Checks the possibility of overscans from EDID extension data.

BUG=141005
TEST=ui_unittests --gtest_filter='X11UtilTest.*' passed

Review URL: https://codereview.chromium.org/11725005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@175421 0039d316-1c4b-4281-b951-d872f2087c98

ui/base/x/x11_util.cc

@@ -331,6 +331,53 @@ bool IsShapeAvailable() {
 
 }
 
+// Get the EDID data from the |output| and stores to |prop|. |nitem| will store
+// the number of characters |prop| will have. It doesn't take the ownership of
+// |prop|, so caller must release it by XFree().
+// Returns true if EDID property is successfully obtained. Otherwise returns
+// false and does not touch |prop| and |nitems|.
+bool GetEDIDProperty(XID output, unsigned long* nitems, unsigned char** prop) {
+  if (!IsRandRAvailable())
+    return false;
+
+  static Atom edid_property = GetAtom(RR_PROPERTY_RANDR_EDID);
+
+  Display* display = GetXDisplay();
+
+  bool has_edid_property = false;
+  int num_properties = 0;
+  Atom* properties = XRRListOutputProperties(display, output, &num_properties);
+  for (int i = 0; i < num_properties; ++i) {
+    if (properties[i] == edid_property) {
+      has_edid_property = true;
+      break;
+    }
+  }
+  XFree(properties);
+  if (!has_edid_property)
+    return false;
+
+  Atom actual_type;
+  int actual_format;
+  unsigned long bytes_after;
+  XRRGetOutputProperty(display,
+                       output,
+                       edid_property,
+                       0,                // offset
+                       128,              // length
+                       false,            // _delete
+                       false,            // pending
+                       AnyPropertyType,  // req_type
+                       &actual_type,
+                       &actual_format,
+                       nitems,
+                       &bytes_after,
+                       prop);
+  DCHECK_EQ(XA_INTEGER, actual_type);
+  DCHECK_EQ(8, actual_format);
+  return true;
+}
+
 }  // namespace
 
 bool XDisplayExists() {
@@ -1248,47 +1295,22 @@ bool GetOutputDeviceData(XID output,
                          uint16* manufacturer_id,
                          uint32* serial_number,
                          std::string* human_readable_name) {
-  if (!IsRandRAvailable())
-    return false;
-
-  static Atom edid_property = GetAtom(RR_PROPERTY_RANDR_EDID);
-
-  Display* display = GetXDisplay();
-
-  bool has_edid_property = false;
-  int num_properties = 0;
-  Atom* properties = XRRListOutputProperties(display, output, &num_properties);
-  for (int i = 0; i < num_properties; ++i) {
-    if (properties[i] == edid_property) {
-      has_edid_property = true;
-      break;
-    }
-  }
-  XFree(properties);
-  if (!has_edid_property)
+  unsigned long nitems = 0;
+  unsigned char *prop = NULL;
+  if (!GetEDIDProperty(output, &nitems, &prop))
     return false;
 
-  Atom actual_type;
-  int actual_format;
-  unsigned long nitems;
-  unsigned long bytes_after;
-  unsigned char *prop;
-  XRRGetOutputProperty(display,
-                       output,
-                       edid_property,
-                       0,                // offset
-                       128,              // length
-                       false,            // _delete
-                       false,            // pending
-                       AnyPropertyType,  // req_type
-                       &actual_type,
-                       &actual_format,
-                       &nitems,
-                       &bytes_after,
-                       &prop);
-  DCHECK_EQ(XA_INTEGER, actual_type);
-  DCHECK_EQ(8, actual_format);
+  bool result = ParseOutputDeviceData(
+      prop, nitems, manufacturer_id, serial_number, human_readable_name);
+  XFree(prop);
+  return result;
+}
 
+bool ParseOutputDeviceData(const unsigned char* prop,
+                           unsigned long nitems,
+                           uint16* manufacturer_id,
+                           uint32* serial_number,
+                           std::string* human_readable_name) {
   // See http://en.wikipedia.org/wiki/Extended_display_identification_data
   // for the details of EDID data format.  We use the following data:
   //   bytes 8-9: manufacturer EISA ID, in big-endian
@@ -1306,37 +1328,34 @@ bool GetOutputDeviceData(XID output,
   const unsigned char kMonitorNameDescriptor = 0xfc;
 
