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