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When started as user 'root' VDR now switches to a lesser privileged user id, keeping the capability to set the system time
This commit is contained in:
Klaus Schmidinger
parent
c65133979f
commit
89df449715
@ -824,6 +824,7 @@ Ludwig Nussel <ludwig.nussel@web.de>
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cThread::Start()
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for removing the LOCK_THREAD from the LIRC thread
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for making the Makefile patch friendlier
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for a patch that was used for implementing setting the user id
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Thomas Koch <tom@harhar.net>
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for his support in keeping the Premiere World channels up to date in 'channels.conf'
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9
HISTORY
9
HISTORY
@ -3963,7 +3963,7 @@ Video Disk Recorder Revision History
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commands may now be executed at any time, and the message will be displayed
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(no more "pending message").
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2005-12-30: Version 1.3.38
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2005-12-31: Version 1.3.38
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- Fixed handling second audio and Dolby Digital PIDs for encrypted channels
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(was broken in version 1.3.37).
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@ -4040,3 +4040,10 @@ Video Disk Recorder Revision History
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- Updated the Greek OSD texts (thanks to Dimitrios Dimitrakos).
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- Changed all "illegal" to "invalid" in error messages (there's nothing "illegal"
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in VDR ;-).
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- When started as user 'root' VDR now switches to a lesser privileged user id,
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keeping the capability to set the system time (based on a patch from Ludwig
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Nussel). By default the user id 'vdr' is used, which can be changed through
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the new command line option '-u'. Note that for security reasons VDR will no
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longer run as user 'root' (unless you explicitly start it with '-u root',
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but this is not recommended!). The 'runvdr' script has been changed to
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use the '-u' option.
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13
INSTALL
13
INSTALL
@ -132,6 +132,19 @@ call to the VDR program, be sure to NOT use the '-d' option! Otherwise
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VDR will go into 'deamon' mode and the initial program call will return
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immediately!
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Setting the system time:
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------------------------
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If you want VDR to set the system time according to the data received
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from the transponder, you need to start VDR as user 'root'. VDR will
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then only keep the capability to set the system time, and set its
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user id to a lesser privileged one ('vdr' by default, can be set
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to a different value with the '-u' option).
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You also need to enable the "EPG/Set system time" option in VDR's
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Setup menu, and select a transponder from which you want to receive
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the time in "Use time from transponder". Make sure you select a transponder
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that has a reliable clock - some transponders are quite off.
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Automatic shutdown:
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-------------------
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4
Makefile
4
Makefile
@ -4,7 +4,7 @@
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# See the main source file 'vdr.c' for copyright information and
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# how to reach the author.
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#
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# $Id: Makefile 1.79 2005/09/02 14:23:38 kls Exp $
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# $Id: Makefile 1.80 2005/12/31 10:14:33 kls Exp $
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.DELETE_ON_ERROR:
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@ -27,7 +27,7 @@ endif
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LSIDIR = ./libsi
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MANDIR = /usr/local/man
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BINDIR = /usr/local/bin
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LIBS = -ljpeg -lpthread -ldl
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LIBS = -ljpeg -lpthread -ldl -lcap
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INCLUDES =
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PLUGINDIR= ./PLUGINS
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8
runvdr
8
runvdr
@ -7,7 +7,7 @@
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#
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# Set the environment variable VDRUSR to the user id you
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# want VDR to run with. If VDRUSR is not set, VDR will run
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# as 'root', which is not necessarily advisable.
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# as user 'vdr'.
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#
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# Since this script loads the DVB driver, it must be started
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# as user 'root'.
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@ -18,11 +18,11 @@
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# See the main source file 'vdr.c' for copyright information and
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# how to reach the author.
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#
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# $Id: runvdr 1.14 2004/11/21 11:30:00 kls Exp $
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# $Id: runvdr 1.15 2005/12/31 13:30:11 kls Exp $
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DVBDIR="../DVB/driver"
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VDRPRG="./vdr"
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VDRCMD="$VDRPRG -w 60 $*"
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VDRCMD="$VDRPRG -u $VDRUSR -w 60 $*"
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LSMOD="`/sbin/lsmod | grep -w '^dvb' | wc -l`"
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KILL="/usr/bin/killall -q -TERM"
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@ -33,7 +33,7 @@ if [ $LSMOD -eq 0 ] ; then
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fi
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while (true) do
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su $VDRUSR -c "$VDRCMD"
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$VDRCMD
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if test $? -eq 0 -o $? -eq 2; then exit; fi
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date
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echo "restarting VDR"
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9
vdr.1
9
vdr.1
@ -8,7 +8,7 @@
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.\" License as specified in the file COPYING that comes with the
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.\" vdr distribution.
