From f0733c13ed8b79bb10e240c4b4a6630784c7d258 Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Thu, 4 May 2017 15:56:14 +0200
Subject: mailinfo & mailsplit: check for EOF while parsing

While POSIX states that it is okay to pass EOF to isspace() (and it seems
to be implied that EOF should *not* be treated as whitespace), and also to
pass EOF to ungetc() (which seems to be intended to fail without buffering
the character), it is much better to handle these cases explicitly. Not
only does it reduce head-scratching (and helps static analysis avoid
reporting false positives), it also lets us handle files containing
nothing but whitespace by erroring out.

Reported via Coverity.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/mailsplit.c b/builtin/mailsplit.c
index 3068168..664400b 100644
--- a/builtin/mailsplit.c
+++ b/builtin/mailsplit.c
@@ -232,6 +232,16 @@ static int split_mbox(const char *file, const char *dir, int allow_bare,
 
 	do {
 		peek = fgetc(f);
+		if (peek == EOF) {
+			if (f == stdin)
+				/* empty stdin is OK */
+				ret = skip;
+			else {
+				fclose(f);
+				error(_("empty mbox: '%s'"), file);
+			}
+			goto out;
+		}
 	} while (isspace(peek));
 	ungetc(peek, f);
 
diff --git a/mailinfo.c b/mailinfo.c
index 6803775..f92cb9f 100644
--- a/mailinfo.c
+++ b/mailinfo.c
@@ -882,7 +882,10 @@ static int read_one_header_line(struct strbuf *line, FILE *in)
 	for (;;) {
 		int peek;
 
-		peek = fgetc(in); ungetc(peek, in);
+		peek = fgetc(in);
+		if (peek == EOF)
+			break;
+		ungetc(peek, in);
 		if (peek != ' ' && peek != '\t')
 			break;
 		if (strbuf_getline_lf(&continuation, in))
@@ -1099,6 +1102,10 @@ int mailinfo(struct mailinfo *mi, const char *msg, const char *patch)
 
 	do {
 		peek = fgetc(mi->input);
+		if (peek == EOF) {
+			fclose(cmitmsg);
+			return error("empty patch: '%s'", patch);
+		}
 	} while (isspace(peek));
 	ungetc(peek, mi->input);
 
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