build-aux/check-structs

   1 #! /usr/bin/python
   2
   3 import os.path
   4 import sys
   5 import re
   6
   7 macros = {}
   8
   9 anyWarnings = False
  10
  11 types = {}
  12 types['char'] = {"size": 1, "alignment": 1}
  13 types['uint8_t'] = {"size": 1, "alignment": 1}
  14 types['ovs_be16'] = {"size": 2, "alignment": 2}
  15 types['ovs_be32'] = {"size": 4, "alignment": 4}
  16 types['ovs_be64'] = {"size": 8, "alignment": 8}
  17 types['ovs_32aligned_be64'] = {"size": 8, "alignment": 4}
  18 types['struct eth_addr'] = {"size": 6, "alignment": 1}
  19
  20 token = None
  21 line = ""
  22 idRe = "[a-zA-Z_][a-zA-Z_0-9]*"
  23 tokenRe = "#?" + idRe + "|[0-9]+|."
  24 includeRe = re.compile(r'\s*#include\s+<(openflow/[^#]+)>')
  25 includePath = ''
  26 inComment = False
  27 inDirective = False
  28 inputStack = []
  29 def getToken():
  30     global token
  31     global line
  32     global inComment
  33     global inDirective
  34     global inputFile
  35     global fileName
  36     while True:
  37         line = line.lstrip()
  38         if line != "":
  39             if line.startswith("/*"):
  40                 inComment = True
  41                 line = line[2:]
  42             elif inComment:
  43                 commentEnd = line.find("*/")
  44                 if commentEnd < 0:
  45                     line = ""
  46                 else:
  47                     inComment = False
  48                     line = line[commentEnd + 2:]
  49             else:
  50                 match = re.match(tokenRe, line)
  51                 token = match.group(0)
  52                 line = line[len(token):]
  53                 if token.startswith('#'):
  54                     inDirective = True
  55                 elif token in macros and not inDirective:
  56                     line = macros[token] + line
  57                     continue
  58                 return True
  59         elif inDirective:
  60             token = "$"
  61             inDirective = False
  62             return True
  63         else:
  64             global lineNumber
  65             while True:
  66                 line = inputFile.readline()
  67                 lineNumber += 1
  68                 while line.endswith("\\\n"):
  69                     line = line[:-2] + inputFile.readline()
  70                     lineNumber += 1
  71                 match = includeRe.match(line)
  72                 if match:
  73                     inputStack.append((fileName, inputFile, lineNumber))
  74                     inputFile = open(includePath + match.group(1))
  75                     lineNumber = 0
  76                     continue
  77                 if line == "":
  78                     if inputStack:
  79                         fileName, inputFile, lineNumber = inputStack.pop()
  80                         continue
  81                     if token == None:
  82                         fatal("unexpected end of input")
  83                     token = None
  84                     return False
  85                 break
  86
  87 def fatal(msg):
  88     sys.stderr.write("%s:%d: error at \"%s\": %s\n" % (fileName, lineNumber, token, msg))
  89     sys.exit(1)
  90
  91 def warn(msg):
  92     global anyWarnings
  93     anyWarnings = True
  94     sys.stderr.write("%s:%d: warning: %s\n" % (fileName, lineNumber, msg))
  95
  96 def skipDirective():
  97     getToken()
  98     while token != '$':
  99         getToken()
 100
 101 def isId(s):
 102     return re.match(idRe + "$", s) != None
 103
 104 def forceId():
 105     if not isId(token):
 106         fatal("identifier expected")
 107
 108 def forceInteger():
 109     if not re.match('[0-9]+$', token):
 110         fatal("integer expected")
 111
 112 def match(t):
 113     if token == t:
 114         getToken()
 115         return True
 116     else:
 117         return False
 118
 119 def forceMatch(t):
 120     if not match(t):
 121         fatal("%s expected" % t)
 122
 123 def parseTaggedName():
 124     assert token in ('struct', 'union')
 125     name = token
 126     getToken()
 127     forceId()
 128     name = "%s %s" % (name, token)
 129     getToken()
 130     return name
 131
 132 def parseTypeName():
 133     if token in ('struct', 'union'):
 134         name = parseTaggedName()
 135     elif isId(token):
 136         name = token
 137         getToken()
 138     else:
 139         fatal("type name expected")
 140
 141     if name in types:
 142         return name
 143     else:
 144         fatal("unknown type \"%s\"" % name)
 145
 146 def parseStruct():
 147     isStruct = token == 'struct'
 148     structName = parseTaggedName()
 149     if token == ";":
 150         return
 151
 152     ofs = size = 0
 153     alignment = 4               # ARM has minimum 32-bit alignment
 154     forceMatch('{')
 155     while not match('}'):
 156         typeName = parseTypeName()
 157         typeSize = types[typeName]['size']
 158         typeAlignment = types[typeName]['alignment']
 159
 160         forceId()
 161         memberName = token
 162         getToken()
 163
 164         if match('['):
