Multiple fixes to reading data from a stream

- littleEndia32/64 arguments were in wrong order in a few places
- add safeReadStr that throws and exception if couldn't read enough data
- throw exceptions when not reading enough data

2 files changed, 23 insertions, 15 deletions

diff --git a/generator/protoc_gen_nim.nim b/generator/protoc_gen_nim.nim
index 22e3cd7..d371859 100644
--- a/generator/protoc_gen_nim.nim
+++ b/generator/protoc_gen_nim.nim
@@ -638,7 +638,7 @@ iterator genReadMapKVProc(msg: Message): string =
     if isMessage(value):
         yield indent("let", 12)
         yield indent("size = readVarint(stream)", 16)
-        yield indent("data = readStr(stream, int(size))", 16)
+        yield indent("data = safeReadStr(stream, int(size))", 16)
         yield indent("pbs = newProtobufStream(newStringStream(data))", 16)
         yield indent(&"value = read{value.typeName}(pbs)", 12)
     else:
@@ -677,7 +677,7 @@ iterator genReadMessageProc(msg: Message): string =
                     yield indent(&"expectWireType(wireType, {field.wiretypeStr})", 12)
                     yield indent("let", 12)
                     yield indent("size = readVarint(stream)", 16)
-                    yield indent("data = readStr(stream, int(size))", 16)
+                    yield indent("data = safeReadStr(stream, int(size))", 16)
                     yield indent("pbs = newProtobufStream(newStringStream(data))", 16)
                     yield indent(&"read{field.typeName}KV(pbs, result.{field.name})", 12)
                 elif isNumeric(field):
@@ -698,7 +698,7 @@ iterator genReadMessageProc(msg: Message): string =
                     yield indent(&"expectWireType(wireType, {field.wiretypeStr})", 12)
                     yield indent("let", 12)
                     yield indent("size = readVarint(stream)", 16)
-                    yield indent("data = readStr(stream, int(size))", 16)
+                    yield indent("data = safeReadStr(stream, int(size))", 16)
                     yield indent("pbs = newProtobufStream(newStringStream(data))", 16)
                     yield indent(&"{setter}(result, {reader}(pbs))", 12)
                 else:
@@ -709,7 +709,7 @@ iterator genReadMessageProc(msg: Message): string =
                 if isMessage(field):
                     yield indent("let", 12)
                     yield indent("size = readVarint(stream)", 16)
-                    yield indent("data = readStr(stream, int(size))", 16)
+                    yield indent("data = safeReadStr(stream, int(size))", 16)
                     yield indent("pbs = newProtobufStream(newStringStream(data))", 16)
                     yield indent(&"{setter}(result, {reader}(pbs))", 12)
                 else:
diff --git a/src/protobuf/stream.nim b/src/protobuf/stream.nim
index d7eeadd..9d843e6 100644
--- a/src/protobuf/stream.nim
+++ b/src/protobuf/stream.nim
@@ -181,7 +181,8 @@ proc writeFixed64*(stream: ProtobufStream, value: uint64) =
 
 proc readFixed64*(stream: ProtobufStream): uint64 =
     var tmp: uint64
-    discard readData(stream, addr(tmp), sizeof(tmp))
+    if readData(stream, addr(tmp), sizeof(tmp)) != sizeof(tmp):
+        raise newException(IOError, "cannot read from stream")
     littleEndian64(addr(result), addr(tmp))
 
 proc writeSFixed64*(stream: ProtobufStream, value: int64) =
@@ -201,8 +202,9 @@ proc writeDouble*(stream: ProtobufStream, value: float64) =
 
 proc readDouble*(stream: ProtobufStream): float64 =
     var tmp: uint64
-    discard readData(stream, addr(tmp), sizeof(tmp))
-    littleEndian64(addr(tmp), addr(result))
+    if readData(stream, addr(tmp), sizeof(tmp)) != sizeof(tmp):
+        raise newException(IOError, "cannot read from stream")
+    littleEndian64(addr(result), addr(tmp))
 
 proc writeFixed32*(stream: ProtobufStream, value: uint32) =
     var
@@ -215,8 +217,9 @@ proc writeFixed32*(stream: ProtobufStream, value: uint32) =
 
 proc readFixed32*(stream: ProtobufStream): uint32 =
     var tmp: uint32
-    discard readData(stream, addr(tmp), sizeof(tmp))
-    littleEndian32(addr(tmp), addr(result))
+    if readData(stream, addr(tmp), sizeof(tmp)) != sizeof(tmp):
+        raise newException(IOError, "cannot read from stream")
+    littleEndian32(addr(result), addr(tmp))
 
 proc writeSFixed32*(stream: ProtobufStream, value: int32) =
     writeFixed32(stream, cast[uint32](value))
@@ -235,8 +238,9 @@ proc writeFloat*(stream: ProtobufStream, value: float32) =
 
 proc readFloat*(stream: ProtobufStream): float32 =
     var tmp: float32
-    discard readData(stream, addr(tmp), sizeof(tmp))
-    littleEndian32(addr(tmp), addr(result))
+    if readData(stream, addr(tmp), sizeof(tmp)) != sizeof(tmp):
+        raise newException(IOError, "cannot read from stream")
+    littleEndian32(addr(result), addr(tmp))
 
 proc writeString*(stream: ProtobufStream, s: string) =
     writeUInt64(stream, len(s).uint64)
@@ -245,10 +249,14 @@ proc writeString*(stream: ProtobufStream, s: string) =
 proc writeBytes*(stream: ProtobufStream, s: bytes) =
     writeString(stream, string(s))
 
+proc safeReadStr*(stream: Stream, size: int): string =
+    result = newString(size)
+    if readData(stream, addr(result[0]), size) != size:
+        raise newException(IOError, "cannot read from stream")
+
 proc readString*(stream: ProtobufStream): string =
-    # TODO: use something else than readStr to get rid of int cast?
-    let size = readUInt64(stream).int
-    result = readStr(stream, size)
+    let size = int(readUInt64(stream))
+    result = safeReadStr(stream, size)
 
 proc readBytes*(stream: ProtobufStream): bytes =
     bytes(readString(stream))
@@ -336,7 +344,7 @@ proc skipField*(stream: ProtobufStream, wiretype: WireType) =
         discard readFixed32(stream)
     of WireType.LengthDelimited:
         let size = readVarint(stream)
-        discard readStr(stream, int(size))
+        discard safeReadStr(stream, int(size))
     else:
         raise newException(Exception, "unsupported wiretype: " & $wiretype)