[PATCH 1/2] mailinfo: support rfc3676 (format=flowed) text/plain messages

[Jay Soffian <jaysoffian@gmail.com>]

RFC 3676 establishes two parameters (Format and DelSP) to be used with
the Text/Plain media type. In the presence of these parameters, trailing
whitespace is used to indicate flowed lines and a canonical quote
indicator is used to indicate quoted lines.

mailinfo now unfolds, unquotes, and un-space-stuffs such messages.

Signed-off-by: Jay Soffian <jaysoffian@gmail.com>
---
It's been a while since I hacked C, so mucho scrutiny appreciated. The
mailinfo testsuite still passes, and this patch is followed by one which
adds a new test for this code, which also passes.

This is based off next, but mailinfo hasn't changed in a while, so it should apply cleanly to master (didn't test that though).

 builtin-mailinfo.c |   40 ++++++++++++++++++++++++++++++++++++++++
 1 files changed, 40 insertions(+), 0 deletions(-)

diff --git a/builtin-mailinfo.c b/builtin-mailinfo.c
index 2600847..deaf92b 100644
--- a/builtin-mailinfo.c
+++ b/builtin-mailinfo.c
@@ -20,6 +20,13 @@ static enum  {
 static enum  {
 	TYPE_TEXT, TYPE_OTHER,
 } message_type;
+/* RFC 3676 Text/Plain Format and DelSp Parameters */
+static enum {
+	FORMAT_NONE, FORMAT_FIXED, FORMAT_FLOWED,
+} tp_format;
+static enum {
+	DELSP_NONE, DELSP_YES, DELSP_NO,
+} tp_delsp;
 
 static char charset[256];
 static int patch_lines;
@@ -193,6 +200,18 @@ static int handle_content_type(char *line)
 
 	if (strcasestr(line, "text/") == NULL)
 		 message_type = TYPE_OTHER;
+	else if (strcasestr(line, "text/plain")) {
+		char attr[256];
+		if (slurp_attr(line, "format=", attr) && !strcasecmp(attr, "flowed")) {
+			tp_format = FORMAT_FLOWED;
+			if (slurp_attr(line, "delsp=", attr) && !strcasecmp(attr, "yes"))
+				tp_delsp = DELSP_YES;
+			else
+				tp_delsp = DELSP_NO;
+		}
+		else
+			tp_format = FORMAT_FIXED;
+	}
 	if (slurp_attr(line, "boundary=", boundary + 2)) {
 		memcpy(boundary, "--", 2);
 		if (content_top++ >= &content[MAX_BOUNDARIES]) {
@@ -681,6 +700,8 @@ again:
 	transfer_encoding = TE_DONTCARE;
 	charset[0] = 0;
 	message_type = TYPE_TEXT;
+	tp_format = FORMAT_NONE;
+	tp_delsp = DELSP_NONE;
 
 	/* slurp in this section's info */
 	while (read_one_header_line(line, sizeof(line), fin))
@@ -770,6 +791,24 @@ static int handle_filter(char *line, unsigned linesize)
 {
 	static int filter = 0;
 
+	if (tp_format == FORMAT_FLOWED && !!strcmp(line, "-- \n")) {
+		char *cp = line;
+		while (*cp == '>' && *cp != 0)
+			cp++;
+		if (*cp == ' ')
+			cp++;
+		line = cp;
+		if (!!strcmp(line, "-- \n")) {
+			while (*cp != '\n' && *cp !=0)
+				cp++;
+			if (cp > line && *cp == '\n' && *(cp-1) == ' ') {
+				if (tp_delsp == DELSP_YES)
+					*(cp-1) = '\0';
+				else
+					*cp = '\0';
+			}
+		}
+	}
 	/* filter tells us which part we left off on
 	 * a non-zero return indicates we hit a filter point
 	 */
@@ -818,6 +857,7 @@ static void handle_body(void)
 
 		switch (transfer_encoding) {
 		case TE_BASE64:
+		case TE_QP:
 		{
 			char *op = line;
 
-- 
1.5.4.1.1281.g75df