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rfc3676.c
548 lines (482 loc) · 14.6 KB
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rfc3676.c
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/**
* @file
* RFC3676 Format Flowed routines
*
* @authors
* Copyright (C) 2005 Andreas Krennmair <ak@synflood.at>
* Copyright (C) 2005 Peter J. Holzer <hjp@hjp.net>
* Copyright (C) 2005-2009 Rocco Rutte <pdmef@gmx.net>
* Copyright (C) 2010 Michael R. Elkins <me@mutt.org>
* Copyright (C) 2017-2023 Richard Russon <rich@flatcap.org>
* Copyright (C) 2018 Federico Kircheis <federico.kircheis@gmail.com>
* Copyright (C) 2020 Pietro Cerutti <gahr@gahr.ch>
*
* @copyright
* 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/>.
*/
/**
* @page neo_rfc3676 RFC3676 Format Flowed routines
*
* RFC3676 Format Flowed routines
*/
#include "config.h"
#include <stdbool.h>
#include <stdio.h>
#include <unistd.h>
#include "mutt/lib.h"
#include "config/lib.h"
#include "email/lib.h"
#include "core/lib.h"
#include "gui/lib.h"
#include "rfc3676.h"
#define FLOWED_MAX 72
/**
* struct FlowedState - State of a Format-Flowed line of text
*/
struct FlowedState
{
size_t width;
size_t spaces;
bool delsp;
};
/**
* get_quote_level - Get the quote level of a line
* @param line Text to examine
* @retval num Quote level
*/
static int get_quote_level(const char *line)
{
int quoted = 0;
const char *p = line;
while (p && (*p == '>'))
{
quoted++;
p++;
}
return quoted;
}
/**
* space_quotes - Should we add spaces between quote levels
* @param state State to use
* @retval true Spaces should be added
*
* Determines whether to add spacing between/after each quote level:
* ` >>>foo`
* becomes
* ` > > > foo`
*/
static int space_quotes(struct State *state)
{
/* Allow quote spacing in the pager even for `$text_flowed`,
* but obviously not when replying. */
const bool c_text_flowed = cs_subset_bool(NeoMutt->sub, "text_flowed");
if (c_text_flowed && (state->flags & STATE_REPLYING))
return 0;
const bool c_reflow_space_quotes = cs_subset_bool(NeoMutt->sub, "reflow_space_quotes");
return c_reflow_space_quotes;
}
/**
* add_quote_suffix - Should we add a trailing space to quotes
* @param state State to use
* @param ql Quote level
* @retval true Spaces should be added
*
* Determines whether to add a trailing space to quotes:
* ` >>> foo`
* as opposed to
* ` >>>foo`
*/
static bool add_quote_suffix(struct State *state, int ql)
{
if (state->flags & STATE_REPLYING)
return false;
if (space_quotes(state))
return false;
if (!ql && !state->prefix)
return false;
/* The prefix will add its own space */
const bool c_text_flowed = cs_subset_bool(NeoMutt->sub, "text_flowed");
if (!c_text_flowed && !ql && state->prefix)
return false;
return true;
}
/**
* print_indent - Print indented text
* @param ql Quote level
* @param state State to work with
* @param add_suffix If true, write a trailing space character
* @retval num Number of characters written
*/
static size_t print_indent(int ql, struct State *state, int add_suffix)
{
size_t wid = 0;
if (state->prefix)
{
/* use given prefix only for format=fixed replies to format=flowed,
* for format=flowed replies to format=flowed, use '>' indentation */
const bool c_text_flowed = cs_subset_bool(NeoMutt->sub, "text_flowed");
if (c_text_flowed)
{
ql++;
}
else
{
state_puts(state, state->prefix);
wid = mutt_strwidth(state->prefix);
}
}
for (int i = 0; i < ql; i++)
{
state_putc(state, '>');
if (space_quotes(state))
state_putc(state, ' ');
}
if (add_suffix)
state_putc(state, ' ');
if (space_quotes(state))
ql *= 2;
return ql + add_suffix + wid;
}
/**
* flush_par - Write out the paragraph
* @param state State to work with
* @param fst State of the flowed text
*/
static void flush_par(struct State *state, struct FlowedState *fst)
{
if (fst->width > 0)
{
state_putc(state, '\n');
fst->width = 0;
}
fst->spaces = 0;
}
/**
* quote_width - Calculate the paragraph width based upon the quote level
* @param state State to use
* @param ql Quote level
* @retval num Paragraph width
*
* The start of a quoted line will be ">>> ", so we need to subtract the space
* required for the prefix from the terminal width.