   if (manufacturer_id) {
-    if (nitems < kManufacturerOffset + kManufacturerLength) {
-      XFree(prop);
+    if (nitems < kManufacturerOffset + kManufacturerLength)
       return false;
-    }
-    *manufacturer_id = *reinterpret_cast<uint16*>(prop + kManufacturerOffset);
+
+    *manufacturer_id =
+        *reinterpret_cast<const uint16*>(prop + kManufacturerOffset);
 #if defined(ARCH_CPU_LITTLE_ENDIAN)
     *manufacturer_id = base::ByteSwap(*manufacturer_id);
 #endif
   }
 
   if (serial_number) {
-    if (nitems < kSerialNumberOffset + kSerialNumberLength) {
-      XFree(prop);
+    if (nitems < kSerialNumberOffset + kSerialNumberLength)
       return false;
-    }
+
     *serial_number = base::ByteSwapToLE32(
-        *reinterpret_cast<uint32*>(prop + kSerialNumberOffset));
+        *reinterpret_cast<const uint32*>(prop + kSerialNumberOffset));
   }
 
-  if (!human_readable_name) {
-    XFree(prop);
+  if (!human_readable_name)
     return true;
-  }
 
   human_readable_name->clear();
   for (unsigned int i = 0; i < kNumDescriptors; ++i) {
-    if (nitems < kDescriptorOffset + (i + 1) * kDescriptorLength) {
+    if (nitems < kDescriptorOffset + (i + 1) * kDescriptorLength)
       break;
-    }
 
-    unsigned char* desc_buf = prop + kDescriptorOffset + i * kDescriptorLength;
+    const unsigned char* desc_buf =
+        prop + kDescriptorOffset + i * kDescriptorLength;
     // If the descriptor contains the display name, it has the following
     // structure:
     //   bytes 0-2, 4: \0
@@ -1348,15 +1367,13 @@ bool GetOutputDeviceData(XID output,
         desc_buf[4] == 0) {
       if (desc_buf[3] == kMonitorNameDescriptor) {
         std::string found_name(
-            reinterpret_cast<char*>(desc_buf + 5), kDescriptorLength - 5);
+            reinterpret_cast<const char*>(desc_buf + 5), kDescriptorLength - 5);
         TrimWhitespaceASCII(found_name, TRIM_TRAILING, human_readable_name);
         break;
       }
     }
   }
 
-  XFree(prop);
-
   if (human_readable_name->empty())
     return false;
 
@@ -1372,6 +1389,96 @@ bool GetOutputDeviceData(XID output,
   return true;
 }
 
+bool GetOutputOverscanFlag(XID output, bool* flag) {
+  unsigned long nitems = 0;
+  unsigned char *prop = NULL;
+  if (!GetEDIDProperty(output, &nitems, &prop))
+    return false;
+
+  bool found = ParseOutputOverscanFlag(prop, nitems, flag);
+  XFree(prop);
+  return found;
+}
+
+bool ParseOutputOverscanFlag(const unsigned char* prop,
+                             unsigned long nitems,
+                             bool *flag) {
+  // See http://en.wikipedia.org/wiki/Extended_display_identification_data
+  // for the extension format of EDID.  Also see EIA/CEA-861 spec for
+  // the format of the extensions and how video capability is encoded.
+  //  - byte 0: tag.  should be 02h.
+  //  - byte 1: revision.  only cares revision 3 (03h).
+  //  - byte 4-: data block.
+  const unsigned int kExtensionBase = 128;
+  const unsigned int kExtensionSize = 128;
+  const unsigned int kNumExtensionsOffset = 126;
+  const unsigned int kDataBlockOffset = 4;
+  const unsigned char kCEAExtensionTag = '\x02';
+  const unsigned char kExpectedExtensionRevision = '\x03';
+  const unsigned char kExtendedTag = 7;
+  const unsigned char kExtendedVideoCapabilityTag = 0;
+  const unsigned int kPTOverscan = 4;
+  const unsigned int kITOverscan = 2;
+  const unsigned int kCEOverscan = 0;
+
+  if (nitems <= kNumExtensionsOffset)
+    return false;
+
+  unsigned char num_extensions = prop[kNumExtensionsOffset];
+
+  for (size_t i = 0; i < num_extensions; ++i) {
+    // Skip parsing the whole extension if size is not enough.
+    if (nitems <= kExtensionBase + (i + 1) * kExtensionSize)
+      break;
+
+    const unsigned char* extension = prop + kExtensionBase + i * kExtensionSize;
+    unsigned char tag = extension[0];
+    unsigned char revision = extension[1];
+    if (tag != kCEAExtensionTag || revision != kExpectedExtensionRevision)
+      continue;
+
+    unsigned char timing_descriptors_start =
+        std::min(extension[2], static_cast<unsigned char>(kExtensionSize));
+    const unsigned char* data_block = extension + kDataBlockOffset;
+    while (data_block < extension + timing_descriptors_start) {
+      // A data block is encoded as:
+      // - byte 1 high 3 bits: tag. '07' for extended tags.
+      // - byte 1 remaining bits: the length of data block.
+      // - byte 2: the extended tag.  '0' for video capability.
+      // - byte 3: the capability.
+      unsigned char tag = data_block[0] >> 5;
+      unsigned char payload_length = data_block[0] & 0x1f;
+      if (static_cast<unsigned long>(data_block + payload_length - prop) >
+          nitems)
+        break;
+
+      if (tag != kExtendedTag && payload_length < 2) {
+        data_block += payload_length + 1;
+        continue;
+      }
+
+      unsigned char extended_tag_code = data_block[1];
+      if (extended_tag_code != kExtendedVideoCapabilityTag) {
+        data_block += payload_length;
+        continue;
+      }
+
+      // The difference between preferred, IT, and CE video formats
+      // doesn't matter. Sets |flag| to true if any of these flags are true.
+      if ((data_block[2] & (1 << kPTOverscan)) ||
+          (data_block[2] & (1 << kITOverscan)) ||
+          (data_block[2] & (1 << kCEOverscan))) {
+        *flag = true;
+      } else {
+        *flag = false;
+      }
+      return true;
+    }
+  }
+
+  return false;
+}
+
 std::vector<std::string> GetDisplayNames(const std::vector<XID>& output_ids) {
   std::vector<std::string> names;
   for (size_t i = 0; i < output_ids.size(); ++i) {

