sdiff.c

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/* SDIFF -- interactive merge front end to diff
   Copyright (C) 1992, 1993 Free Software Foundation, Inc.

This file is part of GNU DIFF.

GNU DIFF 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.

GNU DIFF 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 GNU DIFF; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

/* GNU SDIFF was written by Thomas Lord. */

#include "system.h"
#include <stdio.h>
#include <ctype.h>
#include <signal.h>
#include "getopt.h"

/* Size of chunks read from files which must be parsed into lines. */
#define SDIFF_BUFSIZE ((size_t) 65536)

/* Default name of the diff program */
#ifndef DIFF_PROGRAM
#define DIFF_PROGRAM "/usr/bin/diff"
#endif

/* Users' editor of nonchoice */
#ifndef DEFAULT_EDITOR
#define DEFAULT_EDITOR "ed"
#endif

extern char version_string[];
static char const *prog;
static char const *diffbin = DIFF_PROGRAM;
static char const *edbin = DEFAULT_EDITOR;

static char *tmpname;
static int volatile tmpmade;
static pid_t volatile diffpid;

struct line_filter;

static FILE *ck_fdopen PARAMS((int, char const *));
static FILE *ck_fopen PARAMS((char const *, char const *));
static RETSIGTYPE catchsig PARAMS((int));
static VOID *xmalloc PARAMS((size_t));
static char const *expand_name PARAMS((char *, int, char const *));
static int edit PARAMS((struct line_filter *, int, struct line_filter *, int, FILE*));
static int interact PARAMS((struct line_filter *, struct line_filter *, struct line_filter *, FILE*));
static int lf_snarf PARAMS((struct line_filter *, char *, size_t));
static int skip_white PARAMS((void));
static size_t ck_fread PARAMS((char *, size_t, FILE *));
static size_t lf_refill PARAMS((struct line_filter *));
static void checksigs PARAMS((void));
static void ck_fclose PARAMS((FILE *));
static void ck_fflush PARAMS((FILE *));
static void ck_fwrite PARAMS((char const *, size_t, FILE *));
static void cleanup PARAMS((void));
static void diffarg PARAMS((char const *));
static void execdiff PARAMS((int, char const *, char const *, char const *));
static void exiterr PARAMS((void));
static void fatal PARAMS((char const *));
static void flush_line PARAMS((void));
static void give_help PARAMS((void));
static void lf_copy PARAMS((struct line_filter *, int, FILE *));
static void lf_init PARAMS((struct line_filter *, FILE *));
static void lf_skip PARAMS((struct line_filter *, int));
static void perror_fatal PARAMS((char const *));
static void trapsigs PARAMS((void));
static void untrapsig PARAMS((int));
static void usage PARAMS((void));

/* this lossage until the gnu libc conquers the universe */
#define PVT_tmpdir "/tmp"
static char *private_tempnam PARAMS((char const *, char const *, int, size_t *));
static int diraccess PARAMS((char const *));
static int exists PARAMS((char const *));

/* Options: */

/* name of output file if -o spec'd */
static char *out_file;

/* do not print common lines if true, set by -s option */
static int suppress_common_flag;

static struct option const longopts[] =
{
  {"ignore-blank-lines", 0, 0, 'B'},
  {"speed-large-files", 0, 0, 'H'},
  {"ignore-matching-lines", 1, 0, 'I'},
  {"ignore-all-space", 0, 0, 'W'}, /* swap W and w for historical reasons */
  {"text", 0, 0, 'a'},
  {"ignore-space-change", 0, 0, 'b'},
  {"minimal", 0, 0, 'd'},
  {"ignore-case", 0, 0, 'i'},
  {"left-column", 0, 0, 'l'},
  {"output", 1, 0, 'o'},
  {"suppress-common-lines", 0, 0, 's'},
  {"expand-tabs", 0, 0, 't'},
  {"width", 1, 0, 'w'},
  {"version", 0, 0, 'v'},
  {0, 0, 0, 0}
};

/* prints usage message and quits */
static void
usage ()
{
  fprintf (stderr, "Usage: %s [options] from-file to-file\n", prog);
  fprintf (stderr, "Options:\n\
       [-abBdHilstv] [-I regexp] [-o outfile] [-w columns]\n\
       [--text] [--minimal] [--speed-large-files] [--expand-tabs]\n\
       [--ignore-case] [--ignore-matching-lines=regexp]\n\
       [--ignore-space-change] [--ignore-blank-lines] [--ignore-all-space]\n\
       [--suppress-common-lines] [--left-column] [--output=outfile]\n\
       [--version] [--width=columns]\n");
  exit (2);
}

static void
cleanup ()
{
  if (0 < diffpid)
    kill (diffpid, SIGPIPE);
  if (tmpmade)
    unlink (tmpname);
}

static void
exiterr ()
{
  cleanup ();
  untrapsig (0);
  checksigs ();
  exit (2);
}

static void
fatal (msg)
     char const *msg;
{
  fprintf (stderr, "%s: %s\n", prog, msg);
  exiterr ();
}

static void
perror_fatal (msg)
     char const *msg;
{
  int e = errno;
  checksigs ();
  fprintf (stderr, "%s: ", prog);
  errno = e;
  perror (msg);
  exiterr ();
}


