Very Computer

I need to find away to examine a process's memory, call stack and
symbol table WHILE it is running.  Preferablly I do not want to use
ptrace since the process itself needs to examine the these values.
The application is where it function X which can be called by an
arbitary number of other functions (directly or indirectly).  Function
X needs to know for any given parameter the first function in the call
stack that has that parameter as a paramter.  Ex.

#define MAXLINE 1024

main()
{
        a("hi");
        b("foo");

Quote:}

a(char *s)
{
        b(s);

Quote:}

b(char *s)
{
        c(s);

Quote:}

c(char *s)
{
        char func_name[MAXLINE];

        func_name=find_func(s,"char *");        // the function that I
am asking about in the post

        printf("%s\n",func_name);

Quote:}

would print:

int a("hi")
int b("foo")

The actual output will be a lot more terse.

Accessing process's memory from within the process
itself should pose little difficulty ;-)

Quote:> call stack and symbol table WHILE it is running.  

Doing so is quite possible, but very system-dependent
and not entirely trivial.

To get you started with call-stack, look at mpatrol sources:
http://www.cbmamiga.demon.co.uk/mpatrol

Quote:> Preferablly I do not want to use
> ptrace since the process itself needs to examine the these values.

I do not believe a process can ptrace itself.

Quote:> The application is where it function X which can be called by an
> arbitary number of other functions (directly or indirectly).  Function
> X needs to know for any given parameter the first function in the call
> stack that has that parameter as a paramter.  Ex.

You are not asking for just call stack, you are also asking
the 'X()' to decode all arguments to all functions in the
current call stack.

To decode parameters, your executable would have to
be compiled with '-g', and you would need to dig
into whatever debug format your platform uses.

For a single platform support, you are looking at
something like 1-2 month of development effort.

Do you really want it this bad?
Perhaps there is an easier way to achieve whatever X()
is intended to achieve?

Cheers,

I have seen a number of ways to do this in the past but none are that
portable.

If you are using gcc on your system you can look at the function
__builtin_return_address(const int) and it will return a pointer to a
function name for the stack frame number provided, though it must be a
constant int for some reason.

Another but more complicated way is to exec gdb in a pipe and have it
perform a backtrace for you. This is more portable because each OS has
it's own implimentation for walking the stack and gdb always knows how
to do it, so you don't have to modify your code for each OS you need to
run on.

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