cmd/sgblog-comment-add/main.go

   1 /*
   2 SGBlog -- Git-backed CGI/inetd blogging/phlogging engine
   3 Copyright (C) 2020 Sergey Matveev <stargrave@stargrave.org>
   4
   5 This program is free software: you can redistribute it and/or modify
   6 it under the terms of the GNU Affero General Public License as
   7 published by the Free Software Foundation, version 3 of the License.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU Affero General Public License
  15 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16 */
  17
  18 // Git-backed CGI/inetd blogging/phlogging engine
  19 package main
  20
  21 import (
  22         "bytes"
  23         "crypto/sha1"
  24         "encoding/hex"
  25         "flag"
  26         "fmt"
  27         "io/ioutil"
  28         "log"
  29         "mime"
  30         "net/mail"
  31         "os"
  32         "os/exec"
  33         "strconv"
  34         "strings"
  35         "syscall"
  36         "time"
  37
  38         "go.cypherpunks.ru/netstring/v2"
  39         "go.stargrave.org/sgblog"
  40 )
  41
  42 // Remove various whitespaces and excess lines, because git-notes-add
  43 // will remove and we have to know exact bytes count
  44 func cleanupBody(body string) string {
  45         lines := strings.Split(string(body), "\n")
  46         for i, line := range lines {
  47                 line = strings.ReplaceAll(line, "       ", "    ")
  48                 line = strings.TrimRight(line, " \r")
  49                 lines[i] = line
  50         }
  51         for lines[0] == "" {
  52                 lines = lines[1:]
  53         }
  54         for lines[len(lines)-1] == "" {
  55                 lines = lines[:len(lines)-1]
  56         }
  57         withoutDups := make([]string, 0, len(lines))
  58         emptyMet := false
  59         for _, line := range lines {
  60                 if line == "" {
  61                         if emptyMet {
  62                                 continue
  63                         }
  64                         emptyMet = true
  65                 } else {
  66                         emptyMet = false
  67                 }
  68                 withoutDups = append(withoutDups, line)
  69         }
  70         return strings.Join(withoutDups, "\n")
  71 }
  72
  73 func main() {
  74         gitCmd := flag.String("git-cmd", "/usr/local/bin/git", "Path to git executable")
  75         gitDir := flag.String("git-dir", "", "Path to .git repository")
  76         notesRef := flag.String("ref", "comments", "notes reference name")
  77         umask := flag.String("umask", "027", "umask value")
  78         dryRun := flag.Bool("dryrun", false, "Show comment, do not add")
  79         committerEmail := flag.String(
  80                 "committer-email",
  81                 "comment@blog.example.com",
  82                 "Git committer's email",
  83         )
  84         flag.Parse()
  85         uid := syscall.Geteuid()
  86         if err := syscall.Setuid(uid); err != nil {
  87                 log.Fatal(err)
  88         }
  89         umaskInt, err := strconv.ParseUint(*umask, 8, 16)
  90         if err != nil {
  91                 panic(err)
  92         }
  93         syscall.Umask(int(umaskInt))
  94
  95         msg, err := mail.ReadMessage(os.Stdin)
  96         if err != nil {
  97                 log.Fatal(err)
  98         }
  99         subj, r, err := parseEmail(msg)
 100         if err != nil {
 101                 log.Fatal(err)
 102         }
 103         body, err := ioutil.ReadAll(r)
 104         if err != nil {
 105                 log.Fatal(err)
 106         }
 107         from := msg.Header.Get("From")
 108         if from == "" {
 109                 log.Fatal("From is missing")
 110         }
 111         if len(body) == 0 {
 112                 log.Fatal("no body")
 113         }
 114         from, err = new(mime.WordDecoder).DecodeHeader(from)
 115         if err != nil {
 116                 log.Fatal(err)
 117         }
 118
 119         subj = strings.TrimPrefix(subj, "Re: ")
 120         if h, err := hex.DecodeString(subj); err != nil || len(h) != sha1.Size {
 121                 os.Exit(0)
 122         }
 123         fromCols := strings.Fields(from)
 124         if len(fromCols) == 1 {
 125                 if idx := strings.Index(from, "@"); idx != -1 {
 126                         from = strings.Trim(from[:idx], "<>")
 127                 }
 128         } else {
 129                 from = strings.Join(fromCols[:len(fromCols)-1], " ")
 130         }
 131
 132         cmd := exec.Command(
 133                 *gitCmd, "--git-dir", *gitDir,
 134                 "notes", "--ref", *notesRef, "show", subj,
 135         )
 136         note, _ := cmd.Output()
 137         note = bytes.TrimRight(note, "\r\n")
 138
 139         buf := bytes.NewBuffer(note)
 140         w := netstring.NewWriter(buf)
 141         w.WriteChunk([]byte(fmt.Sprintf(
 142                 "From: %s\nDate: %s\n\n%s",
 143                 from,
 144                 time.Now().UTC().Format(sgblog.WhenFmt),
 145                 cleanupBody(string(body)),
 146         )))
 147
 148         if *dryRun {
 149                 fmt.Print(buf.String())
 150                 os.Exit(0)
 151         }
 152
 153         cmd = exec.Command(
 154                 *gitCmd, "--git-dir", *gitDir,
 155                 "notes", "--ref", *notesRef, "add",
 156                 "-F", "-", "-f", subj,
 157         )
 158         cmd.Env = append(
 159                 cmd.Env,
 160                 "GIT_AUTHOR_NAME=SGBlog "+sgblog.Version,
 161                 "GIT_AUTHOR_EMAIL="+*committerEmail,
 162                 "GIT_COMMITTER_NAME=SGBlog "+sgblog.Version,
 163                 "GIT_COMMITTER_EMAIL="+*committerEmail,
 164         )
 165         cmd.Stdin = buf
 166         if err = cmd.Run(); err != nil {
 167                 log.Fatal(err)
 168         }
 169 }