Fix subtle issues in opj_skip_from_memory and add unit tests.

core/src/fxcodec/codec/fx_codec_jpx_unittest.cpp

+// Copyright 2014 PDFium 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 <stdint.h>
+
+#include <limits>
+
+#include "codec_int.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "../../../testing/fx_string_testhelpers.h"
+
+static const OPJ_OFF_T kSkipError = static_cast<OPJ_OFF_T>(-1);
+static const OPJ_SIZE_T kReadError = static_cast<OPJ_SIZE_T>(-1);
+static const OPJ_SIZE_T kWriteError = static_cast<OPJ_SIZE_T>(-1);
+
+static unsigned char stream_data[] = {
+    0x00, 0x01, 0x02, 0x03,
+    0x84, 0x85, 0x86, 0x87,  // Include some hi-bytes, too.
+};
+
+TEST(fxcodec, DecodeDataNullDecodeData) {
+    unsigned char buffer[16];
+    DecodeData* ptr = nullptr;
+
+    // Error codes, not segvs, should callers pass us a NULL pointer.
+    EXPECT_EQ(kReadError, opj_read_from_memory(buffer, sizeof(buffer), ptr));
+    EXPECT_EQ(kWriteError, opj_write_from_memory(buffer, sizeof(buffer), ptr));
+    EXPECT_EQ(kSkipError, opj_skip_from_memory(1, ptr));
+    EXPECT_FALSE(opj_seek_from_memory(1, ptr));
+}
+
+TEST(fxcodec, DecodeDataNullStream) {
+    DecodeData dd(nullptr, 0);
+    unsigned char buffer[16];
+
+    // Reads of size 0 do nothing but return an error code.
+    memset(buffer, 0xbd, sizeof(buffer));
+    EXPECT_EQ(kReadError, opj_read_from_memory(buffer, 0, &dd));
+    EXPECT_EQ(0xbd, buffer[0]);
+
+    // Reads of nonzero size do nothing but return an error code.
+    memset(buffer, 0xbd, sizeof(buffer));
+    EXPECT_EQ(kReadError, opj_read_from_memory(buffer, sizeof(buffer), &dd));
+    EXPECT_EQ(0xbd, buffer[0]);
+
+    // writes of size 0 do nothing but return an error code.
+    EXPECT_EQ(kReadError, opj_write_from_memory(buffer, 0, &dd));
+
+    // writes of nonzero size do nothing but return an error code.
+    EXPECT_EQ(kReadError, opj_write_from_memory(buffer, sizeof(buffer), &dd));
+
+    // Skips of size 0 always return an error code.
+    EXPECT_EQ(kReadError, opj_skip_from_memory(0, &dd));
+
+    // Skips of nonzero size 0 always return an error code.
+    EXPECT_EQ(kReadError, opj_skip_from_memory(1, &dd));
+
+    // Seeks to 0 offset return in error.
+    EXPECT_FALSE(opj_seek_from_memory(0, &dd));
+
+    // Seeks to non-zero offsets return in error.
