Can I ptrace(2) a non-child process ?

[Ugo Cei]

I am having problems with the ptrace(2) syscall under SunOS 4.0.3.
What I am trying to do is to read the address space of a program that
is run under a debugger (gdb) from a program that is the parent of the
debugger. My program runs the debugger, then queries it to get the pid
of the debugged program and the address of a variable. At some point
it calls

	ptrace(PTRACE_ATTACH, pid, 0, 0, 0);

to start tracing the "grandchild" process. This calls exits with an
error of "not owner". I have also tried to call

	ptrace(PTRACE_READDATA, pid, address, size, dest);

without trying to attach the grandchild process, but I get a "no such
process" error.

TFM says that "... process does not have to be a child of the requestor ...",
but maybe there is some problem when the process to be traced is
already being traced by another process (gdb in my case). Is there any
way to circumvent these problems ? If not, how could I accomplish the
same thing (reading the address space of a program being run under a
debugger) without hacking the debugger source ?

Since I need this fairly quickly, even an ugly hack would do for the
moment. Please, don't suggest to instruct gdb to print out the data
then to read it from a pipe: I need to read very large arrays and this
method, although working, is far too slow.

aTdHvAaNnKcSe

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