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.\"
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.\" $Id: vdr.1 1.16 2005/12/30 15:09:01 kls Exp $
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.\" $Id: vdr.1 1.17 2005/12/31 12:55:16 kls Exp $
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.\"
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.TH vdr 1 "19 Dec 2004" "1.3.18" "Video Disk Recorder"
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.SH NAME
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@ -128,6 +128,13 @@ Call \fIcmd\fR to shutdown the computer.
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.BI \-t\ tty ,\ \-\-terminal= tty
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Set the controlling terminal.
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.TP
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.BI \-u\ user ,\ \-\-user= user
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Run as user \fIuser\fR in case vdr was started as user 'root'.
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Starting vdr as 'root' is necessary if the system time shall
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be set from the transponder data, but for security reasons
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during normal operation vdr switches to a lesser privileged
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user id. By default the user 'vdr' is used.
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.TP
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.BI \-v\ dir ,\ \-\-video= dir
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Use \fIdir\fR as video directory.
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The default is \fI/video\fR.
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91
vdr.c
91
vdr.c
@ -22,13 +22,17 @@
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*
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* The project's page is at http://www.cadsoft.de/vdr
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*
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* $Id: vdr.c 1.223 2005/12/30 15:07:47 kls Exp $
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* $Id: vdr.c 1.224 2005/12/31 13:30:11 kls Exp $
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*/
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#include <getopt.h>
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#include <grp.h>
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#include <locale.h>
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#include <pwd.h>
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#include <signal.h>
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#include <stdlib.h>
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#include <sys/capability.h>
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#include <sys/prctl.h>
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#include <termios.h>
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#include <unistd.h>
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#include "audio.h"
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@ -72,6 +76,57 @@
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static int Interrupted = 0;
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static bool SetUser(const char *UserName)
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{
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if (UserName) {
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struct passwd *user = getpwnam(UserName);
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if (!user) {
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fprintf(stderr, "vdr: unknown user: '%s'\n", UserName);
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return false;
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}
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if (setgid(user->pw_gid) < 0) {
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fprintf(stderr, "vdr: cannot set group id %u: %s\n", (unsigned int)user->pw_gid, strerror(errno));
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return false;
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}
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if (initgroups(user->pw_name, user->pw_gid) < 0) {
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fprintf(stderr, "vdr: cannot set supplemental group ids for user %s: %s\n", user->pw_name, strerror(errno));
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return false;
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}
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if (setuid(user->pw_uid) < 0) {
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fprintf(stderr, "vdr: cannot set user id %u: %s\n", (unsigned int)user->pw_uid, strerror(errno));
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return false;
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}
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}
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return true;
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}
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static bool SetCapSysTime(void)
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{
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// drop all capabilities except cap_sys_time
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cap_t caps = cap_from_text("= cap_sys_time=ep");
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if (!caps) {
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fprintf(stderr, "vdr: cap_from_text failed: %s\n", strerror(errno));
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return false;
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}
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if (cap_set_proc(caps) == -1) {
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fprintf(stderr, "vdr: cap_set_proc failed: %s\n", strerror(errno));
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cap_free(caps);
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return false;
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}
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cap_free(caps);
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return true;
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}
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static bool SetKeepCaps(bool On)
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{
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// set keeping capabilities during setuid() on/off
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if (prctl(PR_SET_KEEPCAPS, On ? 1 : 0, 0, 0, 0) != 0) {
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fprintf(stderr, "vdr: prctl failed\n");
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return false;
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}
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return true;
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}
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static void SignalHandler(int signum)
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{
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if (signum != SIGPIPE) {
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@ -102,11 +157,14 @@ int main(int argc, char *argv[])
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// Command line options:
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#define DEFAULTVDRUSER "vdr"
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#define DEFAULTSVDRPPORT 2001
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#define DEFAULTWATCHDOG 0 // seconds
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#define DEFAULTPLUGINDIR PLUGINDIR
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#define DEFAULTEPGDATAFILENAME "epg.data"
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bool StartedAsRoot = false;
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const char *VdrUser = DEFAULTVDRUSER;
