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1  MAINTENANCE README FOR PCRE  MAINTENANCE README FOR PCRE
2  ---------------------------  ===========================
3    
4  The files in the "maint" directory of the PCRE source contain data, scripts,  The files in the "maint" directory of the PCRE source contain data, scripts,
5  and programs that are used for the maintenance of PCRE, but which do not form  and programs that are used for the maintenance of PCRE, but which do not form
# Line 14  also contains some notes for maintainers Line 14  also contains some notes for maintainers
14    
15    
16  Files in the maint directory  Files in the maint directory
17  ----------------------------  ============================
18    
19  ----------------- This file is now OBSOLETE and no longer used ----------------  ---------------- This file is now OBSOLETE and no longer used ----------------
20  Builducptable    A Perl script that creates the contents of the ucptable.h file  Builducptable    A Perl script that creates the contents of the ucptable.h file
21                   from two Unicode data files, which themselves are downloaded                   from two Unicode data files, which themselves are downloaded
22                   from the Unicode web site. Run this script in the "maint"                   from the Unicode web site. Run this script in the "maint"
23                   directory.                   directory.
24  ----------------- This file is now OBSOLETE and no longer used ----------------  ---------------- This file is now OBSOLETE and no longer used ----------------
25    
26  GenerateUtt.py   A Python script to generate part of the pcre_tables.c file  GenerateUtt.py   A Python script to generate part of the pcre_tables.c file
27                   that contains Unicode script names in a long string with                   that contains Unicode script names in a long string with
28                   offsets, which is tedious to maintain by hand.                   offsets, which is tedious to maintain by hand.
29    
30  ManyConfigTests  A shell script that runs "configure, make, test" a number of  ManyConfigTests  A shell script that runs "configure, make, test" a number of
31                   times with different configuration settings.                   times with different configuration settings.
32    
33  MultiStage2.py   A Python script that generates the file pcre_ucd.c from three  MultiStage2.py   A Python script that generates the file pcre_ucd.c from three
34                   Unicode data tables, which are themselves downloaded from the                   Unicode data tables, which are themselves downloaded from the
35                   Unicode web site. Run this script in the "maint" directory.                   Unicode web site. Run this script in the "maint" directory.
36                   The generated file contains the tables for a 2-stage lookup                   The generated file contains the tables for a 2-stage lookup
37                   of Unicode properties.                   of Unicode properties.
38    
39    pcre_chartables.c.non-standard
40                     This is a set of character tables that came from a Windows
41                     system. It has characters greater than 128 that are set as
42                     spaces, amongst other things. I kept it so that it can be
43                     used for testing from time to time.
44    
45  README           This file.  README           This file.
46    
47  Unicode.tables   The files in this directory, DerivedGeneralCategory.txt,  Unicode.tables   The files in this directory (CaseFolding.txt,
48                   Scripts.txt and UnicodeData.txt, were downloaded from the                   DerivedGeneralCategory.txt, GraphemeBreakProperty.txt,
49                     Scripts.txt and UnicodeData.txt) were downloaded from the
50                   Unicode web site. They contain information about Unicode                   Unicode web site. They contain information about Unicode
51                   characters and scripts.                   characters and scripts.
52    
53  ucptest.c        A short C program for testing the Unicode property macros  ucptest.c        A short C program for testing the Unicode property macros
54                   that do lookups in the pcre_ucd.c data, mainly useful after                   that do lookups in the pcre_ucd.c data, mainly useful after
# Line 61  utf8.c           A short, freestanding C Line 68  utf8.c           A short, freestanding C
68    
69    
70  Updating to a new Unicode release  Updating to a new Unicode release
71  ---------------------------------  =================================
72    
73  When there is a new release of Unicode, the files in Unicode.tables must be  When there is a new release of Unicode, the files in Unicode.tables must be
74  refreshed from the web site. If the new version of Unicode adds new character  refreshed from the web site. If the new version of Unicode adds new character
# Line 70  GenerateUtt.py scripts must be edited to Line 77  GenerateUtt.py scripts must be edited to
77  can be run to generate a new version of pcre_ucd.c, and GenerateUtt.py can be  can be run to generate a new version of pcre_ucd.c, and GenerateUtt.py can be
78  run to generate the tricky tables for inclusion in pcre_tables.c.  run to generate the tricky tables for inclusion in pcre_tables.c.
