From f98bb2ddcbfed7033ae93ae8fe98b0540a9fb42f Mon Sep 17 00:00:00 2001
From: Delio Brignoli <brignoli.delio@gmail.com>
Date: Sat, 20 Aug 2016 10:51:28 +0200
Subject: [PATCH] py/mpprint: Fail an assertion with unsupported format
specifiers.
Arguments of an unknown type cannot be skipped and continuing to parse a
format string after encountering an unknown format specifier leads to
undefined behaviour. This patch helps to find use of unsupported formats.
---
py/mpprint.c | 4 +++-
tests/unix/extra_coverage.py.exp | 1 -
unix/coverage.c | 2 --
3 files changed, 3 insertions(+), 4 deletions(-)
diff --git a/py/mpprint.c b/py/mpprint.c
index cb49b1227..97ea33ad2 100644
--- a/py/mpprint.c
+++ b/py/mpprint.c
@@ -537,10 +537,12 @@ int mp_vprintf(const mp_print_t *print, const char *fmt, va_list args) {
chrs += mp_print_int(print, arg_value, *fmt == 'd', 10, 'a', flags, fill, width);
break;
}
- // fall through to default case to print unknown format char
+ assert(!"unsupported fmt char");
}
#endif
default:
+ // if it's not %% then it's an unsupported format character
+ assert(*fmt == '%' || !"unsupported fmt char");
print->print_strn(print->data, fmt, 1);
chrs += 1;
break;
diff --git a/tests/unix/extra_coverage.py.exp b/tests/unix/extra_coverage.py.exp
index db282b152..44749c45e 100644
--- a/tests/unix/extra_coverage.py.exp
+++ b/tests/unix/extra_coverage.py.exp
@@ -7,7 +7,6 @@ ab abc
false true
(null)
-t
-2147483648
2147483648
80000000
diff --git a/unix/coverage.c b/unix/coverage.c
index 9d5372554..ce1da50e2 100644
--- a/unix/coverage.c
+++ b/unix/coverage.c
@@ -12,7 +12,6 @@ STATIC mp_obj_t extra_coverage(void) {
// mp_printf (used by ports that don't have a native printf)
{
mp_printf(&mp_plat_print, "# mp_printf\n");
- mp_printf(&mp_plat_print, "%"); // nothing after percent
mp_printf(&mp_plat_print, "%d %+d % d\n", -123, 123, 123); // sign
mp_printf(&mp_plat_print, "%05d\n", -123); // negative number with zero padding
mp_printf(&mp_plat_print, "%ld\n", 123); // long
@@ -21,7 +20,6 @@ STATIC mp_obj_t extra_coverage(void) {
mp_printf(&mp_plat_print, "%.*s\n", -1, "abc"); // negative string precision
mp_printf(&mp_plat_print, "%b %b\n", 0, 1); // bools
mp_printf(&mp_plat_print, "%s\n", NULL); // null string
- mp_printf(&mp_plat_print, "%t\n"); // non-format char
mp_printf(&mp_plat_print, "%d\n", 0x80000000); // should print signed
mp_printf(&mp_plat_print, "%u\n", 0x80000000); // should print unsigned
mp_printf(&mp_plat_print, "%x\n", 0x80000000); // should print unsigned
--
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