mirror of
https://github.com/wazero/wazero
synced 2026-06-21 14:12:37 +00:00
Edoardo Vacchi
101 lines
4.1 KiB
Go
101 lines
4.1 KiB
Go
package wasi_snapshot_preview1
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import (
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"context"
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"github.com/tetratelabs/wazero/api"
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"github.com/tetratelabs/wazero/experimental/sys"
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"github.com/tetratelabs/wazero/internal/wasip1"
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"github.com/tetratelabs/wazero/internal/wasm"
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)
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// environGet is the WASI function named EnvironGetName that reads
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// environment variables.
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//
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// # Parameters
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//
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// - environ: offset to begin writing environment offsets in uint32
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// little-endian encoding to api.Memory
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// - environSizesGet result environc * 4 bytes are written to this offset
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// - environBuf: offset to write the null-terminated variables to api.Memory
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// - the format is like os.Environ: null-terminated "key=val" entries
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// - environSizesGet result environLen bytes are written to this offset
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//
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// Result (Errno)
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//
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// The return value is 0 except the following error conditions:
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// - sys.EFAULT: there is not enough memory to write results
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//
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// For example, if environSizesGet wrote environc=2 and environLen=9 for
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// environment variables: "a=b", "b=cd" and parameters environ=11 and
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// environBuf=1, this function writes the below to api.Memory:
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//
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// environLen uint32le uint32le
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// +------------------------------------+ +--------+ +--------+
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// | | | | | |
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// []byte{?, 'a', '=', 'b', 0, 'b', '=', 'c', 'd', 0, ?, 1, 0, 0, 0, 5, 0, 0, 0, ?}
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// environBuf --^ ^ ^
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// environ offset for "a=b" --+ |
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// environ offset for "b=cd" --+
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//
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// See environSizesGet
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// See https://github.com/WebAssembly/WASI/blob/snapshot-01/phases/snapshot/docs.md#environ_get
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// See https://en.wikipedia.org/wiki/Null-terminated_string
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var environGet = newHostFunc(wasip1.EnvironGetName, environGetFn, []wasm.ValueType{i32, i32}, "environ", "environ_buf")
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func environGetFn(_ context.Context, mod api.Module, params []uint64) sys.Errno {
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sysCtx := mod.(*wasm.ModuleInstance).Sys
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environ, environBuf := uint32(params[0]), uint32(params[1])
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return writeOffsetsAndNullTerminatedValues(mod.Memory(), sysCtx.Environ(), environ, environBuf, sysCtx.EnvironSize())
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}
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// environSizesGet is the WASI function named EnvironSizesGetName that
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// reads environment variable sizes.
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//
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// # Parameters
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//
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// - resultEnvironc: offset to write the count of environment variables to
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// api.Memory
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// - resultEnvironvLen: offset to write the null-terminated environment
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// variable length to api.Memory
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//
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// Result (Errno)
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//
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// The return value is 0 except the following error conditions:
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// - sys.EFAULT: there is not enough memory to write results
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//
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// For example, if environ are "a=b","b=cd" and parameters resultEnvironc=1 and
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// resultEnvironvLen=6, this function writes the below to api.Memory:
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//
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// uint32le uint32le
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// +--------+ +--------+
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// | | | |
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// []byte{?, 2, 0, 0, 0, ?, 9, 0, 0, 0, ?}
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// resultEnvironc --^ ^
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// 2 variables --+ |
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// resultEnvironvLen --|
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// len([]byte{'a','=','b',0, |
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// 'b','=','c','d',0}) --+
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//
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// See environGet
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// https://github.com/WebAssembly/WASI/blob/snapshot-01/phases/snapshot/docs.md#environ_sizes_get
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// and https://en.wikipedia.org/wiki/Null-terminated_string
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var environSizesGet = newHostFunc(wasip1.EnvironSizesGetName, environSizesGetFn, []wasm.ValueType{i32, i32}, "result.environc", "result.environv_len")
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func environSizesGetFn(_ context.Context, mod api.Module, params []uint64) sys.Errno {
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sysCtx := mod.(*wasm.ModuleInstance).Sys
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mem := mod.Memory()
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resultEnvironc, resultEnvironvLen := uint32(params[0]), uint32(params[1])
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// environc and environv_len offsets are not necessarily sequential, so we
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// have to write them independently.
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if !mem.WriteUint32Le(resultEnvironc, uint32(len(sysCtx.Environ()))) {
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return sys.EFAULT
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}
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if !mem.WriteUint32Le(resultEnvironvLen, sysCtx.EnvironSize()) {
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return sys.EFAULT
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}
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return 0
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}
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