79    
80    If MultiStage2.py gives the error "ValueError: list.index(x): x not in list",
81    the cause is usually a missing (or misspelt) name in the list of scripts. I
82    couldn't find a straightforward list of scripts on the Unicode site, but
83    there's a useful Wikipedia page that list them, and notes the Unicode version
84    in which they were introduced:
85    
86    http://en.wikipedia.org/wiki/Unicode_scripts#Table_of_Unicode_scripts
87    
88  The ucptest program can be compiled and used to check that the new tables in  The ucptest program can be compiled and used to check that the new tables in
89  pcre_ucd.c work properly, using the data files in ucptestdata to check a number  pcre_ucd.c work properly, using the data files in ucptestdata to check a number
90  of test characters.  of test characters. The source file ucptest.c must be updated whenever new
91    Unicode script names are added.
92    
93    Note also that both the pcresyntax.3 and pcrepattern.3 man pages contain lists
94    of Unicode script names.
95    
96    
97  Preparing for a PCRE release  Preparing for a PCRE release
98  ----------------------------  ============================
99    
100  This section contains a checklist of things that I consult before building a  This section contains a checklist of things that I consult before building a
101  distribution for a new release.  distribution for a new release.
102    
103  . Ensure that the version number and version date are correct in configure.ac.  . Ensure that the version number and version date are correct in configure.ac.
104    
105    . Update the library version numbers in configure.ac according to the rules
106      given below.
107    
108  . If new build options have been added, ensure that they are added to the CMake  . If new build options have been added, ensure that they are added to the CMake
109    files as well as to the autoconf files.    files as well as to the autoconf files. The relevant files are CMakeLists.txt
110      and config-cmake.h.in. After making a release tarball, test it out with CMake
111      if there have been changes here.
112    
113  . Run ./autogen.sh to ensure everything is up-to-date.  . Run ./autogen.sh to ensure everything is up-to-date.
114    
115  . Compile and test with many different config options, and combinations of  . Compile and test with many different config options, and combinations of
116    options. The maint/ManyConfigTests script now encapsulates this testing.    options. Also, test with valgrind by running "RunTest valgrind" and
117      "RunGrepTest valgrind" (which takes quite a long time). The script
118      maint/ManyConfigTests now encapsulates this testing. It runs tests with
119      different configurations, and it also runs some of them with valgrind, all of
120      which can take quite some time.
121    
122  . Run perltest.pl on the test data for tests 1, 4, 6, and 11. The first two can  . Run perltest.pl on the test data for tests 1, 4, and 6. The output
   be run with Perl 5.8 or 5.10; the last two require Perl 5.10. The output  
123    should match the PCRE test output, apart from the version identification at    should match the PCRE test output, apart from the version identification at
124    the start of each test. The other tests are not Perl-compatible (they use    the start of each test. The other tests are not Perl-compatible (they use
125    various PCRE-specific features or options).    various PCRE-specific features or options).
126    
127  . Test with valgrind by running "RunTest valgrind". There is also "RunGrepTest  . It is possible to test with the emulated memmove() function by undefining
128    valgrind", though that takes quite a long time.    HAVE_MEMMOVE and HAVE_BCOPY in config.h, though I do not do this often. You
129      may see a number of "pcre_memmove defined but not used" warnings for the
130      modules in which there is no call to memmove(). These can be ignored.
131    
132    . Documentation: check AUTHORS, ChangeLog (check version and date), LICENCE,
133      NEWS (check version and date), NON-AUTOTOOLS-BUILD, and README. Many of these
134      won't need changing, but over the long term things do change.
135    
136    . I used to test new releases myself on a number of different operating
137      systems, using different compilers as well. For example, on Solaris it is
138      helpful to test using Sun's cc compiler as a change from gcc. Adding
139      -xarch=v9 to the cc options does a 64-bit test, but it also needs -S 64 for
140      pcretest to increase the stack size for test 2. Since I retired I can no
141      longer do this, but instead I rely on putting out release candidates for
142      folks on the pcre-dev list to test.
143    
144    
145  . It may also useful to test with Electric Fence, though the fact that it  Updating version info for libtool
146    grumbles for missing free() calls can be a nuisance. (A missing free() in  =================================
   pcretest is hardly a big problem.) To build with EF, use:  
147    
148      LIBS='/usr/lib/libefence.a -lpthread' with ./configure.  This set of rules for updating library version information came from a web page
149    whose URL I have forgotten. The version information consists of three parts:
150    (current, revision, age).