+    EXPECT_FALSE(opj_seek_from_memory(1, &dd));
+}
+
+TEST(fxcodec, DecodeDataReadInBounds) {
+    unsigned char buffer[16];
+    {
+        DecodeData dd(stream_data, sizeof(stream_data));
+
+        // Exact sized read in a single call.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(8u, opj_read_from_memory(buffer, sizeof(buffer), &dd));
+        EXPECT_EQ(0x00, buffer[0]);
+        EXPECT_EQ(0x01, buffer[1]);
+        EXPECT_EQ(0x02, buffer[2]);
+        EXPECT_EQ(0x03, buffer[3]);
+        EXPECT_EQ(0x84, buffer[4]);
+        EXPECT_EQ(0x85, buffer[5]);
+        EXPECT_EQ(0x86, buffer[6]);
+        EXPECT_EQ(0x87, buffer[7]);
+        EXPECT_EQ(0xbd, buffer[8]);
+    }
+    {
+        DecodeData dd(stream_data, sizeof(stream_data));
+
+        // Simple read.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(2u, opj_read_from_memory(buffer, 2, &dd));
+        EXPECT_EQ(0x00, buffer[0]);
+        EXPECT_EQ(0x01, buffer[1]);
+        EXPECT_EQ(0xbd, buffer[2]);
+
+        // Read of size 0 doesn't affect things.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(0u, opj_read_from_memory(buffer, 0, &dd));
+        EXPECT_EQ(0xbd, buffer[0]);
+
+        // Read exactly up to end of data.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(6u, opj_read_from_memory(buffer, 6, &dd));
+        EXPECT_EQ(0x02, buffer[0]);
+        EXPECT_EQ(0x03, buffer[1]);
+        EXPECT_EQ(0x84, buffer[2]);
+        EXPECT_EQ(0x85, buffer[3]);
+        EXPECT_EQ(0x86, buffer[4]);
+        EXPECT_EQ(0x87, buffer[5]);
+        EXPECT_EQ(0xbd, buffer[6]);
+
+        // Read of size 0 at EOF is still an error.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(kReadError, opj_read_from_memory(buffer, 0, &dd));
+        EXPECT_EQ(0xbd, buffer[0]);
+    }
+}
+
+TEST(fxcodec, DecodeDataReadBeyondBounds) {
+    unsigned char buffer[16];
+    {
+        DecodeData dd(stream_data, sizeof(stream_data));
+
+        // Read beyond bounds in a single step.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(8u, opj_read_from_memory(buffer, sizeof(buffer) + 1, &dd));
+        EXPECT_EQ(0x00, buffer[0]);
+        EXPECT_EQ(0x01, buffer[1]);
+        EXPECT_EQ(0x02, buffer[2]);
+        EXPECT_EQ(0x03, buffer[3]);
+        EXPECT_EQ(0x84, buffer[4]);
+        EXPECT_EQ(0x85, buffer[5]);
+        EXPECT_EQ(0x86, buffer[6]);
+        EXPECT_EQ(0x87, buffer[7]);
+        EXPECT_EQ(0xbd, buffer[8]);
+    }
+    {
+        DecodeData dd(stream_data, sizeof(stream_data));
+
+        // Read well beyond bounds in a single step.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(8u, opj_read_from_memory(
+            buffer, std::numeric_limits<OPJ_SIZE_T>::max(), &dd));
+        EXPECT_EQ(0x00, buffer[0]);
+        EXPECT_EQ(0x01, buffer[1]);
+        EXPECT_EQ(0x02, buffer[2]);
+        EXPECT_EQ(0x03, buffer[3]);
+        EXPECT_EQ(0x84, buffer[4]);
+        EXPECT_EQ(0x85, buffer[5]);
+        EXPECT_EQ(0x86, buffer[6]);
+        EXPECT_EQ(0x87, buffer[7]);
+        EXPECT_EQ(0xbd, buffer[8]);
+    }
+    {
+        DecodeData dd(stream_data, sizeof(stream_data));
+
+        // Read of size 6 gets first 6 bytes.
+        // rest of buffer intact.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(6u, opj_read_from_memory(buffer, 6, &dd));
+        EXPECT_EQ(0x00, buffer[0]);
+        EXPECT_EQ(0x01, buffer[1]);
+        EXPECT_EQ(0x02, buffer[2]);
+        EXPECT_EQ(0x03, buffer[3]);
+        EXPECT_EQ(0x84, buffer[4]);
+        EXPECT_EQ(0x85, buffer[5]);
+        EXPECT_EQ(0xbd, buffer[6]);
+
+        // Read of size 6 gets remaining two bytes.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(2u, opj_read_from_memory(buffer, 6, &dd));
+        EXPECT_EQ(0x86, buffer[0]);
+        EXPECT_EQ(0x87, buffer[1]);
+        EXPECT_EQ(0xbd, buffer[2]);
+
+        // Read of 6 more gets nothing and leaves rest of buffer intact.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(kReadError, opj_read_from_memory(buffer, 6, &dd));
+        EXPECT_EQ(0xbd, buffer[0]);
+    }
+}
+
+TEST(fxcodec, DecodeDataWriteInBounds) {
+    unsigned char stream[16];
+    static unsigned char buffer_data[] = {
+        0x00, 0x01, 0x02, 0x03, 0x80,
+        0x80, 0x81, 0x82, 0x83, 0x84,
+    };
+    {
+        // Pretend the stream can only hold 4 bytes.
