4.169. strace

The strace utility did not properly track switches between 32-bit and 64-bit process execution domains (so called "personalities") when tracing multiple processes with multiple "personalities". This caused strace to output the wrong system call names and arguments for the traced processes. This update corrects personality tracking in strace so that it now prints system call names and arguments as expected.

Prior to this update, the strace utility incorrectly decoded system calls when tracing a 32 bit process on a 64 bit machine, because strace on IBM System z platforms is not multi-arch aware. This update provides an additional strace executable (strace32) which can be used to trace 32 bit processes on 64 bit machines.

Prior to this update, the strace utility incorrectly exited a system call loop when the child process was interrupted. As a consequence, strace reported that the last system call exited with a ERESTART_RESTARTBLOCK condition. This update modifies the loop exit so that strace now correctly reports that the interrupted system call is unfinished.

Prior to this update, the kernel could, under certain circumstances, fail to send a SIGTRAP signal to the strace utility. As a consequence, the strace utility could become suspended if the target process blocked the debugging signal SIGTRAP. With this update, strace now checks for this situation and re-synchronizes with system call notifications when necessary.

Prior to this update, traces were not detached but forcefully terminated when the SIGTERM signal terminated the strace process while the trace executed a fork or a cloned system call. This update modifies the underlying code to cleanly detach traces when a strace process is terminated.

Prior to this update, the strace utility incorrectly printed 64 bit arguments for certain system calls such as "fadvise". This update modifies the underlying code so that the correct "fadvise" arguments are printed as expected.

Prior to this update, a misinterpreted status caused strace to leave the traced process in a stopped state when detaching from a process. This update modifies the underlying code to leave the process in the correct state after detaching.

Prior to this update, the strace utility extracted arguments for the "semtimedop" system call from the wrong location on the IBM System z platforms. As a consequence, arguments for the "semtimedop" system call were incorrectly displayed. This update modifies strace to extract the arguments from the correct memory location so that the arguments for the "semtimedop" system call are displayed as expected.

Prior to this update, the strace utility did not correctly track switches between 32-bit and 64-bit process execution domains, so called "personalities", when tracing multiple processes with multiple "personalities". As a consequence, strace logged the wrong system call names and arguments for the traced processes. This update corrects personality tracking in strace so that it now prints system call names and arguments as expected.