handler.c

/**
 * Copyright (C) 1996-2000,2002,2010,2013 Michael R. Elkins <me@mutt.org>
 *
 * 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 of the License, 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, see <http://www.gnu.org/licenses/>.
 */

#include "config.h"
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>
#include "mutt.h"
#include "charset.h"
#include "copy.h"
#include "filter.h"
#include "keymap.h"
#include "mime.h"
#include "mutt_crypt.h"
#include "mutt_curses.h"
#include "rfc1524.h"
#include "rfc3676.h"

#define BUFI_SIZE 1000
#define BUFO_SIZE 2000


typedef int (*handler_t)(BODY *, STATE *);

// clang-format off
const int Index_hex[128] = {
    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
     0, 1, 2, 3,  4, 5, 6, 7,  8, 9,-1,-1, -1,-1,-1,-1,
    -1,10,11,12, 13,14,15,-1, -1,-1,-1,-1, -1,-1,-1,-1,
    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
    -1,10,11,12, 13,14,15,-1, -1,-1,-1,-1, -1,-1,-1,-1,
    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1
};

const int Index_64[128] = {
    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
    -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,62, -1,-1,-1,63,
    52,53,54,55, 56,57,58,59, 60,61,-1,-1, -1,-1,-1,-1,
    -1, 0, 1, 2,  3, 4, 5, 6,  7, 8, 9,10, 11,12,13,14,
    15,16,17,18, 19,20,21,22, 23,24,25,-1, -1,-1,-1,-1,
    -1,26,27,28, 29,30,31,32, 33,34,35,36, 37,38,39,40,
    41,42,43,44, 45,46,47,48, 49,50,51,-1, -1,-1,-1,-1
};
// clang-format on

static void print_part_line(STATE *s, BODY *b, int n)
{
  char length[5];
  mutt_pretty_size(length, sizeof(length), b->length);
  state_mark_attach(s);
  char *charset = mutt_get_parameter("charset", b->parameter);
  if (n != 0)
    state_printf(s, _("[-- Alternative Type #%d: "), n);
  else
    state_printf(s, _("[-- Type: "));
  state_printf(s, _("%s/%s%s%s, Encoding: %s, Size: %s --]\n"), TYPE(b),
               b->subtype, charset ? "; charset=" : "", charset ? charset : "",
               ENCODING(b->encoding), length);
}

static void state_prefix_put(const char *d, size_t dlen, STATE *s)
{
  if (s->prefix)
    while (dlen--)
      state_prefix_putc(*d++, s);
  else
    fwrite(d, dlen, 1, s->fpout);
}

static void convert_to_state(iconv_t cd, char *bufi, size_t *l, STATE *s)
{
  char bufo[BUFO_SIZE];
  ICONV_CONST char *ib = NULL;
  char *ob = NULL;
  size_t ibl, obl;

  if (!bufi)
  {
    if (cd != (iconv_t)(-1))
    {
      ob = bufo, obl = sizeof(bufo);
      iconv(cd, 0, 0, &ob, &obl);
      if (ob != bufo)
        state_prefix_put(bufo, ob - bufo, s);
    }
    return;
  }

  if (cd == (iconv_t)(-1))
  {
    state_prefix_put(bufi, *l, s);
    *l = 0;
    return;
  }

  ib = bufi, ibl = *l;
  for (;;)
  {
    ob = bufo, obl = sizeof(bufo);
    mutt_iconv(cd, &ib, &ibl, &ob, &obl, 0, "?");
    if (ob == bufo)
      break;
    state_prefix_put(bufo, ob - bufo, s);
  }
  memmove(bufi, ib, ibl);
  *l = ibl;
}

static void decode_xbit(STATE *s, long len, int istext, iconv_t cd)
{
  int c, ch;
  char bufi[BUFI_SIZE];
  size_t l = 0;

  if (istext)
  {
    state_set_prefix(s);

    while ((c = fgetc(s->fpin)) != EOF && len--)
    {
      if (c == '\r' && len)
      {
        if ((ch = fgetc(s->fpin)) == '\n')
        {
          c = ch;
          len--;
        }
        else
          ungetc(ch, s->fpin);
      }

      bufi[l++] = c;
      if (l == sizeof(bufi))
        convert_to_state(cd, bufi, &l, s);
    }

    convert_to_state(cd, bufi, &l, s);
    convert_to_state(cd, 0, 0, s);

    state_reset_prefix(s);
  }
  else
    mutt_copy_bytes(s->fpin, s->fpout, len);
}

static int qp_decode_triple(char *s, char *d)
{
  /* soft line break */
  if (*s == '=' && !(*(s + 1)))
    return 1;

  /* quoted-printable triple */
  if (*s == '=' && isxdigit((unsigned char) *(s + 1)) &&
      isxdigit((unsigned char) *(s + 2)))
  {
    *d = (hexval(*(s + 1)) << 4) | hexval(*(s + 2));
    return 0;
  }

  /* something else */
  return -1;
}

static void qp_decode_line(char *dest, char *src, size_t *l, int last)
{
  char *d = NULL, *s = NULL;
  char c = 0;

  int kind = -1;
  int soft = 0;

  /* decode the line */

  for (d = dest, s = src; *s;)
  {
    switch ((kind = qp_decode_triple(s, &c)))
    {
      case 0:
        *d++ = c;
        s += 3;
        break; /* qp triple */
      case -1:
        *d++ = *s++;
        break; /* single character */
      case 1:
        soft = 1;
        s++;
        break; /* soft line break */
    }
  }

  if (!soft && last == '\n')
  {
    /* neither \r nor \n as part of line-terminating CRLF
     * may be qp-encoded, so remove \r and \n-terminate;
     * see RfC2045, sect. 6.7, (1): General 8bit representation */
    if (kind == 0 && c == '\r')
      *(d - 1) = '\n';
    else
      *d++ = '\n';
  }

  *d = '\0';
  *l = d - dest;
}

/*
 * Decode an attachment encoded with quoted-printable.
 *
 * Why doesn't this overflow any buffers?  First, it's guaranteed
 * that the length of a line grows when you _en_-code it to
 * quoted-printable.  That means that we always can store the
 * result in a buffer of at most the _same_ size.
 *
 * Now, we don't special-case if the line we read with fgets()
 * isn't terminated.  We don't care about this, since STRING > 78,
 * so corrupted input will just be corrupted a bit more.  That
 * implies that STRING+1 bytes are always sufficient to store the
 * result of qp_decode_line.
 *
 * Finally, at soft line breaks, some part of a multibyte character
 * may have been left over by convert_to_state().  This shouldn't
 * be more than 6 characters, so STRING + 7 should be sufficient
 * memory to store the decoded data.
 *
 * Just to make sure that I didn't make some off-by-one error
 * above, we just use STRING*2 for the target buffer's size.
 *
 */
static void decode_quoted(STATE *s, long len, int istext, iconv_t cd)
{
  char line[STRING];
  char decline[2 * STRING];
  size_t l = 0;
  size_t linelen; /* number of input bytes in `line' */
  size_t l3;

  int last; /* store the last character in the input line */

  if (istext)
    state_set_prefix(s);

  while (len > 0)
  {
    last = 0;

