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Pass preopen-relative paths to WASI path_* functions #1821

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Merged
swankjesse merged 2 commits into from
Jul 19, 2026
+43 −23
Merged

Pass preopen-relative paths to WASI path_* functions #1821

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167da97
Pass preopen-relative paths to WASI `path_*` functions
eyupcanakman Jun 28, 2026
9e34196
Return the preopen and its relative path from `preopenForPath`
eyupcanakman Jul 3, 2026
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47 changes: 31 additions & 16 deletions okio-wasifilesystem/src/wasmWasiMain/kotlin/okio/WasiFileSystem.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -143,7 +143,7 @@ object WasiFileSystem : FileSystem() {
withScopedMemoryAllocator { allocator ->
val returnPointer = allocator.allocate(64)
val preopen = preopenForPath(path) ?: return null
val (pathAddress, pathSize) = allocator.write(path.toString())
val (pathAddress, pathSize) = allocator.write(preopen.relativePath(path))

val errno = path_filestat_get(
fd = preopen.fd,
Expand Down Expand Up @@ -358,10 +358,11 @@ object WasiFileSystem : FileSystem() {

override fun createDirectory(dir: Path, mustCreate: Boolean) {
withScopedMemoryAllocator { allocator ->
val (pathAddress, pathSize) = allocator.write(dir.toString())
val preopen = preopenForPath(dir) ?: throw FileNotFoundException("no preopen: $dir")
val (pathAddress, pathSize) = allocator.write(preopen.relativePath(dir))

val errno = path_create_directory(
fd = preopenForPath(dir)?.fd ?: throw FileNotFoundException("no preopen: $dir"),
fd = preopen.fd,
path = pathAddress.address.toInt(),
pathSize = pathSize,
)
Expand All @@ -376,14 +377,18 @@ object WasiFileSystem : FileSystem() {

override fun atomicMove(source: Path, target: Path) {
withScopedMemoryAllocator { allocator ->
val (sourcePathAddress, sourcePathSize) = allocator.write(source.toString())
val (targetPathAddress, targetPathSize) = allocator.write(target.toString())
val sourcePreopen = preopenForPath(source)
?: throw FileNotFoundException("no preopen: $source")
val targetPreopen = preopenForPath(target)
?: throw FileNotFoundException("no preopen: $target")
val (sourcePathAddress, sourcePathSize) = allocator.write(sourcePreopen.relativePath(source))
val (targetPathAddress, targetPathSize) = allocator.write(targetPreopen.relativePath(target))

val errno = path_rename(
fd = preopenForPath(source)?.fd ?: throw FileNotFoundException("no preopen: $source"),
fd = sourcePreopen.fd,
old_path = sourcePathAddress.address.toInt(),
old_pathSize = sourcePathSize,
new_fd = preopenForPath(target)?.fd ?: throw FileNotFoundException("no preopen: $target"),
new_fd = targetPreopen.fd,
new_path = targetPathAddress.address.toInt(),
new_pathSize = targetPathSize,
)
Expand All @@ -397,11 +402,11 @@ object WasiFileSystem : FileSystem() {

override fun delete(path: Path, mustExist: Boolean) {
withScopedMemoryAllocator { allocator ->
val (pathAddress, pathSize) = allocator.write(path.toString())
val preopenFd = preopenForPath(path) ?: throw FileNotFoundException("no preopen: $path")
val preopen = preopenForPath(path) ?: throw FileNotFoundException("no preopen: $path")
val (pathAddress, pathSize) = allocator.write(preopen.relativePath(path))

var errno = path_unlink_file(
fd = preopenFd.fd,
fd = preopen.fd,
path = pathAddress.address.toInt(),
pathSize = pathSize,
)
Expand All @@ -416,7 +421,7 @@ object WasiFileSystem : FileSystem() {
Errno.isdir.ordinal,
-> {
errno = path_remove_directory(
fd = preopenFd.fd,
fd = preopen.fd,
path = pathAddress.address.toInt(),
pathSize = pathSize,
)
Expand All @@ -440,7 +445,7 @@ object WasiFileSystem : FileSystem() {
else -> target.relativeTo(sourceParent)
}

val (sourcePathAddress, sourcePathSize) = allocator.write(source.toString())
val (sourcePathAddress, sourcePathSize) = allocator.write(sourcePreopen.relativePath(source))
val (targetPathAddress, targetPathSize) = allocator.write(targetRelative.toString())

val errno = path_symlink(
Expand All @@ -461,12 +466,12 @@ object WasiFileSystem : FileSystem() {
fdflags: fdflags = 0,
): fd {
withScopedMemoryAllocator { allocator ->
val preopenFd = preopenForPath(path) ?: throw FileNotFoundException("no preopen: $path")
val (pathAddress, pathSize) = allocator.write(path.toString())
val preopen = preopenForPath(path) ?: throw FileNotFoundException("no preopen: $path")
val (pathAddress, pathSize) = allocator.write(preopen.relativePath(path))

val returnPointer: Pointer = allocator.allocate(4) // fd is u32.
val errno = path_open(
fd = preopenFd.fd,
fd = preopen.fd,
dirflags = 0,
path = pathAddress.address.toInt(),
pathSize = pathSize,
Expand Down Expand Up @@ -508,5 +513,15 @@ object WasiFileSystem : FileSystem() {
val path: Path,
val segmentsBytes: List<ByteString>,
val fd: fd,
)
) {
/**
* Returns [target] as a path string relative to this preopen. WASI resolves path arguments
* against the preopen's file descriptor, and Node.js rejects absolute paths (`notcapable`), so
* the absolute path must be made relative before it is passed to a WASI path function.
*/
fun relativePath(target: Path): String = when {
target.isRelative -> target.toString()
else -> target.relativeTo(path).toString()
}
}
}