Check error codes returned by POSIX-ish APIs and throw IOE

core/androidNative/src/files/FileSystemAndroid.kt

@@ -35,13 +35,20 @@ internal actual class OpaqueDirEntry(private val dir: CPointer<cnames.structs.DI
     }
 
     actual override fun close() {
-        closedir(dir)
+        if (closedir(dir) != 0) {
+            val err = errno
+            val strerr = strerror(err)?.toKString() ?: "unknown error"
+            throw IOException("closedir failed with errno $err ($strerr)")
+        }
     }
 }
 
 @OptIn(ExperimentalForeignApi::class)
 internal actual fun opendir(path: String): OpaqueDirEntry {
     val dirent = platform.posix.opendir(path)
     if (dirent != null) return OpaqueDirEntry(dirent)
-    throw IOException("Can't open directory $path: ${strerror(errno)?.toKString() ?: "reason unknown"}")
+
+    val err = errno
+    val strerr = strerror(err)?.toKString() ?: "unknown error"
+    throw IOException("Can't open directory $path: $err ($strerr)")
 }

core/native/src/files/PathsNative.kt

@@ -64,6 +64,12 @@ internal expect fun isAbsoluteImpl(path: String): Boolean
 
 public actual fun Path(path: String): Path = Path(path, null)
 
+private fun throwIOExceptionForErrno(operation: String): Nothing {
+    val err = errno
+    val strerr = strerror(err)?.toKString() ?: "unknown error"
+    throw IOException("$operation failed with errno $err ($strerr)")
+}
+
 internal class FileSource(
     private val file: CPointer<FILE>
 ) : RawSource {
@@ -85,15 +91,17 @@ internal class FileSource(
         return when {
             bytesRead == byteCount -> bytesRead
             feof(file) != 0 -> if (bytesRead == 0L) -1L else bytesRead
-            ferror(file) != 0 -> throw IOException(errno.toString())
+            ferror(file) != 0 -> throwIOExceptionForErrno("write")
             else -> bytesRead
         }
     }
 
     override fun close() {
         if (closed) return
         closed = true
-        fclose(file)
+        if (fclose(file) != 0) {
+            throwIOExceptionForErrno("fclose")
+        }
     }
 }
 
@@ -130,21 +138,21 @@ internal class FileSink(
             variantFwrite(pinned.addressOf(0), byteCount.toUInt(), file).toLong()
         }
         if (bytesWritten < byteCount) {
-            throw IOException(errno.toString())
+            throwIOExceptionForErrno("file write")
         }
     }
 
     override fun flush() {
         if (fflush(file) != 0) {
-            throw IOException(errno.toString())
+            throwIOExceptionForErrno("fflush")
         }
     }
 
     override fun close() {
         if (closed) return
         closed = true
         if (fclose(file) != 0) {
-            throw IOException(errno.toString())
+            throwIOExceptionForErrno("fclose")
         }
     }
 }

core/nativeNonAndroid/src/files/FileSystemNativeNonAndroid.kt

@@ -23,13 +23,20 @@ internal actual class OpaqueDirEntry(private val dir: CPointer<DIR>) : AutoClose
     }
 
     actual override fun close() {
-        closedir(dir)
+        if (closedir(dir) != 0) {
+            val err = errno
+            val strerr = strerror(err)?.toKString() ?: "unknown error"
+            throw IOException("closedir failed with errno $err ($strerr)")
+        }
     }
 }
 
 @OptIn(ExperimentalForeignApi::class)
 internal actual fun opendir(path: String): OpaqueDirEntry {
     val dirent = platform.posix.opendir(path)
     if (dirent != null) return OpaqueDirEntry(dirent)
-    throw IOException("Can't open directory $path: ${strerror(errno)?.toKString() ?: "reason unknown"}")
+
+    val err = errno
+    val strerr = strerror(err)?.toKString() ?: "unknown error"
+    throw IOException("Can't open directory $path: $err ($strerr)")
 }

core/wasmWasi/src/files/FileSystemWasm.kt

@@ -344,7 +344,10 @@ internal object WasiFileSystem : SystemFileSystemImpl() {
             }
             return children
         } finally {
-            fd_close(dir_fd)
+            val res = Errno(fd_close(dir_fd))
+            if (res != Errno.success) {
+                throw IOException("fd_close failed for directory '$directory': ${res.description}")
+            }
         }
     }
 }
@@ -488,7 +491,10 @@ private class FileSink(private val fd: Fd) : RawSink {
     override fun close() {
         if (!closed) {
             closed = true
-            fd_close(fd)
+            val res = Errno(fd_close(fd))
+            if (res != Errno.success) {
+                throw IOException("fd_close failed: ${res.description}")
+            }
         }
     }
 }
@@ -536,7 +542,10 @@ private class FileSource(private val fd: Fd) : RawSource {
     override fun close() {
         if (!closed) {
             closed = true
-            fd_close(fd)
+            val res = Errno(fd_close(fd))
+            if (res != Errno.success) {
+                throw IOException("fd_close failed: ${res.description}")
+            }
         }
     }
 }