scripts/tracetool/format/log_stap.py

   1 # -*- coding: utf-8 -*-
   2
   3 """
   4 Generate .stp file that printfs log messages (DTrace with SystemTAP only).
   5 """
   6
   7 __author__     = "Daniel P. Berrange <berrange@redhat.com>"
   8 __copyright__  = "Copyright (C) 2014-2019, Red Hat, Inc."
   9 __license__    = "GPL version 2 or (at your option) any later version"
  10
  11 __maintainer__ = "Daniel Berrange"
  12 __email__      = "berrange@redhat.com"
  13
  14 import re
  15
  16 from tracetool import out
  17 from tracetool.backend.dtrace import binary, probeprefix
  18 from tracetool.backend.simple import is_string
  19 from tracetool.format.stap import stap_escape
  20
  21 def global_var_name(name):
  22     return probeprefix().replace(".", "_") + "_" + name
  23
  24 STATE_SKIP = 0
  25 STATE_LITERAL = 1
  26 STATE_MACRO = 2
  27
  28 def c_macro_to_format(macro):
  29     if macro.startswith("PRI"):
  30         return macro[3]
  31
  32     raise Exception("Unhandled macro '%s'" % macro)
  33
  34 def c_fmt_to_stap(fmt):
  35     state = 0
  36     bits = []
  37     literal = ""
  38     macro = ""
  39     escape = 0;
  40     for i in range(len(fmt)):
  41         if fmt[i] == '\\':
  42             if escape:
  43                 escape = 0
  44             else:
  45                 escape = 1
  46             if state != STATE_LITERAL:
  47                 raise Exception("Unexpected escape outside string literal")
  48             literal = literal + fmt[i]
  49         elif fmt[i] == '"' and not escape:
  50             if state == STATE_LITERAL:
  51                 state = STATE_SKIP
  52                 bits.append(literal)
  53                 literal = ""
  54             else:
  55                 if state == STATE_MACRO:
  56                     bits.append(c_macro_to_format(macro))
  57                     macro = ""
  58                 state = STATE_LITERAL
  59         elif fmt[i] == ' ' or fmt[i] == '\t':
  60             if state == STATE_MACRO:
  61                 bits.append(c_macro_to_format(macro))
  62                 macro = ""
  63                 state = STATE_SKIP
  64             elif state == STATE_LITERAL:
  65                 literal = literal + fmt[i]
  66         else:
  67             escape = 0
  68             if state == STATE_SKIP:
  69                 state = STATE_MACRO
  70
  71             if state == STATE_LITERAL:
  72                 literal = literal + fmt[i]
  73             else:
  74                 macro = macro + fmt[i]
  75
  76     if state == STATE_MACRO:
  77         bits.append(c_macro_to_format(macro))
  78     elif state == STATE_LITERAL:
  79         bits.append(literal)
  80
  81     # All variables in systemtap are 64-bit in size
  82     # The "%l" integer size qualifier is thus redundant
  83     # and "%ll" is not valid at all. Similarly the size_t
  84     # based "%z" size qualifier is not valid. We just
  85     # strip all size qualifiers for sanity.
  86     fmt = re.sub("%(\d*)(l+|z)(x|u|d)", "%\\1\\3", "".join(bits))
  87     return fmt
  88
  89 def generate(events, backend, group):
  90     out('/* This file is autogenerated by tracetool, do not edit. */',
  91         '')
  92
  93     for event_id, e in enumerate(events):
  94         if 'disable' in e.properties:
  95             continue
  96
  97         out('probe %(probeprefix)s.log.%(name)s = %(probeprefix)s.%(name)s ?',
  98             '{',
  99             probeprefix=probeprefix(),
 100             name=e.name)
 101
 102         # Get references to userspace strings
 103         for type_, name in e.args:
 104             name = stap_escape(name)
 105             if is_string(type_):
 106                 out('    try {',
 107                     '        arg%(name)s_str = %(name)s ? ' +
 108                     'user_string_n(%(name)s, 512) : "<null>"',
 109                     '    } catch {}',
 110                     name=name)
 111
 112         # Determine systemtap's view of variable names
 113         fields = ["pid()", "gettimeofday_ns()"]
 114         for type_, name in e.args:
 115             name = stap_escape(name)
 116             if is_string(type_):
 117                 fields.append("arg" + name + "_str")
 118             else:
 119                 fields.append(name)
 120
 121         # Emit the entire record in a single SystemTap printf()
 122         arg_str = ', '.join(arg for arg in fields)
 123         fmt_str = "%d@%d " + e.name + " " + c_fmt_to_stap(e.fmt) + "\\n"
 124         out('    printf("%(fmt_str)s", %(arg_str)s)',
 125             fmt_str=fmt_str, arg_str=arg_str)
 126
 127         out('}')
 128
 129     out()