ui/base/x/x11_util.h

@@ -276,6 +276,29 @@ UI_EXPORT bool GetOutputDeviceData(XID output,
                                    uint32* serial_number,
                                    std::string* human_readable_name);
 
+// Gets the overscan flag from |output| and stores to |flag|. Returns true if
+// the flag is found. Otherwise returns false and doesn't touch |flag|. The
+// output will produce overscan if |flag| is set to true, but the output may
+// still produce overscan even though it returns true and |flag| is set to
+// false.
+UI_EXPORT bool GetOutputOverscanFlag(XID output, bool* flag);
+
+// Parses |prop| as EDID data and stores extracted data into |manufacturer_id|,
+// |serial_number|, and |human_readable_name| and returns true. NULL can be
+// passed for unwanted output parameters. This is exported for
+// x11_util_unittest.cc.
+UI_EXPORT bool ParseOutputDeviceData(const unsigned char* prop,
+                                     unsigned long nitems,
+                                     uint16* manufacturer_id,
+                                     uint32* serial_number,
+                                     std::string* human_readable_name);
+
+// Parses |prop| as EDID data and stores the overscan flag to |flag|. Returns
+// true if the flag is found. This is exported for x11_util_unittest.cc.
+UI_EXPORT bool ParseOutputOverscanFlag(const unsigned char* prop,
+                                       unsigned long nitems,
+                                       bool* flag);
+
 // Gets the names of the all displays physically connected to the system.
 UI_EXPORT std::vector<std::string> GetDisplayNames(
     const std::vector<XID>& output_id);

