1 /*
2 * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package sun.nio.ch;
27
28 import java.io.FileDescriptor;
29 import java.io.IOException;
30 import java.nio.ByteBuffer;
31
32
33 /**
34 * File-descriptor based I/O utilities that are shared by NIO classes.
35 */
36
37 public class IOUtil {
38
39 /**
40 * Max number of iovec structures that readv/writev supports
41 */
42 static final int IOV_MAX;
43
44 private IOUtil() { } // No instantiation
45
46 static int write(FileDescriptor fd, ByteBuffer src, long position,
47 NativeDispatcher nd)
48 throws IOException
49 {
50 if (src instanceof DirectBuffer)
51 return writeFromNativeBuffer(fd, src, position, nd);
52
53 // Substitute a native buffer
54 int pos = src.position();
55 int lim = src.limit();
56 assert (pos <= lim);
57 int rem = (pos <= lim ? lim - pos : 0);
58 ByteBuffer bb = Util.getTemporaryDirectBuffer(rem);
59 try {
60 bb.put(src);
61 bb.flip();
62 // Do not update src until we see how many bytes were written
63 src.position(pos);
64
65 int n = writeFromNativeBuffer(fd, bb, position, nd);
66 if (n > 0) {
67 // now update src
68 src.position(pos + n);
69 }
70 return n;
71 } finally {
72 Util.offerFirstTemporaryDirectBuffer(bb);
73 }
74 }
75
76 private static int writeFromNativeBuffer(FileDescriptor fd, ByteBuffer bb,
77 long position, NativeDispatcher nd)
78 throws IOException
79 {
80 int pos = bb.position();
81 int lim = bb.limit();
82 assert (pos <= lim);
83 int rem = (pos <= lim ? lim - pos : 0);
84
85 int written = 0;
86 if (rem == 0)
87 return 0;
88 if (position != -1) {
89 written = nd.pwrite(fd,
90 ((DirectBuffer)bb).address() + pos,
91 rem, position);
92 } else {
93 written = nd.write(fd, ((DirectBuffer)bb).address() + pos, rem);
94 }
95 if (written > 0)
96 bb.position(pos + written);
97 return written;
98 }
99
100 static long write(FileDescriptor fd, ByteBuffer[] bufs, NativeDispatcher nd)
101 throws IOException
102 {
103 return write(fd, bufs, 0, bufs.length, nd);
104 }
105
106 static long write(FileDescriptor fd, ByteBuffer[] bufs, int offset, int length,
107 NativeDispatcher nd)
108 throws IOException
109 {
110 IOVecWrapper vec = IOVecWrapper.get(length);
111
112 boolean completed = false;
113 int iov_len = 0;
114 try {
115
116 // Iterate over buffers to populate native iovec array.
117 int count = offset + length;
118 int i = offset;
119 while (i < count && iov_len < IOV_MAX) {
120 ByteBuffer buf = bufs[i];
121 int pos = buf.position();
122 int lim = buf.limit();
123 assert (pos <= lim);
124 int rem = (pos <= lim ? lim - pos : 0);
125 if (rem > 0) {
126 vec.setBuffer(iov_len, buf, pos, rem);
127
128 // allocate shadow buffer to ensure I/O is done with direct buffer
129 if (!(buf instanceof DirectBuffer)) {
130 ByteBuffer shadow = Util.getTemporaryDirectBuffer(rem);
131 shadow.put(buf);
132 shadow.flip();
133 vec.setShadow(iov_len, shadow);
134 buf.position(pos); // temporarily restore position in user buffer
135 buf = shadow;
136 pos = shadow.position();
137 }
138
139 vec.putBase(iov_len, ((DirectBuffer)buf).address() + pos);
140 vec.putLen(iov_len, rem);
141 iov_len++;
142 }
143 i++;
144 }
145 if (iov_len == 0)
146 return 0L;
147
148 long bytesWritten = nd.writev(fd, vec.address, iov_len);
149
150 // Notify the buffers how many bytes were taken
151 long left = bytesWritten;
152 for (int j=0; j<iov_len; j++) {
153 if (left > 0) {
154 ByteBuffer buf = vec.getBuffer(j);
155 int pos = vec.getPosition(j);
156 int rem = vec.getRemaining(j);
157 int n = (left > rem) ? rem : (int)left;
158 buf.position(pos + n);
159 left -= n;
160 }
161 // return shadow buffers to buffer pool
162 ByteBuffer shadow = vec.getShadow(j);
163 if (shadow != null)
164 Util.offerLastTemporaryDirectBuffer(shadow);
165 vec.clearRefs(j);
166 }
167
168 completed = true;
169 return bytesWritten;
170
171 } finally {
172 // if an error occurred then clear refs to buffers and return any shadow
173 // buffers to cache
174 if (!completed) {
175 for (int j=0; j<iov_len; j++) {
176 ByteBuffer shadow = vec.getShadow(j);
177 if (shadow != null)
178 Util.offerLastTemporaryDirectBuffer(shadow);
179 vec.clearRefs(j);
180 }
181 }
182 }
183 }
184
185 static int read(FileDescriptor fd, ByteBuffer dst, long position,
186 NativeDispatcher nd)
187 throws IOException
188 {
189 if (dst.isReadOnly())
190 throw new IllegalArgumentException("Read-only buffer");
191 if (dst instanceof DirectBuffer)
192 return readIntoNativeBuffer(fd, dst, position, nd);
193
194 // Substitute a native buffer