+        DecodeData dd(stream, 4);
+
+        memset(stream, 0xbd, sizeof(stream));
+        EXPECT_EQ(4u, opj_write_from_memory(buffer_data, 4, &dd));
+        EXPECT_EQ(0x00, stream[0]);
+        EXPECT_EQ(0x01, stream[1]);
+        EXPECT_EQ(0x02, stream[2]);
+        EXPECT_EQ(0x03, stream[3]);
+        EXPECT_EQ(0xbd, stream[4]);
+    }
+    {
+        // Pretend the stream can only hold 4 bytes.
+        DecodeData dd(stream, 4);
+
+        memset(stream, 0xbd, sizeof(stream));
+        EXPECT_EQ(2u, opj_write_from_memory(buffer_data, 2, &dd));
+        EXPECT_EQ(2u, opj_write_from_memory(buffer_data, 2, &dd));
+        EXPECT_EQ(0x00, stream[0]);
+        EXPECT_EQ(0x01, stream[1]);
+        EXPECT_EQ(0x00, stream[2]);
+        EXPECT_EQ(0x01, stream[3]);
+        EXPECT_EQ(0xbd, stream[4]);
+    }
+}
+
+TEST(fxcodec, DecodeDataWriteBeyondBounds) {
+    unsigned char stream[16];
+    static unsigned char buffer_data[] = {
+        0x10, 0x11, 0x12, 0x13,
+        0x94, 0x95, 0x96, 0x97,
+    };
+    {
+        // Pretend the stream can only hold 4 bytes.
+        DecodeData dd(stream, 4);
+
+        // Write ending past EOF transfers up til EOF.
+        memset(stream, 0xbd, sizeof(stream));
+        EXPECT_EQ(4u, opj_write_from_memory(buffer_data, 5, &dd));
+        EXPECT_EQ(0x10, stream[0]);
+        EXPECT_EQ(0x11, stream[1]);
+        EXPECT_EQ(0x12, stream[2]);
+        EXPECT_EQ(0x13, stream[3]);
+        EXPECT_EQ(0xbd, stream[4]);
+
+        // Subsequent writes fail.
+        memset(stream, 0xbd, sizeof(stream));
+        EXPECT_EQ(kWriteError, opj_write_from_memory(buffer_data, 5, &dd));
+        EXPECT_EQ(0xbd, stream[0]);
+    }
+    {
+        // Pretend the stream can only hold 4 bytes.
+        DecodeData dd(stream, 4);
+
+        // Write ending past EOF (two steps) transfers up til EOF.
+        memset(stream, 0xbd, sizeof(stream));
+        EXPECT_EQ(2u, opj_write_from_memory(buffer_data, 2, &dd));
+        EXPECT_EQ(2u, opj_write_from_memory(buffer_data, 4, &dd));
+        EXPECT_EQ(0x10, stream[0]);
+        EXPECT_EQ(0x11, stream[1]);
+        EXPECT_EQ(0x10, stream[2]);
+        EXPECT_EQ(0x11, stream[3]);
+        EXPECT_EQ(0xbd, stream[4]);
+
+        // Subsequent writes fail.
+        memset(stream, 0xbd, sizeof(stream));
+        EXPECT_EQ(kWriteError, opj_write_from_memory(buffer_data, 5, &dd));
+        EXPECT_EQ(0xbd, stream[0]);
+    }
+}
+
+// Note: Some care needs to be taken here because the skip/seek functions
+// take OPJ_OFF_T's as arguments, which are typically a signed type.
