Reads in at most one less than buf.length characters from this and stores them into the
buffer pointed to by buf.
Reading stops after an EOS or newline ('\n'). If a newline is read, it is stored into the buffer. A '\0' is stored after the last character in the buffer.
| this |
stream |
| buf |
line buffer |
| max |
max length of a line |
|
the number of characters read into |