WASI: implement argsAlloc and argsFree #2364
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std/os.zig
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| var count: usize = undefined; | ||
| var buf_size: usize = undefined; | ||
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| _ = os.wasi.args_sizes_get(&count, &buf_size); |
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This should assert that there is no error, or handle it. If it asserts that there is no error, it should explain why the error is impossible.
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The return values are not documented at all. I looked at the source code of wasmtime and Lucet and they are not consistent. I have introduced error.ArgsSizesGetFailed and error.ArgsGetFailed in the meantime.
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In that case we can follow the pattern set by std/os.zig where an unexpected/undocumented error code is returned. Look for unexpectedErrorPosix and unexpectedErrorWindows.
Generally it's accepted that an undocumented error code might be returned from the OS which translates to error.Unexpected and has a mechanism for logging error codes with a build option.
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I've changed them to unexpectedErrorPosix. Most of WASI functions (if they are applicable), are similar to POSIX.
| @@ -2203,6 +2235,16 @@ pub fn argsAlloc(allocator: *mem.Allocator) ![]const []u8 { | |||
| } | |||
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| pub fn argsFree(allocator: *mem.Allocator, args_alloc: []const []u8) void { | |||
| if (builtin.os == Os.wasi) { | |||
| const last_item = args_alloc[args_alloc.len - 1]; | |||
| const last_byte_addr = @ptrToInt(last_item.ptr) + last_item.len + 1; // null terminated | |||
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If this has a +1 doesn't the other function need a -1?
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The strings in argv_buf, that is written to by the args_get function, are contiguous null terminated c-strings. My assumption here is that mem.toSlice doesn't include the final null-terminated character and I've added it myself here.
Implementing ArgIterator for WASI would require introducing a
freefunction to the internally allocated buffer so I've simply introduced a compileError for WASI.