    /*
     * It's ok to use a fixed size buffer for input, even if the line turns
     * out to be longer than this.  Just process the line in chunks.  This
     * really shouldn't happen according the MIME spec, since Q-P encoded
     * lines are at most 76 characters, but we should be liberal about what
     * we accept.
     */
    if (fgets(line, MIN((ssize_t) sizeof(line), len + 1), s->fpin) == NULL)
      break;

    linelen = strlen(line);
    len -= linelen;

    /*
     * inspect the last character we read so we can tell if we got the
     * entire line.
     */
    last = linelen ? line[linelen - 1] : 0;

    /* chop trailing whitespace if we got the full line */
    if (last == '\n')
    {
      while (linelen > 0 && ISSPACE(line[linelen - 1]))
        linelen--;
      line[linelen] = 0;
    }

    /* decode and do character set conversion */
    qp_decode_line(decline + l, line, &l3, last);
    l += l3;
    convert_to_state(cd, decline, &l, s);
  }

  convert_to_state(cd, 0, 0, s);
  state_reset_prefix(s);
}

void mutt_decode_base64(STATE *s, long len, int istext, iconv_t cd)
{
  char buf[5];
  int c1, c2, c3, c4, ch, cr = 0, i;
  char bufi[BUFI_SIZE];
  size_t l = 0;

  buf[4] = 0;

  if (istext)
    state_set_prefix(s);

  while (len > 0)
  {
    for (i = 0; i < 4 && len > 0; len--)
    {
      if ((ch = fgetc(s->fpin)) == EOF)
        break;
      if (ch >= 0 && ch < 128 && (base64val(ch) != -1 || ch == '='))
        buf[i++] = ch;
    }
    if (i != 4)
    {
      /* "i" may be zero if there is trailing whitespace, which is not an error */
      if (i != 0)
        mutt_debug(2, "%s:%d [mutt_decode_base64()]: "
                      "didn't get a multiple of 4 chars.\n",
                   __FILE__, __LINE__);
      break;
    }

    c1 = base64val(buf[0]);
    c2 = base64val(buf[1]);
    ch = (c1 << 2) | (c2 >> 4);

    if (cr && ch != '\n')
      bufi[l++] = '\r';

    cr = 0;

    if (istext && ch == '\r')
      cr = 1;
    else
      bufi[l++] = ch;

    if (buf[2] == '=')
      break;
    c3 = base64val(buf[2]);
    ch = ((c2 & 0xf) << 4) | (c3 >> 2);

    if (cr && ch != '\n')
      bufi[l++] = '\r';

    cr = 0;

    if (istext && ch == '\r')
      cr = 1;
    else
      bufi[l++] = ch;

    if (buf[3] == '=')
      break;
    c4 = base64val(buf[3]);
    ch = ((c3 & 0x3) << 6) | c4;

    if (cr && ch != '\n')
      bufi[l++] = '\r';
    cr = 0;

    if (istext && ch == '\r')
      cr = 1;
    else
      bufi[l++] = ch;

    if (l + 8 >= sizeof(bufi))
      convert_to_state(cd, bufi, &l, s);
  }

  if (cr)
    bufi[l++] = '\r';

  convert_to_state(cd, bufi, &l, s);
  convert_to_state(cd, 0, 0, s);

  state_reset_prefix(s);
}

static unsigned char decode_byte(char ch)
{
  if (ch == 96)
    return 0;
  return ch - 32;
}

static void decode_uuencoded(STATE *s, long len, int istext, iconv_t cd)
{
  char tmps[SHORT_STRING];
  char linelen, c, l, out;
  char *pt = NULL;
  char bufi[BUFI_SIZE];
  size_t k = 0;

  if (istext)
    state_set_prefix(s);

  while (len > 0)
  {
    if ((fgets(tmps, sizeof(tmps), s->fpin)) == NULL)
      return;
    len -= mutt_strlen(tmps);
    if ((mutt_strncmp(tmps, "begin", 5) == 0) && ISSPACE(tmps[5]))
      break;
  }
  while (len > 0)
  {
    if ((fgets(tmps, sizeof(tmps), s->fpin)) == NULL)
      return;
    len -= mutt_strlen(tmps);
    if (mutt_strncmp(tmps, "end", 3) == 0)
      break;
    pt = tmps;
    linelen = decode_byte(*pt);
    pt++;
    for (c = 0; c < linelen;)
    {
      for (l = 2; l <= 6; l += 2)
      {
        out = decode_byte(*pt) << l;
        pt++;
        out |= (decode_byte(*pt) >> (6 - l));
        bufi[k++] = out;
        c++;
        if (c == linelen)
          break;
      }
      convert_to_state(cd, bufi, &k, s);
      pt++;
    }
  }

  convert_to_state(cd, bufi, &k, s);
  convert_to_state(cd, 0, 0, s);

  state_reset_prefix(s);
}

/* ----------------------------------------------------------------------------
 * A (not so) minimal implementation of RFC1563.
 */

#define IndentSize (4)

enum
{
  RICH_PARAM = 0,
  RICH_BOLD,
  RICH_UNDERLINE,
  RICH_ITALIC,
  RICH_NOFILL,
  RICH_INDENT,
  RICH_INDENT_RIGHT,
  RICH_EXCERPT,
  RICH_CENTER,
  RICH_FLUSHLEFT,
  RICH_FLUSHRIGHT,
  RICH_COLOR,
  RICH_LAST_TAG
};

static const struct
{
  const wchar_t *tag_name;
  int index;
} EnrichedTags[] = {
  { L"param", RICH_PARAM },
  { L"bold", RICH_BOLD },
  { L"italic", RICH_ITALIC },
  { L"underline", RICH_UNDERLINE },
  { L"nofill", RICH_NOFILL },
  { L"excerpt", RICH_EXCERPT },
  { L"indent", RICH_INDENT },
  { L"indentright", RICH_INDENT_RIGHT },
  { L"center", RICH_CENTER },
  { L"flushleft", RICH_FLUSHLEFT },
  { L"flushright", RICH_FLUSHRIGHT },
  { L"flushboth", RICH_FLUSHLEFT },
  { L"color", RICH_COLOR },
  { L"x-color", RICH_COLOR },
  { NULL, -1 },
};

struct enriched_state
{
  wchar_t *buffer;
  wchar_t *line;
  wchar_t *param;
  size_t buff_len;
  size_t line_len;
  size_t line_used;
  size_t line_max;
  size_t indent_len;
  size_t word_len;
  size_t buff_used;
  size_t param_used;
  size_t param_len;
  int tag_level[RICH_LAST_TAG];
  int WrapMargin;
  STATE *s;
};

static void enriched_wrap(struct enriched_state *stte)
{
  int x;
  int extra;

  if (stte->line_len)
  {
    if (stte->tag_level[RICH_CENTER] || stte->tag_level[RICH_FLUSHRIGHT])
    {
      /* Strip trailing white space */
      size_t y = stte->line_used - 1;

