60-644788-screen-4.1.0-4.0.3-interoperability.patch

   1 Author: Julien Cristau <jcristau@debian.org>
   2 Debian-Bug: #644788
   3
   4 Author: Axel Beckert <abe@debian.org>
   5 Debian-Bug: #684342
   6
   7 The following patch, while not all that pretty, seems to allow me to
   8 attach to a screen started with either the squeeze or sid version.
   9 I'm sure there's corner cases, but.
  10
  11 Cheers,
  12 Julien
  13
  14 Index: screen/screen.h
  15 ===================================================================
  16 --- screen.orig/screen.h        2012-08-09 01:01:28.000000000 +0200
  17 +++ screen/screen.h     2012-08-09 01:01:28.000000000 +0200
  18 @@ -240,6 +240,57 @@ struct msg
  19      } m;
  20  };
  21
  22 +struct old_msg
  23 +{
  24 +  int protocol_revision;       /* reduce harm done by incompatible messages */
  25 +  int type;
  26 +  char m_tty[MAXPATHLEN];      /* ttyname */
  27 +  union
  28 +    {
  29 +      struct
  30 +       {
  31 +         int lflag;
  32 +         int aflag;
  33 +         int flowflag;
  34 +         int hheight;          /* size of scrollback buffer */
  35 +         int nargs;
  36 +         char line[MAXPATHLEN];
  37 +         char dir[MAXPATHLEN];
  38 +         char screenterm[20];  /* is screen really "screen" ? */
  39 +       }
  40 +      create;
  41 +      struct
  42 +       {
  43 +         char auser[20 + 1];   /* username */
  44 +         int apid;             /* pid of frontend */
  45 +         int adaptflag;        /* adapt window size? */
  46 +         int lines, columns;   /* display size */
  47 +         char preselect[20];
  48 +         int esc;              /* his new escape character unless -1 */
  49 +         int meta_esc;         /* his new meta esc character unless -1 */
  50 +         char envterm[20 + 1]; /* terminal type */
  51 +         int encoding;         /* encoding of display */
  52 +       }
  53 +      attach;
  54 +      struct
  55 +       {
  56 +         char duser[20 + 1];   /* username */
  57 +         int dpid;             /* pid of frontend */
  58 +       }
  59 +      detach;
  60 +      struct
  61 +       {
  62 +         char auser[20 + 1];   /* username */
  63 +         int nargs;
  64 +         char cmd[MAXPATHLEN]; /* command */
  65 +         int apid;             /* pid of frontend */
  66 +         char preselect[20];
  67 +       }
  68 +      command;
  69 +      char message[MAXPATHLEN * 2];
  70 +    } m;
  71 +};
  72 +
  73  /*
  74   * And the signals the attacher receives from the backend
  75   */
  76 Index: screen/socket.c
  77 ===================================================================
  78 --- screen.orig/socket.c        2012-08-09 01:01:28.000000000 +0200
  79 +++ screen/socket.c     2012-08-09 01:01:29.000000000 +0200
  80 @@ -1067,7 +1067,9 @@ ReceiveMsg()
  81      }
  82    if (left > 0)
  83      {
  84 -      if (left != sizeof(m))
  85 +      if (left == sizeof(struct msg) - sizeof(struct old_msg))
  86 +        ;/* old format message, ignore */
  87 +      else if (left != sizeof(m))
  88          Msg(0, "Message %d of %d bytes too small", left, (int)sizeof(m));
  89        else
  90         debug("No data on socket.\n");
  91 Index: screen/attacher.c
  92 ===================================================================
  93 --- screen.orig/attacher.c      2012-08-09 01:01:28.000000000 +0200
  94 +++ screen/attacher.c   2012-08-09 01:32:08.000000000 +0200
  95 @@ -133,6 +133,48 @@ struct msg *m;
  96    return 0;
  97  }
  98
  99 +int
 100 +WriteOldMessage(struct msg *m)
 101 +{
 102 +  sleep(1); /* give the server some time to reopen the pipe */
 103 +  if (m->type == MSG_ATTACH && (m->m.attach.detachfirst == MSG_ATTACH ||
 104 +                               m->m.attach.detachfirst == MSG_DETACH ||
 105 +                               m->m.attach.detachfirst == MSG_POW_DETACH))
 106 +    {
 107 +      struct old_msg old_m;
 108 +      int s;
 109 +      int r, l = sizeof(old_m);
 110 +
 111 +      s = MakeClientSocket(0);
 112 +      if (s < 0)
 113 +       return 0;
 114 +      old_m.protocol_revision = (('m'<<24) | ('s'<<16) | ('g'<<8) | 0);
 115 +      old_m.type = m->type;
 116 +      memcpy(old_m.m_tty, m->m_tty, sizeof(old_m.m_tty));
 117 +      memcpy(old_m.m.attach.auser, m->m.attach.auser, sizeof(old_m.m.attach.auser));
 118 +      old_m.m.attach.apid = m->m.attach.apid;
 119 +      old_m.m.attach.adaptflag = m->m.attach.adaptflag;
 120 +      old_m.m.attach.lines = m->m.attach.lines;
 121 +      old_m.m.attach.columns = m->m.attach.columns;
 122 +      memcpy(old_m.m.attach.preselect, m->m.attach.preselect, sizeof(old_m.m.attach.preselect));
 123 +      old_m.m.attach.esc = m->m.attach.esc;
 124 +      old_m.m.attach.meta_esc = m->m.attach.meta_esc;
 125 +      memcpy(old_m.m.attach.envterm, m->m.attach.envterm, sizeof(old_m.m.attach.envterm));
 126 +      old_m.m.attach.encoding = m->m.attach.encoding;
 127 +      while(l > 0)
 128 +        {
 129 +          r = write(s, (char *)&old_m + (sizeof(struct old_msg) - l), l);
 130 +          if (r == -1 && errno == EINTR)
 131 +       continue;
 132 +          if (r == -1 || r == 0)
 133 +       return -1;
 134 +          l -= r;
 135 +        }
 136 +      close(s);
 137 +    }
 138 +  return 0;
 139 +}
 140 +
 141
 142  int
 143  Attach(how)
 144 @@ -397,6 +439,7 @@ int how;
 145    if (WriteMessage(lasts, &m))
 146      Panic(errno, "WriteMessage");
 147    close(lasts);
 148 +  WriteOldMessage(&m);
 149    debug1("Attach(%d): sent\n", m.type);
 150  #ifdef MULTIUSER
 151    if (multi && (how == MSG_ATTACH || how == MSG_CONT))