+TEST(fxcodec, DecodeDataSkip) {
+    unsigned char buffer[16];
+    {
+        DecodeData dd(stream_data, sizeof(stream_data));
+
+        // Skiping within buffer is allowed.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(1, opj_skip_from_memory(1, &dd));
+        EXPECT_EQ(1u, opj_read_from_memory(buffer, 1, &dd));
+        EXPECT_EQ(0x01, buffer[0]);
+        EXPECT_EQ(0xbd, buffer[1]);
+
+        // Skiping 0 bytes changes nothing.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(0, opj_skip_from_memory(0, &dd));
+        EXPECT_EQ(1u, opj_read_from_memory(buffer, 1, &dd));
+        EXPECT_EQ(0x02, buffer[0]);
+        EXPECT_EQ(0xbd, buffer[1]);
+
+        // Skiping to EOS-1 is possible.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(4, opj_skip_from_memory(4, &dd));
+        EXPECT_EQ(1u, opj_read_from_memory(buffer, 1, &dd));
+        EXPECT_EQ(0x87, buffer[0]);
+        EXPECT_EQ(0xbd, buffer[1]);
+
+        // Next read fails.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(kReadError, opj_read_from_memory(buffer, 1, &dd));
+        EXPECT_EQ(0xbd, buffer[0]);
+    }
+    {
+        DecodeData dd(stream_data, sizeof(stream_data));
+
+        // Skiping directly to EOS is allowed.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(8, opj_skip_from_memory(8, &dd));
+
+        // Next read fails.
+        EXPECT_EQ(kReadError, opj_read_from_memory(buffer, 1, &dd));
+        EXPECT_EQ(0xbd, buffer[0]);
+    }
+    {
+        DecodeData dd(stream_data, sizeof(stream_data));
+
+        // Skipping beyond end of stream is allowed and returns full distance.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(9, opj_skip_from_memory(9, &dd));
+
+        // Next read fails.
+        EXPECT_EQ(kReadError, opj_read_from_memory(buffer, 1, &dd));
+        EXPECT_EQ(0xbd, buffer[0]);
+    }
+    {
+        DecodeData dd(stream_data, sizeof(stream_data));
+
+        // Skipping way beyond EOS is allowd, doesn't wrap, and returns
+        // full distance.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(4, opj_skip_from_memory(4, &dd));
+        EXPECT_EQ(std::numeric_limits<OPJ_OFF_T>::max(), opj_skip_from_memory(
+            std::numeric_limits<OPJ_OFF_T>::max(), &dd));
+
+        // Next read fails. If it succeeds, it may mean we wrapped.
+        EXPECT_EQ(kReadError, opj_read_from_memory(buffer, 1, &dd));
+        EXPECT_EQ(0xbd, buffer[0]);
+    }
+    {
+        DecodeData dd(stream_data, sizeof(stream_data));
+
+        // Negative skip within buffer not is allowed, position unchanged.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(4, opj_skip_from_memory(4, &dd));
+        EXPECT_EQ(kSkipError, opj_skip_from_memory(-2, &dd));
+
+        // Next read succeeds as if nothing has happenned.
+        EXPECT_EQ(1u, opj_read_from_memory(buffer, 1, &dd));
+        EXPECT_EQ(0x84, buffer[0]);
+        EXPECT_EQ(0xbd, buffer[1]);
+
+        // Negative skip before buffer is not allowed, position unchanged.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(kSkipError, opj_skip_from_memory(-4, &dd));
+
+        // Next read succeeds as if nothing has happenned.
+        EXPECT_EQ(1u, opj_read_from_memory(buffer, 1, &dd));
+        EXPECT_EQ(0x85, buffer[0]);
+        EXPECT_EQ(0xbd, buffer[1]);
+    }
+    {
+        DecodeData dd(stream_data, sizeof(stream_data));
+
+        // Negative skip way before buffer is not allowed, doesn't wrap
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(4, opj_skip_from_memory(4, &dd));
+        EXPECT_EQ(kSkipError, opj_skip_from_memory(
+            std::numeric_limits<OPJ_OFF_T>::min(), &dd));
+
+        // Next read succeeds. If it fails, it may mean we wrapped.
+        EXPECT_EQ(1, opj_read_from_memory(buffer, 1, &dd));
+        EXPECT_EQ(0x84, buffer[0]);
+        EXPECT_EQ(0xbd, buffer[1]);
+    }
+    {
+        DecodeData dd(stream_data, sizeof(stream_data));
+
+        // Negative skip after EOS isn't alowed, still EOS.