      while (y && iswspace(stte->line[y]))
      {
        stte->line[y] = (wchar_t) '\0';
        y--;
        stte->line_used--;
        stte->line_len--;
      }
      if (stte->tag_level[RICH_CENTER])
      {
        /* Strip leading whitespace */
        y = 0;

        while (stte->line[y] && iswspace(stte->line[y]))
          y++;
        if (y)
        {
          size_t z;

          for (z = y; z <= stte->line_used; z++)
          {
            stte->line[z - y] = stte->line[z];
          }

          stte->line_len -= y;
          stte->line_used -= y;
        }
      }
    }

    extra = stte->WrapMargin - stte->line_len - stte->indent_len -
            (stte->tag_level[RICH_INDENT_RIGHT] * IndentSize);
    if (extra > 0)
    {
      if (stte->tag_level[RICH_CENTER])
      {
        x = extra / 2;
        while (x)
        {
          state_putc(' ', stte->s);
          x--;
        }
      }
      else if (stte->tag_level[RICH_FLUSHRIGHT])
      {
        x = extra - 1;
        while (x)
        {
          state_putc(' ', stte->s);
          x--;
        }
      }
    }
    state_putws((const wchar_t *) stte->line, stte->s);
  }

  state_putc('\n', stte->s);
  stte->line[0] = (wchar_t) '\0';
  stte->line_len = 0;
  stte->line_used = 0;
  stte->indent_len = 0;
  if (stte->s->prefix)
  {
    state_puts(stte->s->prefix, stte->s);
    stte->indent_len += mutt_strlen(stte->s->prefix);
  }

  if (stte->tag_level[RICH_EXCERPT])
  {
    x = stte->tag_level[RICH_EXCERPT];
    while (x)
    {
      if (stte->s->prefix)
      {
        state_puts(stte->s->prefix, stte->s);
        stte->indent_len += mutt_strlen(stte->s->prefix);
      }
      else
      {
        state_puts("> ", stte->s);
        stte->indent_len += mutt_strlen("> ");
      }
      x--;
    }
  }
  else
    stte->indent_len = 0;
  if (stte->tag_level[RICH_INDENT])
  {
    x = stte->tag_level[RICH_INDENT] * IndentSize;
    stte->indent_len += x;
    while (x)
    {
      state_putc(' ', stte->s);
      x--;
    }
  }
}

static void enriched_flush(struct enriched_state *stte, int wrap)
{
  if (!stte->tag_level[RICH_NOFILL] &&
      (stte->line_len + stte->word_len >
       (stte->WrapMargin - (stte->tag_level[RICH_INDENT_RIGHT] * IndentSize) - stte->indent_len)))
    enriched_wrap(stte);

  if (stte->buff_used)
  {
    stte->buffer[stte->buff_used] = (wchar_t) '\0';
    stte->line_used += stte->buff_used;
    if (stte->line_used > stte->line_max)
    {
      stte->line_max = stte->line_used;
      safe_realloc(&stte->line, (stte->line_max + 1) * sizeof(wchar_t));
    }
    wcscat(stte->line, stte->buffer);
    stte->line_len += stte->word_len;
    stte->word_len = 0;
    stte->buff_used = 0;
  }
  if (wrap)
    enriched_wrap(stte);
  fflush(stte->s->fpout);
}


static void enriched_putwc(wchar_t c, struct enriched_state *stte)
{
  if (stte->tag_level[RICH_PARAM])
  {
    if (stte->tag_level[RICH_COLOR])
    {
      if (stte->param_used + 1 >= stte->param_len)
        safe_realloc(&stte->param, (stte->param_len += STRING) * sizeof(wchar_t));

      stte->param[stte->param_used++] = c;
    }
    return; /* nothing to do */
  }

  /* see if more space is needed (plus extra for possible rich characters) */
  if (stte->buff_len < stte->buff_used + 3)
  {
    stte->buff_len += LONG_STRING;
    safe_realloc(&stte->buffer, (stte->buff_len + 1) * sizeof(wchar_t));
  }

  if ((!stte->tag_level[RICH_NOFILL] && iswspace(c)) || c == (wchar_t) '\0')
  {
    if (c == (wchar_t) '\t')
      stte->word_len += 8 - (stte->line_len + stte->word_len) % 8;
    else
      stte->word_len++;

    stte->buffer[stte->buff_used++] = c;
    enriched_flush(stte, 0);
  }
  else
  {
    if (stte->s->flags & MUTT_DISPLAY)
    {
      if (stte->tag_level[RICH_BOLD])
      {
        stte->buffer[stte->buff_used++] = c;
        stte->buffer[stte->buff_used++] = (wchar_t) '\010';
        stte->buffer[stte->buff_used++] = c;
      }
      else if (stte->tag_level[RICH_UNDERLINE])
      {
        stte->buffer[stte->buff_used++] = '_';
        stte->buffer[stte->buff_used++] = (wchar_t) '\010';
        stte->buffer[stte->buff_used++] = c;
      }
      else if (stte->tag_level[RICH_ITALIC])
      {
        stte->buffer[stte->buff_used++] = c;
        stte->buffer[stte->buff_used++] = (wchar_t) '\010';
        stte->buffer[stte->buff_used++] = '_';
      }
      else
      {
        stte->buffer[stte->buff_used++] = c;
      }
    }
    else
    {
      stte->buffer[stte->buff_used++] = c;
    }
    stte->word_len++;
  }
}

static void enriched_puts(const char *s, struct enriched_state *stte)
{
  const char *c = NULL;

  if (stte->buff_len < stte->buff_used + mutt_strlen(s))
  {
    stte->buff_len += LONG_STRING;
    safe_realloc(&stte->buffer, (stte->buff_len + 1) * sizeof(wchar_t));
  }
  c = s;
  while (*c)
  {
    stte->buffer[stte->buff_used++] = (wchar_t) *c;
    c++;
  }
}

static void enriched_set_flags(const wchar_t *tag, struct enriched_state *stte)
{
  const wchar_t *tagptr = tag;
  int i, j;

  if (*tagptr == (wchar_t) '/')
    tagptr++;

  for (i = 0, j = -1; EnrichedTags[i].tag_name; i++)
    if (wcscasecmp(EnrichedTags[i].tag_name, tagptr) == 0)
    {
      j = EnrichedTags[i].index;
      break;
    }

  if (j != -1)
  {
    if (j == RICH_CENTER || j == RICH_FLUSHLEFT || j == RICH_FLUSHRIGHT)
      enriched_flush(stte, 1);