151    
152    Then all normal runs use it to check for buffer overflow. Also run everything  1. Start with version information of 0:0:0 for each libtool library.
   with:  
153    
154      EF_PROTECT_BELOW=1 <whatever>  2. Update the version information only immediately before a public release of
155       your software. More frequent updates are unnecessary, and only guarantee
156       that the current interface number gets larger faster.
157    
158    because there have been problems with lookbehinds that looked too far.  3. If the library source code has changed at all since the last update, then
159       increment revision; c:r:a becomes c:r+1:a.
160    
161  . Test with the emulated memmove() function by undefining HAVE_MEMMOVE and  4. If any interfaces have been added, removed, or changed since the last
162    HAVE_BCOPY in config.h. You may see a number of "pcre_memmove defined but not     update, increment current, and set revision to 0.
   used" warnings for the modules in which there is no call to memmove(). These  
   can be ignored.  
163    
164  . Documentation: check AUTHORS, COPYING, ChangeLog (check version and date),  5. If any interfaces have been added since the last public release, then
165    INSTALL, LICENCE, NEWS (check version and date), NON-UNIX-USE, and README.     increment age.
   Many of these won't need changing, but over the long term things do change.  
166    
167  . Man pages: Check all man pages for \ not followed by e or f or " because  6. If any interfaces have been removed or changed since the last public
168    that indicates a markup error.     release, then set age to 0.
169    
170  . When the release is built, test it on a number of different operating  The following explanation may help in understanding the above rules a bit
171    systems if possible, and using different compilers as well. For example,  better. Consider that there are three possible kinds of reaction from users to
172    on Solaris it is helpful to test using Sun's cc compiler as a change from  changes in a shared library:
173    gcc. Adding -xarch=v9 to the cc options does a 64-bit test, but it also  
174    needs -S 64 for pcretest to increase the stack size for test 2.  1. Programs using the previous version may use the new version as a drop-in
175       replacement, and programs using the new version can also work with the
176       previous one. In other words, no recompiling nor relinking is needed. In
177       this case, increment revision only, don't touch current or age.
178    
179    2. Programs using the previous version may use the new version as a drop-in
180       replacement, but programs using the new version may use APIs not present in
181       the previous one. In other words, a program linking against the new version
182       may fail if linked against the old version at run time. In this case, set
183       revision to 0, increment current and age.
184    
185    3. Programs may need to be changed, recompiled, relinked in order to use the
186       new version. Increment current, set revision and age to 0.
187    
188    
189  Making a PCRE release  Making a PCRE release
190  ---------------------  =====================
191    
192  Run PrepareRelease and commit the files that it changes (by removing trailing  Run PrepareRelease and commit the files that it changes (by removing trailing
193  spaces). Then run "make distcheck" to create the tarballs and the zipball.  spaces). The first thing this script does is to run CheckMan on the man pages;
194  Double-check with "svn status", then create an SVN tagged copy:  if it finds any markup errors, it reports them and then aborts.
195    
196    Once PrepareRelease has run clean, run "make distcheck" to create the tarballs
197    and the zipball. Double-check with "svn status", then create an SVN tagged
198    copy:
199    
200    svn copy svn://vcs.exim.org/pcre/code/trunk \    svn copy svn://vcs.exim.org/pcre/code/trunk \
201             svn://vcs.exim.org/pcre/code/tags/pcre-8.xx             svn://vcs.exim.org/pcre/code/tags/pcre-8.xx
202    
203  Don't forget to update Freshmeat when the new release is out, and to tell  Don't forget to update Freshmeat when the new release is out, and to tell
204  webmaster@pcre.org and the mailing list.  webmaster@pcre.org and the mailing list. Also, update the list of version
205    numbers in Bugzilla (edit products).
206    
207    
208  Future ideas (wish list)  Future ideas (wish list)
209  ------------------------  ========================
210    
211  This section records a list of ideas so that they do not get forgotten. They  This section records a list of ideas so that they do not get forgotten. They
212  vary enormously in their usefulness and potential for implementation. Some are  vary enormously in their usefulness and potential for implementation. Some are
# Line 169  others are relatively new. Line 228  others are relatively new.
228    
229    * "Ends with literal string" - note that a single character doesn't gain much    * "Ends with literal string" - note that a single character doesn't gain much
230      over the existing "required byte" (reqbyte) feature that just remembers one      over the existing "required byte" (reqbyte) feature that just remembers one
231      byte.      data unit.
