/* uudecode.c -- uudecode utility.
 * Copyright (C) 1994, 1995 Free Software Foundation, Inc.
 *
 * This product 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 product 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 product; see the file COPYING.  If not, write to
 * the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */

/* Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *       This product includes software developed by the University of
 *       California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/* Reworked to GNU style by Ian Lance Taylor, ian@airs.com, August 93.  */

#include "internal.h"

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

/*struct passwd *getpwnam();*/

/* Single character decode.  */
#define	DEC(Char) (((Char) - ' ') & 077)

static int read_stduu (const char *inname)
{
  char buf[2 * BUFSIZ];

  while (1) {
    int n;
    char *p;

    if (fgets (buf, sizeof(buf), stdin) == NULL) {
      errorMsg("%s: Short file\n", inname);
      return FALSE;
    }
    p = buf;

    /* N is used to avoid writing out all the characters at the end of
       the file.  */
    n = DEC (*p);
    if (n <= 0)
      break;
    for (++p; n > 0; p += 4, n -= 3) {
      char ch;

      if (n >= 3) {
        ch = DEC (p[0]) << 2 | DEC (p[1]) >> 4;
        putchar (ch);
        ch = DEC (p[1]) << 4 | DEC (p[2]) >> 2;
        putchar (ch);
        ch = DEC (p[2]) << 6 | DEC (p[3]);
        putchar (ch);
      } else {
        if (n >= 1) {
          ch = DEC (p[0]) << 2 | DEC (p[1]) >> 4;
          putchar (ch);
        }
        if (n >= 2) {
          ch = DEC (p[1]) << 4 | DEC (p[2]) >> 2;
          putchar (ch);
        }
      }
    }
  }

  if (fgets (buf, sizeof(buf), stdin) == NULL
      || strcmp (buf, "end\n")) {
    errorMsg("%s: No `end' line\n", inname);
    return FALSE;
  }

  return TRUE;
}

static int read_base64 (const char *inname)
{
  static const char b64_tab[256] = {
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*000-007*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*010-017*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*020-027*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*030-037*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*040-047*/
    '\177', '\177', '\177', '\76',  '\177', '\177', '\177', '\77',  /*050-057*/
    '\64',  '\65',  '\66',  '\67',  '\70',  '\71',  '\72',  '\73',  /*060-067*/
    '\74',  '\75',  '\177', '\177', '\177', '\100', '\177', '\177', /*070-077*/
    '\177', '\0',   '\1',   '\2',   '\3',   '\4',   '\5',   '\6',   /*100-107*/
    '\7',   '\10',  '\11',  '\12',  '\13',  '\14',  '\15',  '\16',  /*110-117*/
    '\17',  '\20',  '\21',  '\22',  '\23',  '\24',  '\25',  '\26',  /*120-127*/
    '\27',  '\30',  '\31',  '\177', '\177', '\177', '\177', '\177', /*130-137*/
    '\177', '\32',  '\33',  '\34',  '\35',  '\36',  '\37',  '\40',  /*140-147*/
    '\41',  '\42',  '\43',  '\44',  '\45',  '\46',  '\47',  '\50',  /*150-157*/
    '\51',  '\52',  '\53',  '\54',  '\55',  '\56',  '\57',  '\60',  /*160-167*/
    '\61',  '\62',  '\63',  '\177', '\177', '\177', '\177', '\177', /*170-177*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*200-207*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*210-217*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*220-227*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*230-237*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*240-247*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*250-257*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*260-267*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*270-277*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*300-307*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*310-317*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*320-327*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*330-337*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*340-347*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*350-357*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*360-367*/
    '\177', '\177', '\177', '\177', '\177', '\177', '\177', '\177', /*370-377*/
  };
  unsigned char buf[2 * BUFSIZ];

  while (1) {
    int last_data = 0;
    unsigned char *p;

    if (fgets (buf, sizeof(buf), stdin) == NULL) {
      errorMsg("%s: Short file\n", inname);
      return FALSE;
    }
    p = buf;

    if (memcmp (buf, "====", 4) == 0)
      break;
    if (last_data != 0) {
      errorMsg("%s: data following `=' padding character\n", inname);
      return FALSE;
    }

