Add a wasm-validate example program (bytecodealliance#202)

Shows off how to to use `validate` and makes it pretty nifty to install
from crates.io if you want.

Author: yurydelendik

Cargo.toml

@@ -12,7 +12,9 @@ exclude = ["fuzz/**/*", "tests/**/*", "testsuite/**/*"]
 edition = "2018"
 
 [dev-dependencies]
+anyhow = "1.0"
 criterion = "0.3"
+getopts = "0.2"
 wast = "7.0.0"
 
 [badges]

examples/wasm-validate.rs

@@ -0,0 +1,61 @@
+use anyhow::{Context, Result};
+use std::env;
+
+fn main() -> Result<()> {
+    // Use the `getopts` crate to parse the `-o` option as well as `-h`
+    let program = env::args().nth(0).unwrap();
+    let mut opts = getopts::Options::new();
+    opts.optflag(
+        "",
+        "enable-reference-types",
+        "Enable wasm reference types feature",
+    );
+    opts.optflag("", "enable-threads", "Enable wasm threads feature");
+    opts.optflag("", "enable-simd", "Enable wasm simd feature");
+    opts.optflag(
+        "",
+        "enable-bulk-memory",
+        "Enable wasm bulk memory operations feature",
+    );
+    opts.optflag("", "enable-multi-value", "Enable wasm multi-value feature");
+    #[cfg(feature = "deterministic")]
+    opts.optflag(
+        "",
+        "deterministic-only",
+        "Require only deterministic instructions",
+    );
+    opts.optflag("h", "help", "print this help menu");
+    let matches = opts.parse(env::args_os().skip(1))?;
+    if matches.opt_present("h") {
+        return Ok(print_usage(&program, opts));
+    }
+    let input = match matches.free.len() {
+        0 => {
+            print_usage(&program, opts);
+            std::process::exit(1);
+        }
+        1 => &matches.free[0],
+        _ => anyhow::bail!("more than one input file specified on command line"),
+    };
+
+    let config = wasmparser::ValidatingParserConfig {
+        operator_config: wasmparser::OperatorValidatorConfig {
+            enable_threads: matches.opt_present("enable-threads"),
+            enable_reference_types: matches.opt_present("enable-reference-types"),
+            enable_simd: matches.opt_present("enable-simd"),
+            enable_bulk_memory: matches.opt_present("enable-bulk-memory"),
+            enable_multi_value: matches.opt_present("enable-multi-value"),
+            #[cfg(feature = "deterministic")]
+            deterministic_only: matches.opt_present("deterministic-only"),
+        },
+    };
+    let wasm = std::fs::read(input).context(format!("failed to read input: {}", input))?;
+    wasmparser::validate(&wasm, Some(config)).unwrap();
+
+    Ok(())
+}
+
+fn print_usage(program: &str, opts: getopts::Options) {
+    let brief = format!("Usage: {} FILE [options]", program);
+    print!("{}", opts.usage(&brief));
+}