232    
233    * These probably need to go in study():    * These probably need to go in pcre_study():
234    
235      o Remember an initial string rather than just 1 char?      o Remember an initial string rather than just 1 char?
236    
237      o A required byte from alternatives - not just the last char, but an      o A required data unit from alternatives - not just the last unit, but an
238        earlier one if common to all alternatives.        earlier one if common to all alternatives.
239    
240      o Friedl contains other ideas.      o Friedl contains other ideas.
241    
242      * pcre_study() does not set initial byte flags for Unicode property types
243        such as \p; I don't know how much benefit there would be for, for example,
244        setting the bits for 0-9 and all bytes >= xC0 when a pattern starts with
245        \p{N}.
246    
247      * There is scope for more "auto-possessifying" in connection with \p and \P.
248    
249  . If Perl gets to a consistent state over the settings of capturing sub-  . If Perl gets to a consistent state over the settings of capturing sub-
250    patterns inside repeats, see if we can match it. One example of the    patterns inside repeats, see if we can match it. One example of the
251    difference is the matching of /(main(O)?)+/ against mainOmain, where PCRE    difference is the matching of /(main(O)?)+/ against mainOmain, where PCRE
# Line 188  others are relatively new. Line 254  others are relatively new.
254    
255  . Perl 6 will be a revolution. Is it a revolution too far for PCRE?  . Perl 6 will be a revolution. Is it a revolution too far for PCRE?
256    
 . Unicode  
   
   * Note that in Perl, \s matches \pZ and similarly for \d, \w and the POSIX  
     character classes. For the moment, I've chosen not to support this for  
     backward compatibility, for speed, and because it would be messy to  
     implement.  
   
   * A different approach to Unicode might be to use a typedef to do everything  
     in unsigned shorts instead of unsigned chars. Actually, we'd have to have a  
     new typedef to distinguish data from bits of compiled pattern that are in  
     bytes, I think. There would need to be conversion functions in and out. I  
     don't think this is particularly trivial - and anyway, Unicode now has  
     characters that need more than 16 bits, so is this at all sensible?  
   
   * There has been a request for direct support of 16-bit characters and  
     UTF-16. However, since Unicode is moving beyond purely 16-bit characters,  
     is this worth it at all? One possible way of handling 16-bit characters  
     would be to "load" them in the same way that UTF-8 characters are loaded.  
   
257  . Allow errorptr and erroroffset to be NULL. I don't like this idea.  . Allow errorptr and erroroffset to be NULL. I don't like this idea.
258    
259  . Line endings:  . Line endings:
# Line 232  others are relatively new. Line 279  others are relatively new.
279    support --outputfile=name.    support --outputfile=name.
280    
281  . Consider making UTF-8 and UCP the default for PCRE n.0 for some n > 8.  . Consider making UTF-8 and UCP the default for PCRE n.0 for some n > 8.
282      (And now presumably UTF-16 and UCP for the 16-bit library.)
283    
284  . Add a user pointer to pcre_malloc/free functions -- some option would be  . Add a user pointer to pcre_malloc/free functions -- some option would be
285    needed to retain backward compatibility.    needed to retain backward compatibility.
# Line 246  others are relatively new. Line 294  others are relatively new.
294  . Wild thought: the ability to compile from PCRE's internal byte code to a real  . Wild thought: the ability to compile from PCRE's internal byte code to a real
295    FSM and a very fast (third) matcher to process the result. There would be    FSM and a very fast (third) matcher to process the result. There would be
296    even more restrictions than for pcre_dfa_exec(), however. This is not easy.    even more restrictions than for pcre_dfa_exec(), however. This is not easy.
297      This is probably obsolete now that we have the JIT support.
298    
299  . Should pcretest have some private locale data, to avoid relying on the  . Should pcretest have some private locale data, to avoid relying on the
300    available locales for the test data, since different OS have different ideas?    available locales for the test data, since different OS have different ideas?
# Line 256  others are relatively new. Line 305  others are relatively new.
305    
306  . Someone suggested --disable-callout to save code space when callouts are  . Someone suggested --disable-callout to save code space when callouts are
307    never wanted. This seems rather marginal.    never wanted. This seems rather marginal.
