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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
27                     that contains Unicode script names in a long string with
28                     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  Unicode.tables   The files in this directory, DerivedGeneralCategory.txt,  README           This file.
46    
47    Unicode.tables   The files in this directory, DerivedGeneralCategory.txt,
48                   Scripts.txt and UnicodeData.txt, were downloaded from the                   Scripts.txt and UnicodeData.txt, were downloaded from the
49                   Unicode web site. They contain information about Unicode                   Unicode web site. They contain information about Unicode
50                   characters and scripts.                   characters and scripts.
# Line 40  Unicode.tables   The files in this direc Line 52  Unicode.tables   The files in this direc
52  ucptest.c        A short C program for testing the Unicode property macros  ucptest.c        A short C program for testing the Unicode property macros
53                   that do lookups in the pcre_ucd.c data, mainly useful after                   that do lookups in the pcre_ucd.c data, mainly useful after
54                   rebuilding the Unicode property table. Compile and run this in                   rebuilding the Unicode property table. Compile and run this in
55                   the "maint" directory.                   the "maint" directory (see comments at its head).
56    
57  ucptestdata      A directory containing two files, testinput1 and testoutput1,  ucptestdata      A directory containing two files, testinput1 and testoutput1,
58                   to use in conjunction with the ucptest program.                   to use in conjunction with the ucptest program.
# Line 55  utf8.c           A short, freestanding C Line 67  utf8.c           A short, freestanding C
67    
68    
69  Updating to a new Unicode release  Updating to a new Unicode release
70  ---------------------------------  =================================
71    
72  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
73  refreshed from the web site, and the MultiStage2.py script can then be run to  refreshed from the web site. If the new version of Unicode adds new character
74  generate a new version of pcre_ucd.c. The ucptest program can be used to check  scripts, the source file ucp.h and both the MultiStage2.py and the
75  that the resulting table works properly, using the data files in ucptestdata to  GenerateUtt.py scripts must be edited to add the new names. Then MultiStage2.py
76  check a number of test characters.  can be run to generate a new version of pcre_ucd.c, and GenerateUtt.py can be
77    run to generate the tricky tables for inclusion in pcre_tables.c.
78    
79    If MultiStage2.py gives the error "ValueError: list.index(x): x not in list",
80    the cause is usually a missing (or misspelt) name in the list of scripts. I
81    couldn't find a straightforward list of scripts on the Unicode site, but
82    there's a useful Wikipedia page that list them, and notes the Unicode version
83    in which they were introduced:
84    
85    http://en.wikipedia.org/wiki/Unicode_scripts#Table_of_Unicode_scripts
86    
87    The ucptest program can be compiled and used to check that the new tables in
88    pcre_ucd.c work properly, using the data files in ucptestdata to check a number
89    of test characters. The source file ucptest.c must be updated whenever new
90    Unicode script names are added.
91    
92    Note also that both the pcresyntax.3 and pcrepattern.3 man pages contain lists
93    of Unicode script names.
94    
95    
96  Preparing for a PCRE release  Preparing for a PCRE release
97  ----------------------------  ============================
98    
99  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
100  distribution for a new release.  distribution for a new release.
101    
102  . 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.
103    ChangeLog, and NEWS.  
104    . Update the library version numbers in configure.ac according to the rules
105      given below.
106    
107  . 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
108    files as well as to the autoconf files.    files as well as to the autoconf files. The relevant files are CMakeLists.txt
109      and config-cmake.h.in. After making a release tarball, test it out with CMake
110      if there have been changes here.
111    
112  . Run ./autogen.sh to ensure everything is up-to-date.  . Run ./autogen.sh to ensure everything is up-to-date.
113    
114  . Compile and test with many different config options, and combinations of  . Compile and test with many different config options, and combinations of
115    options. The maint/ManyConfigTests script now encapsulates this testing.    options. Also, test with valgrind by running "RunTest valgrind" and
116      "RunGrepTest valgrind" (which takes quite a long time). The script
117      maint/ManyConfigTests now encapsulates this testing. It runs tests with
118      different configurations, and it also runs some of them with valgrind, all of
119      which can take quite some time.
120    
121    . Run perltest.pl on the test data for tests 1, 4, and 6. The output
122      should match the PCRE test output, apart from the version identification at
123      the start of each test. The other tests are not Perl-compatible (they use
124      various PCRE-specific features or options).
125    
126    . It is possible to test with the emulated memmove() function by undefining
127      HAVE_MEMMOVE and HAVE_BCOPY in config.h, though I do not do this often. You
128      may see a number of "pcre_memmove defined but not used" warnings for the
129      modules in which there is no call to memmove(). These can be ignored.
130    
131    . Documentation: check AUTHORS, ChangeLog (check version and date), LICENCE,
132      NEWS (check version and date), NON-AUTOTOOLS-BUILD, and README. Many of these
133      won't need changing, but over the long term things do change.
134    
135    . I used to test new releases myself on a number of different operating
136      systems, using different compilers as well. For example, on Solaris it is
137      helpful to test using Sun's cc compiler as a change from gcc. Adding
138      -xarch=v9 to the cc options does a 64-bit test, but it also needs -S 64 for
139      pcretest to increase the stack size for test 2. Since I retired I can no
140      longer do this, but instead I rely on putting out release candidates for
141      folks on the pcre-dev list to test.
142    
143    
144    Updating version info for libtool
145    =================================
146    
147  . Run perltest.pl on the test data for tests 1 and 4. The output should match  This set of rules for updating library version information came from a web page
148    the PCRE test output, apart from the version identification at the top. The  whose URL I have forgotten. The version information consists of three parts:
149    other tests are not Perl-compatible (they use various special PCRE options).  (current, revision, age).
