/**
* Check to see if a stream still has data.
*
* @return True if data can be read from the stream, false otherwise.
*
* @remarks TTY devices require special handling. But, if stdin is opened
* through a pipe, it won't be marked as a TTY, so we need to check for
* that also.
*/
bool SysFile::hasData()
{
// not available for reads? Can't have data
if (!readable)
{
return false;
}
if (isTTY || (isStdIn() && !hasBufferedInput()))
{
int bytesWaiting;
ioctl(fileHandle, FIONREAD, &bytesWaiting);
if (bytesWaiting)
{
return true;
}
else
{
return false;
}
}
// we might have something buffered, but also check the
// actual stream.
return !atEof();
}
/* PycBuffer */
int PycBuffer::getByte()
{
if (atEof())
return EOF;
int ch = (int)(*(m_buffer + m_pos));
++m_pos;
return ch & 0xFF; // Make sure it's just a byte!
}
bool SysFile::seekForwardLines(int64_t startPosition, int64_t &lineCount, int64_t &endPosition)
{
// make sure we flush any output data
flush();
// get a buffer for searching
char *mybuffer = (char *)malloc(LINE_POSITIONING_BUFFER);
if (mybuffer == NULL)
{
errInfo = ENOMEM;
return false;
}
for (;;)
{
int readLength = LINE_POSITIONING_BUFFER;
// This is likely due to hitting the end-of-file. We'll just
// return our current count and indicate this worked.
if (!setPosition(startPosition, startPosition))
{
free(mybuffer);
// set the return position and get outta here
endPosition = startPosition;
return true;
}
size_t bytesRead;
if (!read(mybuffer, readLength, bytesRead))
{
free(mybuffer);
// if we've hit an eof condition, this is the end
if (atEof())
{
// set the return position and get outta here
endPosition = startPosition;
return true;
}
// read error,
return false;
}
// have we hit the eof?
if (bytesRead == 0)
{
free(mybuffer);
// set the return position and get outta here
endPosition = startPosition;
return true;
}
size_t offset = 0;
while (offset < bytesRead)
{
// we're only interested in \n character, since this will
// mark the transition point between lines.
if (mybuffer[offset] == '\n')
{
// reduce the line count by one.
lineCount--;
// reached the requested point?
if (lineCount == 0)
{
// set the return position and get outta here
endPosition = startPosition + offset + 1;
free(mybuffer);
return true;
}
}
// step to the next character;
offset++;
}
// move the start position...if at the end, we might not
// get a full buffer
startPosition += bytesRead;
}
}
