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Use printf instead of $'' to pass a multi-line string to bash #2874

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Nov 12, 2024
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Use printf instead of $'' to pass a multi-line string to bash #2874

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21 changes: 16 additions & 5 deletions pkg/hostagent/requirements.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ package hostagent
import (
"errors"
"fmt"
"strings"
"time"

"github.com/lima-vm/lima/pkg/limayaml"
Expand Down Expand Up @@ -61,14 +62,17 @@ func (a *HostAgent) waitForRequirements(label string, requirements []requirement
// EOF
// /usr/bin/env ruby
//
// ssh.ExecuteScript will strip the `#!` prefix from the first line and invoke the rest
// of the line as the command. The full script is then passed via STDIN. We use the $' '
// form of shell quoting to be able to use \n as newline escapes to fit everything on a
// ssh.ExecuteScript will strip the `#!` prefix from the first line and invoke the
// rest of the line as the command. The full script is then passed via STDIN. We use
// "$(printf '…')" to be able to use \n as newline escapes, to fit everything on a
// single line:
//
// #!/bin/bash -c $'while … done<<EOF\n$(sudo …)\nEOF\n/usr/bin/env ruby'
// #!/bin/bash -c "$(printf 'while … done<<EOF\n$(sudo …)\nEOF\n/usr/bin/env ruby')"
// #!/usr/bin/env ruby
// …
//
// An earlier implementation used $'…' for quoting, but that isn't supported if the
// user switched the default shell to fish.
func prefixExportParam(script string) (string, error) {
interpreter, err := ssh.ParseScriptInterpreter(script)
if err != nil {
Expand All @@ -77,7 +81,14 @@ func prefixExportParam(script string) (string, error) {

// TODO we should have a symbolic constant for `/mnt/lima-cidata`
exportParam := `while read -r line; do [ -n "$line" ] && export "$line"; done<<EOF\n$(sudo cat /mnt/lima-cidata/param.env)\nEOF\n`
return fmt.Sprintf("#!/bin/bash -c $'%s%s'\n%s", exportParam, interpreter, script), nil

// double up all '%' characters so we can pass them through unchanged in the format string of printf
interpreter = strings.ReplaceAll(interpreter, "%", "%%")
exportParam = strings.ReplaceAll(exportParam, "%", "%%")
// strings will be interpolated into single-quoted strings, so protect any existing single quotes
interpreter = strings.ReplaceAll(interpreter, "'", `'"'"'`)
exportParam = strings.ReplaceAll(exportParam, "'", `'"'"'`)
Comment on lines +85 to +90
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All these replacements are not really needed because the input strings don't include % or ' characters. but it feels like the right thing to do to make them correct for that case as well.

return fmt.Sprintf("#!/bin/bash -c \"$(printf '%s%s')\"\n%s", exportParam, interpreter, script), nil
}

func (a *HostAgent) waitForRequirement(r requirement) error {
Expand Down
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