On 11/25/2013 02:10 AM, Pádraig Brady wrote:
> On 11/25/2013 12:15 AM, Bernhard Voelker wrote:
>> +cat > k.c <<'EOF' || framework_failure_
>> +#include <stdio.h>
>> +#include <stdlib.h>
>> +#include <unistd.h>
>> +
>> +int unlinkat (int dirfd, const char *pathname, int flags)
>> +{
>> + /* Prove that LD_PRELOAD works: create the evidence file "x". */
>> + fclose (fopen ("x", "w"));
>> +
>> + /* Immediately terminate, unless indicated otherwise. */
>> + if (! getenv("CU_TEST_SKIP_EXIT"))
>> + _exit (0);
>> +
>> + /* Pretend success. */
>> + return 0;
>> +}
>> +EOF
>> +exercise_rm_rf_root ()
>
> s/rf/r/
>
>> +{
>> + # Remove the evidence file "x"; verify that.
>> + rm -f x || framework_failure_
>> + test -f x && framework_failure_
>> +
>> + local pid
>> + if [ "$CU_TEST_SKIP_EXIT" = 1 ]; then
>> + # Pass on this variable into 'rm's environment.
>> + LD_PRELOAD=./k.so CU_TEST_SKIP_EXIT=1 rm \
>> + -rv --one-file-system "$@" > out 2> err & pid=$!
>> + else
>> + LD_PRELOAD=./k.so rm -rv --one-file-system "$@" > out 2> err & pid=$!
>> + fi
>> +
>> + # Wait for the evidence file to appear, or until the process has
>> terminated.
>> + for i in $(seq 10); do
>> + test -f x && break
>> + kill -0 $pid || break
>> + sleep .1
>> + done
>> +
>> + # At this point, rm(1) usually has already terminated. Kill it anyway.
>> + kill -9 $pid
>
> So this might race with rm being preempted between the touch() and the exit(),
> causing a false failure? It's probably best to not kill if the 'x' file
> exists,
> as it's very unlikely that rm will run as normal in that case.
outch, the race is even more likely for the newly added "rm -r file1 / file2"
case where unlinkat() is called twice without the immediate _exit() due to
CU_TEST_SKIP_EXIT=1.
I have to reconsider, but won't have time for that today.
Thanks!
Have a nice day,
Berny