308    
309  . Check names that consist entirely of digits: PCRE allows, but do Perl and  . Check names that consist entirely of digits: PCRE allows, but do Perl and
310    Python, etc?    Python, etc?
311    
312  . A user suggested a parameter to limit the length of string matched, for  . A user suggested a parameter to limit the length of string matched, for
313    example if the parameter is N, the current match should fail if the matched    example if the parameter is N, the current match should fail if the matched
314    substring exceeds N. This could apply to both match functions. The value    substring exceeds N. This could apply to both match functions. The value
315    could be a new field in the extra block.    could be a new field in the extra block.
316    
317  . Callouts with arguments: (?Cn:ARG) for instance.  . Callouts with arguments: (?Cn:ARG) for instance.
318    
319  . A user is going to supply a patch to generalize the API for user-specific  . A user is going to supply a patch to generalize the API for user-specific
320    memory allocation so that it is more flexible in threaded environments. Thiw    memory allocation so that it is more flexible in threaded environments. This
321    was promised a long time ago, and never appeared...    was promised a long time ago, and never appeared. However, this is a live
322      issue not only for threaded environments, but for libraries that use PCRE and
323      want not to be beholden to their caller's memory allocation.
324    
325    . Write a wrapper to maintain a structure with specified runtime parameters,
326      such as recurse limit, and pass these to PCRE each time it is called. Also
327      maybe malloc and free. A user sent a prototype. This relates the the previous
328      item.
329    
330  . Write a function that generates random matching strings for a compiled regex.  . Write a function that generates random matching strings for a compiled regex.
331    
332  . Write a wrapper to maintain a structure with specified runtime parameters,  . Pcregrep: an option to specify the output line separator, either as a string
333    such as recurse limit, and pass these to PCRE each time it is called. Also    or select from a fixed list. This is not dead easy, because at the moment it
   maybe malloc and free. A user sent a prototype.  
   
 . Pcregrep: an option to specify the output line separator, either as a string  
   or select from a fixed list. This is not dead easy, because at the moment it  
334    outputs whatever is in the input file.    outputs whatever is in the input file.
335    
336  . Improve the code for duplicate checking in pcre_dfa_exec(). An incomplete,  . Improve the code for duplicate checking in pcre_dfa_exec(). An incomplete,
337    non-thread-safe patch showed that this can help performance for patterns    non-thread-safe patch showed that this can help performance for patterns
338    where there are many alternatives. However, a simple thread-safe    where there are many alternatives. However, a simple thread-safe
339    implementation that I tried made things worse in many simple cases, so this    implementation that I tried made things worse in many simple cases, so this
340    is not an obviously good thing.    is not an obviously good thing.
341    
342  . Make the longest lookbehind available via pcre_fullinfo(). This is not  . Make the longest lookbehind available via pcre_fullinfo(). This is not
343    straightforward because lookbehinds can be nested inside lookbehinds. This    straightforward because lookbehinds can be nested inside lookbehinds. This
344    case will have to be identified, and the amounts added. This should then give    case will have to be identified, and the amounts added. This should then give
345    the maximum possible lookbehind length. The reason for wanting this is to    the maximum possible lookbehind length. The reason for wanting this is to
346    help when implementing multi-segment matching using pcre_exec() with partial    help when implementing multi-segment matching using pcre_exec() with partial
347    matching and overlapping segments.    matching and overlapping segments.
348    
349  . PCRE cannot at present distinguish between subpatterns with different names,  . PCRE cannot at present distinguish between subpatterns with different names,
350    but the same number (created by the use of ?|). In order to do so, a way of    but the same number (created by the use of ?|). In order to do so, a way of
351    remembering *which* subpattern numbered n matched is needed. Bugzilla #760.    remembering *which* subpattern numbered n matched is needed. Bugzilla #760.
352      Now that (*MARK) has been implemented, it can perhaps be used as a way round
353      this problem.
354    
355    . Instead of having #ifdef HAVE_CONFIG_H in each module, put #include
356      "something" and the the #ifdef appears only in one place, in "something".
357    
358  Philip Hazel  Philip Hazel
359  Email local part: ph10  Email local part: ph10
360  Email domain: cam.ac.uk  Email domain: cam.ac.uk
361  Last updated: 26 September 2009  Last updated: 20 September 2012

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