*/
static int quote_width(struct State *state, int ql)
{
const int screen_width = (state->flags & STATE_DISPLAY) ? state->wraplen : 80;
const short c_reflow_wrap = cs_subset_number(NeoMutt->sub, "reflow_wrap");
int width = mutt_window_wrap_cols(screen_width, c_reflow_wrap);
const bool c_text_flowed = cs_subset_bool(NeoMutt->sub, "text_flowed");
if (c_text_flowed && (state->flags & STATE_REPLYING))
{
/* When replying, force a wrap at FLOWED_MAX to comply with RFC3676
* guidelines */
if (width > FLOWED_MAX)
width = FLOWED_MAX;
ql++; /* When replying, we will add an additional quote level */
}
/* adjust the paragraph width subtracting the number of prefix chars */
width -= space_quotes(state) ? ql * 2 : ql;
/* When displaying (not replying), there may be a space between the prefix
* string and the paragraph */
if (add_quote_suffix(state, ql))
width--;
/* failsafe for really long quotes */
if (width <= 0)
width = FLOWED_MAX; /* arbitrary, since the line will wrap */
return width;
}
/**
* print_flowed_line - Print a format-flowed line
* @param line Text to print
* @param state State to work with
* @param ql Quote level
* @param fst State of the flowed text
* @param term If true, terminate with a new line
*/
static void print_flowed_line(char *line, struct State *state, int ql,
struct FlowedState *fst, bool term)
{
size_t width, w, words = 0;
char *p = NULL;
char last;
if (!line || (*line == '\0'))
{
/* flush current paragraph (if any) first */
flush_par(state, fst);
print_indent(ql, state, 0);
state_putc(state, '\n');
return;
}
width = quote_width(state, ql);
last = line[mutt_str_len(line) - 1];
mutt_debug(LL_DEBUG5, "f=f: line [%s], width = %ld, spaces = %zu\n", line,
(long) width, fst->spaces);
for (words = 0; (p = mutt_str_sep(&line, " "));)
{
mutt_debug(LL_DEBUG5, "f=f: word [%s], width: %zu, remaining = [%s]\n", p,
fst->width, line);
/* remember number of spaces */
if (*p == '\0')
{
mutt_debug(LL_DEBUG3, "f=f: additional space\n");
fst->spaces++;
continue;
}
/* there's exactly one space prior to every but the first word */
if (words)
fst->spaces++;
w = mutt_strwidth(p);
/* see if we need to break the line but make sure the first word is put on
* the line regardless; if for DelSp=yes only one trailing space is used,
* we probably have a long word that we should break within (we leave that
* up to the pager or user) */
if (!(!fst->spaces && fst->delsp && (last != ' ')) && (w < width) &&
(w + fst->width + fst->spaces > width))
{
mutt_debug(LL_DEBUG3, "f=f: break line at %zu, %zu spaces left\n",
fst->width, fst->spaces);
/* only honor trailing spaces for format=flowed replies */
const bool c_text_flowed = cs_subset_bool(NeoMutt->sub, "text_flowed");
if (c_text_flowed)
for (; fst->spaces; fst->spaces--)
state_putc(state, ' ');
state_putc(state, '\n');
fst->width = 0;
fst->spaces = 0;
words = 0;
}
if (!words && !fst->width)
fst->width = print_indent(ql, state, add_quote_suffix(state, ql));
fst->width += w + fst->spaces;
for (; fst->spaces; fst->spaces--)
state_putc(state, ' ');
state_puts(state, p);
words++;
}
if (term)
flush_par(state, fst);
