_scanf.c: Implement 'm' modifier for 'c' and '[' conversions.

The current code implements the 'm' modifier only for 's'
conversions and would cause a segfault if it was used for 'c'
or '[' conversions. This patch extends the code to cover these
cases too.

The original version could write scanned data outside the passed buffer
because index i used in the '[' conversion handling block was clobbered.

Signed-off-by: Will Newton <will.newton@imgtec.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/test/stdio/scanf_m.c b/test/stdio/scanf_m.c
new file mode 100644
index 000000000..0ce78b6e4
--- /dev/null
+++ b/test/stdio/scanf_m.c
@@ -0,0 +1,24 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int main(void)
+{
+	const char *buf = "hello world";
+	char *ps = NULL, *pc = NULL;
+	char s[6], c;
+
+	/* Check that %[...]/%c work. */
+	sscanf(buf, "%[a-z] %c", s, &c);
+	/* Check that %m[...]/%mc work. */
+	sscanf(buf, "%m[a-z] %mc", &ps, &pc);
+
+	if (strcmp(ps, "hello") != 0 || *pc != 'w' ||
+	    strcmp(s, "hello") != 0 || c != 'w')
+		return 1;
+
+	free(ps);
+	free(pc);
+
+	return 0;
+}