From a7ab34ebbce60f2af159f9010a2e3629756af3d1 Mon Sep 17 00:00:00 2001 From: human Date: Thu, 7 Jan 2021 16:31:52 +0200 Subject: fix truncating in defineFile() - in the C part: enable FUSE_CAP_ATOMIC_O_TRUNC so that open() will get called with O_TRUNC in flags instead of truncate() being called separately - this also prevents truncate() from calling setData() with an empty string when a file is opened with O_TRUNC - in defineFile()->open(): if O_TRUNC is used, don't call getData() but start with an empty file as if it had just been truncated - in defineFile()->write()/truncate(): correct buffer resizing/copying --- extension/background.js | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) (limited to 'extension') diff --git a/extension/background.js b/extension/background.js index 179a2b8..127f4f9 100644 --- a/extension/background.js +++ b/extension/background.js @@ -19,6 +19,9 @@ const unix = { S_IFREG: 0100000, // regular S_IFLNK: 0120000, // symbolic link S_IFSOCK: 0140000, // socket + + // Open flags + O_TRUNC: 01000, } class UnixError extends Error { @@ -110,6 +113,7 @@ const Cache = { return handle; }, getObjectForHandle(handle) { return this.store[handle]; }, + setObjectForHandle(handle, object) { this.store[handle] = object; }, removeObjectForHandle(handle) { delete this.store[handle]; } }; function toUtf8Array(stringOrArray) { @@ -141,7 +145,10 @@ const defineFile = (getData, setData) => ({ // We call getData() once when the file is opened, then cache that // data for all subsequent reads from that application. - async open({path}) { return { fh: Cache.storeObject(toUtf8Array(await getData(path))) }; }, + async open({path, flags}) { + const data = !(flags & unix.O_TRUNC) ? await getData(path) : ""; + return { fh: Cache.storeObject(toUtf8Array(data)) }; + }, async read({path, fh, size, offset}) { return { buf: String.fromCharCode(...Cache.getObjectForHandle(fh).slice(offset, offset + size)) } }, @@ -150,9 +157,11 @@ const defineFile = (getData, setData) => ({ const bufarr = stringToUtf8Array(buf); if (offset + bufarr.length > arr.length) { const newArr = new Uint8Array(offset + bufarr.length); - newArr.set(arr); arr = newArr; + newArr.set(arr.slice(0, Math.min(offset, arr.length))); + arr = newArr; + Cache.setObjectForHandle(fh, arr); } - for (let i = 0; i < bufarr.length; i++) { arr[offset + i] = bufarr[i]; } + arr.set(bufarr, offset); // I guess caller should override write() if they want to actually // patch and not just re-set the whole string (for example, // if they want to hot-reload just one function the user modified) @@ -165,11 +174,12 @@ const defineFile = (getData, setData) => ({ // (but `echo hi > foo.txt`, the main thing I care about, uses // O_TRUNC which thankfully doesn't do that) let arr = toUtf8Array(await getData(path)); - if (size > arr.length) { + if (size !== arr.length) { const newArr = new Uint8Array(size); - newArr.set(arr); arr = newArr; + newArr.set(arr.slice(0, Math.min(size, arr.length))); + arr = newArr; } - await setData(path, utf8ArrayToString(arr.slice(0, size))); return {}; + await setData(path, utf8ArrayToString(arr)); return {}; } }); -- cgit v1.2.3