Re: static user probes

[Stan Cox <scox at redhat dot com>]

Maneesh Soni wrote:

> Which is stap-probes.c file and why is this required?

That is just an editing problem.  It isn't required

> Is this .d file written by the user or generated automatically?
> what is the use of it?

It is written by the user and describes the argument signature for the 
probes.

> Do you mean, stap-probes-tstlable.c? Could you also share the .py?

Sure.  Here is an stap example which will now hit a probe and print 
arguments and also the python script.

***** cat tstlabel.c *****  test program
#include <stdlib.h>
#include "stap-probes.h"

foo ()
{
  STAP_PROBE(tstlabel,label1);
}

bar (int i)
{
  STAP_PROBE(tstlabel,label2,i);
}

baz (int i, char* s)
{
  STAP_PROBE(tstlabel,label3,i,s);
}

main ()
{
  foo();
  bar(2);
  baz(3,"abc");
}

***** cat stap-probes.h ***** marker include file
#define STAP_PROBE(provider,probe,...)        \
  _stap_probe_ ## probe (__VA_ARGS__);

***** cat tstlabel.d ***** used to create stap-probes-tstlabel.c
provider tstlabel {
   probe label1();
   probe label2(int);
   probe label3(int, char*);
};


***** cat stap-probes-tstlabel.c ***** currently, a generated file
_stap_probe_label1 ()
{
   return 1;
}

_stap_probe_label2 (int a)
{
   return 1;
}

_stap_probe_label3 (int a, char* b)
{
   return 1;
}

***** cat 19180.stp ***** script to test above
probe process.mark("label1")
{
   printf("label3\n")
}

probe process.mark("label2")
{
   printf("label3 arg1=%d\n", $a)
}
probe process.mark("label3")
{
   printf("label3 arg1=%d arg2=%#x\n", $a, $b)
}


stap -c /home/scox/stap/1918/tstlabel.x 19180.stp
label1
label2 arg1=2
label3 arg1=3 arg2=0x4005e8

import sys

class provider:
    arglist = dict()
    def open(self, provider):
        self.f = open(provider)
        while (True):
            line = self.f.readline()
            if (line == ""):
                break
            if (line.find("provider") > 0):
                tokens = line.split()
                self.provider = tokens[1]
            elif (line.find("probe") > 0):
                this_probe = line[line.find("probe ")+5:line.find("(")].strip()
                args = (line[line.find("(")+1:line.find(")")])
                new_args = ""
                i = 0
                c = 0
                letters = "abcdefghijklmnopqrstuvwxyz"
                while (i < len(args)):
                    if (args[i:i+1] == ","):
                        new_args = new_args + " " + letters[c] + args[i]
                        c += 1
                    else:
                        new_args = new_args + args[i]
                    i += 1
                if (len(args) > 0):
                    self.arglist[this_probe] = new_args + " " + letters[c]
    def get(self, arg):
        print arg
        if (arg in self.arglist):
            return self.arglist[arg]
        else:
            return ""

class probe:
    isopen = False
    def open(self, provider):
        if (not self.isopen):
            self.f = open("stap-probes-" + provider + ".c", "w")
        self.isopen = True
    def add(self, probe, arglist):
        self.f.write("_stap_probe_" + probe + " (" + arglist + ")\n")
        self.f.write("{\n   return 1;\n}\n\n")
    def close(self, fn):
        self.f.close()

########################################################################
# main
########################################################################

def usage ():
    print "Usage " + sys.argv[0] + " File.d File.c <File.c>..."
    sys.exit(1)

def open_file (arg):
    if (len (sys.argv) <= arg):
        return False
    try:
        file = open(sys.argv[arg], 'r')
    except IOError:
        print (sys.argv[arg] + " not found")
        sys.exit(1)
    return file

if (len (sys.argv) < 3):
    usage()

providers = provider()
providers.open(sys.argv[1])

current_file = 2
d_file = open_file(current_file)
filename = sys.argv[current_file]
p_file = probe()

while (True):
    line = d_file.readline()
    if (line == ""):
        current_file += 1
        d_file = open_file(current_file)
        if (not d_file):
            break
    if (line.find("STAP_PROBE") > 0):
        p_file.open(line[line.find("(")+1:line.find(",")])
        partial_line=line[line.find(",")+1:]
        print partial_line
        comma = partial_line.find(",")
        rparen = partial_line.find(")")
        if (comma == -1):
            token_end = rparen
        else:
            token_end = comma
        this_probe = partial_line[0:token_end].strip()
        p_file.add(this_probe,providers.get(this_probe))