#define PROG_NAME "jsuudecode"
#define PROG_DESC "Jorge Stolfi's version of \"uudecode\""
#define PROG_VERS "1.1"

/* Copyright © 1983 Regents of the University of California. */
/* See the copyright, authorship, and warranty notice at end of file. */
/* Last edited on 2009-01-08 03:57:35 by stolfi" */

#define PROG_HELP  \
  PROG_NAME " < INFILE > OUTFILE"

#define PROG_INFO \
  "NAME\n" \
  "  " PROG_NAME " - " PROG_DESC "\n" \
  "\n" \
  "SYNOPSIS\n" \
  PROG_HELP "\n" \
  "\n" \
  "DESCRIPTION\n" \
  "  A simplified version of uudecode(1).  Reads from standard" \
  " input a file produced by uuencode(1).  Writes" \
  " to standard output the decoded plain file.\n" \
  "\n" \
  "AUTHORS\n" \
  "  The author of uudecode(1) is unknown.\n" \
  "  Copyright © 1983 Regents of the University of California.\n" \
  "\n" \
  "  Modified 12 April 1990 by Mark Adler.\n" \
  "\n" \
  "  Modifed 13 February 1991 by Greg Roelofs.\n" \
  "\n" \
  "  Modified 13 April 1991 by Gary Mussar.\n" \
  "\n" \
  "  Radically simplified 19 March 2005 by Jorge Stolfi: for" \
  " Linux-only, works strictly as a filter."

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

void decode(FILE *in, FILE *out);
/* Copy from in to out, decoding as you go along. */

void outdec(char *p, FILE *f, int n);
/* Output a group of 3 bytes (4 input characters). The input chars are
  pointed to by p, they are to be output to file f. Argument n is used
  to tell us not to output all of them at the end of the file. */

/* single-character decode */
#define DEC(c)	(((c) - ' ') & 077)

int main(int argc, char **argv)
{
  FILE *in = stdin;
  FILE *out = stdout;
  char buf[80];

  /* Check command line args: */
  if (argc > 1) 
    { printf("%s version %s, usage:\n%s\n", PROG_NAME, PROG_VERS, PROG_HELP); exit(1); }

  /* Search and skip header line: */
  for (;;)
    { if (fgets(buf, sizeof buf, in) == NULL)
        { fprintf(stderr, "No begin line\n"); exit(1); }
      if (strncmp(buf, "begin ", 6) == 0) break;
    }

  decode(in, out);

  if (fgets(buf, sizeof buf, in) == NULL || strcmp(buf, "end\n")) 
    { fprintf(stderr, "No end line\n"); exit(1); }
 
  return 0;
}

void decode(FILE *in, FILE *out)
{
  char buf[80];
  char *bp;
  int n, i, expected;

  for (;;) 
    {
      /* for each input line */
      if (fgets(buf, sizeof buf, in) == NULL) 
        { printf("Short file\n"); exit(10); }
      n = DEC(buf[0]);
      if ((n <= 0) || (buf[0] == '\n')) break;

      /* Calculate expected # of chars and pad if necessary */
      expected = ((n+2)/3)<<2;
      for (i = strlen(buf)-1; i <= expected; i++) buf[i] = ' ';
      bp = &buf[1];
      while (n > 0) { outdec(bp, out, n); bp += 4; n -= 3; }
    }
}

void outdec(char *p, FILE *f, int n)
{
  int c1, c2, c3;
  c1 = DEC(*p) << 2 | DEC(p[1]) >> 4;
  c2 = DEC(p[1]) << 4 | DEC(p[2]) >> 2;
  c3 = DEC(p[2]) << 6 | DEC(p[3]);
  if (n >= 1) putc(c1, f);
  if (n >= 2) putc(c2, f);
  if (n >= 3) putc(c3, f);
}

/*
** Modified 12 April 1990 by Mark Adler for use on MSDOS systems with
** Microsoft C and Turbo C.
**
** Modifed 13 February 1991 by Greg Roelofs for use on VMS systems.  As
** with the MS-DOS version, the setting of the file mode has been disabled.
** Compile and link normally (but note that the shared-image link option
** produces a binary only 6 blocks long, as opposed to the 137-block one
** produced by an ordinary link).  To set up the VMS symbol to run the
** program ("run uudecode filename" won't work), do:
**		uudecode :== "$disk:[directory]uudecode.exe"
** and don't forget the leading "$" or it still won't work.  The binaries
** produced by this program are in VMS "stream-LF" format; this makes no
** difference to VMS when running decoded executables, nor to VMS unzip,
** but other programs such as zoo or arc may or may not require the file
** to be "BILFed" (or "unBILFed" or whatever).  Also, unlike the other
** flavors, VMS files don't get overwritten (a higher version is created).
** 
** Modified 13 April 1991 by Gary Mussar to be forgiving of systems that
** appear to be stripping trailing blanks.
**
** Modified 19 mar 2005 by Jorge Stolfi: radically simplified: for
** Linux-only, works strictly as a filter.
*/

/* COPYRIGHT, AUTHORSHIP, AND WARRANTY NOTICE:
**
**   Copyright (c) 1983 Regents of the University of California.
**   All rights reserved.
**
** Redistribution and use in source and binary forms are permitted
** provided that the above copyright notice and this paragraph are
** duplicated in all such forms and that any documentation,
** advertising materials, and other materials related to such
** distribution and use acknowledge that the software was developed
** by the University of California, Berkeley.  The name of the
** University may not be used to endorse or promote products derived
** from this software without specific prior written permission.
** THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
** IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
** WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/