    if (*tag == (wchar_t) '/')
    {
      if (stte->tag_level[j]) /* make sure not to go negative */
        stte->tag_level[j]--;
      if ((stte->s->flags & MUTT_DISPLAY) && j == RICH_PARAM && stte->tag_level[RICH_COLOR])
      {
        stte->param[stte->param_used] = (wchar_t) '\0';
        if (wcscasecmp(L"black", stte->param) == 0)
        {
          enriched_puts("\033[30m", stte);
        }
        else if (wcscasecmp(L"red", stte->param) == 0)
        {
          enriched_puts("\033[31m", stte);
        }
        else if (wcscasecmp(L"green", stte->param) == 0)
        {
          enriched_puts("\033[32m", stte);
        }
        else if (wcscasecmp(L"yellow", stte->param) == 0)
        {
          enriched_puts("\033[33m", stte);
        }
        else if (wcscasecmp(L"blue", stte->param) == 0)
        {
          enriched_puts("\033[34m", stte);
        }
        else if (wcscasecmp(L"magenta", stte->param) == 0)
        {
          enriched_puts("\033[35m", stte);
        }
        else if (wcscasecmp(L"cyan", stte->param) == 0)
        {
          enriched_puts("\033[36m", stte);
        }
        else if (wcscasecmp(L"white", stte->param) == 0)
        {
          enriched_puts("\033[37m", stte);
        }
      }
      if ((stte->s->flags & MUTT_DISPLAY) && j == RICH_COLOR)
      {
        enriched_puts("\033[0m", stte);
      }

      /* flush parameter buffer when closing the tag */
      if (j == RICH_PARAM)
      {
        stte->param_used = 0;
        stte->param[0] = (wchar_t) '\0';
      }
    }
    else
      stte->tag_level[j]++;

    if (j == RICH_EXCERPT)
      enriched_flush(stte, 1);
  }
}

static int text_enriched_handler(BODY *a, STATE *s)
{
  enum
  {
    TEXT,
    LANGLE,
    TAG,
    BOGUS_TAG,
    NEWLINE,
    ST_EOF,
    DONE
  } state = TEXT;

  long bytes = a->length;
  struct enriched_state stte;
  wchar_t wc = 0;
  int tag_len = 0;
  wchar_t tag[LONG_STRING + 1];

  memset(&stte, 0, sizeof(stte));
  stte.s = s;
  stte.WrapMargin =
      ((s->flags & MUTT_DISPLAY) ?
           (MuttIndexWindow->cols - 4) :
           ((MuttIndexWindow->cols - 4) < 72) ? (MuttIndexWindow->cols - 4) : 72);
  stte.line_max = stte.WrapMargin * 4;
  stte.line = safe_calloc(1, (stte.line_max + 1) * sizeof(wchar_t));
  stte.param = safe_calloc(1, (STRING) * sizeof(wchar_t));

  stte.param_len = STRING;
  stte.param_used = 0;

  if (s->prefix)
  {
    state_puts(s->prefix, s);
    stte.indent_len += mutt_strlen(s->prefix);
  }

  while (state != DONE)
  {
    if (state != ST_EOF)
    {
      if (!bytes || (wc = fgetwc(s->fpin)) == WEOF)
        state = ST_EOF;
      else
        bytes--;
    }

    switch (state)
    {
      case TEXT:
        switch (wc)
        {
          case '<':
            state = LANGLE;
            break;

          case '\n':
            if (stte.tag_level[RICH_NOFILL])
            {
              enriched_flush(&stte, 1);
            }
            else
            {
              enriched_putwc((wchar_t) ' ', &stte);
              state = NEWLINE;
            }
            break;

          default:
            enriched_putwc(wc, &stte);
        }
        break;

      case LANGLE:
        if (wc == (wchar_t) '<')
        {
          enriched_putwc(wc, &stte);
          state = TEXT;
          break;
        }
        else
        {
          tag_len = 0;
          state = TAG;
        }
      /* Yes, fall through (it wasn't a <<, so this char is first in TAG) */
      case TAG:
        if (wc == (wchar_t) '>')
        {
          tag[tag_len] = (wchar_t) '\0';
          enriched_set_flags(tag, &stte);
          state = TEXT;
        }
        else if (tag_len < LONG_STRING) /* ignore overly long tags */
          tag[tag_len++] = wc;
        else
          state = BOGUS_TAG;
        break;

      case BOGUS_TAG:
        if (wc == (wchar_t) '>')
          state = TEXT;
        break;

      case NEWLINE:
        if (wc == (wchar_t) '\n')
          enriched_flush(&stte, 1);
        else
        {
          ungetwc(wc, s->fpin);
          bytes++;
          state = TEXT;
        }
        break;

      case ST_EOF:
        enriched_putwc((wchar_t) '\0', &stte);
        enriched_flush(&stte, 1);
        state = DONE;
        break;

      case DONE: /* not reached, but gcc complains if this is absent */
        break;
    }
  }

  state_putc('\n', s); /* add a final newline */

  FREE(&(stte.buffer));
  FREE(&(stte.line));
  FREE(&(stte.param));

  return 0;
}

/* for compatibility with metamail */
static int is_mmnoask(const char *buf)
{
  char tmp[LONG_STRING], *p = NULL, *q = NULL;
  int lng;

  if ((p = getenv("MM_NOASK")) != NULL && *p)
  {
    if (mutt_strcmp(p, "1") == 0)
      return 1;

    strfcpy(tmp, p, sizeof(tmp));
    p = tmp;

    while ((p = strtok(p, ",")) != NULL)
    {
      if ((q = strrchr(p, '/')) != NULL)
      {
        if (*(q + 1) == '*')
        {
          if (ascii_strncasecmp(buf, p, q - p) == 0)
            return 1;
        }
        else
        {
          if (ascii_strcasecmp(buf, p) == 0)
            return 1;
        }
      }
      else
      {
        lng = mutt_strlen(p);
        if (buf[lng] == '/' && (mutt_strncasecmp(buf, p, lng) == 0))
          return 1;
      }

      p = NULL;
    }
  }

  return 0;
}

/*
 * Returns:
 * 1    if the body part should be filtered by a mailcap entry prior to viewing inline.
 *
 * 0    otherwise
 */
static int is_autoview(BODY *b)
{
  char type[SHORT_STRING];
  int is_av = 0;

  snprintf(type, sizeof(type), "%s/%s", TYPE(b), b->subtype);

  if (option(OPTIMPLICITAUTOVIEW))
  {
    /* $implicit_autoview is essentially the same as "auto_view *" */
    is_av = 1;
  }
  else
  {
    /* determine if this type is on the user's auto_view list */
    LIST *t = AutoViewList;

    mutt_check_lookup_list(b, type, sizeof(type));
    for (; t; t = t->next)
    {
      int i = mutt_strlen(t->data) - 1;
      if ((i > 0 && t->data[i - 1] == '/' && t->data[i] == '*' &&
           (ascii_strncasecmp(type, t->data, i) == 0)) ||
          (ascii_strcasecmp(type, t->data) == 0))
        is_av = 1;
    }

    if (is_mmnoask(type))
      is_av = 1;
  }

  /* determine if there is a mailcap entry suitable for auto_view
   *
   * WARNING: type is altered by this call as a result of `mime_lookup' support */
  if (is_av)
    return rfc1524_mailcap_lookup(b, type, NULL, MUTT_AUTOVIEW);

  return 0;
}

#define TXTHTML 1
#define TXTPLAIN 2
#define TXTENRICHED 3

static int alternative_handler(BODY *a, STATE *s)
{
  BODY *choice = NULL;
  BODY *b = NULL;
  LIST *t = NULL;
  int type = 0;
  int mustfree = 0;
  int rc = 0;
  int count = 0;

  if (a->encoding == ENCBASE64 || a->encoding == ENCQUOTEDPRINTABLE || a->encoding == ENCUUENCODED)
  {
    struct stat st;
    mustfree = 1;
    fstat(fileno(s->fpin), &st);
    b = mutt_new_body();
    b->length = (long) st.st_size;
    b->parts = mutt_parse_multipart(s->fpin, mutt_get_parameter("boundary", a->parameter),
                                    (long) st.st_size,
                                    (ascii_strcasecmp("digest", a->subtype) == 0));
  }
  else
    b = a;

  a = b;

