fixincludes/README

   1
   2 FIXINCLUDES OPERATION
   3 =====================
   4
   5 See also:  http://autogen.SourceForge.net/fixinc.html
   6
   7 The set of fixes required was distilled down to just the data required
   8 to specify what needed to happen for each fix.  Those data were edited
   9 into a file named fixincludes/inclhack.def.  A program called AutoGen
  10 (http://autogen.SourceForge.net) uses these definitions to instantiate
  11 several different templates that then produces code for a fixinclude
  12 program (fixincl.x) and a shell script to test its functioning.  On
  13 certain platforms (viz. those that do not have functional bidirectional
  14 pipes), the fixincl program is split into two.  This should only concern
  15 you on DOS and BeOS.
  16
  17 Regards,
  18         Bruce <bkorb@gnu.org>
  19
  20
  21
  22 GCC MAINTAINER INFORMATION
  23 ==========================
  24
  25 If you are having some problem with a system header that is either
  26 broken by the manufacturer, or is broken by the fixinclude process,
  27 then you will need to alter or add information to the include fix
  28 definitions file, ``inclhack.def''.  Please also send relevant
  29 information to gcc-bugs@gcc.gnu.org, gcc-patches@gcc.gnu.org and,
  30 please, to me:  bkorb@gnu.org.
  31
  32 To make your fix, you will need to do several things:
  33
  34 1.  Obtain access to the AutoGen program on some platform.  It does
  35     not have to be your build platform, but it is more convenient.
  36
  37 2.  Edit "inclhack.def" to reflect the changes you need to make.
  38     See below for information on how to make those changes.
  39
  40 3.  Run the "genfixes" shell script to produce a new copy of
  41     the "fixincl.x" file.
  42
  43 4.  Rebuild the compiler and check the header causing the issue.
  44     Make sure it is now properly handled.  Add tests to the
  45     "test_text" entry(ies) that validate your fix.  This will
  46     help ensure that future fixes won't negate your work.
  47     Do *NOT* specify test text for "wrap" or "replacement" fixes.
  48     There is no real possibility that these fixes will fail.
  49     If they do, you will surely know straight away.
  50
  51 5.  Go into the fixincludes build directory and type, "make check".
  52     You are guaranteed to have issues printed out as a result.
  53     Look at the diffs produced.  Make sure you have not clobbered
  54     the proper functioning of a different fix.  Make sure your
  55     fix is properly tested and it does what it is supposed to do.
  56
  57 6.  Now that you have the right things happening, synchronize the
  58     $(srcdir)/tests/base directory with the $(builddir)/tests/res
  59     directory.  The output of "make check" will be some diffs that
  60     should give you some hints about what to do.
  61
  62 7.  Rerun "make check" and verify that there are no issues left.
  63
  64
  65 MAKING CHANGES TO INCLHACK.DEF
  66 ==============================
  67
  68 0.  If you are not the fixincludes maintainer, please send that
  69     person email about any changes you may want to make.  Thanks!
  70
  71 1.  Every fix must have a "hackname" that is compatible with C syntax
  72     for variable names and is unique without regard to alphabetic case.
  73     Please keep them alphabetical by this name.  :-)
  74
  75 2.  If the problem is known to exist only in certain files, then
  76     identify the files with "files = " entries.  If you use fnmatch(3C)
  77     wild card characters in a "files" entry, be certain that the first
  78     "files" entry has no such character.  Otherwise, the "make check"
  79     machinery will attempt to create files with those characters in the
  80     name.  That is inconvenient.
  81
  82 3.  It is relatively expensive to fire off a process to fix a source
  83     file, therefore write apply tests to avoid unnecessary fix
  84     processes.  The preferred apply tests are "select", "bypass", "mach"
  85     and "c-test" because they are performed internally:
  86
  87     * select - Run a regex on the contents of the file being considered.
  88                All such regex-es must match.  Matching is done with
  89                extended regular expressions.
  90
  91     * bypass - Run a regex on the contents of the file being considered.
  92                No such regex may match.
  93
  94     * c_test - call a function in fixtests.c.  See that file.
  95
  96     * files  - the "fnmatch" pattern of the file(s) to examine for
  97                the issue.  There may be several copies of this attribute.
  98                If the header lives in a /usr/include subdirectory, be
  99                sure to include that subdirectory in the name. e.g. net/if.h
 100
 101     * mach   - Match the output of config.guess against a series of fnmatch
 102                patterns.  It must match at least one of the patterns, unless
 103                "not-machine" has also been specified.  In that case, the
 104                config.guess output must not match any of the patterns.
