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1#! /usr/bin/env python3
2
3# Perform massive identifier substitution on C source files.
4# This actually tokenizes the files (to some extent) so it can
5# avoid making substitutions inside strings or comments.
6# Inside strings, substitutions are never made; inside comments,
7# it is a user option (off by default).
8#
9# The substitutions are read from one or more files whose lines,
10# when not empty, after stripping comments starting with #,
11# must contain exactly two words separated by whitespace: the
12# old identifier and its replacement.
13#
14# The option -r reverses the sense of the substitutions (this may be
15# useful to undo a particular substitution).
16#
17# If the old identifier is prefixed with a '*' (with no intervening
18# whitespace), then it will not be substituted inside comments.
19#
20# Command line arguments are files or directories to be processed.
21# Directories are searched recursively for files whose name looks
22# like a C file (ends in .h or .c).  The special filename '-' means
23# operate in filter mode: read stdin, write stdout.
24#
25# Symbolic links are always ignored (except as explicit directory
26# arguments).
27#
28# The original files are kept as back-up with a "~" suffix.
29#
30# Changes made are reported to stdout in a diff-like format.
31#
32# NB: by changing only the function fixline() you can turn this
33# into a program for different changes to C source files; by
34# changing the function wanted() you can make a different selection of
35# files.
36
37import sys
38import re
39import os
40from stat import *
41import getopt
42
43err = sys.stderr.write
44dbg = err
45rep = sys.stdout.write
46
47def usage():
48    progname = sys.argv[0]
49    err('Usage: ' + progname +
50              ' [-c] [-r] [-s file] ... file-or-directory ...\n')
51    err('\n')
52    err('-c           : substitute inside comments\n')
53    err('-r           : reverse direction for following -s options\n')
54    err('-s substfile : add a file of substitutions\n')
55    err('\n')
56    err('Each non-empty non-comment line in a substitution file must\n')
57    err('contain exactly two words: an identifier and its replacement.\n')
58    err('Comments start with a # character and end at end of line.\n')
59    err('If an identifier is preceded with a *, it is not substituted\n')
60    err('inside a comment even when -c is specified.\n')
61
62def main():
63    try:
64        opts, args = getopt.getopt(sys.argv[1:], 'crs:')
65    except getopt.error as msg:
66        err('Options error: ' + str(msg) + '\n')
67        usage()
68        sys.exit(2)
69    bad = 0
70    if not args: # No arguments
71        usage()
72        sys.exit(2)
73    for opt, arg in opts:
74        if opt == '-c':
75            setdocomments()
76        if opt == '-r':
77            setreverse()
78        if opt == '-s':
79            addsubst(arg)
80    for arg in args:
81        if os.path.isdir(arg):
82            if recursedown(arg): bad = 1
83        elif os.path.islink(arg):
84            err(arg + ': will not process symbolic links\n')
85            bad = 1
86        else:
87            if fix(arg): bad = 1
88    sys.exit(bad)
89
90# Change this regular expression to select a different set of files
91Wanted = r'^[a-zA-Z0-9_]+\.[ch]$'
92def wanted(name):
93    return re.match(Wanted, name)
94
95def recursedown(dirname):
96    dbg('recursedown(%r)\n' % (dirname,))
97    bad = 0
98    try:
99        names = os.listdir(dirname)
100    except OSError as msg:
101        err(dirname + ': cannot list directory: ' + str(msg) + '\n')
102        return 1
103    names.sort()
104    subdirs = []
105    for name in names:
106        if name in (os.curdir, os.pardir): continue
107        fullname = os.path.join(dirname, name)
108        if os.path.islink(fullname): pass
109        elif os.path.isdir(fullname):
110            subdirs.append(fullname)
111        elif wanted(name):
112            if fix(fullname): bad = 1
113    for fullname in subdirs:
114        if recursedown(fullname): bad = 1
115    return bad
116
117def fix(filename):
118##  dbg('fix(%r)\n' % (filename,))
119    if filename == '-':
120        # Filter mode
121        f = sys.stdin
122        g = sys.stdout
123    else:
124        # File replacement mode
125        try:
126            f = open(filename, 'r')
127        except IOError as msg:
128            err(filename + ': cannot open: ' + str(msg) + '\n')
129            return 1
130        head, tail = os.path.split(filename)
131        tempname = os.path.join(head, '@' + tail)
132        g = None
133    # If we find a match, we rewind the file and start over but
134    # now copy everything to a temp file.