  /* First, search list of preferred types */
  t = AlternativeOrderList;
  while (t && !choice)
  {
    char *c = NULL;
    int btlen; /* length of basetype */
    int wild;  /* do we have a wildcard to match all subtypes? */

    c = strchr(t->data, '/');
    if (c)
    {
      wild = (c[1] == '*' && c[2] == 0);
      btlen = c - t->data;
    }
    else
    {
      wild = 1;
      btlen = mutt_strlen(t->data);
    }

    if (a->parts)
      b = a->parts;
    else
      b = a;
    while (b)
    {
      const char *bt = TYPE(b);
      if ((ascii_strncasecmp(bt, t->data, btlen) == 0) && (bt[btlen] == 0))
      {
        /* the basetype matches */
        if (wild || (ascii_strcasecmp(t->data + btlen + 1, b->subtype) == 0))
        {
          choice = b;
        }
      }
      b = b->next;
    }
    t = t->next;
  }

  /* Next, look for an autoviewable type */
  if (!choice)
  {
    if (a->parts)
      b = a->parts;
    else
      b = a;
    while (b)
    {
      if (is_autoview(b))
        choice = b;
      b = b->next;
    }
  }

  /* Then, look for a text entry */
  if (!choice)
  {
    if (a->parts)
      b = a->parts;
    else
      b = a;
    while (b)
    {
      if (b->type == TYPETEXT)
      {
        if ((ascii_strcasecmp("plain", b->subtype) == 0) && type <= TXTPLAIN)
        {
          choice = b;
          type = TXTPLAIN;
        }
        else if ((ascii_strcasecmp("enriched", b->subtype) == 0) && type <= TXTENRICHED)
        {
          choice = b;
          type = TXTENRICHED;
        }
        else if ((ascii_strcasecmp("html", b->subtype) == 0) && type <= TXTHTML)
        {
          choice = b;
          type = TXTHTML;
        }
      }
      b = b->next;
    }
  }

  /* Finally, look for other possibilities */
  if (!choice)
  {
    if (a->parts)
      b = a->parts;
    else
      b = a;
    while (b)
    {
      if (mutt_can_decode(b))
        choice = b;
      b = b->next;
    }
  }

  if (choice)
  {
    if (s->flags & MUTT_DISPLAY && !option(OPTWEED))
    {
      fseeko(s->fpin, choice->hdr_offset, SEEK_SET);
      mutt_copy_bytes(s->fpin, s->fpout, choice->offset - choice->hdr_offset);
    }

    if (mutt_strcmp("info", ShowMultipartAlternative) == 0)
    {
      print_part_line(s, choice, 0);
    }
    mutt_body_handler(choice, s);

    if (mutt_strcmp("info", ShowMultipartAlternative) == 0)
    {
      if (a->parts)
        b = a->parts;
      else
        b = a;
      while (b)
      {
        if (choice != b)
        {
          count += 1;
          if (count == 1)
            state_putc('\n', s);

          print_part_line(s, b, count);
        }
        b = b->next;
      }
    }
  }
  else if (s->flags & MUTT_DISPLAY)
  {
    /* didn't find anything that we could display! */
    state_mark_attach(s);
    state_puts(_("[-- Error:  Could not display any parts of "
                 "Multipart/Alternative! --]\n"),
               s);
    rc = -1;
  }

  if (mustfree)
    mutt_free_body(&a);

  return rc;
}

/* handles message/rfc822 body parts */
static int message_handler(BODY *a, STATE *s)
{
  struct stat st;
  BODY *b = NULL;
  LOFF_T off_start;
  int rc = 0;

  off_start = ftello(s->fpin);
  if (off_start < 0)
    return -1;

  if (a->encoding == ENCBASE64 || a->encoding == ENCQUOTEDPRINTABLE || a->encoding == ENCUUENCODED)
  {
    fstat(fileno(s->fpin), &st);
    b = mutt_new_body();
    b->length = (LOFF_T) st.st_size;
    b->parts = mutt_parse_message_rfc822(s->fpin, b);
  }
  else
    b = a;

  if (b->parts)
  {
    mutt_copy_hdr(s->fpin, s->fpout, off_start, b->parts->offset,
                  (((s->flags & MUTT_WEED) ||
                    ((s->flags & (MUTT_DISPLAY | MUTT_PRINTING)) && option(OPTWEED))) ?
                       (CH_WEED | CH_REORDER) :
                       0) |
                      (s->prefix ? CH_PREFIX : 0) | CH_DECODE | CH_FROM |
                      ((s->flags & MUTT_DISPLAY) ? CH_DISPLAY : 0),
                  s->prefix);

    if (s->prefix)
      state_puts(s->prefix, s);
    state_putc('\n', s);

    rc = mutt_body_handler(b->parts, s);
  }

  if (a->encoding == ENCBASE64 || a->encoding == ENCQUOTEDPRINTABLE || a->encoding == ENCUUENCODED)
    mutt_free_body(&b);

  return rc;
}

/* returns 1 if decoding the attachment will produce output */
int mutt_can_decode(BODY *a)
{
  if (is_autoview(a))
    return 1;
  else if (a->type == TYPETEXT)
    return 1;
  else if (a->type == TYPEMESSAGE)
    return 1;
  else if (a->type == TYPEMULTIPART)
  {
    BODY *p = NULL;

    if (WithCrypto)
    {
      if ((ascii_strcasecmp(a->subtype, "signed") == 0) ||
          (ascii_strcasecmp(a->subtype, "encrypted") == 0))
        return 1;
    }

    for (p = a->parts; p; p = p->next)
    {
      if (mutt_can_decode(p))
        return 1;
    }
  }
  else if (WithCrypto && a->type == TYPEAPPLICATION)
  {
    if ((WithCrypto & APPLICATION_PGP) && mutt_is_application_pgp(a))
      return 1;
    if ((WithCrypto & APPLICATION_SMIME) && mutt_is_application_smime(a))
      return 1;
  }

  return 0;
}

static int multipart_handler(BODY *a, STATE *s)
{
  BODY *b = NULL, *p = NULL;
  struct stat st;
  int count;
  int rc = 0;

