HP-UX Reference (11i v2 07/12) - 2 System Calls (vol 5)

p
ptrace(2) ptrace(2)
(PA-RISC Only; TO BE OBSOLETED)
context. The child does not inherit its parent’s event flags. See the ptrace_state
structure description under
PT_GET_PROCESS_STATE
for further details.
PTRACE_VFORK This event flag indicates that the traced process needs to take special action
when it invokes
vfork(). When set, the child process stops after marking
itself as a traced process and adopting its parent’s debugger. The fact that a
PTRACE_VFORK event was handled is logged in the context of both the parent
and child processes. Further, the child’s pid argument value is logged in the
parent’s context and the parent’s pid argument value is logged in the child’s con-
text. The child does not inherit its parent’s event flags. See the ptrace_state
structure description under
PT_GET_PROCESS_STATE
for further details.
It is important to note that the warnings with respect to
vfork() (see
vfork(2)), continue to apply here. It needs to be remembered that when the child
process stops, its parent process is suspended and that the child borrows the
parent’s memory and thread of control until a call is done to either
exec*() or
exit(), or it exits abnormally (see exec(2) and exit(2)).
PTRACE_EXEC This event flag indicates that the traced process needs to take special action
when it invokes exec*(). When set, the traced process stops after logging the
fact that it stopped in response to a PTRACE_EXEC event. It also logs informa-
tion pertaining to the path or file argument of exec*(). This includes a
pointer to the path name string and the length of the path name string. See the
ptrace_state structure description under PT_GET_PROCESS_STATE
for
further details.
PTRACE_EXIT This event flag indicates that the traced process needs to take special action
when it invokes
exit(). When set, the traced process stops after logging the
PTRACE_EXIT event.
PT_SET_EVENT_MASK
This request is used by the calling process to specify event flags and signal mask
values that it wants the traced process to respond to. It does so by writing the
contents of the ptrace_event data structure in the user space pointed to by the
addr argument into the context of the traced process. The data argument
specifies the number of bytes to be transferred. The addr2 argument is ignored.
The request fails if the number of bytes specified is less than zero or greater than
the size of the ptrace_event structure and results in
errno being set to [EIO].
The typedef for the ptrace_event data structure is shown below:
typedef struct ptrace_event{
sigset_t pe_signals;
events_t pe_set_event;
char pe_spare[28];
} ptrace_event_t;
Event flags are set in the pe_set_event member of the ptrace_event data struc-
ture. An event flag is set when the tracing process wants the traced process to
respond to a particular event. As detailed earlier, the event flags defined are
PTRACE_EXEC , PTRACE_EXIT, PTRACE_FORK , PTRACE_SIGNAL, and
PTRACE_VFORK . See the definition of events_t in <sys/ptrace.h> for
more details.
Signal mask values are set in the pe_signals member of the ptrace_event struc-
ture. This member is activated by a PTRACE_SIGNAL event flag being set in
the pe_set_event member. Mask values set in the pe_signals member correspond
to signals that need to be masked from the tracing process that the traced pro-
cess received; that is, these are signals received by the traced process that the
tracing process does not want to be informed about. The pe_signals member is
described by the type definition sigset_t which is defined in <signal.h> .
PT_GET_EVENT_MASK
This request is used by the calling process to determine the event flags and sig-
nal mask values that have been set in the traced process’s context by the last
PT_SET_EVENT_MASK request. The data argument specifies the number of
bytes to be read from the traced process’ context into the ptrace_event data
HP-UX 11i Version 2: December 2007 Update − 4 − Hewlett-Packard Company 303