util: CBufferedFile fixes
This commit is contained in:
Larry Ruane
parent
1985c4efda
commit
efd2474d17
2 changed files with 257 additions and 11 deletions
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@ -735,16 +735,17 @@ protected:
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size_t nBytes = fread((void*)&vchBuf[pos], 1, readNow, src);
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if (nBytes == 0) {
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throw std::ios_base::failure(feof(src) ? "CBufferedFile::Fill: end of file" : "CBufferedFile::Fill: fread failed");
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} else {
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nSrcPos += nBytes;
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return true;
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}
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nSrcPos += nBytes;
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return true;
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}
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public:
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CBufferedFile(FILE *fileIn, uint64_t nBufSize, uint64_t nRewindIn, int nTypeIn, int nVersionIn) :
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nType(nTypeIn), nVersion(nVersionIn), nSrcPos(0), nReadPos(0), nReadLimit(std::numeric_limits<uint64_t>::max()), nRewind(nRewindIn), vchBuf(nBufSize, 0)
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{
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if (nRewindIn >= nBufSize)
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throw std::ios_base::failure("Rewind limit must be less than buffer size");
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src = fileIn;
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}
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@ -777,8 +778,6 @@ public:
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void read(char *pch, size_t nSize) {
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if (nSize + nReadPos > nReadLimit)
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throw std::ios_base::failure("Read attempted past buffer limit");
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if (nSize + nRewind > vchBuf.size())
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throw std::ios_base::failure("Read larger than buffer size");
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while (nSize > 0) {
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if (nReadPos == nSrcPos)
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Fill();
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@ -802,16 +801,19 @@ public:
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//! rewind to a given reading position
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bool SetPos(uint64_t nPos) {
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nReadPos = nPos;
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if (nReadPos + nRewind < nSrcPos) {
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nReadPos = nSrcPos - nRewind;
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size_t bufsize = vchBuf.size();
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if (nPos + bufsize < nSrcPos) {
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// rewinding too far, rewind as far as possible
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nReadPos = nSrcPos - bufsize;
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return false;
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} else if (nReadPos > nSrcPos) {
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}
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if (nPos > nSrcPos) {
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// can't go this far forward, go as far as possible
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nReadPos = nSrcPos;
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return false;
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} else {
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return true;
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}
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nReadPos = nPos;
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return true;
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}
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bool Seek(uint64_t nPos) {
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@ -2,6 +2,7 @@
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include <random.h>
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#include <streams.h>
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#include <test/setup_common.h>
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@ -202,4 +203,247 @@ BOOST_AUTO_TEST_CASE(streams_serializedata_xor)
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std::string(ds.begin(), ds.end()));
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}
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BOOST_AUTO_TEST_CASE(streams_buffered_file)
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{
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FILE* file = fsbridge::fopen("streams_test_tmp", "w+b");
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// The value at each offset is the offset.
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for (uint8_t j = 0; j < 40; ++j) {
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fwrite(&j, 1, 1, file);
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}
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rewind(file);
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// The buffer size (second arg) must be greater than the rewind
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// amount (third arg).
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try {
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CBufferedFile bfbad(file, 25, 25, 222, 333);
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BOOST_CHECK(false);
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} catch (const std::exception& e) {
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BOOST_CHECK(strstr(e.what(),
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"Rewind limit must be less than buffer size") != nullptr);
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}
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// The buffer is 25 bytes, allow rewinding 10 bytes.
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CBufferedFile bf(file, 25, 10, 222, 333);
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BOOST_CHECK(!bf.eof());
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// These two members have no functional effect.
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BOOST_CHECK_EQUAL(bf.GetType(), 222);
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BOOST_CHECK_EQUAL(bf.GetVersion(), 333);
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uint8_t i;
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bf >> i;
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BOOST_CHECK_EQUAL(i, 0);
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bf >> i;
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BOOST_CHECK_EQUAL(i, 1);
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// After reading bytes 0 and 1, we're positioned at 2.
