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 func main() {
  43         gitCmd := flag.String("git-cmd", "/usr/local/bin/git", "Path to git executable")
  44         gitDir := flag.String("git-dir", "", "Path to .git repository")
  45         notesRef := flag.String("ref", "comments", "notes reference name")
  46         umask := flag.String("umask", "027", "umask value")
  47         dryRun := flag.Bool("dryrun", false, "Show comment, do not add")
  48         committerEmail := flag.String(
  49                 "committer-email",
  50                 "comment@blog.example.com",
  51                 "Git committer's email",
  52         )
  53         flag.Parse()
  54         uid := syscall.Geteuid()
  55         if err := syscall.Setuid(uid); err != nil {
  56                 log.Fatal(err)
  57         }
  58         umaskInt, err := strconv.ParseUint(*umask, 8, 16)
  59         if err != nil {
  60                 panic(err)
  61         }
  62         syscall.Umask(int(umaskInt))
  63
  64         msg, err := mail.ReadMessage(os.Stdin)
  65         if err != nil {
  66                 log.Fatal(err)
  67         }
  68         subj, r, err := parseEmail(msg)
  69         if err != nil {
  70                 log.Fatal(err)
  71         }
  72         body, err := ioutil.ReadAll(r)
  73         if err != nil {
  74                 log.Fatal(err)
  75         }
  76         from := msg.Header.Get("From")
  77         if from == "" {
  78                 log.Fatal("From is missing")
  79         }
  80         if len(body) == 0 {
  81                 log.Fatal("no body")
  82         }
  83         from, err = new(mime.WordDecoder).DecodeHeader(from)
  84         if err != nil {
  85                 log.Fatal(err)
  86         }
  87
  88         subj = strings.TrimPrefix(subj, "Re: ")
  89         if h, err := hex.DecodeString(subj); err != nil || len(h) != sha1.Size {
  90                 os.Exit(0)
  91         }
  92         fromCols := strings.Fields(from)
  93         if len(fromCols) == 1 {
  94                 if idx := strings.Index(from, "@"); idx != -1 {
  95                         from = strings.Trim(from[:idx], "<>")
  96                 }
  97         } else {
  98                 from = strings.Join(fromCols[:len(fromCols)-1], " ")
  99         }
 100
 101         cmd := exec.Command(
 102                 *gitCmd, "--git-dir", *gitDir,
 103                 "notes", "--ref", *notesRef, "show", subj,
 104         )
 105         note, _ := cmd.Output()
 106         note = bytes.TrimRight(note, "\r\n")
 107
 108         // Remove trailing whitespaces, because git-notes-add will remove
 109         // them anyway, and we have to know exact bytes count
 110         lines := strings.Split(string(body), "\n")
 111         for i, line := range lines {
 112                 lines[i] = strings.TrimRight(line, " \r")
 113         }
 114         for lines[len(lines)-1] == "" {
 115                 lines = lines[:len(lines)-1]
 116         }
 117
 118         buf := bytes.NewBuffer(note)
 119         w := netstring.NewWriter(buf)
 120         w.WriteChunk([]byte(fmt.Sprintf(
 121                 "From: %s\nDate: %s\n\n%s",
 122                 from,
 123                 time.Now().UTC().Format(sgblog.WhenFmt),
 124                 strings.Join(lines, "\n"),
 125         )))
 126
 127         if *dryRun {
 128                 fmt.Print(buf.String())
 129                 os.Exit(0)
 130         }
 131
 132         cmd = exec.Command(
 133                 *gitCmd, "--git-dir", *gitDir,
 134                 "notes", "--ref", *notesRef, "add",
 135                 "-F", "-", "-f", subj,
 136         )
 137         cmd.Env = append(
 138                 cmd.Env,
 139                 "GIT_AUTHOR_NAME=SGBlog "+sgblog.Version,
 140                 "GIT_AUTHOR_EMAIL="+*committerEmail,
 141                 "GIT_COMMITTER_NAME=SGBlog "+sgblog.Version,
 142                 "GIT_COMMITTER_EMAIL="+*committerEmail,
 143         )
 144         cmd.Stdin = buf
 145         if err = cmd.Run(); err != nil {
 146                 log.Fatal(err)
 147         }
 148 }