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int SVDRPport = DEFAULTSVDRPPORT;
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const char *AudioCommand = NULL;
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const char *ConfigDirectory = NULL;
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@ -157,6 +215,7 @@ int main(int argc, char *argv[])
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{ "record", required_argument, NULL, 'r' },
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{ "shutdown", required_argument, NULL, 's' },
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{ "terminal", required_argument, NULL, 't' },
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{ "user", required_argument, NULL, 'u' },
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{ "version", no_argument, NULL, 'V' },
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{ "vfat", no_argument, NULL, 'v' | 0x100 },
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{ "video", required_argument, NULL, 'v' },
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@ -165,7 +224,7 @@ int main(int argc, char *argv[])
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};
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int c;
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while ((c = getopt_long(argc, argv, "a:c:dD:E:g:hl:L:mp:P:r:s:t:v:Vw:", long_options, NULL)) != -1) {
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while ((c = getopt_long(argc, argv, "a:c:dD:E:g:hl:L:mp:P:r:s:t:u:v:Vw:", long_options, NULL)) != -1) {
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switch (c) {
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case 'a': AudioCommand = optarg;
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break;
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@ -251,6 +310,9 @@ int main(int argc, char *argv[])
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return 2;
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}
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break;
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case 'u': if (*optarg)
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VdrUser = optarg;
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break;
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case 'V': DisplayVersion = true;
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break;
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case 'v' | 0x100:
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@ -273,6 +335,20 @@ int main(int argc, char *argv[])
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}
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}
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// Set user id in case we were started as root:
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if (getuid() == 0) {
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StartedAsRoot = true;
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if (!SetKeepCaps(true))
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return 2;
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if (!SetUser(VdrUser))
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return 2;
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if (!SetKeepCaps(false))
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return 2;
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if (!SetCapSysTime())
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return 2;
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}
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// Help and version info:
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if (DisplayHelp || DisplayVersion) {
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@ -288,12 +364,12 @@ int main(int argc, char *argv[])
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" -D NUM, --device=NUM use only the given DVB device (NUM = 0, 1, 2...)\n"
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" there may be several -D options (default: all DVB\n"
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" devices will be used)\n"
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" -E FILE --epgfile=FILE write the EPG data into the given FILE (default is\n"
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" -E FILE, --epgfile=FILE write the EPG data into the given FILE (default is\n"
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" '%s' in the video directory)\n"
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" '-E-' disables this\n"
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" if FILE is a directory, the default EPG file will be\n"
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" created in that directory\n"
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" -g DIR --grab=DIR write images from the SVDRP command GRAB into the\n"
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" -g DIR, --grab=DIR write images from the SVDRP command GRAB into the\n"
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" given DIR; DIR must be the full path name of an\n"
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" existing directory, without any \"..\", double '/'\n"
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" or symlinks (default: none, same as -g-)\n"
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@ -316,6 +392,8 @@ int main(int argc, char *argv[])
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" -r CMD, --record=CMD call CMD before and after a recording\n"
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" -s CMD, --shutdown=CMD call CMD to shutdown the computer\n"
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" -t TTY, --terminal=TTY controlling tty\n"
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" -u USER, --user=USER run as user USER (default: %s); only applicable\n"
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" if started as root\n"
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" -v DIR, --video=DIR use DIR as video directory (default: %s)\n"
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" -V, --version print version information and exit\n"
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" --vfat encode special characters in recording names to\n"
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@ -328,6 +406,7 @@ int main(int argc, char *argv[])
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LIRC_DEVICE,
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DEFAULTSVDRPPORT,
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RCU_DEVICE,
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DEFAULTVDRUSER,
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VideoDirectory,
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DEFAULTWATCHDOG
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);
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@ -378,7 +457,7 @@ int main(int argc, char *argv[])
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if (DaemonMode) {
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if (daemon(1, 0) == -1) {
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fprintf(stderr, "%m\n");
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fprintf(stderr, "vdr: %m\n");
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esyslog("ERROR: %m");
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return 2;
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}
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@ -392,6 +471,8 @@ int main(int argc, char *argv[])
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}
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isyslog("VDR version %s started", VDRVERSION);
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if (StartedAsRoot)
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isyslog("switched to user '%s'", VdrUser);
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// Main program loop variables - need to be here to have them initialized before any EXIT():
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