+        memset(buffer, 0xbd, sizeof(buffer));
+        EXPECT_EQ(8, opj_skip_from_memory(8, &dd));
+        EXPECT_EQ(kSkipError, opj_skip_from_memory(-4, &dd));
+
+        // Next read fails.
+        EXPECT_EQ(kReadError, opj_read_from_memory(buffer, 1, &dd));
+        EXPECT_EQ(0xbd, buffer[0]);
+    }
+
+}
+
+TEST(fxcodec, DecodeDataSeek) {
+    unsigned char buffer[16];
+    DecodeData dd(stream_data, sizeof(stream_data));
+
+    // Seeking within buffer is allowed and read succeeds
+    memset(buffer, 0xbd, sizeof(buffer));
+    EXPECT_TRUE(opj_seek_from_memory(1, &dd));
+    EXPECT_EQ(1u, opj_read_from_memory(buffer, 1, &dd));
+    EXPECT_EQ(0x01, buffer[0]);
+    EXPECT_EQ(0xbd, buffer[1]);
+
+    // Seeking before start returns error leaving position unchanged.
+    memset(buffer, 0xbd, sizeof(buffer));
+    EXPECT_FALSE(opj_seek_from_memory(-1, &dd));
+    EXPECT_EQ(1, opj_read_from_memory(buffer, 1, &dd));
+    EXPECT_EQ(0x02, buffer[0]);
+    EXPECT_EQ(0xbd, buffer[1]);
+
+    // Seeking way before start returns error leaving position unchanged.
+    memset(buffer, 0xbd, sizeof(buffer));
+    EXPECT_FALSE(opj_seek_from_memory(
+        std::numeric_limits<OPJ_OFF_T>::min(), &dd));
+    EXPECT_EQ(1, opj_read_from_memory(buffer, 1, &dd));
+    EXPECT_EQ(0x03, buffer[0]);
+    EXPECT_EQ(0xbd, buffer[1]);
+
+    // Seeking exactly to EOS is allowed but read fails.
+    memset(buffer, 0xbd, sizeof(buffer));
+    EXPECT_TRUE(opj_seek_from_memory(8, &dd));
+    EXPECT_EQ(kReadError, opj_read_from_memory(buffer, 1, &dd));
+    EXPECT_EQ(0xbd, buffer[0]);
+
+    // Seeking back to zero offset is allowed and read succeeds.
+    memset(buffer, 0xbd, sizeof(buffer));
+    EXPECT_TRUE(opj_seek_from_memory(0, &dd));
+    EXPECT_EQ(1u, opj_read_from_memory(buffer, 1, &dd));
+    EXPECT_EQ(0x00, buffer[0]);
+    EXPECT_EQ(0xbd, buffer[1]);
+
+    // Seeking beyond end of stream is allowed but read fails.
+    memset(buffer, 0xbd, sizeof(buffer));
+    EXPECT_TRUE(opj_seek_from_memory(16, &dd));
+    EXPECT_EQ(kReadError, opj_read_from_memory(buffer, 1, &dd));
+    EXPECT_EQ(0xbd, buffer[0]);
+
+    // Seeking within buffer after seek past EOF restores good state.
+    memset(buffer, 0xbd, sizeof(buffer));
+    EXPECT_TRUE(opj_seek_from_memory(4, &dd));
+    EXPECT_EQ(1u, opj_read_from_memory(buffer, 1, &dd));
+    EXPECT_EQ(0x84, buffer[0]);
+    EXPECT_EQ(0xbd, buffer[1]);
+
+    // Seeking way beyond EOS is allowed, doesn't wrap, and read fails.
+    memset(buffer, 0xbd, sizeof(buffer));
+    EXPECT_TRUE(opj_seek_from_memory(
+        std::numeric_limits<OPJ_OFF_T>::max(), &dd));
+    EXPECT_EQ(kReadError, opj_read_from_memory(buffer, 1, &dd));
+    EXPECT_EQ(0xbd, buffer[0]);
+}