[PATCH] mmap error handling

I have reviewed all occurrences of mmap() in git and fixed three types
of errors/defects:

1) The result is not checked.
2) The file descriptor is closed if mmap() succeeds, but not when it
fails.
3) Various casts applied to -1 are used instead of MAP_FAILED, which is
specifically defined to check mmap() return value.

[jc: This is a second round of Pavel's patch.  He fixed up the problem
that close() potentially clobbering the errno from mmap, which
the first round had.]

Signed-off-by: Pavel Roskin <proski@gnu.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

tools/mailsplit.c

@@ -116,8 +116,9 @@ int main(int argc, char **argv)
 	}
 	size = st.st_size;
 	map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
-	if (-1 == (int)(long)map) {
+	if (map == MAP_FAILED) {
 		perror("mmap");
+		close(fd);
 		exit(1);
 	}
 	close(fd);