[sanitizers] Get the proper printf/scanf version when long double transition is involved.

[• koriakin]

Summary

See D19555 for rationale. As it turns out, this treatment is also necessary
for scanf/printf.

[eugenis]

What about functions like __isoc99_scanf and snprintf_l?

LGTM

[• koriakin]

In D27118#606974, @eugenis wrote:

What about functions like __isoc99_scanf and snprintf_l?

LGTM

__isoc99_* were added after the transition and are unaffected; snprintf_l is BSD-only.

compiler-rt/trunk/lib/sanitizer_common/sanitizer_common_interceptors.inc

 INTERCEPTOR(int, __isoc99_sscanf, const char *str, const char *format, ...)
 FORMAT_INTERCEPTOR_IMPL(__isoc99_sscanf, __isoc99_vsscanf, str, format)
 #endif
 
 #endif
 
 #if SANITIZER_INTERCEPT_SCANF
 #define INIT_SCANF                    \
-  COMMON_INTERCEPT_FUNCTION(scanf);   \
-  COMMON_INTERCEPT_FUNCTION(sscanf);  \
-  COMMON_INTERCEPT_FUNCTION(fscanf);  \
-  COMMON_INTERCEPT_FUNCTION(vscanf);  \
-  COMMON_INTERCEPT_FUNCTION(vsscanf); \
-  COMMON_INTERCEPT_FUNCTION(vfscanf);
+  COMMON_INTERCEPT_FUNCTION_LDBL(scanf);   \
+  COMMON_INTERCEPT_FUNCTION_LDBL(sscanf);  \
+  COMMON_INTERCEPT_FUNCTION_LDBL(fscanf);  \
+  COMMON_INTERCEPT_FUNCTION_LDBL(vscanf);  \
+  COMMON_INTERCEPT_FUNCTION_LDBL(vsscanf); \
+  COMMON_INTERCEPT_FUNCTION_LDBL(vfscanf);
 #else
 #define INIT_SCANF
 #endif
 
 #if SANITIZER_INTERCEPT_ISOC99_SCANF
 #define INIT_ISOC99_SCANF                      \
   COMMON_INTERCEPT_FUNCTION(__isoc99_scanf);   \
   COMMON_INTERCEPT_FUNCTION(__isoc99_sscanf);  \
FORMAT_INTERCEPTOR_IMPL(__isoc99_snprintf, __isoc99_vsnprintf, str, size,
                         format)
 
 #endif  // SANITIZER_INTERCEPT_ISOC99_PRINTF
 
 #endif  // SANITIZER_INTERCEPT_PRINTF
 
 #if SANITIZER_INTERCEPT_PRINTF
 #define INIT_PRINTF                     \
-  COMMON_INTERCEPT_FUNCTION(printf);    \
-  COMMON_INTERCEPT_FUNCTION(sprintf);   \
-  COMMON_INTERCEPT_FUNCTION(snprintf);  \
-  COMMON_INTERCEPT_FUNCTION(asprintf);  \
-  COMMON_INTERCEPT_FUNCTION(fprintf);   \
-  COMMON_INTERCEPT_FUNCTION(vprintf);   \
-  COMMON_INTERCEPT_FUNCTION(vsprintf);  \
-  COMMON_INTERCEPT_FUNCTION(vsnprintf); \
-  COMMON_INTERCEPT_FUNCTION(vasprintf); \
-  COMMON_INTERCEPT_FUNCTION(vfprintf);
+  COMMON_INTERCEPT_FUNCTION_LDBL(printf);    \
+  COMMON_INTERCEPT_FUNCTION_LDBL(sprintf);   \
+  COMMON_INTERCEPT_FUNCTION_LDBL(snprintf);  \
+  COMMON_INTERCEPT_FUNCTION_LDBL(asprintf);  \
+  COMMON_INTERCEPT_FUNCTION_LDBL(fprintf);   \
+  COMMON_INTERCEPT_FUNCTION_LDBL(vprintf);   \
+  COMMON_INTERCEPT_FUNCTION_LDBL(vsprintf);  \
+  COMMON_INTERCEPT_FUNCTION_LDBL(vsnprintf); \
+  COMMON_INTERCEPT_FUNCTION_LDBL(vasprintf); \
+  COMMON_INTERCEPT_FUNCTION_LDBL(vfprintf);
 #else
 #define INIT_PRINTF
 #endif
 
 #if SANITIZER_INTERCEPT_PRINTF_L
 #define INIT_PRINTF_L                     \
   COMMON_INTERCEPT_FUNCTION(snprintf_l);  \
   COMMON_INTERCEPT_FUNCTION(vsnprintf_l);

compiler-rt/trunk/test/sanitizer_common/TestCases/printf-ldbl.c

+// RUN: %clang %s -o %t && %run %t 2>&1
+
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+int main(int argc, char **argv) {
+  char buf[20];
+  long double ld = 4.0;
+  snprintf(buf, sizeof buf, "%Lf %d", ld, 123);
+  assert(!strcmp(buf, "4.000000 123"));
+  return 0;
+}

compiler-rt/trunk/test/sanitizer_common/TestCases/scanf-ldbl.c

+// RUN: %clang %s -o %t && %run %t 2>&1
+
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+int main(int argc, char **argv) {
+  long double ld;
+  memset(&ld, 255, sizeof ld);
+  sscanf("4.0", "%Lf", &ld);
+  assert(ld == 4.0);
+  return 0;
+}