Kyle Cho (JIRA) wrote:
[ https://issues.apache.org/jira/browse/HARMONY-6216?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12721474#action_12721474 ]
Kyle Cho commented on HARMONY-6216:
-----------------------------------
found that the patch breaks the following test case.
public static void main(String args[])
{
BufferedReader reader = new BufferedReader(new
InputStreamReader(System.in));
String line = null;
try {
line = reader.readLine();
} catch (IOException e) {
e.printStackTrace();
}
System.out.println(line);
}
problem with reading zero-length file
-------------------------------------
Key: HARMONY-6216
URL: https://issues.apache.org/jira/browse/HARMONY-6216
Project: Harmony
Issue Type: Bug
Components: Classlib
Affects Versions: 5.0M10
Environment: RedHat EL 5 x86
Reporter: Kyle Cho
Priority: Minor
Attachments: HARMONY-6216.diff
The following test fails:
----------------------- proc.java starts ------------------
import java.io.*;
class proc {
public static void main(String args[])
{
String s0 = "cpu";
String s = null;
String file= "/proc/cpuinfo"; // zero-length special file
try {
BufferedReader br = new BufferedReader(new
FileReader(new File(file)));
do {
if ((s = br.readLine()) == null) {
break;
}
System.out.println("s: "+s);
} while (s.indexOf(s0) == -1);
} catch (IOException ioe) {
ioe.printStackTrace();
}
System.out.println("s: "+s);
}
}
----------------------- proc.java ends -------------------
java.io.IOException
at
org.apache.harmony.luni.platform.OSFileSystem.seek(OSFileSystem.java:110)
at java.io.FileInputStream.available(FileInputStream.java:149)
at java.io.InputStreamReader.read(InputStreamReader.java:249)
at java.io.BufferedReader.fillbuf(BufferedReader.java:107)
at java.io.BufferedReader.readLine(BufferedReader.java:318)
at proc.main(proc.java:11)
s: null
Hi gays,
I have investigated this issue for a while, but can't find a good way to resolve
it :(
It is started by Harmony can't read zero-length special file in Linux, like file
/proc/cpuinfo. Harmony InputStreamReader used available() before reading chars:
if ((in.available() == 0) && (out.position() > offset)) {
// we could return the result without blocking read
break;
}
but available() can't work with zero-length special file, throws IOException (so
do RI). So I removed the whole "if" statement, it break read from stdin, I
realized that the "if" is just for stdin.
For stdin, read will return immediately once has read some bytes, don't need to
try to fill the given buffer full. But for FileInputStream, read operation will
try its best to fill the buffer. That's different.
I have no idea how to combine these two behaviors in one read methods without
using available(). Anyone have ideas or suggestions?
--
Best Regards,
Regis.