}
/**
* print_fixed_line - Print a fixed format line
* @param line Text to print
* @param state State to work with
* @param ql Quote level
* @param fst State of the flowed text
*/
static void print_fixed_line(const char *line, struct State *state, int ql,
struct FlowedState *fst)
{
print_indent(ql, state, add_quote_suffix(state, ql));
if (line && *line)
state_puts(state, line);
state_putc(state, '\n');
fst->width = 0;
fst->spaces = 0;
}
/**
* rfc3676_handler - Handler for format=flowed - Implements ::handler_t - @ingroup handler_api
* @retval 0 Always
*/
int rfc3676_handler(struct Body *b_email, struct State *state)
{
char *buf = NULL;
unsigned int quotelevel = 0;
bool delsp = false;
size_t sz = 0;
struct FlowedState fst = { 0 };
/* respect DelSp of RFC3676 only with f=f parts */
char *t = mutt_param_get(&b_email->parameter, "delsp");
if (t)
{
delsp = mutt_istr_equal(t, "yes");
t = NULL;
fst.delsp = true;
}
mutt_debug(LL_DEBUG3, "f=f: DelSp: %s\n", delsp ? "yes" : "no");
while ((buf = mutt_file_read_line(buf, &sz, state->fp_in, NULL, MUTT_RL_NO_FLAGS)))
{
const size_t buflen = mutt_str_len(buf);
const unsigned int newql = get_quote_level(buf);
/* end flowed paragraph (if we're within one) if quoting level
* changes (should not but can happen, see RFC3676, sec. 4.5.) */
if (newql != quotelevel)
flush_par(state, &fst);
quotelevel = newql;
int buf_off = newql;
/* respect sender's space-stuffing by removing one leading space */
if (buf[buf_off] == ' ')
buf_off++;
/* test for signature separator */
const unsigned int sigsep = mutt_str_equal(buf + buf_off, "-- ");
/* a fixed line either has no trailing space or is the
* signature separator */
const bool fixed = (buflen == buf_off) || (buf[buflen - 1] != ' ') || sigsep;
/* print fixed-and-standalone, fixed-and-empty and sigsep lines as
* fixed lines */
if ((fixed && ((fst.width == 0) || (buflen == 0))) || sigsep)
{
/* if we're within a flowed paragraph, terminate it */
flush_par(state, &fst);
print_fixed_line(buf + buf_off, state, quotelevel, &fst);
continue;
}
/* for DelSp=yes, we need to strip one SP prior to CRLF on flowed lines */
if (delsp && !fixed)
buf[buflen - 1] = '\0';
print_flowed_line(buf + buf_off, state, quotelevel, &fst, fixed);
}
flush_par(state, &fst);
FREE(&buf);
return 0;
}
/**
* mutt_rfc3676_is_format_flowed - Is the Email "format-flowed"?
* @param b Email Body to examine
* @retval true Email is "format-flowed"
*/
bool mutt_rfc3676_is_format_flowed(struct Body *b)
{
if (b && (b->type == TYPE_TEXT) && mutt_istr_equal("plain", b->subtype))
{
const char *format = mutt_param_get(&b->parameter, "format");
if (mutt_istr_equal("flowed", format))
return true;
}
return false;
}
/**
* rfc3676_space_stuff - Perform required RFC3676 space stuffing
* @param filename Attachment file
* @param unstuff If true, remove space stuffing
*
* Space stuffing means that we have to add leading spaces to
* certain lines:
* - lines starting with a space
* - lines starting with 'From '
*
* Care is taken to preserve the e->body->filename, as
* mutt -i -E can directly edit a passed in filename.