    /* The following implementation of the base64 decoding might look
       a bit clumsy but I only try to follow the POSIX standard:
       ``All line breaks or other characters not found in the table
       [with base64 characters] shall be ignored by decoding
       software.''  */
    while (*p != '\n') {
      char c1, c2, c3;

      while ((b64_tab[*p] & '\100') != 0)
        if (*p == '\n' || *p++ == '=')
          break;
      if (*p == '\n')
        /* This leaves the loop.  */
        continue;
      c1 = b64_tab[*p++];

      while ((b64_tab[*p] & '\100') != 0)
        if (*p == '\n' || *p++ == '=') {
          errorMsg("%s: illegal line\n", inname);
          return FALSE;
        }
      c2 = b64_tab[*p++];

      while (b64_tab[*p] == '\177')
        if (*p++ == '\n') {
          errorMsg("%s: illegal line\n", inname);
          return FALSE;
        }
      if (*p == '=') {
        putchar (c1 << 2 | c2 >> 4);
        last_data = 1;
        break;
      }
      c3 = b64_tab[*p++];

      while (b64_tab[*p] == '\177')
        if (*p++ == '\n') {
          errorMsg("%s: illegal line\n", inname);
          return FALSE;
        }
      putchar (c1 << 2 | c2 >> 4);
      putchar (c2 << 4 | c3 >> 2);
      if (*p == '=') {
        last_data = 1;
        break;
      }
      else
        putchar (c3 << 6 | b64_tab[*p++]);
    }
  }

  return TRUE;
}

static int decode (const char *inname,
                   const char *forced_outname)
{
  struct passwd *pw;
  register int n;
  register char *p;
  int mode, n1;
  char buf[2 * BUFSIZ];
  char *outname;
  int do_base64 = 0;

  /* Search for header line.  */

  while (1) {
    if (fgets (buf, sizeof (buf), stdin) == NULL) {
      errorMsg("%s: No `begin' line\n", inname);
      return FALSE;
    }

    if (strncmp (buf, "begin", 5) == 0) {
      if (sscanf (buf, "begin-base64 %o %s", &mode, buf) == 2) {
        do_base64 = 1;
        break;
      } else if (sscanf (buf, "begin %o %s", &mode, buf) == 2)
        break;
    }
  }

  /* If the output file name is given on the command line this rules.  */
  if (forced_outname != NULL)
    outname = (char *) forced_outname;
  else {
    /* Handle ~user/file format.  */
    if (buf[0] != '~')
      outname = buf;
    else {
      p = buf + 1;
      while (*p != '/')
        ++p;
      if (*p == '\0') {
        errorMsg("%s: Illegal ~user\n", inname);
        return FALSE;
      }
      *p++ = '\0';
      pw = getpwnam (buf + 1);
      if (pw == NULL) {
        errorMsg("%s: No user `%s'\n", inname, buf + 1);
        return FALSE;
      }
      n = strlen (pw->pw_dir);
      n1 = strlen (p);
      outname = (char *) alloca ((size_t) (n + n1 + 2));
      memcpy (outname + n + 1, p, (size_t) (n1 + 1));
      memcpy (outname, pw->pw_dir, (size_t) n);
      outname[n] = '/';
    }
  }

  /* Create output file and set mode.  */
  if (strcmp (outname, "/dev/stdout") != 0 && strcmp (outname, "-") != 0
      && (freopen (outname, "w", stdout) == NULL
	  || chmod (outname, mode & (S_IRWXU | S_IRWXG | S_IRWXO))
         )) {
    errorMsg("uudeoce %s: %s %s\n", outname, inname, strerror(errno)); /* */
    return FALSE;
  }

  /* We differenciate decoding standard UU encoding and base64.  A
     common function would only slow down the program.  */

  /* For each input line:  */
  if (do_base64)
    return read_base64 (inname);
  else
    return read_stduu (inname);
}

static const char uudecode_usage[] =
    "uudecode [FILE]...\n"
#ifndef BB_FEATURE_TRIVIAL_HELP
    "\nUudecode a file that is uuencoded.\n\n"
    "Options:\n"
    "\t-o FILE\tdirect output to FILE\n"
#endif
;

int uudecode_main (int argc,
                   char **argv)
{
  int opt;
  int exit_status;
  const char *outname;
  outname = NULL;

  while ((opt = getopt(argc, argv, "o:")) != EOF) {
    switch (opt) {
     case 0:
      break;

     case 'o':
      outname = optarg;
      break;

     default:
      usage(uudecode_usage);
    }
  }

  if (optind == argc)
    exit_status = decode ("stdin", outname) == 0 ? TRUE : FALSE;
  else {
    exit_status = TRUE;
    do {
      if (freopen (argv[optind], "r", stdin) != NULL) {
        if (decode (argv[optind], outname) != 0)
          exit_status = FALSE;
      } else {
        errorMsg("uudecode: %s: %s\n", argv[optind], strerror(errno));
        exit_status = FALSE;
      }
      optind++;
    }
    while (optind < argc);
  }
  return(exit_status);
}