From 4beabf6686c59fbe4ac6d4a4a158eca41a0b682a Mon Sep 17 00:00:00 2001 From: Erik Kundt Date: Wed, 10 Oct 2018 12:28:24 +0200 Subject: Documents library view functions and adds unit test. --- docs/contracts.rst | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'docs') diff --git a/docs/contracts.rst b/docs/contracts.rst index faef3fc2..e4a81684 100644 --- a/docs/contracts.rst +++ b/docs/contracts.rst @@ -485,7 +485,9 @@ Functions can be declared ``view`` in which case they promise not to modify the .. note:: If the compiler's EVM target is Byzantium or newer (default) the opcode ``STATICCALL`` is used for ``view`` functions which enforces the state - to stay unmodified as part of the EVM execution. + to stay unmodified as part of the EVM execution. For library ``view`` functions + ``DELEGATECALL`` is used. Since they are executed in the context of the calling + contract, the static checker is extended to the library. The following statements are considered modifying the state: -- cgit v1.2.3 From 8a15058a217b6765aa5a5085b328edcb84694927 Mon Sep 17 00:00:00 2001 From: Erik Kundt Date: Wed, 10 Oct 2018 15:10:25 +0200 Subject: Adds more specific explanation of library view functions calls. --- docs/contracts.rst | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'docs') diff --git a/docs/contracts.rst b/docs/contracts.rst index e4a81684..0d1b029b 100644 --- a/docs/contracts.rst +++ b/docs/contracts.rst @@ -486,8 +486,10 @@ Functions can be declared ``view`` in which case they promise not to modify the If the compiler's EVM target is Byzantium or newer (default) the opcode ``STATICCALL`` is used for ``view`` functions which enforces the state to stay unmodified as part of the EVM execution. For library ``view`` functions - ``DELEGATECALL`` is used. Since they are executed in the context of the calling - contract, the static checker is extended to the library. + ``DELEGATECALL`` is used, because there is no combined ``DELEGATECALL`` and ``STATICCALL``. + This means library ``view`` functions do not have run-time checks that prevent state + modifications. This should not impact security negatively because library code is + usually known at compile-time and the static checker performs compile-time checks. The following statements are considered modifying the state: -- cgit v1.2.3