[sanitizer] Support "bB" printf GLIBC extension (llvm#128449)

https://www.gnu.org/software/libc/manual/html_node/Table-of-Output-Conversions.html

Without the patch llc triggers non-fatal Asan warning.

Author: vitalybuka

compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors_format.inc

@@ -67,6 +67,10 @@ static const char *maybe_parse_length_modifier(const char *p, char ll[2]) {
 
 // Returns true if the character is an integer conversion specifier.
 static bool format_is_integer_conv(char c) {
+#if SANITIZER_GLIBC
+  if (char_is_one_of(c, "bB"))
+    return true;
+#endif
   return char_is_one_of(c, "diouxXn");
 }
 

compiler-rt/lib/sanitizer_common/tests/sanitizer_format_interceptor_test.cpp

@@ -131,7 +131,6 @@ TEST(SanitizerCommonInterceptors, Scanf) {
   testScanf("a%%%%b", 0);
   testScanf("a%%b%%", 0);
   testScanf("a%%%%%%b", 0);
-  testScanf("a%%%%%b", 0);
   testScanf("a%%%%%f", 1, F);
   testScanf("a%%%lxb", 1, L);
   testScanf("a%lf%%%lxb", 2, D, L);
@@ -207,6 +206,14 @@ TEST(SanitizerCommonInterceptors, Scanf) {
   testScanfPartial("%d%n%n%d %s %s", 3, 5, I, I, I, I, test_buf_size);
   testScanfPartial("%d%n%n%d %s %s", 4, 6, I, I, I, I, test_buf_size,
                    test_buf_size);
+
+#if defined(__GLIBC__)
+  testScanf("%b", 1, I);
+  testScanf("%zb", 1, Z);
+  testScanf("a%%%%%b", 1, I);
+#else
+  testScanf("a%%%%%b", 0);
+#endif
 }
 
 TEST(SanitizerCommonInterceptors, ScanfAllocate) {