bug#46998: wish: package xvfb-run

bug#46998: wish: package xvfb-run

[Dr. Arne Babenhauserheide]

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User-agent: mu4e 1.4.15; emacs 27.1
(emacs:30177): dbind-WARNING **: 01:46:31.849: Could not open X display

http://deb.debian.org/debian/pool/main/x/xorg-server/xorg-server_1.20.10-3.diff.gz

+Usage: $PROGNAME [OPTION ...] COMMAND
+Options:
+DISPLAY=:$SERVERNUM XAUTHORITY=$AUTHFILE "$@"
Dear Guix hackers,

One of my main tools for running graphical programs as part of my build
pipelines is xvfb-run. Since it is not packaged in Guix, I’ve resorted
to manual workarounds, but these have annoying drawbacks:

Xvfb :3 -screen 0 1024x768x16 & time DISPLAY=:3 HOME=/path/to/project/.emacs.d emacs …

I now get errors about the maximum number of clients reached, because
the Xvfb does not get reaped after the build:
Maximum number of clients reached
Therefore I would ask whether it would be possible to package xvfb-run.
It is provided as part of the patches of the xorg-package in Debian:

The included xvfb-run and xvfb-run.1:

--- xorg-server-1.20.10.orig/debian/local/xvfb-run
+++ xorg-server-1.20.10/debian/local/xvfb-run
@@ -0,0 +1,191 @@
+#!/bin/sh
+
+# This script starts an instance of Xvfb, the "fake" X server, runs a command
+# with that server available, and kills the X server when done.  The return
+# value of the command becomes the return value of this script.
+#
+# If anyone is using this to build a Debian package, make sure the package
+# Build-Depends on xvfb and xauth.
+
+set -e
+
+PROGNAME=xvfb-run
+SERVERNUM=99
+AUTHFILE=
+ERRORFILE=/dev/null
+XVFBARGS="-screen 0 1280x1024x24"
+LISTENTCP="-nolisten tcp"
+XAUTHPROTO=.
+
+# Query the terminal to establish a default number of columns to use for
+# displaying messages to the user.  This is used only as a fallback in the event
+# the COLUMNS variable is not set.  ($COLUMNS can react to SIGWINCH while the
+# script is running, and this cannot, only being calculated once.)
+DEFCOLUMNS=$(stty size 2>/dev/null | awk '{print $2}') || true
+case "$DEFCOLUMNS" in
+    *[!0-9]*|'') DEFCOLUMNS=80 ;;
+esac
+
+# Display a message, wrapping lines at the terminal width.
+message () {
+    echo "$PROGNAME: $*" | fmt -t -w ${COLUMNS:-$DEFCOLUMNS}
+}
+
+# Display an error message.
+error () {
+    message "error: $*" >&2
+}
+
+# Display a usage message.
+usage () {
+    if [ -n "$*" ]; then
+        message "usage error: $*"
+    fi
+    cat <<EOF
+Run COMMAND (usually an X client) in a virtual X server environment.
+-a        --auto-servernum          try to get a free server number, starting at
+                                    --server-num
+-e FILE   --error-file=FILE         file used to store xauth errors and Xvfb
+                                    output (default: $ERRORFILE)
+-f FILE   --auth-file=FILE          file used to store auth cookie
+                                    (default: ./.Xauthority)
+-h        --help                    display this usage message and exit
+-n NUM    --server-num=NUM          server number to use (default: $SERVERNUM)
+-l        --listen-tcp              enable TCP port listening in the X server
+-p PROTO  --xauth-protocol=PROTO    X authority protocol name to use
+                                    (default: xauth command's default)
+-s ARGS   --server-args=ARGS        arguments (other than server number and
+                                    "-nolisten tcp") to pass to the Xvfb server
+                                    (default: "$XVFBARGS")
+EOF
+}
+
+# Find a free server number by looking at .X*-lock files in /tmp.
+find_free_servernum() {
+    # Sadly, the "local" keyword is not POSIX.  Leave the next line commented in
