scp: return directory entries from the Zephyr entry walk

[yosuke-wolfssl]

Problem

The WOLFSSH_ZEPHYR branch of FindNextDirEntry() ended in while (1), discarding every entry fs_readdir() returned. It could only reach return WS_FATAL_ERROR or return WS_NEXT_ERROR — the shared return WS_SUCCESS was unreachable on Zephyr.

That function is called only from the WOLFSSH_SCP_RECURSIVE_REQUEST arm of wsScpSendCallback(), and the caller reads WS_NEXT_ERROR as end-of-directory. A peer running scp -r user@host:dir . against a Zephyr server got the directory header and an immediate exit, so every directory transferred empty. Single-file SCP was unaffected. Functional only — no overflow or leak, and the loop always terminated, since fs_readdir() signals end-of-directory with name[0] = 0.

Fix (src/wolfscp.c)

Skip . and .. and fall through to return WS_SUCCESS, matching the POSIX and Windows branches:

    } while (((WSTRLEN(ctx->entry.name) == 1) &&
              (WSTRNCMP(ctx->entry.name, ".", 1) == 0)) ||
             ((WSTRLEN(ctx->entry.name) == 2) &&
              (WSTRNCMP(ctx->entry.name, "..", 2) == 0)));

The skip is not cosmetic everywhere:

Zephyr FS	Reports . / ..?	Effect
FAT (ELM FatFs)	No — dir_read() filters leading .	Skip is a no-op
littlefs	Yes — lfs_dir_read_() synthesizes both	Without it, . is a directory and ScpPushDir() re-descends the same directory unboundedly

Closes f-13315.

Tests (tests/api.c)

test_wolfSSH_SCP_SendRecursiveEntry() stages a one-file directory and drives three WOLFSSH_SCP_RECURSIVE_REQUEST calls through wsScpSendCallback(), asserting enter-dir, then the entry name/size/bytes, then final exit. Driving the callback directly is the only route in — the example client cannot issue scp -r -f. It needs no threads, sockets, mkdtemp or symlinks, so unlike every other SCP test it is not gated !defined(WOLFSSH_ZEPHYR) and runs in the Zephyr CI.

Verification

• Host make check: 8 passed, 3 skipped, 0 failed.
• gcc-13 -Werror sweep: 6/6 configs clean.
• Zephyr qemu_x86 (4.4.99, SDK 1.0.1), FAT RAM disk: Zephyr wolfSSH tests passed.
• Negative controls: with while (1) restored, the Zephyr run fails at the new assertion (-1047 instead of 64 bytes); with the POSIX dot-skip disabled, it fails with -1045, having descended into ..

Not in this PR

Nested-subdirectory descent (the non-final WS_SCP_EXIT_DIR) and the empty-directory case stay uncovered — both pre-existing gaps, flagged in review and deferred.

[Copilot]

🟢 Approval recommended

The change corrects an unreachable-success logic path on Zephyr and adds a deterministic test that exercises the fixed behavior without introducing interface or behavioral risk elsewhere.

Pull request overview

This PR fixes recursive SCP directory traversal on Zephyr by making FindNextDirEntry() return actual directory entries (instead of looping until end-of-directory) and adds a focused API-level test to prevent regressions in Zephyr CI.

Changes:

• Fix Zephyr FindNextDirEntry() to skip . / .. and fall through to WS_SUCCESS, aligning behavior with other platforms.
• Add test_wolfSSH_SCP_SendRecursiveEntry() that directly drives wsScpSendCallback() through enter-dir → one file entry → final exit, including dot-entry skipping behavior.

File summaries

File	Description
src/wolfscp.c	Makes Zephyr directory entry walking return real entries by skipping ./.. and allowing WS_SUCCESS to be reached.
tests/api.c	Adds a Zephyr-capable recursive-send callback-level test to validate directory entry iteration and completion signaling.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Lite

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[yosuke-wolfssl]

CI issues would be gone once PR #1242 is merged