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BOOST_CHECK_EQUAL(bf.GetPos(), 2);
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// Rewind to offset 0, ok (within the 10 byte window).
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BOOST_CHECK(bf.SetPos(0));
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bf >> i;
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BOOST_CHECK_EQUAL(i, 0);
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// We can go forward to where we've been, but beyond may fail.
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BOOST_CHECK(bf.SetPos(2));
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bf >> i;
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BOOST_CHECK_EQUAL(i, 2);
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// If you know the maximum number of bytes that should be
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// read to deserialize the variable, you can limit the read
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// extent. The current file offset is 3, so the following
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// SetLimit() allows zero bytes to be read.
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BOOST_CHECK(bf.SetLimit(3));
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try {
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bf >> i;
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BOOST_CHECK(false);
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} catch (const std::exception& e) {
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BOOST_CHECK(strstr(e.what(),
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"Read attempted past buffer limit") != nullptr);
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}
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// The default argument removes the limit completely.
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BOOST_CHECK(bf.SetLimit());
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// The read position should still be at 3 (no change).
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BOOST_CHECK_EQUAL(bf.GetPos(), 3);
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// Read from current offset, 3, forward until position 10.
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for (uint8_t j = 3; j < 10; ++j) {
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bf >> i;
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BOOST_CHECK_EQUAL(i, j);
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}
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BOOST_CHECK_EQUAL(bf.GetPos(), 10);
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// We're guaranteed (just barely) to be able to rewind to zero.
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BOOST_CHECK(bf.SetPos(0));
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BOOST_CHECK_EQUAL(bf.GetPos(), 0);
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bf >> i;
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BOOST_CHECK_EQUAL(i, 0);
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// We can set the position forward again up to the farthest
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// into the stream we've been, but no farther. (Attempting
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// to go farther may succeed, but it's not guaranteed.)
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BOOST_CHECK(bf.SetPos(10));
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bf >> i;
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BOOST_CHECK_EQUAL(i, 10);
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BOOST_CHECK_EQUAL(bf.GetPos(), 11);
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// Now it's only guaranteed that we can rewind to offset 1
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// (current read position, 11, minus rewind amount, 10).
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BOOST_CHECK(bf.SetPos(1));
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BOOST_CHECK_EQUAL(bf.GetPos(), 1);
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bf >> i;
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BOOST_CHECK_EQUAL(i, 1);
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// We can stream into large variables, even larger than
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// the buffer size.
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BOOST_CHECK(bf.SetPos(11));
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{
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uint8_t a[40 - 11];
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bf >> a;
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for (uint8_t j = 0; j < sizeof(a); ++j) {
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BOOST_CHECK_EQUAL(a[j], 11 + j);
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}
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}
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BOOST_CHECK_EQUAL(bf.GetPos(), 40);
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// We've read the entire file, the next read should throw.
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try {
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bf >> i;
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BOOST_CHECK(false);
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} catch (const std::exception& e) {
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BOOST_CHECK(strstr(e.what(),
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"CBufferedFile::Fill: end of file") != nullptr);
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}
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// Attempting to read beyond the end sets the EOF indicator.
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BOOST_CHECK(bf.eof());
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// Still at offset 40, we can go back 10, to 30.
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BOOST_CHECK_EQUAL(bf.GetPos(), 40);
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BOOST_CHECK(bf.SetPos(30));
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bf >> i;
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BOOST_CHECK_EQUAL(i, 30);
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BOOST_CHECK_EQUAL(bf.GetPos(), 31);
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// We're too far to rewind to position zero.
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BOOST_CHECK(!bf.SetPos(0));
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// But we should now be positioned at least as far back as allowed
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// by the rewind window (relative to our farthest read position, 40).
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BOOST_CHECK(bf.GetPos() <= 30);
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// We can explicitly close the file, or the destructor will do it.
