fix: allow empty I/O content (#859)

Author: lauzadis

.changes/2d39ef91-f11a-4f2a-af23-9331b90926f2.json

@@ -0,0 +1,5 @@
+{
+    "id": "2d39ef91-f11a-4f2a-af23-9331b90926f2",
+    "type": "bugfix",
+    "description": "Allow empty I/O content"
+}

runtime/runtime-core/jvm/src/aws/smithy/kotlin/runtime/content/ByteStreamJVM.kt

@@ -24,8 +24,8 @@ public fun ByteStream.Companion.fromFile(file: File): ByteStream = file.asByteSt
  */
 public fun File.asByteStream(start: Long = 0, endInclusive: Long = length() - 1): ByteStream {
     require(start >= 0) { "start index $start cannot be negative" }
-    require(endInclusive >= start) {
-        "end index $endInclusive must be greater than or equal to start index $start"
+    require(endInclusive >= start - 1) {
+        "end index $endInclusive must be greater than or equal to start index minus one (${start - 1})"
     }
 
     val len = length()
@@ -46,9 +46,10 @@ public fun Path.asByteStream(start: Long = 0, endInclusive: Long = -1): ByteStre
     val f = toFile()
     require(f.exists()) { "cannot create ByteStream, file does not exist: $this" }
     require(f.isFile) { "cannot create a ByteStream from a directory: $this" }
-    require(endInclusive >= -1L) { "endInclusive must be -1 or greater" }
 
     val calculatedEndInclusive = if (endInclusive == -1L) f.length() - 1L else endInclusive
+    require(calculatedEndInclusive >= start - 1) { "end index $calculatedEndInclusive must be greater or equal to start index minus one (${start - 1})" }
+
     return f.asByteStream(start, calculatedEndInclusive)
 }
 

runtime/runtime-core/jvm/src/aws/smithy/kotlin/runtime/io/JavaIO.kt

@@ -22,7 +22,7 @@ public fun Path.source(range: LongRange): SdkSource = source(range.first, range.
  * Create a [SdkSource] from the given path and range
  */
 public fun Path.source(start: Long = 0L, endInclusive: Long = -1): SdkSource {
-    require(endInclusive >= -1L) { "endInclusive must be -1 or greater" }
+    require(endInclusive >= start - 1) { "end index $endInclusive must be greater or equal to start index minus one (${start - 1})" }
 
     val f = toFile()
     val calculatedEndInclusive = if (endInclusive == -1L) f.length() - 1L else endInclusive

runtime/runtime-core/jvm/src/aws/smithy/kotlin/runtime/io/RandomAccessFileSource.kt

@@ -22,7 +22,10 @@ internal class RandomAccessFileSource(
         require(fileObject.exists()) { "cannot create SdkSource, file does not exist: $this" }
         require(fileObject.isFile) { "cannot create a SdkSource from a directory: $this" }
         require(start >= 0L) { "start position should be >= 0, found $start" }
-        require(endInclusive >= 0 && endInclusive <= fileObject.length() - 1) {
+        require(endInclusive >= start - 1) {
+            "end index $endInclusive must be greater than or equal to the start index minus one (${start - 1})"
+        }
+        require(endInclusive <= fileObject.length() - 1) {
             "endInclusive should be less than or equal to the length of the file, was $endInclusive"
         }
 

runtime/runtime-core/jvm/test/aws/smithy/kotlin/runtime/content/ByteStreamJVMTest.kt

@@ -8,6 +8,7 @@ package aws.smithy.kotlin.runtime.content
 import aws.smithy.kotlin.runtime.testing.RandomTempFile
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.test.runTest
+import java.nio.file.Files
 import kotlin.test.*
 
 @OptIn(ExperimentalCoroutinesApi::class)
@@ -36,7 +37,7 @@ class ByteStreamJVMTest {
         val e = assertFailsWith<Throwable> {
             file.asByteStream(5, 1)
         }
-        assertEquals("end index 1 must be greater than or equal to start index 5", e.message)
+        assertEquals("end index 1 must be greater than or equal to start index minus one (4)", e.message)
     }
 
     @Test
@@ -130,4 +131,24 @@ class ByteStreamJVMTest {
 
         assertEquals(1024, stream.contentLength)
     }
+
+    @Test
+    fun `can create byte stream from empty file and path using createTempFile`() = runTest {
+        val file = Files.createTempFile(null, null)
+        val byteStream = file.asByteStream()
+        assertEquals(0, byteStream.contentLength)
+
+        val byteStreamFromPath = file.toAbsolutePath().asByteStream()
+        assertEquals(0, byteStreamFromPath.contentLength)
+    }
+
+    @Test
+    fun `can create byte stream from empty file and path using RandomTempFile`() = runTest {
+        val file = RandomTempFile(sizeInBytes = 0)
+        val byteStream = file.asByteStream()
+        assertEquals(0, byteStream.contentLength)
+
+        val byteStreamFromPath = file.toPath().asByteStream()
+        assertEquals(0, byteStreamFromPath.contentLength)
+    }
 }