filter_appendtotempfile.go

// scriptish is a library to help you port bash scripts to Golang
//
// inspired by:
//
// - http://labix.org/pipe
// - https://github.com/bitfield/script
//
// Copyright 2019-present Ganbaro Digital Ltd
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
//   * Redistributions of source code must retain the above copyright
//     notice, this list of conditions and the following disclaimer.
//
//   * Redistributions in binary form must reproduce the above copyright
//     notice, this list of conditions and the following disclaimer in
//     the documentation and/or other materials provided with the
//     distribution.
//
//   * Neither the names of the copyright holders nor the names of his
//     contributors may be used to endorse or promote products derived
//     from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.

package scriptish

import (
	"io/ioutil"
)

// AppendToTempFile writes the contents of the pipeline's stdin to a
// temporary file. The temporary file's filename is then written to
// the pipeline's stdout.
//
// If the file does not exist, it is created.
func AppendToTempFile(dir string, pattern string, opts ...*StepOption) *SequenceStep {
	// build our Scriptish command
	return NewSequenceStep(
		func(p *Pipe) (int, error) {
			// expand our inputs
			expDir := p.Env.Expand(dir)
			expPattern := p.Env.Expand(pattern)

			// debugging support
			Tracef("AppendToTempFile(%#v, %#v)", dir, pattern)
			Tracef("=> AppendToTempFile(%#v, %#v)", expDir, expPattern)

			// create the temporary file
			fh, err := ioutil.TempFile(expDir, expPattern)
			if err != nil {
				return StatusNotOkay, err
			}

			// debugging support
			Tracef("AppendToTempFile(): created file %#v", fh.Name())

			// remember to automatically close the file when we've finished
			// in here
			defer func() {
				fh.Close()

				// write the temporary file's filename out last
				p.Stdout.WriteString(fh.Name())
				p.Stdout.WriteRune('\n')
			}()

			// write to the file
			for line := range getSinkReader(p) {
				TraceOutput("tempfile", "%s", line)
				_, err = fh.WriteString(line)
				if err != nil {
					return StatusNotOkay, err
				}
				_, err = fh.WriteString("\n")
				if err != nil {
					return StatusNotOkay, err
				}
			}

			// all done
			return StatusOkay, nil
		},
		opts...,
	)
}