+    # the hope Debian Policy eventually changes to allow it in /bin/sh scripts
+    # anyway.
+    #local i
+
+    i=$SERVERNUM
+    while [ -f /tmp/.X$i-lock ]; do
+        i=$(($i + 1))
+    done
+    echo $i
+}
+
+# Clean up files
+clean_up() {
+    if [ -e "$AUTHFILE" ]; then
+        XAUTHORITY=$AUTHFILE xauth remove ":$SERVERNUM" >>"$ERRORFILE" 2>&1
+    fi
+    if [ -n "$XVFB_RUN_TMPDIR" ]; then
+        if ! rm -r "$XVFB_RUN_TMPDIR"; then
+            error "problem while cleaning up temporary directory"
+            exit 5
+        fi
+    fi
+    if [ -n "$XVFBPID" ]; then
+        kill "$XVFBPID" >>"$ERRORFILE" 2>&1
+    fi
+}
+
+# Parse the command line.
+ARGS=$(getopt --options +ae:f:hn:lp:s:w: \
+       --long auto-servernum,error-file:,auth-file:,help,server-num:,listen-tcp,xauth-protocol:,server-args:,wait: \
+       --name "$PROGNAME" -- "$@")
+GETOPT_STATUS=$?
+
+if [ $GETOPT_STATUS -ne 0 ]; then
+    error "internal error; getopt exited with status $GETOPT_STATUS"
+    exit 6
+fi
+
+eval set -- "$ARGS"
+
+while :; do
+    case "$1" in
+        -a|--auto-servernum) SERVERNUM=$(find_free_servernum); AUTONUM="yes" ;;
+        -e|--error-file) ERRORFILE="$2"; shift ;;
+        -f|--auth-file) AUTHFILE="$2"; shift ;;
+        -h|--help) SHOWHELP="yes" ;;
+        -n|--server-num) SERVERNUM="$2"; shift ;;
+        -l|--listen-tcp) LISTENTCP="" ;;
+        -p|--xauth-protocol) XAUTHPROTO="$2"; shift ;;
+        -s|--server-args) XVFBARGS="$2"; shift ;;
+        -w|--wait) shift ;;
+        --) shift; break ;;
+        *) error "internal error; getopt permitted \"$1\" unexpectedly"
+           exit 6
+           ;;
+    esac
+    shift
+done
+
+if [ "$SHOWHELP" ]; then
+    usage
+    exit 0
+fi
+
+if [ -z "$*" ]; then
+    usage "need a command to run" >&2
+    exit 2
+fi
+
+if ! command -v xauth >/dev/null; then
+    error "xauth command not found"
+    exit 3
+fi
+
+# tidy up after ourselves
+trap clean_up EXIT
+
+# If the user did not specify an X authorization file to use, set up a temporary
+# directory to house one.
+if [ -z "$AUTHFILE" ]; then
+    XVFB_RUN_TMPDIR="$(mktemp -d -t $PROGNAME.XXXXXX)"
+    AUTHFILE="$XVFB_RUN_TMPDIR/Xauthority"
+    # Create empty file to avoid xauth warning
+    touch "$AUTHFILE"
+fi
+
+# Start Xvfb.
+MCOOKIE=$(mcookie)
+tries=10
+while [ $tries -gt 0 ]; do
+    tries=$(( $tries - 1 ))
+    XAUTHORITY=$AUTHFILE xauth source - << EOF >>"$ERRORFILE" 2>&1
+add :$SERVERNUM $XAUTHPROTO $MCOOKIE
+EOF
+    # handle SIGUSR1 so Xvfb knows to send a signal when it's ready to accept
+    # connections
+    trap : USR1
+    (trap '' USR1; exec Xvfb ":$SERVERNUM" $XVFBARGS $LISTENTCP -auth $AUTHFILE >>"$ERRORFILE" 2>&1) &
+    XVFBPID=$!
+
+    wait || :
+    if kill -0 $XVFBPID 2>/dev/null; then
+        break
+    elif [ -n "$AUTONUM" ]; then
+        # The display is in use so try another one (if '-a' was specified).
+        SERVERNUM=$((SERVERNUM + 1))
+        SERVERNUM=$(find_free_servernum)
+        continue
+    fi
+    error "Xvfb failed to start" >&2
+    XVFBPID=
+    exit 1
+done
+
+# Start the command and save its exit status.
+set +e
+RETVAL=$?
+set -e
+
+# Return the executed command's exit status.
+exit $RETVAL
+
+# vim:set ai et sts=4 sw=4 tw=80:
--- xorg-server-1.20.10.orig/debian/local/xvfb-run.1
+++ xorg-server-1.20.10/debian/local/xvfb-run.1
@@ -0,0 +1,275 @@
+.\" Copyright 1998-2004 Branden Robinson <branden@debian.org>.
+.\"
+.\" This is free software; you may redistribute it and/or modify
+.\" it under the terms of the GNU General Public License as
+.\" published by the Free Software Foundation; either version 2,
+.\" or (at your option) any later version.