ui/base/x/x11_util_unittest.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/base/x/x11_util.h"
+
+namespace ui {
+
+namespace {
+
+// Sample EDID data extracted from real devices.
+const unsigned char kNormalDisplay[] =
+    "\x00\xff\xff\xff\xff\xff\xff\x00\x22\xf0\x6c\x28\x01\x01\x01\x01"
+    "\x02\x16\x01\x04\xb5\x40\x28\x78\xe2\x8d\x85\xad\x4f\x35\xb1\x25"
+    "\x0e\x50\x54\x00\x00\x00\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01"
+    "\x01\x01\x01\x01\x01\x01\xe2\x68\x00\xa0\xa0\x40\x2e\x60\x30\x20"
+    "\x36\x00\x81\x90\x21\x00\x00\x1a\xbc\x1b\x00\xa0\x50\x20\x17\x30"
+    "\x30\x20\x36\x00\x81\x90\x21\x00\x00\x1a\x00\x00\x00\xfc\x00\x48"
+    "\x50\x20\x5a\x52\x33\x30\x77\x0a\x20\x20\x20\x20\x00\x00\x00\xff"
+    "\x00\x43\x4e\x34\x32\x30\x32\x31\x33\x37\x51\x0a\x20\x20\x00\x71";
+
+const unsigned char kInternalDisplay[] =
+    "\x00\xff\xff\xff\xff\xff\xff\x00\x4c\xa3\x42\x31\x00\x00\x00\x00"
+    "\x00\x15\x01\x03\x80\x1a\x10\x78\x0a\xd3\xe5\x95\x5c\x60\x90\x27"
+    "\x19\x50\x54\x00\x00\x00\x01\x01\x01\x01\x01\x01\x01\x01\x01\x01"
+    "\x01\x01\x01\x01\x01\x01\x9e\x1b\x00\xa0\x50\x20\x12\x30\x10\x30"
+    "\x13\x00\x05\xa3\x10\x00\x00\x19\x00\x00\x00\x0f\x00\x00\x00\x00"
+    "\x00\x00\x00\x00\x00\x23\x87\x02\x64\x00\x00\x00\x00\xfe\x00\x53"
+    "\x41\x4d\x53\x55\x4e\x47\x0a\x20\x20\x20\x20\x20\x00\x00\x00\xfe"
+    "\x00\x31\x32\x31\x41\x54\x31\x31\x2d\x38\x30\x31\x0a\x20\x00\x45";
+
+const unsigned char kOverscanDisplay[] =
+    "\x00\xff\xff\xff\xff\xff\xff\x00\x4c\x2d\xfe\x08\x00\x00\x00\x00"
+    "\x29\x15\x01\x03\x80\x10\x09\x78\x0a\xee\x91\xa3\x54\x4c\x99\x26"
+    "\x0f\x50\x54\xbd\xef\x80\x71\x4f\x81\xc0\x81\x00\x81\x80\x95\x00"
+    "\xa9\xc0\xb3\x00\x01\x01\x02\x3a\x80\x18\x71\x38\x2d\x40\x58\x2c"
+    "\x45\x00\xa0\x5a\x00\x00\x00\x1e\x66\x21\x56\xaa\x51\x00\x1e\x30"
+    "\x46\x8f\x33\x00\xa0\x5a\x00\x00\x00\x1e\x00\x00\x00\xfd\x00\x18"
+    "\x4b\x0f\x51\x17\x00\x0a\x20\x20\x20\x20\x20\x20\x00\x00\x00\xfc"
+    "\x00\x53\x41\x4d\x53\x55\x4e\x47\x0a\x20\x20\x20\x20\x20\x01\x1d"
+    "\x02\x03\x1f\xf1\x47\x90\x04\x05\x03\x20\x22\x07\x23\x09\x07\x07"
+    "\x83\x01\x00\x00\xe2\x00\x0f\x67\x03\x0c\x00\x20\x00\xb8\x2d\x01"
+    "\x1d\x80\x18\x71\x1c\x16\x20\x58\x2c\x25\x00\xa0\x5a\x00\x00\x00"
+    "\x9e\x01\x1d\x00\x72\x51\xd0\x1e\x20\x6e\x28\x55\x00\xa0\x5a\x00"
+    "\x00\x00\x1e\x8c\x0a\xd0\x8a\x20\xe0\x2d\x10\x10\x3e\x96\x00\xa0"
+    "\x5a\x00\x00\x00\x18\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
+    "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
+    "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xc6";
+
+}
+
+TEST(X11UtilTest, ParseEDID) {
+  uint16 manufacturer_id = 0;
+  uint32 serial_number = 0;
+  std::string human_readable_name;
+  EXPECT_TRUE(ParseOutputDeviceData(
+      kNormalDisplay, arraysize(kNormalDisplay),
+      &manufacturer_id, &serial_number, &human_readable_name));
+  EXPECT_EQ(0x22f0u, manufacturer_id);
+  EXPECT_EQ(0x01010101u, serial_number);
+  EXPECT_EQ("HP ZR30w", human_readable_name);
+
+  manufacturer_id = 0;
+  serial_number = 0;
+  human_readable_name.clear();
+  EXPECT_TRUE(ParseOutputDeviceData(
+      kInternalDisplay, arraysize(kInternalDisplay),
+      &manufacturer_id, &serial_number, NULL));
+  EXPECT_EQ(0x4ca3u, manufacturer_id);
+  EXPECT_EQ(0x00000000u, serial_number);
+  EXPECT_EQ("", human_readable_name);
+
+  // Internal display doesn't have name.
+  EXPECT_FALSE(ParseOutputDeviceData(
+      kInternalDisplay, arraysize(kInternalDisplay),
+      NULL, NULL, &human_readable_name));
