Fix Windows SFTP open flags and wolfsshd -D argument parsing(f8827)

[miyazakh]

Summary

• wolfSSH_SFTP_RecvOpen()'s Windows (USE_WINDOWS_API) path built dwCreationDisposition by OR-ing together OPEN_EXISTING / CREATE_ALWAYS bits, but CreateFile()'s creation-disposition parameter is a single enumerated value, not a bitmask. TRUNC and EXCL were also never wired up (left under #if 0), and APPEND access was missing. Add SFTP_WinCreationDisp() to resolve the SFTP CREAT/EXCL/TRUNC flag combination to the one correct CreateFile() disposition, and OR in FILE_APPEND_DATA for WOLFSSH_FXF_APPEND.
• wolfsshd's -D (foreground/no-daemon) argument check on Windows compared cmdArgs[i] with WSTRCMP, but cmdArgs entries come from CommandLineToArgvW and are wide strings. Comparing them as narrow char* data meant -D was never recognized. Use wcscmp() against L"-D" instead.
• Extend the WOLFSSH_TEST_INTERNAL regression-test plumbing in wolfsftp.c/wolfsftp.h to build under USE_WINDOWS_API too (it was previously guarded out on Windows), except for wolfSSH_SFTP_TestInvalidateHeadFd(), which stays POSIX-only since it manipulates a raw fd and Windows tracks a HANDLE instead.
• Add TestSftpWindowsOpenFlagMatrix() (tests/regress.c), which walks the RecvOpen CREAT/EXCL/TRUNC flag matrix on Windows and checks both the open result and the resulting file state for each case:
  • WRITE only, no CREAT, missing file -> fails, file not created
  • WRITE|CREAT, missing file -> creates it (OPEN_ALWAYS)
  • WRITE|CREAT, existing file -> opens without truncating
  • WRITE|CREAT|TRUNC, existing file -> truncates immediately
  • WRITE|CREAT|EXCL, existing file -> fails
  • WRITE|CREAT|EXCL, missing file -> succeeds
  • READ|WRITE|CREAT, missing file -> creates it

Testing

• Built and ran the full test suite on Windows via MSYS2 MinGW64 (_WIN32 -> USE_WINDOWS_API):

  PASS: tests/api.test.exe
  PASS: tests/testsuite.test.exe
  PASS: tests/kex.test.exe
  PASS: tests/regress.test.exe
  PASS: tests/unit.test.exe
  

  tests/regress.test.exe includes the new TestSftpWindowsOpenFlagMatrix(), exercising the corrected CreateFile() disposition logic end to end.

• scripts/external.test and scripts/fwd.test are skipped on Windows as expected (external network / Unix-only port forwarding).

[Copilot]

Pull request overview

This pull request fixes Windows-specific behavior in wolfSSH’s SFTP server open handling and wolfsshd argument parsing, and adds Windows regression coverage to prevent regressions in the SFTP open-flag matrix.

Changes:

• Correct Windows SFTP RecvOpen creation-disposition handling by mapping CREAT/EXCL/TRUNC to a single valid CreateFile() disposition and wiring APPEND access.
• Fix Windows wolfsshd -D detection by comparing CommandLineToArgvW() wide arguments with wcscmp(L"-D").
• Extend internal SFTP test plumbing to build under USE_WINDOWS_API and add a Windows open-flag matrix regression test.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
wolfssh/wolfsftp.h	Enables SFTP internal test hooks on Windows (except POSIX-fd invalidation helper).
src/wolfsftp.c	Adds SFTP_WinCreationDisp() and fixes Windows RecvOpen access/disposition handling; adjusts internal test hook gating for Windows.
tests/regress.c	Refactors shared SFTP reply assertion helper to build on Windows and adds TestSftpWindowsOpenFlagMatrix().
apps/wolfsshd/wolfsshd.c	Fixes -D parsing on Windows by using wcscmp() with wide string literals.

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

[wolfSSL-Fenrir-bot]

Fenrir Automated Review — PR #1173

Scan targets checked: wolfssh-bugs, wolfssh-src

Findings: 6
6 finding(s) posted as inline comments (see file-level comments below)

This review was generated automatically by Fenrir. Findings are non-blocking.

[wolfSSL-Fenrir-bot]

🔵 [Low] APPEND without WRITE grants append-only access, making RecvWrite ignore the requested offset · API contract violations

For WOLFSSH_FXF_APPEND without WOLFSSH_FXF_WRITE, desiredAccess becomes FILE_APPEND_DATA alone. Windows then treats the handle as append-only and WriteFile in wolfSSH_SFTP_RecvWrite (src/wolfsftp.c:4438) ignores the OVERLAPPED offset, so every write lands at EOF. Pre-PR this combination failed to open at all (creationDisp was 0). Adjacent to known finding #8827, which concerns the disposition bitmask, not access rights.

