folly: fbvector: ubsan: avoid memset(nullptr, 0, 0)

[folly.git] / folly / Format.cpp

diff --git a/folly/Format.cpp b/folly/Format.cpp
index b09152daf1f7b82533f162e33683086cad8e7f96..e6df11419f7dce100dc2113739da6089022c5535 100644 (file)
--- a/folly/Format.cpp
+++ b/folly/Format.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright 2015 Facebook, Inc.
+ * Copyright 2016 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,6 +16,8 @@
 
 #include <folly/Format.h>
 
+#include <folly/portability/Constexpr.h>
+
 #include <double-conversion/double-conversion.h>
 
 namespace folly {
@@ -48,11 +50,13 @@ void FormatValue<double>::formatHelper(
   }
 
   // 2+: for null terminator and optional sign shenanigans.
-  char buf[2 + std::max({
-      (2 + DoubleToStringConverter::kMaxFixedDigitsBeforePoint +
-       DoubleToStringConverter::kMaxFixedDigitsAfterPoint),
-      (8 + DoubleToStringConverter::kMaxExponentialDigits),
-      (7 + DoubleToStringConverter::kMaxPrecisionDigits)})];
+  constexpr size_t bufLen =
+      2 + constexpr_max(
+              2 + DoubleToStringConverter::kMaxFixedDigitsBeforePoint +
+                  DoubleToStringConverter::kMaxFixedDigitsAfterPoint,
+              constexpr_max(8 + DoubleToStringConverter::kMaxExponentialDigits,
+                            7 + DoubleToStringConverter::kMaxPrecisionDigits));
+  char buf[bufLen];
   StringBuilder builder(buf + 1, static_cast<int> (sizeof(buf) - 1));
 
   char plusSign;
@@ -209,12 +213,25 @@ void FormatArg::initSlow() {
       if (++p == end) return;
     }
 
-    if (*p >= '0' && *p <= '9') {
-      auto b = p;
+    auto readInt = [&] {
+      auto const c = p;
       do {
         ++p;
       } while (p != end && *p >= '0' && *p <= '9');
-      width = to<int>(StringPiece(b, p));
+      return to<int>(StringPiece(c, p));
+    };
+
+    if (*p == '*') {
+      width = kDynamicWidth;
+      ++p;
+
+      if (p == end) return;
+
+      if (*p >= '0' && *p <= '9') widthIndex = readInt();
+
+      if (p == end) return;
+    } else if (*p >= '0' && *p <= '9') {
+      width = readInt();
 
       if (p == end) return;
     }
@@ -225,12 +242,12 @@ void FormatArg::initSlow() {
     }
 
     if (*p == '.') {
-      auto b = ++p;
+      auto d = ++p;
       while (p != end && *p >= '0' && *p <= '9') {
         ++p;
       }
-      if (p != b) {
-        precision = to<int>(StringPiece(b, p));
+      if (p != d) {
+        precision = to<int>(StringPiece(d, p));
         if (p != end && *p == '.') {
           trailingDot = true;
           ++p;
@@ -287,7 +304,6 @@ void insertThousandsGroupingUnsafe(char* start_buffer, char** end_buffer) {
   uint32_t buffer_read_index = remaining_digits - 1;
   start_buffer[buffer_write_index + 1] = 0;
 
-  uint32_t count = 0;
   bool done = false;
   uint32_t next_group_size = 3;