4.169. strace

An updated strace package that fixes one bug is now available for Red Hat Enterprise Linux 5.
The strace program intercepts and records the system calls called and received by a running process. It can print a record of each system call, its arguments and its return value. The strace utility is useful for diagnosing, debugging and instructional purposes.

Bug Fix

BZ#788666
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.
All users of strace are advised to upgrade to this updated package, which fixes this bug.
Updated strace packages that fix multiple bugs are now available for Red Hat Enterprise Linux 5.
The strace packages provide a utility to intercept and record the system calls called and received by a running process. The strace utility can print a record of each system call, its arguments and its return value. The strace utility is useful for diagnosing, debugging and instructional purposes.

Bug Fixes

BZ#495935
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.
BZ#509152
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.
BZ#512692
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.
BZ#552964
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.
BZ#571437
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.
BZ#580211
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.
BZ#759566
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.
BZ#768203
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.
All users of strace are advised to upgrade to these updated packages, which fix these bugs.