Update README, change wasi primitive lib position and add some exception checks (#146)
Add exception throw when some initial checks fail in executing main or specific function
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wenyongh
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doc/build_wasm_app.md
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182
doc/build_wasm_app.md
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Build WASM app
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=========================
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You can write a simple ```test.c``` as the first sample.
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```C
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#include <stdio.h>
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#include <stdlib.h>
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int main(int argc, char **argv)
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{
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char *buf;
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printf("Hello world!\n");
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buf = malloc(1024);
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if (!buf) {
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printf("malloc buf failed\n");
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return -1;
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}
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printf("buf ptr: %p\n", buf);
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sprintf(buf, "%s", "1234\n");
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printf("buf: %s", buf);
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free(buf);
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return 0;
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}
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```
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There are several methods to build a WASM binary. They are the clang compiler, Docker, Emscripten and so on.
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## Use clang compiler
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The recommended method to build a WASM binary is to use clang compiler ```clang-8```. You can refer to [apt.llvm.org](https://apt.llvm.org) for the detailed instructions. Here are referenced steps to install clang-8 in Ubuntu 16.04 and Ubuntu 18.04.
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(1) Add source to your system source list from llvm website
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For Ubuntu 16.04, add the following lines to /etc/apt/sources.list:
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```Bash
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deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial main
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deb-src http://apt.llvm.org/xenial/ llvm-toolchain-xenial main
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# 8
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deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-8 main
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deb-src http://apt.llvm.org/xenial/ llvm-toolchain-xenial-8 main
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# 9
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deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-9 main
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deb-src http://apt.llvm.org/xenial/ llvm-toolchain-xenial-9 main
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```
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For Ubuntu 18.04, add the following lines to /etc/apt/sources.list:
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```Bash
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# i386 not available
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deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic main
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deb-src http://apt.llvm.org/bionic/ llvm-toolchain-bionic main
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# 8
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deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-8 main
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deb-src http://apt.llvm.org/bionic/ llvm-toolchain-bionic-8 main
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# 9
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deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-9 main
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deb-src http://apt.llvm.org/bionic/ llvm-toolchain-bionic-9 main
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(2) Download and install clang-8 tool-chain using following commands:
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```Bash
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sudo wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key|sudo apt-key add -
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# Fingerprint: 6084 F3CF 814B 57C1 CF12 EFD5 15CF 4D18 AF4F 7421
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sudo apt-get update
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sudo apt-get install llvm-8 lld-8 clang-8
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```
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(3) Create a soft link under /usr/bin:
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```Bash
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cd /usr/bin
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sudo ln -s wasm-ld-8 wasm-ld
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```
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(4) Use the clang-8 command below to build the WASM C source code into the WASM binary.
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```Bash
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clang-8 --target=wasm32 -O3 \
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-z stack-size=4096 -Wl,--initial-memory=65536 \
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-Wl,--allow-undefined,--export=main \
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-Wl,--strip-all,--no-entry -nostdlib \
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-o test.wasm test.c
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```
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You will get ```test.wasm``` which is the WASM app binary.
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## Use cmake
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If you have a cmake project, you can cross compile your project by using the toolchain provided by WAMR, the compiler used by WAMR toolchain is `clang-8`.
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We can generate a `CMakeLists.txt` file for `test.c`:
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```cmake
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cmake_minimum_required (VERSION 3.5)
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project(hello_world)
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add_executable(hello_world test.c)
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```
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It is quite simple to build this project by cmake:
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```Bash
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mkdir build && cd build
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cmake .. -DCMAKE_TOOLCHAIN_FILE=$WAMR_ROOT/test-tools/toolchain/wamr_toolchain.cmake
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make
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```
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You will get ```hello_world``` which is the WASM app binary.
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For more details about wamr toolchain, please refer to [test-tools/toolchain](../test-tools/toolchain/README.md).
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## Use wasi-sdk
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To build a wasm application with wasi support, wasi-sdk is required. Download the [wasi-sdk](https://github.com/CraneStation/wasi-sdk/releases) and extract the archive, then you can use it to build your application:
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```Bash
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/path/to/wasi-sdk/bin/clang test.c -o test.wasm
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```
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You will get ```test.wasm``` which is the WASM app binary.
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## Using Docker
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Another method availble is using [Docker](https://www.docker.com/). We assume you've already configured Docker (see Platform section above) and have a running interactive shell. Currently the Dockerfile only supports compiling apps with clang, with Emscripten planned for the future.
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Use the clang-8 command below to build the WASM C source code into the WASM binary.
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```Bash
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clang-8 --target=wasm32 -O3 \
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-z stack-size=4096 -Wl,--initial-memory=65536 \
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-Wl,--allow-undefined,--export=main \
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-Wl,--strip-all,--no-entry -nostdlib \
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-o test.wasm test.c
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```
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You will get ```test.wasm``` which is the WASM app binary.
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## Use Emscripten tool
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The last method to build a WASM binary is to use Emscripten tool ```emcc```.
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Assuming you are using Linux, you may install emcc from Emscripten EMSDK following the steps below:
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```
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git clone https://github.com/emscripten-core/emsdk.git
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cd emsdk
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./emsdk install latest-fastcomp
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./emsdk activate latest-fastcomp
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```
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The Emscripten website provides other installation methods beyond Linux.
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Use the emcc command below to build the WASM C source code into the WASM binary.
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``` Bash
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cd emsdk
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source emsdk_env.sh (or add it to ~/.bashrc if you don't want to run it each time)
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cd <dir of test.c>
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EMCC_ONLY_FORCED_STDLIBS=1 emcc -g -O3 -s WASM=1 -s ERROR_ON_UNDEFINED_SYMBOLS=0 \
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-s TOTAL_MEMORY=65536 -s TOTAL_STACK=4096 \
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-s ASSERTIONS=1 -s STACK_OVERFLOW_CHECK=2 \
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-s "EXPORTED_FUNCTIONS=['_main']" -o test.wasm test.c
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```
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You will get ```test.wasm``` which is the WASM app binary.
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Run WASM app
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========================
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Assume you are using Linux, the command to run the test.wasm is:
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``` Bash
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cd iwasm/products/linux/build
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./iwasm test.wasm
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```
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You will get the following output:
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```
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Hello world!
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buf ptr: 0x400002b0
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buf: 1234
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```
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If you would like to run the test app on Zephyr, we have embedded a test sample into its OS image. You will need to execute:
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```
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ninja run
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```
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