ports/51651: KDE 3.1.1a: KProcess' stdout redirection fails, if child uses sched_setscheduler
Heiner
h.eichmann at gmx.de
Thu May 1 09:00:29 UTC 2003
>Number: 51651
>Category: ports
>Synopsis: KDE 3.1.1a: KProcess' stdout redirection fails. if child uses sched_setscheduler
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-ports-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Thu May 01 02:00:27 PDT 2003
>Closed-Date:
>Last-Modified:
>Originator: Heiner Eichmann <h.eichmann at gmx.de>
>Release: FreeBSD 4.8-RC2
>Organization:
Sirius Cybernetics Corp.
>Environment:
System: FreeBSD 4.8-RC #2: Thu Apr 3 11:05:05 CEST 2003 root at 7of9.unimatrix-zero.borg:/usr/obj/usr/src/sys/MYKERNEL i386
7of9# ls /var/db/pkg/ | grep ^kde
kde-3.1.1
kdeadmin-3.1.1
kdeartwork-3.1.1
kdebase-3.1.1a
kdeedu-3.1.1
kdegames-3.1.1
kdegraphics-3.1.1
kdelibs-3.1.1a
kdemultimedia-3.1.1
kdenetwork-3.1.1
kdepim-3.1.1
kdeutils-3.1.1
kdevelop-2.1.5
>Description:
See attached file. Compile both programs. Testprog.c simply prints a line to stdout.
Test 1: execute testprog . it will print a line and execute.
Proctest calls testprog (using KProcess), redirects its output into a QString and
prints the collected output out.
Test 2: execute proctest. It prints out the same as above
Test 3: remove the comments in testprog's main, compile it again, give it the suid
flag(!!!!!) and repeat test 1 and 2.
Testprog prints out a line, proctest prints nothing!
The newly added line raises the priority of testprog. After doing it KProcess'
stdout redirection somehow misses the output.
The same tests work fine on a gentoo box, so I guess the problem BSD specific.
Why do I make this crazy tests? K3b (not in the ports so far) uses KProcess
to call cdrecord. If called with the parameter -prcap, cdrecord raises its
priority (rt_raisepri in testprog was stolen from cdrecords source code).
On linux, K3b can analyze cdrecords output; on bsd it can't!
Heiner
# This is a shell archive. Save it in a file, remove anything before
# this line, and then unpack it by entering "sh file". Note, it may
# create directories; files and directories will be owned by you and
# have default permissions.
#
# This archive contains:
#
# Makefile
# proctest.cpp
# testprog.c
#
echo x - Makefile
sed 's/^X//' >Makefile << 'END-of-Makefile'
Xall: proctest testprog
X
Xproctest: proctest.cpp proctest.moc
X# gcc -o proctest -I/usr/X11R6/include -I/usr/local/include -lqt-mt -L/usr/X11R6/lib -pthread -lkdecore -L/usr/local/lib proctest.cpp
X# gcc -o proctest -I/usr/X11R6/include -I/usr/local/include -lqthreads -pthread -lkdecore -L/usr/local/lib proctest.cpp
X gcc -o proctest -I/usr/X11R6/include -I/usr/local/include -lqtmcop -pthread -lkdecore -L/usr/local/lib proctest.cpp
X
Xproctest.moc: proctest.cpp
X moc proctest.cpp -o proctest.moc
X
Xtestprog: testprog.c
X gcc -o testprog testprog.c
END-of-Makefile
echo x - proctest.cpp
sed 's/^X//' >proctest.cpp << 'END-of-proctest.cpp'
X#include <qstring.h>
X#include <kprocess.h>
X
Xclass ProcTest : QObject
X{
X Q_OBJECT
X QString m_processOutput;
Xprivate slots:
X void slotCollectStdout(KProcess *, char * data, int len);
Xpublic:
X void test();
X};
X
X
Xvoid ProcTest::test()
X{
X KProcess proc;
X// proc << "/usr/local/bin/cdrecord" << "dev=0,4,0" << "-checkdrive";
X// proc << "/usr/local/bin/cdrecord" << "dev=0,4,0" << "-prcap";
X proc << "./testprog";
X connect( &proc, SIGNAL(receivedStdout(KProcess *, char *, int)), this, SLOT(slotCollectStdout(KProcess *, char *, int)));
X m_processOutput = "";
X proc.start(KProcess::Block, KProcess::Stdout);
X printf("%s\n", m_processOutput.latin1());
X}
X
X
Xvoid ProcTest::slotCollectStdout(KProcess *, char * data, int len)
X{
X m_processOutput += QString::fromLocal8Bit(data, len);
X}
X
X
Xint main (int argc, char * argv[])
X{
X ProcTest proc;
X proc.test();
X return 0;
X}
X
X#include "proctest.moc"
END-of-proctest.cpp
echo x - testprog.c
sed 's/^X//' >testprog.c << 'END-of-testprog.c'
X#include <sched.h>
X
Xint
Xrt_raisepri(pri)
X int pri;
X{
X struct sched_param scp;
X memset(&scp, '\0', sizeof(scp));
X scp.sched_priority = sched_get_priority_max(SCHED_RR) - pri;
X if (sched_setscheduler(0, SCHED_RR, &scp) < 0) {
X printf("WARNING: Cannot set RR-scheduler\n");
X return (-1);
X }
X return (0);
X}
X
Xint main (int argc, char * argv[])
X{
X// Remove comments here for test 3!!!!!!!!!
X// rt_raisepri(0);
X printf("This is a testline\n");
X return 0;
X}
X
END-of-testprog.c
exit
>How-To-Repeat:
see above
>Fix:
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>Release-Note:
>Audit-Trail:
>Unformatted:
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