195 ByteBuffer bb = Util.getTemporaryDirectBuffer(dst.remaining());
196 try {
197 int n = readIntoNativeBuffer(fd, bb, position, nd);
198 bb.flip();
199 if (n > 0)
200 dst.put(bb);
201 return n;
202 } finally {
203 Util.offerFirstTemporaryDirectBuffer(bb);
204 }
205 }
206
207 private static int readIntoNativeBuffer(FileDescriptor fd, ByteBuffer bb,
208 long position, NativeDispatcher nd)
209 throws IOException
210 {
211 int pos = bb.position();
212 int lim = bb.limit();
213 assert (pos <= lim);
214 int rem = (pos <= lim ? lim - pos : 0);
215
216 if (rem == 0)
217 return 0;
218 int n = 0;
219 if (position != -1) {
220 n = nd.pread(fd, ((DirectBuffer)bb).address() + pos,
221 rem, position);
222 } else {
223 n = nd.read(fd, ((DirectBuffer)bb).address() + pos, rem);
224 }
225 if (n > 0)
226 bb.position(pos + n);
227 return n;
228 }
229
230 static long read(FileDescriptor fd, ByteBuffer[] bufs, NativeDispatcher nd)
231 throws IOException
232 {
233 return read(fd, bufs, 0, bufs.length, nd);
234 }
235
236 static long read(FileDescriptor fd, ByteBuffer[] bufs, int offset, int length,
237 NativeDispatcher nd)
238 throws IOException
239 {
240 IOVecWrapper vec = IOVecWrapper.get(length);
241
242 boolean completed = false;
243 int iov_len = 0;
244 try {
245
246 // Iterate over buffers to populate native iovec array.
247 int count = offset + length;
248 int i = offset;
249 while (i < count && iov_len < IOV_MAX) {
250 ByteBuffer buf = bufs[i];
251 if (buf.isReadOnly())
252 throw new IllegalArgumentException("Read-only buffer");
253 int pos = buf.position();
254 int lim = buf.limit();
255 assert (pos <= lim);
256 int rem = (pos <= lim ? lim - pos : 0);
257
258 if (rem > 0) {
259 vec.setBuffer(iov_len, buf, pos, rem);
260
261 // allocate shadow buffer to ensure I/O is done with direct buffer
262 if (!(buf instanceof DirectBuffer)) {
263 ByteBuffer shadow = Util.getTemporaryDirectBuffer(rem);
264 vec.setShadow(iov_len, shadow);
265 buf = shadow;
266 pos = shadow.position();
267 }
268
269 vec.putBase(iov_len, ((DirectBuffer)buf).address() + pos);
270 vec.putLen(iov_len, rem);
271 iov_len++;
272 }
273 i++;
274 }
275 if (iov_len == 0)
276 return 0L;
277
278 long bytesRead = nd.readv(fd, vec.address, iov_len);
279
280 // Notify the buffers how many bytes were read
281 long left = bytesRead;
282 for (int j=0; j<iov_len; j++) {
283 ByteBuffer shadow = vec.getShadow(j);
284 if (left > 0) {
285 ByteBuffer buf = vec.getBuffer(j);
286 int rem = vec.getRemaining(j);
287 int n = (left > rem) ? rem : (int)left;
288 if (shadow == null) {
289 int pos = vec.getPosition(j);
290 buf.position(pos + n);
291 } else {
292 shadow.limit(shadow.position() + n);
293 buf.put(shadow);
294 }
295 left -= n;
296 }
297 if (shadow != null)
298 Util.offerLastTemporaryDirectBuffer(shadow);
299 vec.clearRefs(j);
300 }
301
302 completed = true;
303 return bytesRead;
304
305 } finally {
306 // if an error occurred then clear refs to buffers and return any shadow
307 // buffers to cache
308 if (!completed) {
309 for (int j=0; j<iov_len; j++) {
310 ByteBuffer shadow = vec.getShadow(j);
311 if (shadow != null)
312 Util.offerLastTemporaryDirectBuffer(shadow);
313 vec.clearRefs(j);
314 }
315 }
316 }
317 }
318
319 public static FileDescriptor newFD(int i) {
320 FileDescriptor fd = new FileDescriptor();
321 setfdVal(fd, i);
322 return fd;
323 }
324
325 static native boolean randomBytes(byte[] someBytes);
326
327 /**
328 * Returns two file descriptors for a pipe encoded in a long.
329 * The read end of the pipe is returned in the high 32 bits,
330 * while the write end is returned in the low 32 bits.
331 */
332 static native long makePipe(boolean blocking);
333
334 static native boolean drain(int fd) throws IOException;
335
336 public static native void configureBlocking(FileDescriptor fd,
337 boolean blocking)
338 throws IOException;
339
340 public static native int fdVal(FileDescriptor fd);
341
342 static native void setfdVal(FileDescriptor fd, int value);
343
344 static native int fdLimit();
345
346 static native int iovMax();
347
348 static native void initIDs();
349
350 /**
351 * Used to trigger loading of native libraries
352 */
353 public static void load() { }
354
355 static {
356 java.security.AccessController.doPrivileged(
357 new java.security.PrivilegedAction<Void>() {
358 public Void run() {
359 System.loadLibrary("net");
360 System.loadLibrary("nio");
361 return null;
362 }
363 });
364
365 initIDs();
366
367 IOV_MAX = iovMax();
368 }
369
370 }