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bf.fclose();
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fs::remove("streams_test_tmp");
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}
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BOOST_AUTO_TEST_CASE(streams_buffered_file_rand)
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{
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// Make this test deterministic.
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SeedInsecureRand(true);
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for (int rep = 0; rep < 50; ++rep) {
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FILE* file = fsbridge::fopen("streams_test_tmp", "w+b");
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size_t fileSize = InsecureRandRange(256);
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for (uint8_t i = 0; i < fileSize; ++i) {
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fwrite(&i, 1, 1, file);
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}
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rewind(file);
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size_t bufSize = InsecureRandRange(300) + 1;
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size_t rewindSize = InsecureRandRange(bufSize);
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CBufferedFile bf(file, bufSize, rewindSize, 222, 333);
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size_t currentPos = 0;
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size_t maxPos = 0;
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for (int step = 0; step < 100; ++step) {
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if (currentPos >= fileSize)
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break;
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// We haven't read to the end of the file yet.
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BOOST_CHECK(!bf.eof());
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BOOST_CHECK_EQUAL(bf.GetPos(), currentPos);
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// Pretend the file consists of a series of objects of varying
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// sizes; the boundaries of the objects can interact arbitrarily
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// with the CBufferFile's internal buffer. These first three
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// cases simulate objects of various sizes (1, 2, 5 bytes).
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switch (InsecureRandRange(5)) {
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case 0: {
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uint8_t a[1];
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if (currentPos + 1 > fileSize)
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continue;
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bf.SetLimit(currentPos + 1);
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bf >> a;
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for (uint8_t i = 0; i < 1; ++i) {
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BOOST_CHECK_EQUAL(a[i], currentPos);
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currentPos++;
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}
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break;
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}
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case 1: {
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uint8_t a[2];
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if (currentPos + 2 > fileSize)
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continue;
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bf.SetLimit(currentPos + 2);
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bf >> a;
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for (uint8_t i = 0; i < 2; ++i) {
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BOOST_CHECK_EQUAL(a[i], currentPos);
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currentPos++;
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}
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break;
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}
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case 2: {
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uint8_t a[5];
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if (currentPos + 5 > fileSize)
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continue;
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bf.SetLimit(currentPos + 5);
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bf >> a;
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for (uint8_t i = 0; i < 5; ++i) {
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BOOST_CHECK_EQUAL(a[i], currentPos);
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currentPos++;
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}
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break;
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}
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case 3: {
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// Find a byte value (that is at or ahead of the current position).
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size_t find = currentPos + InsecureRandRange(8);
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if (find >= fileSize)
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find = fileSize - 1;
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bf.FindByte(static_cast<char>(find));
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// The value at each offset is the offset.
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BOOST_CHECK_EQUAL(bf.GetPos(), find);
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currentPos = find;
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bf.SetLimit(currentPos + 1);
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uint8_t i;
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bf >> i;
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BOOST_CHECK_EQUAL(i, currentPos);
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currentPos++;
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break;
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}
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case 4: {
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size_t requestPos = InsecureRandRange(maxPos + 4);
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bool okay = bf.SetPos(requestPos);
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// The new position may differ from the requested position
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// because we may not be able to rewind beyond the rewind
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// window, and we may not be able to move forward beyond the
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// farthest position we've reached so far.
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currentPos = bf.GetPos();
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BOOST_CHECK_EQUAL(okay, currentPos == requestPos);
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// Check that we can position within the rewind window.
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if (requestPos <= maxPos &&
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maxPos > rewindSize &&
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requestPos >= maxPos - rewindSize) {
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// We requested a position within the rewind window.
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BOOST_CHECK(okay);
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}
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break;
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}
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}
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if (maxPos < currentPos)
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maxPos = currentPos;
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}
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}
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fs::remove("streams_test_tmp");
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}
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BOOST_AUTO_TEST_SUITE_END()
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