*/
static void rfc3676_space_stuff(const char *filename, bool unstuff)
{
FILE *fp_out = NULL;
char *buf = NULL;
size_t blen = 0;
struct Buffer *tmpfile = buf_pool_get();
FILE *fp_in = mutt_file_fopen(filename, "r");
if (!fp_in)
goto bail;
buf_mktemp(tmpfile);
fp_out = mutt_file_fopen(buf_string(tmpfile), "w+");
if (!fp_out)
goto bail;
while ((buf = mutt_file_read_line(buf, &blen, fp_in, NULL, MUTT_RL_NO_FLAGS)) != NULL)
{
if (unstuff)
{
if (buf[0] == ' ')
fputs(buf + 1, fp_out);
else
fputs(buf, fp_out);
}
else
{
if ((buf[0] == ' ') || mutt_str_startswith(buf, "From "))
fputc(' ', fp_out);
fputs(buf, fp_out);
}
fputc('\n', fp_out);
}
FREE(&buf);
mutt_file_fclose(&fp_in);
mutt_file_fclose(&fp_out);
mutt_file_set_mtime(filename, buf_string(tmpfile));
fp_in = mutt_file_fopen(buf_string(tmpfile), "r");
if (!fp_in)
goto bail;
if ((truncate(filename, 0) == -1) || ((fp_out = mutt_file_fopen(filename, "a")) == NULL))
{
mutt_perror("%s", filename);
goto bail;
}
mutt_file_copy_stream(fp_in, fp_out);
mutt_file_set_mtime(buf_string(tmpfile), filename);
unlink(buf_string(tmpfile));
bail:
mutt_file_fclose(&fp_in);
mutt_file_fclose(&fp_out);
buf_pool_release(&tmpfile);
}
/**
* mutt_rfc3676_space_stuff - Perform RFC3676 space stuffing on an Email
* @param e Email
*
* @note We don't check the option `$text_flowed` because we want to stuff based
* the actual content type. The option only decides whether to *set*
* format=flowed on new messages.
*/
void mutt_rfc3676_space_stuff(struct Email *e)
{
if (!e || !e->body || !e->body->filename)
return;
if (mutt_rfc3676_is_format_flowed(e->body))
rfc3676_space_stuff(e->body->filename, false);
}
/**
* mutt_rfc3676_space_unstuff - Remove RFC3676 space stuffing
* @param e Email
*/
void mutt_rfc3676_space_unstuff(struct Email *e)
{
if (!e || !e->body || !e->body->filename)
return;
if (mutt_rfc3676_is_format_flowed(e->body))
rfc3676_space_stuff(e->body->filename, true);
}
/**
* mutt_rfc3676_space_unstuff_attachment - Unstuff attachments
* @param b Email Body (OPTIONAL)
* @param filename Attachment file
*
* This routine is used when saving/piping/viewing rfc3676 attachments.
*
* If b is provided, the function will verify that the Email is format-flowed.
* The filename will be unstuffed, not b->filename or b->fp.
*/
void mutt_rfc3676_space_unstuff_attachment(struct Body *b, const char *filename)
{
if (!filename)
return;
if (b && !mutt_rfc3676_is_format_flowed(b))
return;
rfc3676_space_stuff(filename, true);
}
/**
* mutt_rfc3676_space_stuff_attachment - Stuff attachments
* @param b Email Body (OPTIONAL)
* @param filename Attachment file
*
* This routine is used when filtering rfc3676 attachments.
*
* If b is provided, the function will verify that the Email is format-flowed.
* The filename will be unstuffed, not b->filename or b->fp.
*/
void mutt_rfc3676_space_stuff_attachment(struct Body *b, const char *filename)
{
if (!filename)
return;
if (b && !mutt_rfc3676_is_format_flowed(b))
return;
rfc3676_space_stuff(filename, false);
}