1ad900d179
This refactors GOOS and GOARCH specific code into their own packages. This allows logging interceptors to be built without cyclic package dependencies. Signed-off-by: Adrian Cole <adrian@tetrate.io>
71 lines
1.9 KiB
Go
71 lines
1.9 KiB
Go
package gojs
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import (
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"encoding/binary"
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"errors"
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"github.com/tetratelabs/wazero/api"
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"github.com/tetratelabs/wazero/internal/gojs/util"
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"github.com/tetratelabs/wazero/internal/wasm"
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)
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// Constants about memory layout. See REFERENCE.md
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const (
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endOfPageZero = uint32(4096) // runtime.minLegalPointer
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maxArgsAndEnviron = uint32(8192) // ld.wasmMinDataAddr - runtime.minLegalPointer
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wasmMinDataAddr = endOfPageZero + maxArgsAndEnviron // ld.wasmMinDataAddr
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)
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var le = binary.LittleEndian
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// WriteArgsAndEnviron writes arguments and environment variables to memory, so
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// they can be read by main, Go compiles as the function export "run".
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func WriteArgsAndEnviron(mod api.Module) (argc, argv uint32, err error) {
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mem := mod.Memory()
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sysCtx := mod.(*wasm.CallContext).Sys
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args := sysCtx.Args()
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environ := sysCtx.Environ()
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argc = uint32(len(args))
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offset := endOfPageZero
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strPtr := func(val []byte, field string, i int) (ptr uint32) {
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// TODO: return err and format "%s[%d], field, i"
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ptr = offset
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util.MustWrite(mem, field, offset, append(val, 0))
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offset += uint32(len(val) + 1)
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if pad := offset % 8; pad != 0 {
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offset += 8 - pad
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}
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return
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}
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argvPtrLen := len(args) + 1 + len(environ) + 1
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argvPtrs := make([]uint32, 0, argvPtrLen)
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for i, arg := range args {
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argvPtrs = append(argvPtrs, strPtr(arg, "args", i))
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}
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argvPtrs = append(argvPtrs, 0)
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for i, env := range environ {
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argvPtrs = append(argvPtrs, strPtr(env, "env", i))
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}
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argvPtrs = append(argvPtrs, 0)
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argv = offset
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stop := uint32(argvPtrLen << 3) // argvPtrLen * 8
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if offset+stop >= wasmMinDataAddr {
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err = errors.New("total length of command line and environment variables exceeds limit")
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}
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buf := util.MustRead(mem, "argvPtrs", argv, stop)
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pos := uint32(0)
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for _, ptr := range argvPtrs {
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le.PutUint64(buf[pos:], uint64(ptr))
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pos += 8
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}
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return
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}
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