+
+  manufacturer_id = 0;
+  serial_number = 0;
+  human_readable_name.clear();
+  EXPECT_TRUE(ParseOutputDeviceData(
+      kOverscanDisplay, arraysize(kOverscanDisplay),
+      &manufacturer_id, &serial_number, &human_readable_name));
+  EXPECT_EQ(0x4c2du, manufacturer_id);
+  EXPECT_EQ(0x00000000u, serial_number);
+  EXPECT_EQ("SAMSUNG", human_readable_name);
+}
+
+TEST(X11UtilTest, ParseBrokenEDID) {
+  uint16 manufacturer_id = 0;
+  uint32 serial_number = 0;
+  std::string human_readable_name;
+
+  // length == 0
+  EXPECT_FALSE(ParseOutputDeviceData(
+      kNormalDisplay, 0,
+      &manufacturer_id, &serial_number, &human_readable_name));
+
+  // name is broken. Copying kNormalDisplay and substitute its name data by
+  // some control code.
+  std::string display_data(
+      reinterpret_cast<const char*>(kNormalDisplay), arraysize(kNormalDisplay));
+
+  // display's name data is embedded in byte 95-107 in this specific example.
+  // Fix here too when the contents of kNormalDisplay is altered.
+  display_data[97] = '\x1b';
+  EXPECT_FALSE(ParseOutputDeviceData(
+      reinterpret_cast<const unsigned char*>(display_data.data()),
+      display_data.size(),
+      &manufacturer_id, &serial_number, &human_readable_name));
+
+  // If |human_readable_name| isn't specified, it skips parsing the name.
+  manufacturer_id = 0;
+  serial_number = 0;
+  EXPECT_TRUE(ParseOutputDeviceData(
+      reinterpret_cast<const unsigned char*>(display_data.data()),
+      display_data.size(),
+      &manufacturer_id, &serial_number, NULL));
+  EXPECT_EQ(0x22f0u, manufacturer_id);
+  EXPECT_EQ(0x01010101u, serial_number);
+}
+
+TEST(X11UtilTest, ParseOverscanFlag) {
+  bool flag = false;
+  EXPECT_FALSE(ParseOutputOverscanFlag(
+      kNormalDisplay, arraysize(kNormalDisplay), &flag));
+
+  flag = false;
+  EXPECT_FALSE(ParseOutputOverscanFlag(
+      kInternalDisplay, arraysize(kInternalDisplay), &flag));
+
+  flag = false;
+  EXPECT_TRUE(ParseOutputOverscanFlag(
+      kOverscanDisplay, arraysize(kOverscanDisplay), &flag));
+  EXPECT_TRUE(flag);
+
+  flag = false;
+  // Copy |kOverscanDisplay| and set flags to false in it. The overscan flags
+  // are embedded at byte 150 in this specific example. Fix here too when the
+  // contents of kOverscanDisplay is altered.
+  std::string display_data(reinterpret_cast<const char*>(kOverscanDisplay),
+                           arraysize(kOverscanDisplay));
+  display_data[150] = '\0';
+  EXPECT_TRUE(ParseOutputOverscanFlag(
+      reinterpret_cast<const unsigned char*>(display_data.data()),
+      display_data.size(), &flag));
+  EXPECT_FALSE(flag);
+}
+
+TEST(X11UtilTest, ParseBrokenOverscanData) {
+  // Do not fill valid data here because it anyway fails to parse the data.
+  scoped_array<unsigned char> data(new unsigned char[126]);
+  bool flag = false;
+  EXPECT_FALSE(ParseOutputOverscanFlag(data.get(), 0, &flag));
+  EXPECT_FALSE(ParseOutputOverscanFlag(data.get(), 126, &flag));
+
+  // extending data because ParseOutputOverscanFlag() will access the data.
+  data.reset(new unsigned char[150]);
+  // The number of CEA extensions is stored at byte 126.
+  data[126] = '\x01';
+  EXPECT_FALSE(ParseOutputOverscanFlag(data.get(), 128, &flag));
+  EXPECT_FALSE(ParseOutputOverscanFlag(data.get(), 150, &flag));
+}
+
+}

ui/ui_unittests.gypi

@@ -188,6 +188,7 @@
         }],
         ['OS == "linux"', {
           'sources': [
+            'base/x/x11_util_unittest.cc',
             'gfx/platform_font_pango_unittest.cc',
           ],
         }],