 105
 106     The next test is relatively slow because it must be handled in a
 107     separate shell process.  Some platforms do not support server shells,
 108     so the whole process is even slower and more cumbersome there.
 109
 110     * test   - These should be arguments to the program, "/bin/test".
 111                You may perform multiple commands, if you enclose them
 112                in backquotes and echo out valid test arguments.  For
 113                example, you might echo out '0 -eq 1' if you want a false
 114                result, or '0 -eq 0' for a true result.
 115
 116     These tests are required to:
 117
 118     1.  Be positive for all header files that require the fix.
 119
 120     It is desirable to:
 121
 122     2.  Be negative as often as possible whenever the fix is not
 123         required, avoiding the process overhead.
 124
 125     It is nice if:
 126
 127     3.  The expression is as simple as possible to both
 128         process and understand by people.  :-)
 129
 130         Please take advantage of the fact AutoGen will glue
 131         together string fragments.  It helps.  Also take note
 132         that double quote strings and single quote strings have
 133         different formation rules.  Double quote strings are a
 134         tiny superset of ANSI-C string syntax.  Single quote
 135         strings follow shell single quote string formation
 136         rules, except that the backslash is processed before
 137         '\\', '\'' and '#' characters (using C character syntax).
 138
 139     Each test must pass or the fix is not applied.  For example,
 140     all "select" expressions must be found and not one "bypass"
 141     selection may be found.
 142
 143     Examples of test specifications:
 144
 145       hackname = broken_assert_stdio;
 146       files    = assert.h;
 147       select   = stderr;
 148       bypass   = "include.*stdio.h";
 149
 150     The ``broken_assert_stdio'' fix will be applied only to a file
 151     named "assert.h" if it contains the string "stderr" _and_ it
 152     does _not_ contain the expression "include.*stdio.h".
 153
 154       hackname = no_double_slash;
 155       c_test   = "double_slash";
 156
 157     The ``no_double_slash'' fix will be applied if the
 158     ``double_slash_test()'' function says to.  See ``fixtests.c''
 159     for documentation on how to include new functions into that
 160     module.
 161
 162 4.  There are currently four methods of fixing a file:
 163
 164     1.  a series of sed expressions.  Each will be an individual
 165         "-e" argument to a single invocation of sed.
 166
 167     2.  a shell script.  These scripts are _required_ to read all
 168         of stdin in order to avoid pipe stalls.  They may choose to
 169         discard the input.
 170
 171     3.  Replacement text.  If the replacement is empty, then no
 172         fix is applied.  Otherwise, the replacement text is
 173         written to the output file and no further fixes are
 174         applied.  If you really want a no-op file, replace the
 175         file with a comment.
 176
 177         Replacement text "fixes" must be first in this file!!
 178
 179     4.  A C language subroutine method for both tests and fixes.
 180         See ``fixtests.c'' for instructions on writing C-language
 181         applicability tests and ``fixfixes.c'' for C-language fixing.
 182         These files also contain tables that describe the currently
 183         implemented fixes and tests.
 184
 185     If at all possible, you should try to use one of the C language
 186     fixes as it is far more efficient.  There are currently five
 187     such fixes, three of which are very special purpose:
 188
 189     i) char_macro_def - This function repairs the definition of an
 190         ioctl macro that presumes CPP macro substitution within
 191         pairs of single quote characters.
 192
 193     ii) char_macro_use - This function repairs the usage of ioctl
 194         macros that no longer can wrap an argument with single quotes.
 195
 196     iii) machine_name - This function will look at "#if", "#ifdef",
 197         "#ifndef" and "#elif" directive lines and replace the first
 198         occurrence of a non-reserved name that is traditionally
 199         pre-defined by the native compiler.
 200
 201     The next two are for general use:
 202
 203     iv) wrap - wraps the entire file with "#ifndef", "#define" and
 204         "#endif" self-exclusionary text.  It also, optionally, inserts
 205         a prolog after the "#define" and an epilog just before the
 206         "#endif".  You can use this for a fix as follows:
 207
 208             c_fix     = wrap;
 209             c_fix_arg = "/* prolog text */";
 210             c_fix_arg = "/* epilog text */";
 211
 212         If you want an epilog without a prolog, set the first "c_fix_arg"
 213         to the empty string.  Both or the second "c_fix_arg"s may be
 214         omitted and the file will still be wrapped.
 215
 216         THERE IS A SPECIAL EXCEPTION TO THIS, HOWEVER:
 217
 218         If the regular expression '#if.*__need' is found, then it is
 219         assumed that the file needs to be read and interpreted more
 220         than once.  However, the prolog and epilog text (if any) will
 221         be inserted.
