1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "ui/surface/transport_dib.h"
6
7// Desktop GTK Linux builds use the old-style SYSV SHM based DIBs.
8
9#include <errno.h>
10#include <stdlib.h>
11#include <sys/ipc.h>
12#include <sys/shm.h>
13
14#include "base/logging.h"
15#include "base/memory/scoped_ptr.h"
16#include "skia/ext/platform_canvas.h"
17#include "ui/base/x/x11_util.h"
18#include "ui/gfx/size.h"
19
20// The shmat system call uses this as it's invalid return address
21static void *const kInvalidAddress = (void*) -1;
22
23TransportDIB::TransportDIB()
24    : address_(kInvalidAddress),
25      x_shm_(0),
26      display_(NULL),
27      inflight_counter_(0),
28      detached_(false),
29      size_(0) {
30}
31
32TransportDIB::~TransportDIB() {
33  if (address_ != kInvalidAddress) {
34    shmdt(address_);
35    address_ = kInvalidAddress;
36  }
37
38  if (x_shm_) {
39    DCHECK(display_);
40    ui::DetachSharedMemory(display_, x_shm_);
41  }
42}
43
44// static
45TransportDIB* TransportDIB::Create(size_t size, uint32 sequence_num) {
46  const int shmkey = shmget(IPC_PRIVATE, size, 0600);
47  if (shmkey == -1) {
48    DLOG(ERROR) << "Failed to create SysV shared memory region"
49                << " errno:" << errno;
50    return NULL;
51  } else {
52    VLOG(1) << "Created SysV shared memory region " << shmkey;
53  }
54
55  void* address = shmat(shmkey, NULL /* desired address */, 0 /* flags */);
56  // Here we mark the shared memory for deletion. Since we attached it in the
57  // line above, it doesn't actually get deleted but, if we crash, this means
58  // that the kernel will automatically clean it up for us.
59  shmctl(shmkey, IPC_RMID, 0);
60  if (address == kInvalidAddress)
61    return NULL;
62
63  TransportDIB* dib = new TransportDIB;
64
65  dib->key_.shmkey = shmkey;
66  dib->address_ = address;
67  dib->size_ = size;
68  return dib;
69}
70
71// static
72TransportDIB* TransportDIB::Map(Handle handle) {
73  scoped_ptr<TransportDIB> dib(CreateWithHandle(handle));
74  if (!dib->Map())
75    return NULL;
76  return dib.release();
77}
78
79// static
80TransportDIB* TransportDIB::CreateWithHandle(Handle shmkey) {
81  TransportDIB* dib = new TransportDIB;
82  dib->key_.shmkey = shmkey;
83  return dib;
84}
85
86// static
87bool TransportDIB::is_valid_handle(Handle dib) {
88  return dib >= 0;
89}
90
91// static
92bool TransportDIB::is_valid_id(Id id) {
93  return id.shmkey != -1;
94}
95
96skia::PlatformCanvas* TransportDIB::GetPlatformCanvas(int w, int h) {
97  if ((address_ == kInvalidAddress && !Map()) || !VerifyCanvasSize(w, h))
98    return NULL;
99  return skia::CreatePlatformCanvas(w, h, true,
100                                    reinterpret_cast<uint8_t*>(memory()),
101                                    skia::RETURN_NULL_ON_FAILURE);
102}
103
104bool TransportDIB::Map() {
105  if (!is_valid_id(key_))
106    return false;
107  if (address_ != kInvalidAddress)
108    return true;
109
110  struct shmid_ds shmst;
111  if (shmctl(key_.shmkey, IPC_STAT, &shmst) == -1)
112    return false;
113
114  void* address = shmat(key_.shmkey, NULL /* desired address */, 0 /* flags */);
115  if (address == kInvalidAddress)
116    return false;
117
118  address_ = address;
119  size_ = shmst.shm_segsz;
120  return true;
121}
122
123void* TransportDIB::memory() const {
124  DCHECK_NE(address_, kInvalidAddress);
125  return address_;
126}
127
128TransportDIB::Id TransportDIB::id() const {
129  return key_;
130}
131
132TransportDIB::Handle TransportDIB::handle() const {
133  return key_.shmkey;
134}
135
136XID TransportDIB::MapToX(XDisplay* display) {
137  if (!x_shm_) {
138    x_shm_ = ui::AttachSharedMemory(display, key_.shmkey);
139    display_ = display;
140  }
141
142  return x_shm_;
143}
144
145void TransportDIB::DecreaseInFlightCounter() {
146  CHECK(inflight_counter_);
147  inflight_counter_--;
148  if (!inflight_counter_ && detached_)
149    delete this;
150}
151
152void TransportDIB::Detach() {
153  CHECK(!detached_);
154  detached_ = true;
155  if (!inflight_counter_)
156    delete this;
157}
158
159