static void add_rfc2047(struct strbuf *sb, const char *line, int len,
const char *encoding)
{
int i, last;
for (i = 0; i < len; i++) {
int ch = line[i];
if (non_ascii(ch))
goto needquote;
if ((i + 1 < len) && (ch == '=' && line[i+1] == '?'))
goto needquote;
}
strbuf_add(sb, line, len);
return;
needquote:
strbuf_grow(sb, len * 3 + strlen(encoding) + 100);
strbuf_addf(sb, "=?%s?q?", encoding);
for (i = last = 0; i < len; i++) {
unsigned ch = line[i] & 0xFF;
/*
* We encode ' ' using '=20' even though rfc2047
* allows using '_' for readability. Unfortunately,
* many programs do not understand this and just
* leave the underscore in place.
*/
if (is_rfc2047_special(ch) || ch == ' ') {
strbuf_add(sb, line + last, i - last);
strbuf_addf(sb, "=%02X", ch);
last = i + 1;
}
}
strbuf_add(sb, line + last, len - last);
strbuf_addstr(sb, "?=");
}
static void add_rfc2047(struct strbuf *sb, const char *line, int len,
const char *encoding)
{
static const int max_length = 78; /* per rfc2822 */
int i;
int line_len;
/* How many bytes are already used on the current line? */
for (i = sb->len - 1; i >= 0; i--)
if (sb->buf[i] == '\n')
break;
line_len = sb->len - (i+1);
for (i = 0; i < len; i++) {
int ch = line[i];
if (non_ascii(ch) || ch == '\n')
goto needquote;
if ((i + 1 < len) && (ch == '=' && line[i+1] == '?'))
goto needquote;
}
strbuf_add_wrapped_bytes(sb, line, len, 0, 1, max_length - line_len);
return;
needquote:
strbuf_grow(sb, len * 3 + strlen(encoding) + 100);
strbuf_addf(sb, "=?%s?q?", encoding);
line_len += strlen(encoding) + 5; /* 5 for =??q? */
for (i = 0; i < len; i++) {
unsigned ch = line[i] & 0xFF;
if (line_len >= max_length - 2) {
strbuf_addf(sb, "?=\n =?%s?q?", encoding);
line_len = strlen(encoding) + 5 + 1; /* =??q? plus SP */
}
/*
* We encode ' ' using '=20' even though rfc2047
* allows using '_' for readability. Unfortunately,
* many programs do not understand this and just
* leave the underscore in place.
*/
if (is_rfc2047_special(ch) || ch == ' ' || ch == '\n') {
strbuf_addf(sb, "=%02X", ch);
line_len += 3;
}
else {
strbuf_addch(sb, ch);
line_len++;
}
}
strbuf_addstr(sb, "?=");
}
static void add_rfc2047(struct strbuf *sb, const char *line, size_t len,
const char *encoding, enum rfc2047_type type)
{
static const int max_encoded_length = 76; /* per rfc2047 */
int i;
int line_len = last_line_length(sb);
strbuf_grow(sb, len * 3 + strlen(encoding) + 100);
strbuf_addf(sb, "=?%s?q?", encoding);
line_len += strlen(encoding) + 5; /* 5 for =??q? */
while (len) {
/*
* RFC 2047, section 5 (3):
*
* Each 'encoded-word' MUST represent an integral number of
* characters. A multi-octet character may not be split across
* adjacent 'encoded- word's.
*/
const unsigned char *p = (const unsigned char *)line;
int chrlen = mbs_chrlen(&line, &len, encoding);
int is_special = (chrlen > 1) || is_rfc2047_special(*p, type);
/* "=%02X" * chrlen, or the byte itself */
const char *encoded_fmt = is_special ? "=%02X" : "%c";
int encoded_len = is_special ? 3 * chrlen : 1;
/*
* According to RFC 2047, we could encode the special character
* ' ' (space) with '_' (underscore) for readability. But many
* programs do not understand this and just leave the
* underscore in place. Thus, we do nothing special here, which
* causes ' ' to be encoded as '=20', avoiding this problem.
*/
if (line_len + encoded_len + 2 > max_encoded_length) {
/* It won't fit with trailing "?=" --- break the line */
strbuf_addf(sb, "?=\n =?%s?q?", encoding);
line_len = strlen(encoding) + 5 + 1; /* =??q? plus SP */
}
for (i = 0; i < chrlen; i++)
strbuf_addf(sb, encoded_fmt, p[i]);
line_len += encoded_len;
}
strbuf_addstr(sb, "?=");
}
static void add_rfc2047(struct strbuf *sb, const char *line, int len,
const char *encoding, enum rfc2047_type type)
{
static const int max_encoded_length = 76; /* per rfc2047 */
int i;
int line_len = last_line_length(sb);
strbuf_grow(sb, len * 3 + strlen(encoding) + 100);
strbuf_addf(sb, "=?%s?q?", encoding);
line_len += strlen(encoding) + 5; /* 5 for =??q? */
for (i = 0; i < len; i++) {
unsigned ch = line[i] & 0xFF;
int is_special = is_rfc2047_special(ch, type);
/*
* According to RFC 2047, we could encode the special character
* ' ' (space) with '_' (underscore) for readability. But many
* programs do not understand this and just leave the
* underscore in place. Thus, we do nothing special here, which
* causes ' ' to be encoded as '=20', avoiding this problem.
*/
if (line_len + 2 + (is_special ? 3 : 1) > max_encoded_length) {
strbuf_addf(sb, "?=\n =?%s?q?", encoding);
line_len = strlen(encoding) + 5 + 1; /* =??q? plus SP */
}
if (is_special) {
strbuf_addf(sb, "=%02X", ch);
line_len += 3;
} else {
strbuf_addch(sb, ch);
line_len++;
}
}
strbuf_addstr(sb, "?=");
}