Related known finding #8827 (similar but distinct): Both affect Windows RecvOpen/CreateFile flag handling, but this candidate sets append-only access rights, causing later WriteFile offsets to be ignored; #8827 corrupts the creation-disposition selection by ORing enum values. The causes and required patches differ.

Fix: Only OR in FILE_APPEND_DATA alongside GENERIC_WRITE, or reject APPEND requests that omit WOLFSSH_FXF_WRITE.

[wolfSSL-Fenrir-bot]

🔵 [Low] New Windows flag-matrix test never exercises TRUNCATE_EXISTING or the APPEND path · Missing edge-case coverage on a function the PR also changed

The matrix covers only CREATE_NEW, CREATE_ALWAYS, OPEN_ALWAYS and OPEN_EXISTING. TRUNC is always paired with CREAT, so SFTP_WinCreationDisp's TRUNCATE_EXISTING branch (src/wolfsftp.c:2346) is never reached, and the new WOLFSSH_FXF_APPEND → FILE_APPEND_DATA line is untested.

Fix: Add cases for WRITE|TRUNC on an existing file and for WRITE|APPEND|CREAT, asserting the resulting file size/content.

[wolfSSL-Fenrir-bot]

⚪ [Info] TRUNCATE_EXISTING returned for read-only requests, which CreateFile rejects · Logic errors

READ|TRUNC (no WRITE, no CREAT) yields TRUNCATE_EXISTING while desiredAccess is only GENERIC_READ; CreateFile requires GENERIC_WRITE for that disposition and fails with ERROR_INVALID_PARAMETER. The POSIX branch accepts the same request via open(O_RDONLY|O_TRUNC).

Related known finding #8827 (similar but distinct): Both concern Windows CreateFile disposition selection for SFTP open flags, but this candidate selects TRUNCATE_EXISTING without required write access, while #8827 ORs incompatible disposition enums in RecvOpen. They are different operations, causes, and fixes.

Fix: Only select TRUNCATE_EXISTING when write access was requested, otherwise fall back to OPEN_EXISTING.

[wolfSSL-Fenrir-bot]

🔵 [Low] WOLFSSH_FXF_APPEND still has no effect on Windows · SSH protocol violations

FILE_APPEND_DATA is a no-op for the spec-mandated WRITE|APPEND combination: GENERIC_WRITE (line 2683) already grants FILE_WRITE_DATA, which disables Windows append-only enforcement, and wolfSSH_SFTP_RecvWrite positions every write via an explicit OVERLAPPED offset (line 4438). SSH_FXF_APPEND remains unimplemented on Windows while the POSIX path honors it via O_APPEND. Adjacent to known finding #8827, which faults the creationDisp OR-ing; this is the separately-added access-mask line and needs a different fix.

Related known finding #8827 (similar but distinct): Both are Windows SFTP RecvOpen flag-handling defects, but #8827 faults CreateFile disposition bitwise OR-ing while this finding faults APPEND access/explicit-offset write semantics. The root causes and required patches differ.

Fix: Track APPEND in the file-handle entry and have RecvWrite seek to end-of-file (FILE_END) for such handles instead of using the client offset.

[wolfSSL-Fenrir-bot]

🔵 [Low] -D path pairs CommandLineToArgvW's argc with the caller's argv array · NULL pointer dereference

Recognizing -D here makes the previously dead else { argv = (char**)wargv; } branch live, so mygetopt runs with argc from CommandLineToArgvW (line 2854) against the CRT-parsed array from main. The two parsers are independent: a smaller count silently drops trailing options such as -f \<config> (falling back to the default sshd_config), a larger count makes mygetopt dereference argv[myoptind][0] past the array's NULL terminator (wolfssh/test.h:354).

Fix: Leave argc as the caller-supplied value when using wargv, and only overwrite it with cmdArgC in the branch that builds argv from cmdArgs.

[wolfSSL-Fenrir-bot]

🔵 [Low] New Windows flag matrix omits the two branches the PR adds · Missing edge-case coverage on a function the PR also changed

The matrix covers only CREAT-bearing combinations, leaving both newly added behaviors unexercised: WOLFSSH_FXF_APPEND (desiredAccess |= FILE_APPEND_DATA, wolfsftp.c:2685) and TRUNC without CREAT (the TRUNCATE_EXISTING branch of SFTP_WinCreationDisp, wolfsftp.c:2346). Neither branch would fail the suite if wrong.

Fix: Add cases for WRITE|APPEND (assert data lands at end-of-file) and WRITE|TRUNC on an existing file (assert size drops to 0).