From 844eaace19ecf0f49ff52ec44698f994c009650f Mon Sep 17 00:00:00 2001
From: Rinse <rinse12@tutanota.com>
Date: Wed, 20 May 2026 06:12:40 +0000
Subject: [PATCH] fix(logs): drop stale-stat gate, read directly from position

The previous fix (#41) switched `-f` follow mode from fs.watchFile to
userspace polling, but kept the `fsPromise.stat(file).size > position`
gate before reading. On Windows + NTFS, stat() returns a stale size for
a short window after another process appends to the file, so the gate
evaluates false and the read never fires. Linux/macOS happen to update
the size promptly, masking the bug.

Drop the gate and read directly from `position` in a loop until read()
returns 0 bytes. The read() syscall sees the true file end at call time
and doesn't depend on metadata being fresh.

Re-opens #40.
---
 src/cli/commands/logs.ts | 63 +++++++++++++++++++++++-----------------
 1 file changed, 36 insertions(+), 27 deletions(-)

diff --git a/src/cli/commands/logs.ts b/src/cli/commands/logs.ts
index 7637689..50dc3e5 100644
--- a/src/cli/commands/logs.ts
+++ b/src/cli/commands/logs.ts
@@ -198,40 +198,49 @@ export default class Logs extends Command {
         let position = stat.size;
         let pendingBuffer = "";
 
-        // Watch for new data using polling (works across filesystems including Docker volumes)
+        // Watch for new data by reading directly from `position`. We intentionally do
+        // NOT gate on fsPromise.stat().size — on Windows + NTFS, stat() returns a stale
+        // size for a short window after another process appends, which causes the gate
+        // to miss new bytes. read() sees the true file end at syscall time.
+        const READ_BUF_SIZE = 64 * 1024;
+        const readBuf = Buffer.alloc(READ_BUF_SIZE);
         const readNewData = async () => {
+            let fd: fsPromise.FileHandle | undefined;
             try {
-                const currentStat = await fsPromise.stat(currentLogFile);
-                if (currentStat.size > position) {
-                    const fd = await fsPromise.open(currentLogFile, "r");
-                    const buf = new Uint8Array(currentStat.size - position);
-                    const { bytesRead } = await fd.read(buf, 0, buf.length, position);
-                    await fd.close();
+                fd = await fsPromise.open(currentLogFile, "r");
+                let chunk = "";
+                while (true) {
+                    const { bytesRead } = await fd.read(readBuf, 0, readBuf.length, position);
+                    if (bytesRead === 0) break;
                     position += bytesRead;
+                    chunk += readBuf.subarray(0, bytesRead).toString("utf-8");
+                    if (bytesRead < readBuf.length) break;
+                }
+                if (!chunk) return;
 
-                    const chunk = pendingBuffer + new TextDecoder().decode(buf.subarray(0, bytesRead));
-                    // Split into complete lines; keep any incomplete trailing line in the buffer
-                    const lastNewline = chunk.lastIndexOf("\n");
-                    if (lastNewline === -1) {
-                        pendingBuffer = chunk;
-                        return;
-                    }
-                    pendingBuffer = chunk.slice(lastNewline + 1);
-                    const completeText = chunk.slice(0, lastNewline + 1);
-
-                    if (!since && !until && !streamFilter) {
-                        // No filtering — pass through directly
-                        process.stdout.write(completeText);
-                    } else {
-                        const newEntries = this._parseLogEntries(completeText.replace(/\n$/, ""));
-                        const filteredNew = this._filterEntries(newEntries, since, until);
-                        const streamFilteredNew = streamFilter ? this._filterByStream(filteredNew, streamFilter) : filteredNew;
-                        const output = streamFilteredNew.map((e) => e.lines.join("\n")).join("\n");
-                        if (output) process.stdout.write(output + "\n");
-                    }
+                const combined = pendingBuffer + chunk;
+                const lastNewline = combined.lastIndexOf("\n");
+                if (lastNewline === -1) {
+                    pendingBuffer = combined;
+                    return;
+                }
+                pendingBuffer = combined.slice(lastNewline + 1);
+                const completeText = combined.slice(0, lastNewline + 1);
+
+                if (!since && !until && !streamFilter) {
+                    // No filtering — pass through directly
+                    process.stdout.write(completeText);
+                } else {
+                    const newEntries = this._parseLogEntries(completeText.replace(/\n$/, ""));
+                    const filteredNew = this._filterEntries(newEntries, since, until);
+                    const streamFilteredNew = streamFilter ? this._filterByStream(filteredNew, streamFilter) : filteredNew;
+                    const output = streamFilteredNew.map((e) => e.lines.join("\n")).join("\n");
+                    if (output) process.stdout.write(output + "\n");
                 }
             } catch {
                 // File may have been rotated or deleted
+            } finally {
+                if (fd) await fd.close().catch(() => {});
             }
         };