  if (a->encoding == ENCBASE64 || a->encoding == ENCQUOTEDPRINTABLE || a->encoding == ENCUUENCODED)
  {
    fstat(fileno(s->fpin), &st);
    b = mutt_new_body();
    b->length = (long) st.st_size;
    b->parts = mutt_parse_multipart(s->fpin, mutt_get_parameter("boundary", a->parameter),
                                    (long) st.st_size,
                                    (ascii_strcasecmp("digest", a->subtype) == 0));
  }
  else
    b = a;

  for (p = b->parts, count = 1; p; p = p->next, count++)
  {
    if (s->flags & MUTT_DISPLAY)
    {
      state_mark_attach(s);
      state_printf(s, _("[-- Attachment #%d"), count);
      if (p->description || p->filename || p->form_name)
      {
        state_puts(": ", s);
        state_puts(p->description ? p->description : p->filename ? p->filename : p->form_name, s);
      }
      state_puts(" --]\n", s);
      print_part_line(s, p, 0);
      if (!option(OPTWEED))
      {
        fseeko(s->fpin, p->hdr_offset, SEEK_SET);
        mutt_copy_bytes(s->fpin, s->fpout, p->offset - p->hdr_offset);
      }
      else
        state_putc('\n', s);
    }

    rc = mutt_body_handler(p, s);
    state_putc('\n', s);

    if (rc)
    {
      mutt_error(_("One or more parts of this message could not be displayed"));
      mutt_debug(1, "Failed on attachment #%d, type %s/%s.\n", count, TYPE(p),
                 NONULL(p->subtype));
    }

    if ((s->flags & MUTT_REPLYING) && (option(OPTINCLUDEONLYFIRST)) && (s->flags & MUTT_FIRSTDONE))
      break;
  }

  if (a->encoding == ENCBASE64 || a->encoding == ENCQUOTEDPRINTABLE || a->encoding == ENCUUENCODED)
    mutt_free_body(&b);

  /* make failure of a single part non-fatal */
  if (rc < 0)
    rc = 1;
  return rc;
}

static int autoview_handler(BODY *a, STATE *s)
{
  rfc1524_entry *entry = rfc1524_new_entry();
  char buffer[LONG_STRING];
  char type[STRING];
  char command[LONG_STRING];
  char tempfile[_POSIX_PATH_MAX] = "";
  char *fname = NULL;
  FILE *fpin = NULL;
  FILE *fpout = NULL;
  FILE *fperr = NULL;
  int piped = false;
  pid_t thepid;
  int rc = 0;

  snprintf(type, sizeof(type), "%s/%s", TYPE(a), a->subtype);
  rfc1524_mailcap_lookup(a, type, entry, MUTT_AUTOVIEW);

  fname = safe_strdup(a->filename);
  mutt_sanitize_filename(fname, 1);
  rfc1524_expand_filename(entry->nametemplate, fname, tempfile, sizeof(tempfile));
  FREE(&fname);

  if (entry->command)
  {
    strfcpy(command, entry->command, sizeof(command));

    /* rfc1524_expand_command returns 0 if the file is required */
    piped = rfc1524_expand_command(a, tempfile, type, command, sizeof(command));

    if (s->flags & MUTT_DISPLAY)
    {
      state_mark_attach(s);
      state_printf(s, _("[-- Autoview using %s --]\n"), command);
      mutt_message(_("Invoking autoview command: %s"), command);
    }

    if ((fpin = safe_fopen(tempfile, "w+")) == NULL)
    {
      mutt_perror("fopen");
      rfc1524_free_entry(&entry);
      return -1;
    }

    mutt_copy_bytes(s->fpin, fpin, a->length);

    if (!piped)
    {
      safe_fclose(&fpin);
      thepid = mutt_create_filter(command, NULL, &fpout, &fperr);
    }
    else
    {
      unlink(tempfile);
      fflush(fpin);
      rewind(fpin);
      thepid = mutt_create_filter_fd(command, NULL, &fpout, &fperr, fileno(fpin), -1, -1);
    }

    if (thepid < 0)
    {
      mutt_perror(_("Can't create filter"));
      if (s->flags & MUTT_DISPLAY)
      {
        state_mark_attach(s);
        state_printf(s, _("[-- Can't run %s. --]\n"), command);
      }
      rc = -1;
      goto bail;
    }

    if (s->prefix)
    {
      while (fgets(buffer, sizeof(buffer), fpout) != NULL)
      {
        state_puts(s->prefix, s);
        state_puts(buffer, s);
      }
      /* check for data on stderr */
      if (fgets(buffer, sizeof(buffer), fperr))
      {
        if (s->flags & MUTT_DISPLAY)
        {
          state_mark_attach(s);
          state_printf(s, _("[-- Autoview stderr of %s --]\n"), command);
        }

        state_puts(s->prefix, s);
        state_puts(buffer, s);
        while (fgets(buffer, sizeof(buffer), fperr) != NULL)
        {
          state_puts(s->prefix, s);
          state_puts(buffer, s);
        }
      }
    }
    else
    {
      mutt_copy_stream(fpout, s->fpout);
      /* Check for stderr messages */
      if (fgets(buffer, sizeof(buffer), fperr))
      {
        if (s->flags & MUTT_DISPLAY)
        {
          state_mark_attach(s);
          state_printf(s, _("[-- Autoview stderr of %s --]\n"), command);
        }

        state_puts(buffer, s);
        mutt_copy_stream(fperr, s->fpout);
      }
    }

  bail:
    safe_fclose(&fpout);
    safe_fclose(&fperr);

    mutt_wait_filter(thepid);
    if (piped)
      safe_fclose(&fpin);
    else
      mutt_unlink(tempfile);

    if (s->flags & MUTT_DISPLAY)
      mutt_clear_error();
  }
  rfc1524_free_entry(&entry);

  return rc;
}

static int external_body_handler(BODY *b, STATE *s)
{
  const char *access_type = NULL;
  const char *expiration = NULL;
  time_t expire;

  access_type = mutt_get_parameter("access-type", b->parameter);
  if (!access_type)
  {
    if (s->flags & MUTT_DISPLAY)
    {
      state_mark_attach(s);
      state_puts(_("[-- Error: message/external-body has no access-type "
                   "parameter --]\n"),
                 s);
      return 0;
    }
    else
      return -1;
  }

  expiration = mutt_get_parameter("expiration", b->parameter);
  if (expiration)
    expire = mutt_parse_date(expiration, NULL);
  else
    expire = -1;

  if (ascii_strcasecmp(access_type, "x-mutt-deleted") == 0)
  {
    if (s->flags & (MUTT_DISPLAY | MUTT_PRINTING))
    {
      char *length = NULL;
      char pretty_size[10];

      state_mark_attach(s);
      state_printf(s, _("[-- This %s/%s attachment "), TYPE(b->parts), b->parts->subtype);
      length = mutt_get_parameter("length", b->parameter);
      if (length)
      {
        mutt_pretty_size(pretty_size, sizeof(pretty_size), strtol(length, NULL, 10));
        state_printf(s, _("(size %s bytes) "), pretty_size);
      }
      state_puts(_("has been deleted --]\n"), s);

