| Message ID | 1400519982-9264-1-git-send-email-peter.maydell@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
On 05/19/2014 11:19 AM, Peter Maydell wrote: > When libtool support was added to configure, the new temporary files > were left out of the list of files cleaned up on exit; this results > in a lot of stale .lo files being left around in /tmp. Worse, libtool > creates a /tmp/.libs directory which we can't easily clean up. > > Put all our temporary files in a single temporary directory created > as a subdirectory of the build directory, so we can easily clean it up, > and don't need fragile or complicated code for creation to avoid it > clashing with temporary directories from other instances of QEMU > configure or being subject to attack from adversaries who can write > to /tmp. > > Since the temporaries now live in the build tree, we have no > need to jump through hoops with a trap handler to try to remove > them when configure exits; this fixes some weird bugs where hitting > ^C during a configure run wouldn't actually make it stop, because > we would run the trap handler but then not stop. (It is possible > to get the trap handler semantics right but it is convoluted largely > because of bugs in dash, so it is simpler to just avoid it.) > > Note that "temporary files go in the build directory, not /tmp" is > the way autoconf behaves. > > Signed-off-by: Peter Maydell <peter.maydell@linaro.org> > --- Reviewed-by: Eric Blake <eblake@redhat.com> > > -# NB: do not call "exit" in the trap handler; this is buggy with some shells; > -# see <1285349658-3122-1-git-send-email-loic.minier@linaro.org> > -trap "rm -f $TMPC $TMPO $TMPCXX $TMPE" EXIT INT QUIT TERM While we don't need a trap that jumps through hoops, it may still be nice to have a 'rm -r ${TMPDIR1}' at the end of configure. Just because we cleanup a leftover config-temp on start from an earlier aborted run doesn't mean that a clean run shouldn't clean up after itself.
On 19 May 2014 18:46, Eric Blake <eblake@redhat.com> wrote: > On 05/19/2014 11:19 AM, Peter Maydell wrote: >> -# NB: do not call "exit" in the trap handler; this is buggy with some shells; >> -# see <1285349658-3122-1-git-send-email-loic.minier@linaro.org> >> -trap "rm -f $TMPC $TMPO $TMPCXX $TMPE" EXIT INT QUIT TERM > > While we don't need a trap that jumps through hoops, it may still be > nice to have a 'rm -r ${TMPDIR1}' at the end of configure. Just because > we cleanup a leftover config-temp on start from an earlier aborted run > doesn't mean that a clean run shouldn't clean up after itself. Yeah, I was in two minds about that, but you're right that it's a little neater to clean up after a successful run. thanks -- PMM
diff --git a/.gitignore b/.gitignore index 8a52709..c658613 100644 --- a/.gitignore +++ b/.gitignore @@ -4,6 +4,7 @@ /config-host.* /config-target.* /config.status +/config-temp /trace/generated-tracers.h /trace/generated-tracers.c /trace/generated-tracers-dtrace.h diff --git a/configure b/configure index 605a0ec..e06386a 100755 --- a/configure +++ b/configure @@ -2,26 +2,28 @@ # # qemu configure script (c) 2003 Fabrice Bellard # -# set temporary file name -if test ! -z "$TMPDIR" ; then - TMPDIR1="${TMPDIR}" -elif test ! -z "$TEMPDIR" ; then - TMPDIR1="${TEMPDIR}" -else - TMPDIR1="/tmp" + +# Temporary directory used for files created while +# configure runs. Since it is in the build directory +# we can safely blow away any previous version of it +# (and we need not jump through hoops to try to delete +# it when configure exits.) +TMPDIR1="config-temp" +rm -rf "${TMPDIR1}" +mkdir -p "${TMPDIR1}" +if [ $? -ne 0 ]; then + echo "ERROR: failed to create temporary directory" + exit 1 fi -TMPC="${TMPDIR1}/qemu-conf-${RANDOM}-$$-${RANDOM}.c" -TMPB="qemu-conf-${RANDOM}-$$-${RANDOM}" +TMPB="qemu-conf" +TMPC="${TMPDIR1}/${TMPB}.c" TMPO="${TMPDIR1}/${TMPB}.o" TMPCXX="${TMPDIR1}/${TMPB}.cxx" TMPL="${TMPDIR1}/${TMPB}.lo" TMPA="${TMPDIR1}/lib${TMPB}.la" -TMPE="${TMPDIR1}/qemu-conf-${RANDOM}-$$-${RANDOM}.exe" +TMPE="${TMPDIR1}/${TMPB}.exe" -# NB: do not call "exit" in the trap handler; this is buggy with some shells; -# see <1285349658-3122-1-git-send-email-loic.minier@linaro.org> -trap "rm -f $TMPC $TMPO $TMPCXX $TMPE" EXIT INT QUIT TERM rm -f config.log # Print a helpful header at the top of config.log
When libtool support was added to configure, the new temporary files were left out of the list of files cleaned up on exit; this results in a lot of stale .lo files being left around in /tmp. Worse, libtool creates a /tmp/.libs directory which we can't easily clean up. Put all our temporary files in a single temporary directory created as a subdirectory of the build directory, so we can easily clean it up, and don't need fragile or complicated code for creation to avoid it clashing with temporary directories from other instances of QEMU configure or being subject to attack from adversaries who can write to /tmp. Since the temporaries now live in the build tree, we have no need to jump through hoops with a trap handler to try to remove them when configure exits; this fixes some weird bugs where hitting ^C during a configure run wouldn't actually make it stop, because we would run the trap handler but then not stop. (It is possible to get the trap handler semantics right but it is convoluted largely because of bugs in dash, so it is simpler to just avoid it.) Note that "temporary files go in the build directory, not /tmp" is the way autoconf behaves. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> --- If we really wanted to run a cleanup handler then to cope with dash bugs I think this has to be: trap 'exit $?' INT QUIT TERM trap 'ret=$?; cleanup here; exit $?' EXIT (and even then this doesn't work if you run with -ex...) .gitignore | 1 + configure | 28 +++++++++++++++------------- 2 files changed, 16 insertions(+), 13 deletions(-)