/* malloc freely or DIE! */
static VOID *
xmalloc (size)
     size_t size;
{
  VOID *r = (VOID *) malloc (size);
  if (!r)
    fatal ("virtual memory exhausted");
  return r;
}

static FILE *
ck_fopen (fname, type)
     char const *fname, *type;
{
  FILE *r = fopen (fname, type);
  if (!r)
    perror_fatal (fname);
  return r;
}


static FILE *
ck_fdopen (fd, type)
     int fd;
     char const *type;
{
  FILE *r = fdopen (fd, type);
  if (!r)
    perror_fatal ("fdopen");
  return r;
}

static void
ck_fclose (f)
     FILE *f;
{
  if (fclose (f))
    perror_fatal ("input/output error");
}

static size_t
ck_fread (buf, size, f)
     char *buf;
     size_t size;
     FILE *f;
{
  size_t r = fread (buf, sizeof (char), size, f);
  if (r == 0 && ferror (f))
    perror_fatal ("input error");
  return r;
}

static void
ck_fwrite (buf, size, f)
     char const *buf;
     size_t size;
     FILE *f;
{
  if (fwrite (buf, sizeof (char), size, f) != size)
    perror_fatal ("output error");
}

static void
ck_fflush (f)
     FILE *f;
{
  if (fflush (f) != 0)
    perror_fatal ("output error");
}

#if !HAVE_MEMCHR
char *
memchr (s, c, n)
     char const *s;
     int c;
     size_t n;
{
  unsigned char const *p = (unsigned char const *) s, *lim = p + n;
  for (;  p < lim;  p++)
    if (*p == c)
      return (char *) p;
  return 0;
}
#endif

#ifndef HAVE_WAITPID
/* Emulate waitpid well enough for sdiff, which has at most two children.  */
static pid_t
waitpid (pid, stat_loc, options)
     pid_t pid;
     int *stat_loc;
     int options;
{
  static int ostatus;
  static pid_t opid;
  int npid, status;

  if (pid == opid)
    {
      opid = 0;
      status = ostatus;
    }
  else
    while ((npid = wait (&status)) != pid)
      {
	if (npid < 0)
	  return npid;
	opid = npid;
	ostatus = status;
      }
  *stat_loc = status;
  return pid;
}
#endif

static char const *
expand_name (name, isdir, other_name)
     char *name;
     int isdir;
     char const *other_name;
{
  if (strcmp (name, "-") == 0)
    fatal ("cannot interactively merge standard input");
  if (!isdir)
    return name;
  else
    {
      /* Yield NAME/BASE, where BASE is OTHER_NAME's basename.  */
      char const
	*p = strrchr (other_name, '/'),
	*base = p ? p+1 : other_name;
      size_t namelen = strlen (name), baselen = strlen (base);
      char *r = xmalloc (namelen + baselen + 2);
      memcpy (r, name, namelen);
      r[namelen] = '/';
      memcpy (r + namelen + 1, base, baselen + 1);
      return r;
    }
}



struct line_filter {
  FILE *infile;
  char *bufpos;
  char *buffer;
  char *buflim;
};

static void
lf_init (lf, infile)
     struct line_filter *lf;
     FILE *infile;
{
  lf->infile = infile;
  lf->bufpos = lf->buffer = lf->buflim = xmalloc (SDIFF_BUFSIZE + 1);
  lf->buflim[0] = '\n';
}

/* Fill an exhausted line_filter buffer from its INFILE */
static size_t
lf_refill (lf)
     struct line_filter *lf;
{
  size_t s = ck_fread (lf->buffer, SDIFF_BUFSIZE, lf->infile);
  lf->bufpos = lf->buffer;
  lf->buflim = lf->buffer + s;
  lf->buflim[0] = '\n';
  checksigs ();
  return s;
}

/* Advance LINES on LF's infile, copying lines to OUTFILE */
static void
lf_copy (lf, lines, outfile)
     struct line_filter *lf;
     int lines;
     FILE *outfile;
{
  char *start = lf->bufpos;

  while (lines)
    {
      lf->bufpos = (char *) memchr (lf->bufpos, '\n', lf->buflim - lf->bufpos);
      if (! lf->bufpos)
	{
	  ck_fwrite (start, lf->buflim - start, outfile);
	  if (! lf_refill (lf))
	    return;
	  start = lf->bufpos;
	}
      else
	{
	  --lines;
	  ++lf->bufpos;
	}
    }

  ck_fwrite (start, lf->bufpos - start, outfile);
}

/* Advance LINES on LF's infile without doing output */
static void
lf_skip (lf, lines)
     struct line_filter *lf;
     int lines;
{
  while (lines)
    {
      lf->bufpos = (char *) memchr (lf->bufpos, '\n', lf->buflim - lf->bufpos);
      if (! lf->bufpos)
	{
	  if (! lf_refill (lf))
	    break;
	}
      else
	{
	  --lines;
	  ++lf->bufpos;
	}
    }
}