135    lineno = 0
136    initfixline()
137    while 1:
138        line = f.readline()
139        if not line: break
140        lineno = lineno + 1
141        while line[-2:] == '\\\n':
142            nextline = f.readline()
143            if not nextline: break
144            line = line + nextline
145            lineno = lineno + 1
146        newline = fixline(line)
147        if newline != line:
148            if g is None:
149                try:
150                    g = open(tempname, 'w')
151                except IOError as msg:
152                    f.close()
153                    err(tempname+': cannot create: '+
154                        str(msg)+'\n')
155                    return 1
156                f.seek(0)
157                lineno = 0
158                initfixline()
159                rep(filename + ':\n')
160                continue # restart from the beginning
161            rep(repr(lineno) + '\n')
162            rep('< ' + line)
163            rep('> ' + newline)
164        if g is not None:
165            g.write(newline)
166
167    # End of file
168    if filename == '-': return 0 # Done in filter mode
169    f.close()
170    if not g: return 0 # No changes
171    g.close()
172
173    # Finishing touch -- move files
174
175    # First copy the file's mode to the temp file
176    try:
177        statbuf = os.stat(filename)
178        os.chmod(tempname, statbuf[ST_MODE] & 0o7777)
179    except OSError as msg:
180        err(tempname + ': warning: chmod failed (' + str(msg) + ')\n')
181    # Then make a backup of the original file as filename~
182    try:
183        os.rename(filename, filename + '~')
184    except OSError as msg:
185        err(filename + ': warning: backup failed (' + str(msg) + ')\n')
186    # Now move the temp file to the original file
187    try:
188        os.rename(tempname, filename)
189    except OSError as msg:
190        err(filename + ': rename failed (' + str(msg) + ')\n')
191        return 1
192    # Return success
193    return 0
194
195# Tokenizing ANSI C (partly)
196
197Identifier = '(struct )?[a-zA-Z_][a-zA-Z0-9_]+'
198String = r'"([^\n\\"]|\\.)*"'
199Char = r"'([^\n\\']|\\.)*'"
200CommentStart = r'/\*'
201CommentEnd = r'\*/'
202
203Hexnumber = '0[xX][0-9a-fA-F]*[uUlL]*'
204Octnumber = '0[0-7]*[uUlL]*'
205Decnumber = '[1-9][0-9]*[uUlL]*'
206Intnumber = Hexnumber + '|' + Octnumber + '|' + Decnumber
207Exponent = '[eE][-+]?[0-9]+'
208Pointfloat = r'([0-9]+\.[0-9]*|\.[0-9]+)(' + Exponent + r')?'
209Expfloat = '[0-9]+' + Exponent
210Floatnumber = Pointfloat + '|' + Expfloat
211Number = Floatnumber + '|' + Intnumber
212
213# Anything else is an operator -- don't list this explicitly because of '/*'
214
215OutsideComment = (Identifier, Number, String, Char, CommentStart)
216OutsideCommentPattern = '(' + '|'.join(OutsideComment) + ')'
217OutsideCommentProgram = re.compile(OutsideCommentPattern)
218
219InsideComment = (Identifier, Number, CommentEnd)
220InsideCommentPattern = '(' + '|'.join(InsideComment) + ')'
221InsideCommentProgram = re.compile(InsideCommentPattern)
222
223def initfixline():
224    global Program
225    Program = OutsideCommentProgram
226
227def fixline(line):
228    global Program
229##  print('-->', repr(line))
230    i = 0
231    while i < len(line):
232        match = Program.search(line, i)
233        if match is None: break
234        i = match.start()
235        found = match.group(0)
236##      if Program is InsideCommentProgram: print(end='... ')
237##      else: print(end='    ')
238##      print(found)
239        if len(found) == 2:
240            if found == '/*':
241                Program = InsideCommentProgram
242            elif found == '*/':
243                Program = OutsideCommentProgram
244        n = len(found)
245        if found in Dict:
246            subst = Dict[found]
247            if Program is InsideCommentProgram:
248                if not Docomments:
249                    print('Found in comment:', found)
250                    i = i + n
251                    continue
252                if found in NotInComment:
253##                  print(end='Ignored in comment: ')
254##                  print(found, '-->', subst)
255##                  print('Line:', line, end='')
256                    subst = found
257##              else:
258##                  print(end='Substituting in comment: ')
259##                  print(found, '-->', subst)
260##                  print('Line:', line, end='')
261            line = line[:i] + subst + line[i+n:]
262            n = len(subst)
263        i = i + n
264    return line
265
266Docomments = 0
267def setdocomments():
268    global Docomments
269    Docomments = 1
270
271Reverse = 0
272def setreverse():
273    global Reverse
274    Reverse = (not Reverse)
275
276Dict = {}
277NotInComment = {}
278def addsubst(substfile):
279    try:
280        fp = open(substfile, 'r')
281    except IOError as msg:
282        err(substfile + ': cannot read substfile: ' + str(msg) + '\n')
283        sys.exit(1)
284    with fp:
285        lineno = 0
286        while 1:
287            line = fp.readline()
288            if not line: break
289            lineno = lineno + 1
290            try:
291                i = line.index('#')
292            except ValueError:
293                i = -1          # Happens to delete trailing \n
294            words = line[:i].split()
295            if not words: continue
296            if len(words) == 3 and words[0] == 'struct':
297                words[:2] = [words[0] + ' ' + words[1]]
298            elif len(words) != 2:
299                err(substfile + '%s:%r: warning: bad line: %r' % (substfile, lineno, line))
300                continue
301            if Reverse:
302                [value, key] = words
303            else:
304                [key, value] = words
305            if value[0] == '*':
306                value = value[1:]
307            if key[0] == '*':
308                key = key[1:]
309                NotInComment[key] = value
310            if key in Dict:
311                err('%s:%r: warning: overriding: %r %r\n' % (substfile, lineno, key, value))
312                err('%s:%r: warning: previous: %r\n' % (substfile, lineno, Dict[key]))
313            Dict[key] = value
314
315if __name__ == '__main__':
316    main()
317