tracetool: Rewrite infrastructure as python modules

The tracetool script is written in shell and has hit several portability
problems due to shell quirks or external tools across host platforms.
Additionally the amount of string processing and lack of real data
structures makes it tough to implement code generator backends for
tracers that are more complex.

This patch replaces the shell version of tracetool with a Python
version.  The new tracetool design is:

  scripts/tracetool.py - top-level script
  scripts/tracetool/backend/ - tracer backends live here (simple, ust)
  scripts/tracetool/format/  - output formats live here (.c, .h)

There is common code for trace-events definition parsing so that
backends can focus on generating code rather than parsing input.

Support for all existing backends (nop, stderr, simple, ust,
and dtrace) is added back in follow-up patches.

[Commit description written by Stefan Hajnoczi]

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

scripts/tracetool.py

@@ -0,0 +1,108 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+"""
+Command-line wrapper for the tracetool machinery.
+"""
+
+__author__     = "Lluís Vilanova <vilanova@ac.upc.edu>"
+__copyright__  = "Copyright 2012, Lluís Vilanova <vilanova@ac.upc.edu>"
+__license__    = "GPL version 2 or (at your option) any later version"
+
+__maintainer__ = "Stefan Hajnoczi"
+__email__      = "stefanha@linux.vnet.ibm.com"
+
+
+import sys
+import getopt
+
+from tracetool import error_write, out
+import tracetool.backend
+import tracetool.format
+
+
+_SCRIPT = ""
+
+def error_opt(msg = None):
+    if msg is not None:
+        error_write("Error: " + msg + "\n")
+
+    backend_descr = "\n".join([ "    %-15s %s" % (n, d)
+                                for n,d in tracetool.backend.get_list() ])
+    format_descr = "\n".join([ "    %-15s %s" % (n, d)
+                               for n,d in tracetool.format.get_list() ])
+    error_write("""\
+Usage: %(script)s --format=<format> --backend=<backend> [<options>]
+
+Backends:
+%(backends)s
+
+Formats:
+%(formats)s
+
+Options:
+    --help                   This help message.
+    --list-backends          Print list of available backends.
+    --check-backend          Check if the given backend is valid.
+""" % {
+            "script" : _SCRIPT,
+            "backends" : backend_descr,
+            "formats" : format_descr,
+            })
+
+    if msg is None:
+        sys.exit(0)
+    else:
+        sys.exit(1)
+
+
+def main(args):
+    global _SCRIPT
+    _SCRIPT = args[0]
+
+    long_opts  = [ "backend=", "format=", "help", "list-backends", "check-backend" ]
+    long_opts += [ "binary=", "target-type=", "target-arch=", "probe-prefix=" ]
+
+    try:
+        opts, args = getopt.getopt(args[1:], "", long_opts)
+    except getopt.GetoptError as err:
+        error_opt(str(err))
+
+    check_backend = False
+    arg_backend = ""
+    arg_format = ""
+    for opt, arg in opts:
+        if opt == "--help":
+            error_opt()
+
+        elif opt == "--backend":
+            arg_backend = arg
+        elif opt == "--format":
+            arg_format = arg
+
+        elif opt == "--list-backends":
+            backends = tracetool.backend.get_list()
+            out(", ".join([ b for b,_ in backends ]))
+            sys.exit(0)
+        elif opt == "--check-backend":
+            check_backend = True
+
+        else:
+            error_opt("unhandled option: %s" % opt)
+
+    if arg_backend is None:
+        error_opt("backend not set")
+
+    if check_backend:
+        if tracetool.backend.exists(arg_backend):
+            sys.exit(0)
+        else:
+            sys.exit(1)
+
+    try:
+        tracetool.generate(sys.stdin, arg_format, arg_backend)
+    except tracetool.TracetoolError as e:
+        error_opt(str(e))
+
+if __name__ == "__main__":
+    main(sys.argv)