      if (expire != -1)
      {
        state_mark_attach(s);
        state_printf(s, _("[-- on %s --]\n"), expiration);
      }
      if (b->parts->filename)
      {
        state_mark_attach(s);
        state_printf(s, _("[-- name: %s --]\n"), b->parts->filename);
      }

      mutt_copy_hdr(s->fpin, s->fpout, ftello(s->fpin), b->parts->offset,
                    (option(OPTWEED) ? (CH_WEED | CH_REORDER) : 0) | CH_DECODE, NULL);
    }
  }
  else if (expiration && expire < time(NULL))
  {
    if (s->flags & MUTT_DISPLAY)
    {
      state_mark_attach(s);
      state_printf(s, _("[-- This %s/%s attachment is not included, --]\n"),
                   TYPE(b->parts), b->parts->subtype);
      state_attach_puts(_("[-- and the indicated external source has --]\n"
                          "[-- expired. --]\n"),
                        s);

      mutt_copy_hdr(s->fpin, s->fpout, ftello(s->fpin), b->parts->offset,
                    (option(OPTWEED) ? (CH_WEED | CH_REORDER) : 0) | CH_DECODE | CH_DISPLAY,
                    NULL);
    }
  }
  else
  {
    if (s->flags & MUTT_DISPLAY)
    {
      state_mark_attach(s);
      state_printf(s, _("[-- This %s/%s attachment is not included, --]\n"),
                   TYPE(b->parts), b->parts->subtype);
      state_mark_attach(s);
      state_printf(
          s, _("[-- and the indicated access-type %s is unsupported --]\n"), access_type);
      mutt_copy_hdr(s->fpin, s->fpout, ftello(s->fpin), b->parts->offset,
                    (option(OPTWEED) ? (CH_WEED | CH_REORDER) : 0) | CH_DECODE | CH_DISPLAY,
                    NULL);
    }
  }

  return 0;
}

void mutt_decode_attachment(BODY *b, STATE *s)
{
  int istext = mutt_is_text_part(b);
  iconv_t cd = (iconv_t)(-1);

  if (istext && s->flags & MUTT_CHARCONV)
  {
    char *charset = mutt_get_parameter("charset", b->parameter);
    if (!charset && AssumedCharset && *AssumedCharset)
      charset = mutt_get_default_charset();
    if (charset && Charset)
      cd = mutt_iconv_open(Charset, charset, MUTT_ICONV_HOOK_FROM);
  }
  else if (istext && b->charset)
    cd = mutt_iconv_open(Charset, b->charset, MUTT_ICONV_HOOK_FROM);

  fseeko(s->fpin, b->offset, SEEK_SET);
  switch (b->encoding)
  {
    case ENCQUOTEDPRINTABLE:
      decode_quoted(s, b->length, istext || ((WithCrypto & APPLICATION_PGP) &&
                                             mutt_is_application_pgp(b)),
                    cd);
      break;
    case ENCBASE64:
      mutt_decode_base64(s, b->length, istext || ((WithCrypto & APPLICATION_PGP) &&
                                                  mutt_is_application_pgp(b)),
                         cd);
      break;
    case ENCUUENCODED:
      decode_uuencoded(s, b->length, istext || ((WithCrypto & APPLICATION_PGP) &&
                                                mutt_is_application_pgp(b)),
                       cd);
      break;
    default:
      decode_xbit(s, b->length, istext || ((WithCrypto & APPLICATION_PGP) &&
                                           mutt_is_application_pgp(b)),
                  cd);
      break;
  }

  if (cd != (iconv_t)(-1))
    iconv_close(cd);
}

/* when generating format=flowed ($text_flowed is set) from format=fixed,
 * strip all trailing spaces to improve interoperability;
 * if $text_flowed is unset, simply verbatim copy input
 */
static int text_plain_handler(BODY *b, STATE *s)
{
  char *buf = NULL;
  size_t l = 0, sz = 0;

  while ((buf = mutt_read_line(buf, &sz, s->fpin, NULL, 0)))
  {
    if ((mutt_strcmp(buf, "-- ") != 0) && option(OPTTEXTFLOWED))
    {
      l = mutt_strlen(buf);
      while (l > 0 && buf[l - 1] == ' ')
        buf[--l] = 0;
    }
    if (s->prefix)
      state_puts(s->prefix, s);
    state_puts(buf, s);
    state_putc('\n', s);
  }

  FREE(&buf);
  return 0;
}

static int run_decode_and_handler(BODY *b, STATE *s, handler_t handler, int plaintext)
{
  int origType;
  char *savePrefix = NULL;
  FILE *fp = NULL;
#ifndef USE_FMEMOPEN
  char tempfile[_POSIX_PATH_MAX];
#endif
  size_t tmplength = 0;
  LOFF_T tmpoffset = 0;
  int decode = 0;
  int rc = 0;

  fseeko(s->fpin, b->offset, SEEK_SET);

#ifdef USE_FMEMOPEN
  char *temp = NULL;
  size_t tempsize = 0;
#endif

  /* see if we need to decode this part before processing it */
  if (b->encoding == ENCBASE64 || b->encoding == ENCQUOTEDPRINTABLE ||
      b->encoding == ENCUUENCODED || plaintext || mutt_is_text_part(b)) /* text subtypes may
                                                        * require character
                                                        * set conversion even
                                                        * with 8bit encoding.
                                                        */
  {
    origType = b->type;

    if (!plaintext)
    {
      /* decode to a tempfile, saving the original destination */
      fp = s->fpout;
#ifdef USE_FMEMOPEN
      s->fpout = open_memstream(&temp, &tempsize);
      if (!s->fpout)
      {
        mutt_error(_("Unable to open memory stream!"));
        mutt_debug(1, "Can't open memory stream.\n");
        return -1;
      }
#else
      mutt_mktemp(tempfile, sizeof(tempfile));
      if ((s->fpout = safe_fopen(tempfile, "w")) == NULL)
      {
        mutt_error(_("Unable to open temporary file!"));
        mutt_debug(1, "Can't open %s.\n", tempfile);
        return -1;
      }
#endif
      /* decoding the attachment changes the size and offset, so save a copy
        * of the "real" values now, and restore them after processing
        */
      tmplength = b->length;
      tmpoffset = b->offset;

      /* if we are decoding binary bodies, we don't want to prefix each
        * line with the prefix or else the data will get corrupted.
        */
      savePrefix = s->prefix;
      s->prefix = NULL;

      decode = 1;
    }
    else
      b->type = TYPETEXT;

    mutt_decode_attachment(b, s);

    if (decode)
    {
      b->length = ftello(s->fpout);
      b->offset = 0;
#ifdef USE_FMEMOPEN
      /* When running under torify, safe_fclose(&s->fpout) does not seem to
       * update tempsize. On the other hand, fflush does.  See
       * https://github.com/neomutt/neomutt/issues/440 */
      fflush(s->fpout);
#endif
      safe_fclose(&s->fpout);

