mailinfo: do not get confused with logical lines that are too long.

It basically considers all the continuation lines to be lines of their
own, and if the total line is bigger than what we can fit in it, we just
truncate the result rather than stop in the middle and then get confused
when we try to parse the "next" line (which is just the remainder of the
first line).

[jc: added test, and tightened boundary a bit per list discussion.]

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 54 insertions, 18 deletions

diff --git a/builtin-mailinfo.c b/builtin-mailinfo.c
index 583da38b67..cf5ef29c0f 100644
--- a/builtin-mailinfo.c
+++ b/builtin-mailinfo.c
@@ -406,6 +406,11 @@ static int is_rfc2822_header(char *line)
 	 */
 	int ch;
 	char *cp = line;
+
+	/* Count mbox From headers as headers */
+	if (!memcmp(line, "From ", 5) || !memcmp(line, ">From ", 6))
+		return 1;
+
 	while ((ch = *cp++)) {
 		if (ch == ':')
 			return cp != line;
@@ -417,30 +422,61 @@ static int is_rfc2822_header(char *line)
 	return 0;
 }
 
+/*
+ * sz is size of 'line' buffer in bytes.  Must be reasonably
+ * long enough to hold one physical real-world e-mail line.
+ */
 static int read_one_header_line(char *line, int sz, FILE *in)
 {
-	int ofs = 0;
-	while (ofs < sz) {
-		int peek, len;
-		if (fgets(line + ofs, sz - ofs, in) == NULL)
-			break;
-		len = eatspace(line + ofs);
-		if ((len == 0) || !is_rfc2822_header(line)) {
-			/* Re-add the newline */
-			line[ofs + len] = '\n';
-			line[ofs + len + 1] = '\0';
-			break;
-		}
-		ofs += len;
-		/* Yuck, 2822 header "folding" */
+	int len;
+
+	/*
+	 * We will read at most (sz-1) bytes and then potentially
+	 * re-add NUL after it.  Accessing line[sz] after this is safe
+	 * and we can allow len to grow up to and including sz.
+	 */
+	sz--;
+
+	/* Get the first part of the line. */
+	if (!fgets(line, sz, in))
+		return 0;
+
+	/*
+	 * Is it an empty line or not a valid rfc2822 header?
+	 * If so, stop here, and return false ("not a header")
+	 */
+	len = eatspace(line);
+	if (!len || !is_rfc2822_header(line)) {
+		/* Re-add the newline */
+		line[len] = '\n';
+		line[len + 1] = '\0';
+		return 0;
+	}
+
+	/*
+	 * Now we need to eat all the continuation lines..
+	 * Yuck, 2822 header "folding"
+	 */
+	for (;;) {
+		int peek, addlen;
+		static char continuation[1000];
+
 		peek = fgetc(in); ungetc(peek, in);
 		if (peek != ' ' && peek != '\t')
 			break;
+		if (!fgets(continuation, sizeof(continuation), in))
+			break;
+		addlen = eatspace(continuation);
+		if (len < sz - 1) {
+			if (addlen >= sz - len)
+				addlen = sz - len - 1;
+			memcpy(line + len, continuation, addlen);
+			len += addlen;
+		}
 	}
-	/* Count mbox From headers as headers */
-	if (!ofs && (!memcmp(line, "From ", 5) || !memcmp(line, ">From ", 6)))
-		ofs = 1;
-	return ofs;
+	line[len] = 0;
+
+	return 1;
 }
 
 static int decode_q_segment(char *in, char *ot, char *ep, int rfc2047)