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54 lines
1.6 KiB
Go
54 lines
1.6 KiB
Go
// Copyright IBM Corp. 2013, 2025
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// SPDX-License-Identifier: BUSL-1.1
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package function
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import (
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"bytes"
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"compress/gzip"
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"encoding/base64"
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"fmt"
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"github.com/zclconf/go-cty/cty"
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"github.com/zclconf/go-cty/cty/function"
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)
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// Base64GzipFunc constructs a function that compresses a string with gzip and then encodes the result in
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// Base64 encoding.
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var Base64GzipFunc = function.New(&function.Spec{
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Params: []function.Parameter{
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{
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Name: "str",
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Type: cty.String,
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},
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},
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Type: function.StaticReturnType(cty.String),
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Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
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s := args[0].AsString()
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var b bytes.Buffer
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gz := gzip.NewWriter(&b)
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if _, err := gz.Write([]byte(s)); err != nil {
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return cty.UnknownVal(cty.String), fmt.Errorf("failed to write gzip raw data: %w", err)
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}
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if err := gz.Flush(); err != nil {
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return cty.UnknownVal(cty.String), fmt.Errorf("failed to flush gzip writer: %w", err)
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}
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if err := gz.Close(); err != nil {
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return cty.UnknownVal(cty.String), fmt.Errorf("failed to close gzip writer: %w", err)
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}
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return cty.StringVal(base64.StdEncoding.EncodeToString(b.Bytes())), nil
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},
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})
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// Base64Gzip compresses a string with gzip and then encodes the result in
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// Base64 encoding.
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//
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// Packer uses the "standard" Base64 alphabet as defined in RFC 4648 section 4.
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//
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// Strings in the Packer language are sequences of unicode characters rather
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// than bytes, so this function will first encode the characters from the string
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// as UTF-8, then apply gzip compression, and then finally apply Base64 encoding.
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func Base64Gzip(str cty.Value) (cty.Value, error) {
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return Base64GzipFunc.Call([]cty.Value{str})
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}
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