In the test, the message can be improved; though the exception should never occur
it will be misleading if it does.
    "Changing property user.dir should have no effect on the getCanonicalPath"

It is cleaner to throw AssertionError for the test failure.
Throwing FileSystemException makes it look like it came from inside the file system implementation.

Regards, Roger

On 2/13/2018 6:45 PM, yumin qi wrote:

   In fact, if property "user.dir" is cached, the problem will go away
without any changes to native or UnixFileSystem.java, since it won't
canonicalize the string supplied from user. The output will be
   getProperty("user.dir") + "/" + file. (The result is not as expected,
user can not change the property, means user has to work around the problem
to reach their targeted directory to do things like loading classes)

   Any change to "user.dir" in java program does not have any effect.
   For Windows:

--- a/src/java.base/windows/classes/java/io/WinNTFileSystem.java Fri Feb 02
10:32:59 2018 -0800
+++ b/src/java.base/windows/classes/java/io/WinNTFileSystem.java Tue Feb 13
23:40:21 2018 +0000
@@ -43,12 +43,14 @@
      private final char slash;
      private final char altSlash;
      private final char semicolon;
+    private final String userDir;

      public WinNTFileSystem() {
          Properties props = GetPropertyAction.privilegedGetProperties();
          slash = props.getProperty("file.separator").charAt(0);
          semicolon = props.getProperty("path.separator").charAt(0);
          altSlash = (this.slash == '\\') ? '/' : '\\';
+        userDir = props.getProperty("user.dir");

      private boolean isSlash(char c) {
@@ -347,7 +349,7 @@
      private String getUserPath() {
          /* For both compatibility and security,
             we must look this up every time */
-        return normalize(System.getProperty("user.dir"));
+        return normalize(userDir);

      private String getDrive(String path) {

   Does it need normalize(userDir) in getUserPath()? I think we need here.

   I will update the webrev and send for another round of review: the change
in native will be reverted, and made changes to UnixFileSystem.java.


On Mon, Feb 12, 2018 at 3:09 AM, Alan Bateman <alan.bate...@oracle.com>

On 09/02/2018 18:01, Alan Bateman wrote:


I'll study the patch you have but I think we also need to create issues
to get us to the point where changing this system property in a running VM
doesn't impact running code.

Looking at it again, I think we should change java.io.UnixFileSystem (and
the Windows equivalent) to cache the value of user.dir to avoid difficult
to diagnose issues with bad code changing the value of this property in a
running VM. This should reduce the issue down to cases where user.dir is
changed on the command line (never supported either of course) to a value
that is not "/" but has trailing or duplicate slashes.

When reduced down then the alternatives are to change the native
canonicalize method as you have done or alternatively do it once at
UnixFileSystem initialization time so that canonicalize does not have to
deal with this case. The former would require changing the description of
the function (it currently reads "The input path is assumed to contain no
duplicate slashes"), the latter avoids any changes to the native


diff -r 0937e5f799df src/java.base/unix/classes/jav
--- a/src/java.base/unix/classes/java/io/UnixFileSystem.java    Sat Feb
10 07:06:16 2018 -0500
+++ b/src/java.base/unix/classes/java/io/UnixFileSystem.java    Mon Feb
12 10:49:40 2018 +0000
@@ -34,12 +34,14 @@
      private final char slash;
      private final char colon;
      private final String javaHome;
+    private final String userDir;

      public UnixFileSystem() {
          Properties props = GetPropertyAction.privilegedGetProperties();
          slash = props.getProperty("file.separator").charAt(0);
          colon = props.getProperty("path.separator").charAt(0);
          javaHome = props.getProperty("java.home");
+        userDir = props.getProperty("user.dir");

@@ -128,7 +130,11 @@

      public String resolve(File f) {
          if (isAbsolute(f)) return f.getPath();
-        return resolve(System.getProperty("user.dir"), f.getPath());
+        SecurityManager sm = System.getSecurityManager();
+        if (sm != null) {
+            sm.checkPropertyAccess("user.dir");
+        }
+        return resolve(userDir, f.getPath());

      // Caches for canonicalization results to improve startup performance.

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