 165             if token == ']':
 166                 count = 0
 167             else:
 168                 forceInteger()
 169                 count = int(token)
 170                 getToken()
 171             forceMatch(']')
 172         else:
 173             count = 1
 174
 175         nBytes = typeSize * count
 176         if isStruct:
 177             if ofs % typeAlignment:
 178                 shortage = typeAlignment - (ofs % typeAlignment)
 179                 warn("%s member %s is %d bytes short of %d-byte alignment"
 180                      % (structName, memberName, shortage, typeAlignment))
 181                 size += shortage
 182                 ofs += shortage
 183             size += nBytes
 184             ofs += nBytes
 185         else:
 186             if nBytes > size:
 187                 size = nBytes
 188         if typeAlignment > alignment:
 189             alignment = typeAlignment
 190
 191         forceMatch(';')
 192     if size % alignment:
 193         shortage = alignment - (size % alignment)
 194         if (structName == "struct ofp10_packet_in" and
 195             shortage == 2 and
 196             memberName == 'data' and
 197             count == 0):
 198             # This is intentional
 199             pass
 200         else:
 201             warn("%s needs %d bytes of tail padding" % (structName, shortage))
 202         size += shortage
 203     types[structName] = {"size": size, "alignment": alignment}
 204     return structName
 205
 206 def checkStructs():
 207     if len(sys.argv) < 2:
 208         sys.stderr.write("at least one non-option argument required; "
 209                          "use --help for help")
 210         sys.exit(1)
 211
 212     if '--help' in sys.argv:
 213         argv0 = os.path.basename(sys.argv[0])
 214         print '''\
 215 %(argv0)s, for checking struct and struct member alignment
 216 usage: %(argv0)s -Ipath HEADER [HEADER]...
 217
 218 This program reads the header files specified on the command line and
 219 verifies that all struct members are aligned on natural boundaries
 220 without any need for the compiler to add additional padding.  It also
 221 verifies that each struct's size is a multiple of 32 bits (because
 222 some ABIs for ARM require all structs to be a multiple of 32 bits), or
 223 64 bits if the struct has any 64-bit members, again without the
 224 compiler adding additional padding.  Finally, it checks struct size
 225 assertions using OFP_ASSERT.
 226
 227 This program is specialized for reading Open vSwitch's OpenFlow header
 228 files.  It will not work on arbitrary header files without extensions.\
 229 ''' % {"argv0": argv0}
 230         sys.exit(0)
 231
 232     global fileName
 233     for fileName in sys.argv[1:]:
 234         if fileName.startswith('-I'):
 235             global includePath
 236             includePath = fileName[2:]
 237             if not includePath.endswith('/'):
 238                 includePath += '/'
 239             continue
 240         global inputFile
 241         global lineNumber
 242         inputFile = open(fileName)
 243         lineNumber = 0
 244         lastStruct = None
 245         while getToken():
 246             if token in ("#ifdef", "#ifndef", "#include",
 247                          "#endif", "#elif", "#else"):
 248                 skipDirective()
 249             elif token == "#define":
 250                 getToken()
 251                 name = token
 252                 if line.startswith('('):
 253                     skipDirective()
 254                 else:
 255                     definition = ""
 256                     getToken()
 257                     while token != '$':
 258                         definition += token
 259                         getToken()
 260                     macros[name] = definition
 261             elif token == "enum":
 262                 while token != ';':
 263                     getToken()
 264             elif token in ('struct', 'union'):
 265                 lastStruct = parseStruct()
 266             elif match('OFP_ASSERT') or match('BOOST_STATIC_ASSERT'):
 267                 forceMatch('(')
 268                 forceMatch('sizeof')
 269                 forceMatch('(')
 270                 typeName = parseTypeName()
 271                 if typeName != lastStruct:
 272                     warn("checking size of %s but %s was most recently defined"
 273                          % (typeName, lastStruct))
 274                 forceMatch(')')
 275                 forceMatch('=')
 276                 forceMatch('=')
 277                 forceInteger()
 278                 size = int(token)
 279                 getToken()
 280                 forceMatch(')')
 281                 if types[typeName]['size'] != size:
 282                     warn("%s is %d bytes long but declared as %d" % (
 283                             typeName, types[typeName]['size'], size))
 284             else:
 285                 fatal("parse error")
 286         inputFile.close()
 287     if anyWarnings:
 288         sys.exit(1)
 289
 290 if __name__ == '__main__':
 291     checkStructs()