Fix file:write CREATE_NEW temp-file path resolution on Windows [Issue #5016]

[ravindu25]

Summary

• Public issue: WSO2MI-4.4.0 with File Connector v6.0.2 file write operation is not working in Windows environment wso2/product-integrator-mi#4907
• Symptom: file:write in CREATE_NEW mode fails 100% of the time on Windows with FileSystemException: Could not find file with URI "/wso2/mi/LocalEntry/out/fileName.csv.tmp" because it is a relative path, and no base URI was provided.

Root Cause

In WriteFile.java lines 448–449 (CREATE_NEW branch), the temp file was constructed by string-concatenating targetFile.getParent().getName().getPath() + "/" + basename + ".tmp" and passing that string to fileSystemHandlerConnection.resolveFileWithSuspension(String).

FileName.getPath() in Commons VFS intentionally returns only the path component relative to the rootFile — on Windows, the drive letter (C:) is part of the rootFile and is not included in getPath(). The concatenated string therefore has no URI scheme and no drive letter (e.g. /wso2/mi/LocalEntry/out/fileName.csv.tmp), which matches the URI in the customer's stack trace exactly. DefaultFileSystemManager.resolveFile(String) cannot find a provider for a scheme-less string with no drive letter and throws the documented exception.

The same string-concatenation pattern accidentally "works" on Linux because the resulting bare absolute path under / happens to look valid to VFS — but it silently resolves to the wrong filesystem location (a latent data-loss bug).

Fix

Replace the manual string concatenation with the standard VFS parent-relative resolve idiom:

// Before (buggy):
try (FileObject tempFile = fileSystemHandlerConnection.resolveFileWithSuspension(
        targetFile.getParent().getName().getPath() + Const.FILE_SEPARATOR
                + targetFile.getName().getBaseName() + ".tmp")) {

// After (fixed):
try (FileObject tempFile = targetFile.getParent().resolveFile(
        targetFile.getName().getBaseName() + ".tmp")) {

FileObject.resolveFile(String) resolves the child name against the parent FileObject, which already carries the scheme and rootFile (drive letter or UNC share). This restores the behavior of v4.0.28 (fsManager.resolveFile(parent, basename + ".tmp")), which worked correctly on Windows.

No new imports. No other lines changed. The body of the try-with-resources block (tempFile.createFile(), performContentWrite/performBodyWrite, tempFile.moveTo(targetFile)) is untouched.

Verification

Verified at library level against the exact commons-vfs2_2.2.0.wso2v20_3.jar shipped in wso2mi-4.4.0.30.zip:

Case	Before (buggy)	After (patched)
Windows file:///C:/...	/C:/wso2/mi/.../fileName.csv.tmp (no scheme, no drive — matches customer stack trace)	file:///C:/wso2/mi/.../fileName.csv.tmp ✓
Linux file:///...	/wso2/mi/.../fileName.csv.tmp (resolves to wrong VFS location)	file:///wso2/mi/.../fileName.csv.tmp ✓
UNC file:////SERVER/share/...	/wso2/.../fileName.csv.tmp (no server+share)	file:////SERVER/share/.../fileName.csv.tmp ✓
End-to-end I/O (createFile() → write → moveTo)	N/A (would throw FileSystemException)	23-byte CSV written and renamed successfully ✓

Note on live-server verification: Connector v6.0.2 is compiled against the WSO2-orbit-shaded org.wso2.org.apache.commons.vfs2.* namespace, which ships from MI U49 onward. The only product pack available in this environment is U30. End-to-end live verification requires a U49+ pack (WSO2 subscription required) — the reviewer / release engineer should verify on U49+ before customer hand-off.

Tests Added

src/test/java/org/wso2/carbon/connector/operations/WriteFileTempFileResolutionTest.java — 10 TestNG tests (9 pass, 1 skipped if smb2 provider absent) covering:

• Windows-parsed file:///C:/… — scheme + drive letter preserved
• Linux-parsed file:///… — parent-relative behavior
• UNC file:////SERVER/share/… — server + share preserved
• smb2://host/share/… — scheme + host preserved (skipped if provider unavailable)
• URI-reserved chars / %20-encoded path — encoding preserved
• Drive-root parent edge case — no double-slash in resolved URI
• End-to-end createFile() → write → moveTo() succeeds
• Diagnostic: OLD bare-path concat is the necessary-and-sufficient condition for the customer's FileSystemException

Run with:

mvn -q test-compile && mvn -q dependency:build-classpath -DincludeScope=test -Dmdep.outputFile=/tmp/test-classpath.txt
CP="target/test-classes:target/classes:$(cat /tmp/test-classpath.txt)"
java -cp "$CP" org.testng.TestNG src/test/resources/testng-unit.xml

(The repo's surefire config has a hard-coded -XX:MaxPermSize=128m that fails on JDK 9+ — direct TestNG invocation is the documented workaround until the pom's argLine is parameterised.)

Known Limitations / Follow-up

1. PR base branch: esb-connector-file has no wso2-support/* or release-6.0.x branch (release branches stop at release-5.0.3; v6.x continues on master). Per the WSO2 support patch convention, a PR for a customer patch should NOT target master. Maintainers should confirm whether master is acceptable for this patch release or whether a wso2-support/6.0.x branch should be created first.

2. Sibling operations not fixed: The same getName().getPath() + FILE_SEPARATOR + … concatenation pattern exists in CheckFileExist, MoveFiles, and other operations. They are explicitly out of scope for this customer-patch ticket but will fail on Windows with the same exception. A follow-up cleanup ticket against esb-connector-file should be opened.

3. pom version bump: The plan defers the pom.xml version bump from 6.0.2 to 6.0.3 to release time, per connector maintainer convention.