 222
 223     v) format - Replaces text selected with a regular expression with
 224         a specialized formating string.  The formatting works as follows:
 225         The format text is copied to the output until a '%' character
 226         is found.  If the character after the '%' is another '%', then
 227         one '%' is output and processing continues.  If the following
 228         character is not a digit, then the '%' and that character are
 229         copied and processing continues.  Finally, if the '%' *is*
 230         followed by a digit, that digit is used as an index into the
 231         regmatch_t array to replace the two characters with the matched
 232         text.  i.e.: "%0" is replaced by the full matching text, "%1"
 233         is the first matching sub-expression, etc.
 234
 235         This is used as follows:
 236
 237             c_fix     = format;
 238             c_fix_arg = "#ifndef %1\n%0\n#endif";
 239             c_fix_arg = "#define[ \t]+([A-Z][A-Z0-9a-z_]*).*";
 240
 241         This would wrap a one line #define inside of a "#ifndef"/"#endif"
 242         pair.  The second "c_fix_arg" may be omitted *IF* there is at least
 243         one select clause and the first one identifies the text you wish to
 244         reformat.  It will then be used as the second "c_fix_arg".  You may
 245         delete the selected text by supplying an empty string for the
 246         replacement format (the first "c_fix_arg").
 247
 248         Note: In general, a format c_fix may be used in place of one
 249         sed expression.  However, it will need to be rewritten by
 250         hand.  For example:
 251
 252         sed = 's@^#if __GNUC__ == 2 && __GNUC_MINOR__ >= 7$'
 253                '@& || __GNUC__ >= 3@';
 254
 255         may be rewritten using a format c_fix as:
 256
 257         c_fix     = format;
 258         c_fix_arg = '%0 || __GNUC__ >= 3';
 259         c_fix_arg = '^#if __GNUC__ == 2 && __GNUC_MINOR__ >= 7$';
 260
 261         Multiple sed substitution expressions probably ought to remain sed
 262         expressions in order to maintain clarity.  Also note that if the
 263         second sed expression is the same as the first select expression,
 264         then you may omit the second c_fix_arg.  The select expression will
 265         be picked up and used in its absence.
 266
 267 EXAMPLES OF FIXES:
 268 ==================
 269
 270       hackname = AAA_ki_iface;
 271       replace; /* empty replacement -> no fixing the file */
 272
 273     When this ``fix'' is invoked, it will prevent any fixes
 274     from being applied.
 275
 276     ------------------
 277
 278       hackname = AAB_svr4_no_varargs;
 279       replace  = "/* This file was generated by fixincludes.  */\n"
 280                  "#ifndef _SYS_VARARGS_H\n"
 281                  "#define _SYS_VARARGS_H\n\n"
 282
 283                  "#ifdef __STDC__\n"
 284                  "#include <stdarg.h>\n"
 285                  "#else\n"
 286                  "#include <varargs.h>\n"
 287                  "#endif\n\n"
 288
 289                  "#endif  /* _SYS_VARARGS_H */\n";
 290
 291     When this ``fix'' is invoked, the replacement text will be
 292     emitted into the replacement include file.  No further fixes
 293     will be applied.
 294
 295     ------------------
 296
 297         hackname  = hpux11_fabsf;
 298         files     = math.h;
 299         select    = "^[ \t]*#[ \t]*define[ \t]+fabsf\\(.*";
 300         bypass    = "__cplusplus";
 301
 302         c_fix     = format;
 303         c_fix_arg = "#ifndef __cplusplus\n%0\n#endif";
 304
 305         test_text =
 306         "#  define fabsf(x) ((float)fabs((double)(float)(x)))\n";
 307
 308     This fix will ensure that the #define for fabs is wrapped
 309     with C++ protection, providing the header is not already
 310     C++ aware.
 311
 312     ------------------
 313
 314 5.  Testing fixes.
 315
 316     The brute force method is, of course, to configure and build
 317     GCC.  But you can also:
 318
 319         cd ${top_builddir}/gcc
 320         rm -rf include-fixed/ stmp-fixinc
 321         make stmp-fixinc
 322
 323     I would really recommend, however:
 324
 325         cd ${top_builddir}/fixincludes
 326         make check
 327
 328     To do this, you *must* have autogen installed on your system.
 329     The "check" step will proceed to construct a shell script that
 330     will exercise all the fixes, using the sample test_text
 331     provided with each fix.  Once done, the changes made will
 332     be compared against the changes saved in the source directory.
 333     If you are changing the tests or fixes, the change will likely
 334     be highlighted.