1 files changed, 200 insertions, 0 deletions
diff --git a/memory/replace/logalloc/FdPrintf.cpp b/memory/replace/logalloc/FdPrintf.cpp
new file mode 100644
index 0000000000..4a8e48af78
--- /dev/null
+++ b/memory/replace/logalloc/FdPrintf.cpp
@@ -0,0 +1,200 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <cstdarg>
+
+#ifdef _WIN32
+#  include <windows.h>
+#else
+#  include <unistd.h>
+#endif
+#include <cmath>
+#include <cstring>
+#include "mozilla/Assertions.h"
+#include "mozilla/Unused.h"
+#include "FdPrintf.h"
+
+/* Template class allowing a limited number of increments on a value */
+template <typename T>
+class CheckedIncrement {
+ public:
+  CheckedIncrement(T aValue, size_t aMaxIncrement)
+      : mValue(aValue), mMaxIncrement(aMaxIncrement) {}
+
+  T operator++(int) {
+    if (!mMaxIncrement) {
+      MOZ_CRASH("overflow detected");
+    }
+    mMaxIncrement--;
+    return mValue++;
+  }
+
+  T& operator++() {
+    (*this)++;
+    return mValue;
+  }
+
+  void advance(T end) {
+    // Only makes sense if T is a pointer type.
+    size_t diff = end - mValue;
+    if (diff > mMaxIncrement) {
+      MOZ_CRASH("overflow detected");
+    }
+    mMaxIncrement -= diff;
+    mValue = end;
+  };
+
+  void rewind(T pos) {
+    size_t diff = mValue - pos;
+    mMaxIncrement += diff;
+    mValue = pos;
+  }
+
+  operator T() { return mValue; }
+  T value() { return mValue; }
+
+ private:
+  T mValue;
+  size_t mMaxIncrement;
+};
+
+template <typename T>
+static unsigned NumDigits(T n) {
+  if (n < 1) {
+    // We want one digit, it will be 0.
+    return 1;
+  }
+
+  double l = log10(static_cast<double>(n));
+  double cl = ceil(l);
+  return l == cl ? unsigned(cl) + 1 : unsigned(cl);
+}
+
+static void LeftPad(CheckedIncrement<char*>& b, size_t pad) {
+  while (pad-- > 0) {
+    *(b++) = ' ';
+  }
+}
+
+// Write the digits into the buffer.
+static void WriteDigits(CheckedIncrement<char*>& b, size_t i,
+                        size_t num_digits) {
+  size_t x = pow(10, double(num_digits - 1));
+  do {
+    *(b++) = "0123456789"[(i / x) % 10];
+    x /= 10;
+  } while (x > 0);
+}
+
+void FdPrintf(intptr_t aFd, const char* aFormat, ...) {
+  if (aFd == 0) {
+    return;
+  }
+  char buf[256];
+  CheckedIncrement<char*> b(buf, sizeof(buf));
+  CheckedIncrement<const char*> f(aFormat, strlen(aFormat) + 1);
+  va_list ap;
+  va_start(ap, aFormat);
+  while (true) {
+    switch (*f) {
+      case '\0':
+        goto out;
+
+      case '%': {
+        // The start of the format specifier is used if this specifier is
+        // invalid.
+        const char* start = f;
+
+        // Read the field width
+        f++;
+        char* end = nullptr;
+        size_t width = strtoul(f, &end, 10);
+        // If strtol can't find a number that's okay, that means 0 in our
+        // case, but we must advance f).
+        f.advance(end);
+
+        switch (*f) {
+          case 'z': {
+            if (*(++f) == 'u') {
+              size_t i = va_arg(ap, size_t);
+
+              size_t num_digits = NumDigits(i);
+              LeftPad(b, width > num_digits ? width - num_digits : 0);
+              WriteDigits(b, i, num_digits);
+            } else {
+              // If the format specifier is unknown then write out '%' and
+              // rewind to the beginning of the specifier causing it to be
+              // printed normally.
+              *(b++) = '%';
+              f.rewind(start);
+            }
+            break;
+          }
+
+          case 'p': {
+            intptr_t ptr = va_arg(ap, intptr_t);
+            *(b++) = '0';
+            *(b++) = 'x';
+            int x = sizeof(intptr_t) * 8;
+            bool wrote_msb = false;
+            do {
+              x -= 4;
+              size_t hex_digit = ptr >> x & 0xf;
+              if (hex_digit || wrote_msb) {
+                *(b++) = "0123456789abcdef"[hex_digit];
+                wrote_msb = true;
+              }
+            } while (x > 0);
+            if (!wrote_msb) {
+              *(b++) = '0';
+            }
+            break;
+          }
+
+          case 's': {
+            const char* str = va_arg(ap, const char*);
+            size_t len = strlen(str);
+
+            LeftPad(b, width > len ? width - len : 0);
+
+            while (*str) {
+              *(b++) = *(str++);
+            }
+
+            break;
+          }
+
+          case '%':
+            // Print a single raw '%'.
+            *(b++) = '%';
+            break;
+
+          default:
+            // If the format specifier is unknown then write out '%' and
+            // rewind to the beginning of the specifier causing it to be
+            // printed normally.
+            *(b++) = '%';
+            f.rewind(start);
+            break;
+        }
+        break;
+      }
+      default:
+        *(b++) = *f;
+        break;
+    }
+    f++;
+  }
+out:
+#ifdef _WIN32
+  // See comment in FdPrintf.h as to why WriteFile is used.
+  DWORD written;
+  WriteFile(reinterpret_cast<HANDLE>(aFd), buf, b - buf, &written, nullptr);
+#else
+  MOZ_UNUSED(write(aFd, buf, b - buf));
+#endif
+  va_end(ap);
+}