[Bug libgcj/12350] New: StringBuffer.substring handles shared flag incorrected.

[Bug libgcj/12350] New: StringBuffer.substring handles shared flag incorrected.

[suckfish at ihug dot co dot nz]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12350

           Summary: StringBuffer.substring handles shared flag incorrected.
           Product: gcc
           Version: 3.4
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: libgcj
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: suckfish at ihug dot co dot nz
                CC: gcc-bugs at gcc dot gnu dot org

The substring method of java.lang.StringBuffer can clear the boolean shared
field of the object.  This is incorrect.  The value may be shared for some
reason other than the current call to substring.

Test case and patch inline below.

-----------------test case------------------
public class test
{
    static public void main (String[] ignored) throws Throwable
    {
	StringBuffer b = new StringBuffer ("Good string.  More than 16 chars.");

	// Should cause sharing.
	String s = b.toString();

	// Take a char by char unshared copy of s.
	String t = new String (s.toCharArray());

	b.substring (0, 4);	// BUG: Clears shared flag.
	b.replace (0, 4, "Bad "); // Modifies shared data.

	System.out.println (s);
	assert s.equals (t);
    }

}
-------------------patch---------------------
Index: libjava/java/lang/StringBuffer.java
===================================================================
RCS file: /cvsroot/gcc/gcc/libjava/java/lang/StringBuffer.java,v
retrieving revision 1.15
diff -u -r1.15 StringBuffer.java
--- libjava/java/lang/StringBuffer.java 24 Mar 2003 00:50:18 -0000      1.15
+++ libjava/java/lang/StringBuffer.java 21 Sep 2003 08:53:19 -0000
@@ -565,7 +565,9 @@
     if (len == 0)
       return "";
     // Share the char[] unless 3/4 empty.
-    shared = (len << 2) >= value.length;
+    boolean shared = (len << 2) >= value.length;
+    if (shared)
+      this.shared = true;
     // Package constructor avoids an array copy.
     return new String(value, beginIndex, len, shared);
   }

[Bug libgcj/12350] StringBuffer.substring handles shared flag incorrected.

[suckfish at ihug dot co dot nz]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12350



------- Additional Comments From suckfish at ihug dot co dot nz  2003-09-21 09:14 -------
http://gcc.gnu.org/ml/java-patches/2003-q3/msg00741.html

[Bug libgcj/12350] StringBuffer.substring handles shared flag incorrected.

[cvs-commit at gcc dot gnu dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12350



------- Additional Comments From cvs-commit at gcc dot gnu dot org  2003-09-22 08:17 -------
Subject: Bug 12350

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	bryce@gcc.gnu.org	2003-09-22 08:17:49

Modified files:
	libjava        : ChangeLog 
	libjava/java/lang: StringBuffer.java 
	libjava/testsuite: ChangeLog 
Added files:
	libjava/testsuite/libjava.lang: PR12350.java PR12350.out 

Log message:
	2003-09-21  Ralph Loader  <suckfish@ihug.co.nz>
	
	PR java/12350:
	* java/lang/StringBuffer.java (substring): Fix handling of shared
	flag.
	
	2003-09-21  Ralph Loader  <suckfish@ihug.co.nz>
	
	PR java/12350
	* libjava.lang/PR12350.java: New file.
	* libjava.lang/PR12350.out: New file.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/libjava/ChangeLog.diff?cvsroot=gcc&r1=1.2167&r2=1.2168
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/libjava/java/lang/StringBuffer.java.diff?cvsroot=gcc&r1=1.15&r2=1.16
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/libjava/testsuite/ChangeLog.diff?cvsroot=gcc&r1=1.291&r2=1.292
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/libjava/testsuite/libjava.lang/PR12350.java.diff?cvsroot=gcc&r1=NONE&r2=1.1
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/libjava/testsuite/libjava.lang/PR12350.out.diff?cvsroot=gcc&r1=NONE&r2=1.1

[Bug libgcj/12350] StringBuffer.substring handles shared flag incorrected.

[bryce at mckinlay dot net dot nz]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12350


bryce at mckinlay dot net dot nz changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |FIXED


------- Additional Comments From bryce at mckinlay dot net dot nz  2003-09-22 08:21 -------
Fix checked in.

[Bug libgcj/12350] StringBuffer.substring handles shared flag incorrected.

[pinskia at gcc dot gnu dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12350


pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |3.4