+.\"
+.\" This is distributed in the hope that it will be useful, but
+.\" WITHOUT ANY WARRANTY; without even the implied warranty of
+.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+.\" GNU General Public License for more details.
+.\"
+.\" You should have received a copy of the GNU General Public License with
+.\" the Debian operating system, in /usr/share/common-licenses/GPL;  if
+.\" not, write to the Free Software Foundation, Inc., 59 Temple Place,
+.\" Suite 330, Boston, MA 02111-1307 USA
+.\"
+.\" We need the URL macro from groff's www macro package, but also want
+.\" things to work all right for people who don't have it.  So we define
+.\" our own URL macro and let the www macro package override it if it's
+.\" available.
+.de URL
+\\$2 \(laURL: \\$1 \(ra\\$3
+..
+.if \n[.g] .mso www.tmac
+.TH xvfb\-run 1 "2004\-11\-12" "Debian Project"
+.SH NAME
+xvfb\-run \- run specified X client or command in a virtual X server environment
+.SH SYNOPSIS
+.B xvfb\-run
+[
+.I options
+]
+.I command
+.SH DESCRIPTION
+.B xvfb\-run
+is a wrapper for the
+.BR Xvfb (1x)
+command which simplifies the task of running commands (typically an X
+client, or a script containing a list of clients to be run) within a virtual
+X server environment.
+.PP
+.B xvfb\-run
+sets up an X authority file (or uses an existing user\-specified one),
+writes a cookie to it (see
+.BR xauth (1x))
+and then starts the
+.B Xvfb
+X server as a background process.
+The process ID of
+.B Xvfb
+is stored for later use.
+The specified
+.I command
+is then run using the X display corresponding to the
+.B Xvfb
+server
+just started and the X authority file created earlier.
+.PP
+When the
+.I command
+exits, its status is saved, the
+.B Xvfb
+server is killed (using the process ID stored earlier), the X authority
+cookie removed, and the authority file deleted (if the user did not specify
+one to use).
+.B xvfb\-run
+then exits with the exit status of
+.IR command .
+.PP
+.B xvfb\-run
+requires the
+.B xauth
+command to function.
+.SH OPTIONS
+.TP
+.B \-a\fR,\fB \-\-auto\-servernum
+Try to get a free server number, starting at 99, or the argument to
+.BR \-\-server\-num .
+.TP
+.BI \-e\  file \fR,\fB\ \-\-error\-file= file
+Store output from
+.B xauth
+and
+.B Xvfb
+in
+.IR file .
+The default is
+.IR /dev/null .
+.TP
+.BI \-f\  file \fR,\fB\ \-\-auth\-file= file
+Store X authentication data in
+.IR file .
+By default, a temporary directory called
+.IR xvfb\-run. PID
+(where PID is the process ID of
+.B xvfb\-run
+itself) is created in the directory specified by the environment variable
+.B TMPDIR
+(or
+.I /tmp
+if that variable is null or unset), and the
+.BR tempfile (1)
+command is used to create a file in that temporary directory called
+.IR Xauthority .
+.TP
+.B \-h\fR,\fB \-\-help
+Display a usage message and exit.
+.TP
+.BI \-n\  servernumber \fR,\fB\ \-\-server\-num= servernumber
+Use
+.I servernumber
+as the server number (but see the
+.B \-a\fR,\fB \-\-auto\-servernum
+option above).
+The default is 99.
+.TP
+.B \-l\fR,\fB \-\-listen\-tcp
+Enable TCP port listening in the X server.
+For security reasons (to avoid denial\-of\-service attacks or exploits),
+TCP port listening is disabled by default.
+.TP
+.BI \-p\  protocolname \fR,\fB\ \-\-xauth\-protocol= protocolname
+Use
+.I protocolname
+as the X authority protocol to use.
+The default is \(oq.\(cq, which
+.B xauth
+interprets as its own default protocol, which is MIT\-MAGIC\-COOKIE\-1.
+.TP
+.BI \-s\  arguments \fR,\fB\ \-\-server\-args= arguments
+Pass
+.I arguments
+to the
+.B Xvfb
+server.
+Be careful to quote any whitespace characters that may occur within
+.I arguments
+to prevent them from regarded as separators for
