On Tue, Jul 24, 2012 at 21:17:04 +0200, Julien Cristau wrote:
> Did this stuff ever get fixed? screen's NEWS.Debian suggests it isn't,
> which I find rather annoying. Said NEWS file also recommends
> downloading and running code from a random web server as root, which
> really doesn't seem appropriate, even in the context of this bug. If
> this is indeed the state of screen in wheezy I'm thinking it'd be better
> to go back to the previous (pre-compatibility-break) version.
>
I'm unimpressed. Seems like working around this in screen itself is way
simpler than the horrible kludge in the current maintainer scripts. The
following patch, while not all that pretty, seems to allow me to attach
to a screen started with either the squeeze or sid version. I'm sure
there's corner cases, but.
Cheers,
Julien
Index: screen-4.1.0~20120320gitdb59704/screen.h
===================================================================
--- screen-4.1.0~20120320gitdb59704.orig/screen.h
+++ screen-4.1.0~20120320gitdb59704/screen.h
@@ -240,6 +240,57 @@ struct msg
} m;
};
+struct old_msg
+{
+ int protocol_revision; /* reduce harm done by incompatible messages */
+ int type;
+ char m_tty[MAXPATHLEN]; /* ttyname */
+ union
+ {
+ struct
+ {
+ int lflag;
+ int aflag;
+ int flowflag;
+ int hheight; /* size of scrollback buffer */
+ int nargs;
+ char line[MAXPATHLEN];
+ char dir[MAXPATHLEN];
+ char screenterm[20]; /* is screen really "screen" ? */
+ }
+ create;
+ struct
+ {
+ char auser[20 + 1]; /* username */
+ int apid; /* pid of frontend */
+ int adaptflag; /* adapt window size? */
+ int lines, columns; /* display size */
+ char preselect[20];
+ int esc; /* his new escape character unless -1 */
+ int meta_esc; /* his new meta esc character unless -1 */
+ char envterm[20 + 1]; /* terminal type */
+ int encoding; /* encoding of display */
+ }
+ attach;
+ struct
+ {
+ char duser[20 + 1]; /* username */
+ int dpid; /* pid of frontend */
+ }
+ detach;
+ struct
+ {
+ char auser[20 + 1]; /* username */
+ int nargs;
+ char cmd[MAXPATHLEN]; /* command */
+ int apid; /* pid of frontend */
+ char preselect[20];
+ }
+ command;
+ char message[MAXPATHLEN * 2];
+ } m;
+};
+
/*
* And the signals the attacher receives from the backend
*/
Index: screen-4.1.0~20120320gitdb59704/socket.c
===================================================================
--- screen-4.1.0~20120320gitdb59704.orig/socket.c
+++ screen-4.1.0~20120320gitdb59704/socket.c
@@ -1067,7 +1067,9 @@ ReceiveMsg()
}
if (left > 0)
{
- if (left != sizeof(m))
+ if (left == sizeof(struct msg) - sizeof(struct old_msg))
+ ;/* old format message, ignore */
+ else if (left != sizeof(m))
Msg(0, "Message %d of %d bytes too small", left, (int)sizeof(m));
else
debug("No data on socket.\n");
Index: screen-4.1.0~20120320gitdb59704/attacher.c
===================================================================
--- screen-4.1.0~20120320gitdb59704.orig/attacher.c
+++ screen-4.1.0~20120320gitdb59704/attacher.c
@@ -133,6 +133,46 @@ struct msg *m;
return 0;
}
+int
+WriteOldMessage(struct msg *m)
+{
+ sleep(1); /* give the server some time to reopen the pipe */
+ if (m->type == MSG_ATTACH && m->m.attach.detachfirst == MSG_ATTACH)
+ {
+ struct old_msg old_m;
+ int s;
+ int r, l = sizeof(old_m);
+
+ s = MakeClientSocket(0);
+ if (s < 0)
+ return 0;
+ old_m.protocol_revision = (('m'<<24) | ('s'<<16) | ('g'<<8) | 0);
+ old_m.type = m->type;
+ memcpy(old_m.m_tty, m->m_tty, sizeof(old_m.m_tty));
+ memcpy(old_m.m.attach.auser, m->m.attach.auser, sizeof(old_m.m.attach.auser));
+ old_m.m.attach.apid = m->m.attach.apid;
+ old_m.m.attach.adaptflag = m->m.attach.adaptflag;
+ old_m.m.attach.lines = m->m.attach.lines;
+ old_m.m.attach.columns = m->m.attach.columns;
+ memcpy(old_m.m.attach.preselect, m->m.attach.preselect, sizeof(old_m.m.attach.preselect));
+ old_m.m.attach.esc = m->m.attach.esc;
+ old_m.m.attach.meta_esc = m->m.attach.meta_esc;
+ memcpy(old_m.m.attach.envterm, m->m.attach.envterm, sizeof(old_m.m.attach.envterm));
+ old_m.m.attach.encoding = m->m.attach.encoding;
+ while(l > 0)
+ {
+ r = write(s, (char *)&old_m + (sizeof(struct old_msg) - l), l);
+ if (r == -1 && errno == EINTR)
+ continue;
+ if (r == -1 || r == 0)
+ return -1;
+ l -= r;
+ }
+ close(s);
+ }
+ return 0;
+}
+
int
Attach(how)
@@ -397,6 +437,7 @@ int how;
if (WriteMessage(lasts, &m))
Panic(errno, "WriteMessage");
close(lasts);
+ WriteOldMessage(&m);
debug1("Attach(%d): sent\n", m.type);
#ifdef MULTIUSER
if (multi && (how == MSG_ATTACH || how == MSG_CONT))
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