '\n');
	}
      if (beg != lastout)
	lastout = 0;
      save = residue + lim - beg;
      totalcc += buflim - bufbeg - save;
      if (out_line)
	nlscan(beg);
    }
  if (residue)
    {
      nlines += grepbuf(bufbeg + save - residue, buflim);
      if (pending)
	prpending(buflim);
    }
  return nlines;
}

static char version[] = "GNU grep version 2.0";

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

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

/* Go through the matchers vector and look for the specified matcher.
   If we find it, install it in compile and execute, and return 1.  */
int
setmatcher(name)
     char *name;
{
  int i;

  for (i = 0; matchers[i].name; ++i)
    if (strcmp(name, matchers[i].name) == 0)
      {
	compile = matchers[i].compile;
	execute = matchers[i].execute;
	return 1;
      }
  return 0;
}

int
main(argc, argv)
     int argc;
     char *argv[];
{
  char *keys;
  size_t keycc, oldcc, keyalloc;
  int keyfound, count_matches, no_filenames, list_files, suppress_errors;
  int opt, cc, desc, count, status;
  FILE *fp;
  extern char *optarg;
  extern int optind;

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

  keys = NULL;
  keycc = 0;
  keyfound = 0;
  count_matches = 0;
  no_filenames = 0;
  list_files = 0;
  suppress_errors = 0;
  matcher = NULL;

  while ((opt = getopt(argc, argv, "0123456789A:B:CEFGVX:bce:f:hiLlnqsvwxy"))
	 != 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 'E':
	if (matcher && strcmp(matcher, "egrep") != 0)
	  fatal("you may specify only one of -E, -F, or -G", 0);
	matcher = "posix-egrep";
	break;
      case 'F':
	if (matcher && strcmp(matcher, "fgrep") != 0)
	  fatal("you may specify only one of -E, -F, or -G", 0);;
	matcher = "fgrep";
	break;
      case 'G':
	if (matcher && strcmp(matcher, "grep") != 0)
	  fatal("you may specify only one of -E, -F, or -G", 0);
	matcher = "grep";
	break;
      case 'V':
	fprintf(stderr, "%s\n", version);
	break;
      case 'X':
	if (matcher)
	  fatal("matcher already specified", 0);
	matcher = optarg;
	break;
      case 'b':
	out_byte = 1;
	break;
      case 'c':
	out_quiet = 1;
	count_matches = 1;
	break;
      case 'e':
	cc = strlen(optarg);
	keys = xrealloc(keys, keycc + cc + 1);
	if (keyfound)
	  keys[keycc++] = '\n';
	strcpy(&keys[keycc], optarg);
	keycc += cc;
	keyfound = 1;
	break;
      case 'f':
	fp = strcmp(optarg, "-") != 0 ? fopen(optarg, "r") : stdin;
	if (!fp)
	  fatal(optarg, errno);
	for (keyalloc = 1; keyalloc <= keycc; keyalloc *= 2)
	  ;
	keys = xrealloc(keys, keyalloc);
	oldcc = keycc;
	if (keyfound)
	  keys[keycc++] = '\n';
	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);
	/* Nuke the final newline to avoid matching a null string. */
	if (keycc - oldcc > 0 && keys[keycc - 1] == '\n')
	  --keycc;
	keyfound = 1;
	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;
	break;
      case 'l':
	out_quiet = 1;
	list_files = 1;
	break;
      case 'n':
	out_line = 1;
	break;
      case 'q':
	out_quiet = 1;
	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;
      default:
	usage();
	break;
      }

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

  if (!matcher)
    matcher = prog;

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

  (*compile)(keys, keycc);

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

  status = 1;

  if (optind < argc)
    while (optind < argc)
      {
	desc = strcmp(argv[optind], "-") ? open(argv[optind], O_RDONLY) : 0;
	if (desc < 0)
	  {
	    if (!suppress_errors)
	      error(argv[optind], errno);
	  }
	else
	  {
	    filename = desc == 0 ? "(standard input)" : argv[optind];
	    count = grep(desc);
	    if (count_matches)
	      {
		if (out_file)
		  printf("%s:", filename);
		printf("%d\n", count);
	      }
	    if (count)
	      {
		status = 0;
		if (list_files == 1)
		  printf("%s\n", filename);
	      }
	    else if (list_files == -1)
	      printf("%s\n", filename);
	  }
	if (desc != 0)
	  close(desc);
	++optind;
      }
  else
    {
      filename = "(standard input)";
      count = grep(0);
      if (count_matches)
	printf("%d\n", count);
      if (count)
	{
	  status = 0;
	  if (list_files == 1)
	    printf("(standard input)\n");
	}
      else if (list_files == -1)
	printf("(standard input)\n");
    }

  exit(errseen ? 2 : status);
}