+.BR xvfb\-run 's
+own arguments.
+Also, note that specification of \(oq\-nolisten tcp\(cq in
+.I arguments
+may override the function of
+.BR xvfb\-run 's
+own
+.B \-l\fR,\fB \-\-listen\-tcp
+option, and that specification of the server number (e.g., \(oq:1\(cq) may
+be ignored because of the way the X server parses its argument list.
+Use the
+.B xvfb\-run
+option
+.BI \-n\  servernumber \fR,\fB\ \-\-server\-num= servernumber
+to achieve the latter function.
+The default is \(oq\-screen 0 1280x1024x24\(cq.
+.TP
+.BI \-w\  delay \fR,\fB\ \-\-wait= delay
+Ignored for compatibility with earlier versions.
+.SH ENVIRONMENT
+.TP
+.B COLUMNS
+indicates the width of the terminal device in character cells.
+This value is used for formatting diagnostic messages.
+If not set, the terminal is queried using
+.BR stty (1)
+to determine its width.
+If that fails, a value of \(oq80\(cq is assumed.
+.TP
+.B TMPDIR
+specifies the directory in which to place
+.BR xvfb\-run 's
+temporary directory for storage of the X authority file; only used if the
+.B \-f
+or
+.B \-\-auth\-file
+options are not specified.
+.SH "OUTPUT FILES"
+.PP
+Unless the
+.B \-f
+or
+.B \-\-auth\-file
+options are specified, a temporary
+directory and file within it are created (and deleted) to store the X
+authority cookies used by the
+.B Xvfb
+server and client(s) run under it.
+See
+.BR tempfile (1).
+If \-f or \-\-auth\-file are used, then the specified X authority file is
+only written to, not created or deleted (though
+.B xauth
+creates an authority file itself if told to use use that does not already
+exist).
+.PP
+An error file with a user\-specified name is also created if the
+.B \-e
+or
+.B \-\-error\-file
+options are specified; see above.
+.SH "EXIT STATUS"
+.B xvfb\-run
+uses its exit status as well as output to standard error to communicate
+diagnostics.
+The exit status of \(oq1\(cq is not used, and should be interpreted as failure
+of the specified command.
+.TP
+0
+.B xvfb\-run
+only uses this exit status if the
+.B \-h\fR,\fB \-\-help
+option is given.
+In all other situations, this may be interpreted as success of the specified
+command.
+.TP
+2
+No command to run was specified.
+.TP
+3
+The
+.B xauth
+command is not available.
+.TP
+4
+The temporary directory that was going to be used already exists; since
+.B xvfb\-run
+produces a uniquely named directory, this may indicate an attempt by another
+process on the system to exploit a temporary file race condition.
+.TP
+5
+A problem was encountered while cleaning up the temporary directory.
+.TP
+6
+A problem was encountered while using
+.BR getopt (1)
+to parse the command\-line arguments.
+.SH EXAMPLES
+.TP
+.B xvfb\-run \-\-auto\-servernum \-\-server\-num=1 xlogo
+runs the
+.BR xlogo (1x)
+demonstration client inside the
+.B Xvfb
+X server on the first available server number greater than or equal to 1.
+.TP
+.B xvfb\-run \-\-server\-args="\-screen 0 1024x768x24" ico \-faces
+runs the
+.BR ico (1x)
+demonstration client (and passes it the
+.B \-faces
+argument) inside the
+.B Xvfb
+X server, configured with a root window of 1024 by 768 pixels and a color
+depth of 24 bits.
+.PP
+Note that the demo X clients used in the above examples will not exit on
+their own, so they will have to be killed before
+.B xvfb\-run
+will exit.
+.SH BUGS
+See
+.URL "https://bugs.debian.org/xvfb" "the Debian Bug Tracking System" .
+If you wish to report a bug in
+.BR xvfb\-run ,
+please use the 
+.BR reportbug (1)
+command.
+.SH AUTHOR
+.B xvfb\-run
+was written by Branden Robinson and Jeff Licquia with sponsorship from
+Progeny Linux Systems.
+.SH "SEE ALSO"
+.BR Xvfb (1x),
+.BR xauth (1x)
+.\" vim:set et tw=80:

