serialize.go

Documentation: github.com/coreos/go-systemd/v22/unit

     1  // Copyright 2015 CoreOS, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package unit
    16  
    17  import (
    18  	"bytes"
    19  	"io"
    20  )
    21  
    22  // Serialize encodes all of the given UnitOption objects into a
    23  // unit file. When serialized the options are sorted in their
    24  // supplied order but grouped by section.
    25  func Serialize(opts []*UnitOption) io.Reader {
    26  	var buf bytes.Buffer
    27  
    28  	if len(opts) == 0 {
    29  		return &buf
    30  	}
    31  
    32  	// Index of sections -> ordered options
    33  	idx := map[string][]*UnitOption{}
    34  	// Separately preserve order in which sections were seen
    35  	sections := []string{}
    36  	for _, opt := range opts {
    37  		sec := opt.Section
    38  		if _, ok := idx[sec]; !ok {
    39  			sections = append(sections, sec)
    40  		}
    41  		idx[sec] = append(idx[sec], opt)
    42  	}
    43  
    44  	for i, sect := range sections {
    45  		writeSectionHeader(&buf, sect)
    46  		writeNewline(&buf)
    47  
    48  		opts := idx[sect]
    49  		for _, opt := range opts {
    50  			writeOption(&buf, opt)
    51  			writeNewline(&buf)
    52  		}
    53  		if i < len(sections)-1 {
    54  			writeNewline(&buf)
    55  		}
    56  	}
    57  
    58  	return &buf
    59  }
    60  
    61  // SerializeSections will serializes the unit file from the given
    62  // UnitSections.
    63  func SerializeSections(sections []*UnitSection) io.Reader {
    64  
    65  	var buf bytes.Buffer
    66  
    67  	for i, s := range sections {
    68  		writeSectionHeader(&buf, s.Section)
    69  		writeNewline(&buf)
    70  
    71  		for _, e := range s.Entries {
    72  			writeOption(&buf, &UnitOption{s.Section, e.Name, e.Value})
    73  			writeNewline(&buf)
    74  		}
    75  
    76  		if i < len(sections)-1 {
    77  			writeNewline(&buf)
    78  		}
    79  	}
    80  
    81  	return &buf
    82  }
    83  
    84  func writeNewline(buf *bytes.Buffer) {
    85  	buf.WriteRune('\n')
    86  }
    87  
    88  func writeSectionHeader(buf *bytes.Buffer, section string) {
    89  	buf.WriteRune('[')
    90  	buf.WriteString(section)
    91  	buf.WriteRune(']')
    92  }
    93  
    94  func writeOption(buf *bytes.Buffer, opt *UnitOption) {
    95  	buf.WriteString(opt.Name)
    96  	buf.WriteRune('=')
    97  	buf.WriteString(opt.Value)
    98  }
    99
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