      /* restore final destination and substitute the tempfile for input */
      s->fpout = fp;
      fp = s->fpin;
#ifdef USE_FMEMOPEN
      if (tempsize)
      {
        s->fpin = fmemopen(temp, tempsize, "r");
      }
      else
      { /* fmemopen cannot handle zero-length buffers */
        s->fpin = safe_fopen("/dev/null", "r");
      }
      if (!s->fpin)
      {
        mutt_perror(_("failed to re-open memstream!"));
        return -1;
      }
#else
      s->fpin = fopen(tempfile, "r");
      unlink(tempfile);
#endif
      /* restore the prefix */
      s->prefix = savePrefix;
    }

    b->type = origType;
  }

  /* process the (decoded) body part */
  if (handler)
  {
    rc = handler(b, s);

    if (rc)
    {
      mutt_debug(1, "Failed on attachment of type %s/%s.\n", TYPE(b), NONULL(b->subtype));
    }

    if (decode)
    {
      b->length = tmplength;
      b->offset = tmpoffset;

      /* restore the original source stream */
      safe_fclose(&s->fpin);
#ifdef USE_FMEMOPEN
      FREE(&temp);
#endif
      s->fpin = fp;
    }
  }
  s->flags |= MUTT_FIRSTDONE;

  return rc;
}

static int valid_pgp_encrypted_handler(BODY *b, STATE *s)
{
  int rc;
  BODY *octetstream = NULL;

  octetstream = b->parts->next;
  rc = crypt_pgp_encrypted_handler(octetstream, s);
  b->goodsig |= octetstream->goodsig;

  return rc;
}

static int malformed_pgp_encrypted_handler(BODY *b, STATE *s)
{
  int rc;
  BODY *octetstream = NULL;

  octetstream = b->parts->next->next;
  /* exchange encodes the octet-stream, so re-run it through the decoder */
  rc = run_decode_and_handler(octetstream, s, crypt_pgp_encrypted_handler, 0);
  b->goodsig |= octetstream->goodsig;

  return rc;
}

int mutt_body_handler(BODY *b, STATE *s)
{
  if (!b || !s)
    return -1;

  int plaintext = 0;
  handler_t handler = NULL;
  int rc = 0;

  int oflags = s->flags;

  /* first determine which handler to use to process this part */

  if (is_autoview(b))
  {
    handler = autoview_handler;
    s->flags &= ~MUTT_CHARCONV;
  }
  else if (b->type == TYPETEXT)
  {
    if (ascii_strcasecmp("plain", b->subtype) == 0)
    {
      /* avoid copying this part twice since removing the transfer-encoding is
       * the only operation needed.
       */
      if ((WithCrypto & APPLICATION_PGP) && mutt_is_application_pgp(b))
        handler = crypt_pgp_application_pgp_handler;
      else if (option(OPTREFLOWTEXT) &&
               (ascii_strcasecmp("flowed", mutt_get_parameter("format", b->parameter)) == 0))
        handler = rfc3676_handler;
      else
        handler = text_plain_handler;
    }
    else if (ascii_strcasecmp("enriched", b->subtype) == 0)
      handler = text_enriched_handler;
    else /* text body type without a handler */
      plaintext = 0;
  }
  else if (b->type == TYPEMESSAGE)
  {
    if (mutt_is_message_type(b->type, b->subtype))
      handler = message_handler;
    else if (ascii_strcasecmp("delivery-status", b->subtype) == 0)
      plaintext = 1;
    else if (ascii_strcasecmp("external-body", b->subtype) == 0)
      handler = external_body_handler;
  }
  else if (b->type == TYPEMULTIPART)
  {
    char *p = NULL;

    if ((mutt_strcmp("inline", ShowMultipartAlternative) != 0) &&
        (ascii_strcasecmp("alternative", b->subtype) == 0))
      handler = alternative_handler;
    else if (WithCrypto && (ascii_strcasecmp("signed", b->subtype) == 0))
    {
      p = mutt_get_parameter("protocol", b->parameter);

      if (!p)
        mutt_error(_("Error: multipart/signed has no protocol."));
      else if (s->flags & MUTT_VERIFY)
        handler = mutt_signed_handler;
    }
    else if (mutt_is_valid_multipart_pgp_encrypted(b))
      handler = valid_pgp_encrypted_handler;
    else if (mutt_is_malformed_multipart_pgp_encrypted(b))
      handler = malformed_pgp_encrypted_handler;

    if (!handler)
      handler = multipart_handler;

    if (b->encoding != ENC7BIT && b->encoding != ENC8BIT && b->encoding != ENCBINARY)
    {
      mutt_debug(1, "Bad encoding type %d for multipart entity, "
                    "assuming 7 bit\n",
                 b->encoding);
      b->encoding = ENC7BIT;
    }
  }
  else if (WithCrypto && b->type == TYPEAPPLICATION)
  {
    if (option(OPTDONTHANDLEPGPKEYS) && (ascii_strcasecmp("pgp-keys", b->subtype) == 0))
    {
      /* pass raw part through for key extraction */
      plaintext = 1;
    }
    else if ((WithCrypto & APPLICATION_PGP) && mutt_is_application_pgp(b))
      handler = crypt_pgp_application_pgp_handler;
    else if ((WithCrypto & APPLICATION_SMIME) && mutt_is_application_smime(b))
      handler = crypt_smime_application_smime_handler;
  }

  /* only respect disposition == attachment if we're not
     displaying from the attachment menu (i.e. pager) */
  if ((!option(OPTHONORDISP) || (b->disposition != DISPATTACH || option(OPTVIEWATTACH))) &&
      (plaintext || handler))
  {
    rc = run_decode_and_handler(b, s, handler, plaintext);
  }
  /* print hint to use attachment menu for disposition == attachment
     if we're not already being called from there */
  else if ((s->flags & MUTT_DISPLAY) ||
           (b->disposition == DISPATTACH && !option(OPTVIEWATTACH) &&
            option(OPTHONORDISP) && (plaintext || handler)))
  {
    state_mark_attach(s);
    if (option(OPTHONORDISP) && b->disposition == DISPATTACH)
      fputs(_("[-- This is an attachment "), s->fpout);
    else
      state_printf(s, _("[-- %s/%s is unsupported "), TYPE(b), b->subtype);
    if (!option(OPTVIEWATTACH))
    {
      char keystroke[SHORT_STRING];

      if (km_expand_key(keystroke, sizeof(keystroke),
                        km_find_func(MENU_PAGER, OP_VIEW_ATTACHMENTS)))
        fprintf(s->fpout, _("(use '%s' to view this part)"), keystroke);
      else
        fputs(_("(need 'view-attachments' bound to key!)"), s->fpout);
    }
    fputs(" --]\n", s->fpout);
  }

  s->flags = oflags | (s->flags & MUTT_FIRSTDONE);
  if (rc)
  {
    mutt_debug(1, "Bailing on attachment of type %s/%s.\n", TYPE(b), NONULL(b->subtype));
  }

  return rc;
}