Best wishes,
Arne
-- 
Unpolitisch sein
heißt politisch sein
ohne es zu merken
Date: Mon, 08 Mar 2021 01:57:32 +0100
Message-ID: <87im62fon7.fsf@web.de>

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bug#46998: wish: package xvfb-run

[Maxime Devos]

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On Mon, 2021-03-08 at 01:57 +0100, Dr. Arne Babenhauserheide wrote:
> User-agent: mu4e 1.4.15; emacs 27.1
> (emacs:30177): dbind-WARNING **: 01:46:31.849: Could not open X display
> 
> http://deb.debian.org/debian/pool/main/x/xorg-server/xorg-server_1.20.10-3.diff.gz
> 
> +Usage: $PROGNAME [OPTION ...] COMMAND
> +Options:
> +DISPLAY=:$SERVERNUM XAUTHORITY=$AUTHFILE "$@"
> Dear Guix hackers,
> 
> One of my main tools for running graphical programs as part of my build
> pipelines is xvfb-run. Since it is not packaged in Guix, I’ve resorted
> to manual workarounds, but these have annoying drawbacks:
> 
> Xvfb :3 -screen 0 1024x768x16 & time DISPLAY=:3 HOME=/path/to/project/.emacs.d emacs …

build pipelines = (a) something for in guix package definitions, to be
run in the build container, or (b) as part of the Makefile or similar
for software, that you are compiling *outside* guix' build containter?

I'm assuming the latter as I read you're starting the editor "emacs".

> I now get errors about the maximum number of clients reached, because
> the Xvfb does not get reaped after the build:

If (a) is the case, and "after the build" here means "after guix build
PACKAGE" completes, then this seems a bug in how the guix daemon sets up it
build containers.

> Maximum number of clients reached
> Therefore I would ask whether it would be possible to package xvfb-run.
> It is provided as part of the patches of the xorg-package in Debian:

I'm no guix maintainer, but I don't see why not.  Myself I would prefer
this as a separate package "xvfb-run" that only has Debian's "xvfb-run"
script and its man page though.

In any case, the references to "stty", "awk", "cat", "xauth", "mktemp",
"xvfb", "touch", "rm", "fmt" would need to be replaced with the full
store path (using substitute* I presume).  The alternative would be
defining a wrapper script adjusting the $PATH, which doesn't seem ideal
for xvfb-run.

Are you planning to write a patch to guix yourself with (i) the adjusted
xorg-server, or (ii) a new xvfb-run package?

Greetings,
Maxime

> Best wishes,
> Arne

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bug#46998: wish: package xvfb-run

[Tobias Geerinckx-Rice via Bug reports for GNU Guix]

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Maxime Devos 写道：
> I'm no guix maintainer, but I don't see why not.  Myself I would 
> prefer
> this as a separate package "xvfb-run" that only has Debian's 
> "xvfb-run"
> script and its man page though.

I agree it should be separate from xorg-server.

It's a separate package, with Debian upstream, that just happens 
to use one very unorthodox archive format (...‘par’?).  It's 
ridiculous and I like it.

Kind regards,

T G-R

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bug#46998: wish: package xvfb-run

[Tobias Geerinckx-Rice via Bug reports for GNU Guix]

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Tobias Geerinckx-Rice 写道：
> It's ridiculous and I like it.

Done as 9f87758fd5a5fd2e4c04683aebee13d9a19218b8.

Kind regards,

T G-R

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bug#46998: wish: package xvfb-run

[Dr. Arne Babenhauserheide]

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Tobias Geerinckx-Rice <me@tobias.gr> writes:

> Tobias Geerinckx-Rice 写道：
>> It's ridiculous and I like it.
>
> Done as 9f87758fd5a5fd2e4c04683aebee13d9a19218b8.

You’re awesome! Thank you!

Best wishes,
Arne
-- 
Unpolitisch sein
heißt politisch sein
ohne es zu merken

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