/* Snarf a line into a buffer.  Return EOF if EOF, 0 if error, 1 if OK.  */
static int
lf_snarf (lf, buffer, bufsize)
     struct line_filter *lf;
     char *buffer;
     size_t bufsize;
{
  char *start = lf->bufpos;

  for (;;)
    {
      char *next = (char *) memchr (start, '\n', lf->buflim + 1 - start);
      size_t s = next - start;
      if (bufsize <= s)
	return 0;
      memcpy (buffer, start, s);
      if (next < lf->buflim)
	{
	  buffer[s] = 0;
	  lf->bufpos = next + 1;
	  return 1;
	}
      if (! lf_refill (lf))
	return s ? 0 : EOF;
      buffer += s;
      bufsize -= s;
      start = next;
    }
}



int
main (argc, argv)
     int argc;
     char *argv[];
{
  int opt;
  int version_requested = 0;
  char *editor = getenv ("EDITOR");
  char *differ = getenv ("DIFF");

  prog = argv[0];
  if (editor)
    edbin = editor;
  if (differ)
    diffbin = differ;

  diffarg ("diff");

  /* parse command line args */
  while ((opt = getopt_long (argc, argv, "abBdHiI:lo:stvw:W", longopts, 0))
	 != EOF)
    {
      switch (opt)
	{
	case 'a':
	  diffarg ("-a");
	  break;

	case 'b':
	  diffarg ("-b");
	  break;

	case 'B':
	  diffarg ("-B");
	  break;

	case 'd':
	  diffarg ("-d");
	  break;

	case 'H':
	  diffarg ("-H");
	  break;

	case 'i':
	  diffarg ("-i");
	  break;

	case 'I':
	  diffarg ("-I");
	  diffarg (optarg);
	  break;

	case 'l':
	  diffarg ("--left-column");
	  break;

	case 'o':
	  out_file = optarg;
	  break;

	case 's':
	  suppress_common_flag = 1;
	  break;

	case 't':
	  diffarg ("-t");
	  break;

	case 'v':
	  version_requested = 1;
	  fprintf (stderr, "GNU sdiff version %s\n", version_string);
	  ck_fflush (stderr);
	  break;

	case 'w':
	  diffarg ("-W");
	  diffarg (optarg);
	  break;

	case 'W':
	  diffarg ("-w");
	  break;

	default:
	  usage ();
	}
    }

  /* check: did user just want version message? if so exit. */
  if (version_requested && argc - optind == 0)
    exit (0);

  if (argc - optind != 2)
    usage ();

  if (! out_file)
    /* easy case: diff does everything for us */
    execdiff (suppress_common_flag, "-y", argv[optind], argv[optind + 1]);
  else
    {
      FILE *left, *right, *out, *diffout;
      int diff_fds[2];
      int interact_ok;
      pid_t pid;
      struct line_filter lfilt;
      struct line_filter rfilt;
      struct line_filter diff_filt;
      int leftdir = diraccess (argv[optind]);
      int rightdir = diraccess (argv[optind + 1]);

      if (leftdir && rightdir)
	fatal ("both files to be compared are directories");

      left = ck_fopen (expand_name (argv[optind], leftdir, argv[optind + 1]), "r");
      ;
      right = ck_fopen (expand_name (argv[optind + 1], rightdir, argv[optind]), "r");
      out = ck_fopen (out_file, "w");

      if (pipe (diff_fds))
	perror_fatal ("pipe");

      trapsigs ();

      diffpid = pid = vfork ();

      if (pid == 0)
	{
	  signal (SIGINT, SIG_IGN);  /* in case user interrupts editor */
	  signal (SIGPIPE, SIG_DFL);

	  close (diff_fds[0]);
	  if (diff_fds[1] != STDOUT_FILENO)
	    {
	      dup2 (diff_fds[1], STDOUT_FILENO);
	      close (diff_fds[1]);
	    }

	  execdiff (0, "--sdiff-merge-assist", argv[optind], argv[optind + 1]);
	}

      if (pid < 0)
	perror_fatal ("fork failed");

      close (diff_fds[1]);
      diffout = ck_fdopen (diff_fds[0], "r");

      lf_init (&diff_filt, diffout);
      lf_init (&lfilt, left);
      lf_init (&rfilt, right);

      interact_ok = interact (&diff_filt, &lfilt, &rfilt, out);

      ck_fclose (diffout);
      ck_fclose (left);
      ck_fclose (right);
      ck_fclose (out);

      {
	int wstatus;

	while (waitpid (pid, &wstatus, 0) < 0)
	  if (errno == EINTR)
	    checksigs ();
	  else
	    perror_fatal ("wait failed");
	diffpid = 0;

	if (tmpmade)
	  {
	    unlink (tmpname);
	    tmpmade = 0;
	  }