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Add doc example for extracting WASI preopens

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This commit is contained in:
Jakub Konka 2020-06-11 22:06:57 +02:00
parent a282ac7a91
commit e4a8598ddd
1 changed files with 24 additions and 3 deletions
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doc/langref.html.in
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@ -9702,7 +9702,7 @@ The result is 3</code></pre>
{#header_open|WASI#}
<p>Zig's support for WebAssembly System Interface (WASI) is under active development.
Example of using the standard library and reading command line arguments:</p>
{#code_begin|exe|wasi#}
{#code_begin|exe|args#}
{#target_wasi#}
const std = @import("std");
@ -9716,10 +9716,31 @@ pub fn main() !void {
}
}
{#code_end#}
<pre><code>$ wasmer run wasi.wasm 123 hello
0: wasi.wasm
<pre><code>$ wasmtime args.wasm 123 hello
0: args.wasm
1: 123
2: hello</code></pre>
<p>A more interesting example would be extracting the list of preopens from the runtime.
This is now supported in the standard library via {#syntax#}std.fs.wasi.PreopenList{#endsyntax#}:</p>
{#code_begin|exe|preopens#}
{#target_wasi#}
const std = @import("std");
const PreopenList = std.fs.wasi.PreopenList;
pub fn main() !void {
var preopens = PreopenList.init(std.heap.page_allocator);
defer preopens.deinit();
try preopens.populate();
for (preopens.asSlice()) |preopen, i| {
std.debug.warn("{}: {}\n", .{ i, preopen });
}
}
{#code_end#}
<pre><code>$ wasmtime --dir=. preopens.wasm
0: { .fd = 3, .Dir = '.' }
</code></pre>
{#header_close#}
{#header_close#}
{#header_open|Targets#}