150    
151  . Test with valgrind by running "RunTest valgrind". There is also "RunGrepTest  1. Start with version information of 0:0:0 for each libtool library.
   valgrind", though that takes quite a long time.  
152    
153  . It may also useful to test with Electric Fence, though the fact that it  2. Update the version information only immediately before a public release of
154    grumbles for missing free() calls can be a nuisance. (A missing free() in     your software. More frequent updates are unnecessary, and only guarantee
155    pcretest is hardly a big problem.) To build with EF, use:     that the current interface number gets larger faster.
156    
157      LIBS='/usr/lib/libefence.a -lpthread' with ./configure.  3. If the library source code has changed at all since the last update, then
158       increment revision; c:r:a becomes c:r+1:a.
159    
160    Then all normal runs use it to check for buffer overflow. Also run everything  4. If any interfaces have been added, removed, or changed since the last
161    with:     update, increment current, and set revision to 0.
162    
163      EF_PROTECT_BELOW=1 <whatever>  5. If any interfaces have been added since the last public release, then
164       increment age.
165    
166    because there have been problems with lookbehinds that looked too far.  6. If any interfaces have been removed or changed since the last public
167       release, then set age to 0.
168    
169  . Test with the emulated memmove() function by undefining HAVE_MEMMOVE and  The following explanation may help in understanding the above rules a bit
170    HAVE_BCOPY in config.h. You may see a number of "pcre_memmove defined but not  better. Consider that there are three possible kinds of reaction from users to
171    used" warnings for the modules in which there is no call to memmove(). These  changes in a shared library:
   can be ignored.  
172    
173  . Documentation: check AUTHORS, COPYING, ChangeLog (check date), INSTALL,  1. Programs using the previous version may use the new version as a drop-in
174    LICENCE, NEWS (check date), NON-UNIX-USE, and README. Many of these won't     replacement, and programs using the new version can also work with the
175    need changing, but over the long term things do change.     previous one. In other words, no recompiling nor relinking is needed. In
176       this case, increment revision only, don't touch current or age.
177    
178  . Man pages: Check all man pages for \ not followed by e or f or " because  2. Programs using the previous version may use the new version as a drop-in
179    that indicates a markup error.     replacement, but programs using the new version may use APIs not present in
180       the previous one. In other words, a program linking against the new version
181       may fail if linked against the old version at run time. In this case, set
182       revision to 0, increment current and age.
183    
184  . When the release is built, test it on a number of different operating  3. Programs may need to be changed, recompiled, relinked in order to use the
185    systems if possible, and using different compilers as well. For example,     new version. Increment current, set revision and age to 0.
   on Solaris it is helpful to test using Sun's cc compiler as a change from  
   gcc. Adding -xarch=v9 to the cc options does a 64-bit test, but it also  
   needs -S 64 for pcretest to increase the stack size for test 2.  
186    
187    
188  Making a PCRE release  Making a PCRE release
189  ---------------------  =====================
190    
191  Run PrepareRelease and commit the files that it changes (by removing trailing  Run PrepareRelease and commit the files that it changes (by removing trailing
192  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;
193  Double-check with "svn status", then create an SVN tagged copy:  if it finds any markup errors, it reports them and then aborts.
194    
195    Once PrepareRelease has run clean, run "make distcheck" to create the tarballs
196    and the zipball. Double-check with "svn status", then create an SVN tagged
197    copy:
198    
199    svn copy svn://vcs.exim.org/pcre/code/trunk \    svn copy svn://vcs.exim.org/pcre/code/trunk \
200             svn://vcs.exim.org/pcre/code/tags/pcre-7.x             svn://vcs.exim.org/pcre/code/tags/pcre-8.xx
201    
202  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
203  webmaster@pcre.org and the mailing list.  webmaster@pcre.org and the mailing list. Also, update the list of version
204    numbers in Bugzilla (edit products).
205    
206    
207  Future ideas (wish list)  Future ideas (wish list)
208  ------------------------  ========================
209    
210  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
211  vary enormously in their usefulness and potential for implementation. Some are  vary enormously in their usefulness and potential for implementation. Some are
# Line 156  others are relatively new. Line 226  others are relatively new.
226      to have little effect, and maybe makes things worse.      to have little effect, and maybe makes things worse.
227    
228    * "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
229      over the existing "required byte" (reqbyte) feature that just saves one      over the existing "required byte" (reqbyte) feature that just remembers one
230      byte.      data unit.
231    
232    * These probably need to go in study():    * These probably need to go in pcre_study():
233    
234      o Remember an initial string rather than just 1 char?      o Remember an initial string rather than just 1 char?
235    
236      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
237        earlier one if common to all alternatives.        earlier one if common to all alternatives.
238    
     o Minimum length of subject needed.  
   
239      o Friedl contains other ideas.      o Friedl contains other ideas.
240    
241      * pcre_study() does not set initial byte flags for Unicode property types
242        such as \p; I don't know how much benefit there would be for, for example,
243        setting the bits for 0-9 and all bytes >= xC0 when a pattern starts with
244        \p{N}.
245    
246      * There is scope for more "auto-possessifying" in connection with \p and \P.
247    
248  . 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-
249    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
250    difference is the matching of /(main(O)?)+/ against mainOmain, where PCRE    difference is the matching of /(main(O)?)+/ against mainOmain, where PCRE
# Line 178  others are relatively new. Line 253  others are relatively new.
253    
254  . 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?
255    
 . 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.  
   
256  . 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.
257    
258  . Line endings:  . Line endings:
259    
260    * Option to use NUL as a line terminator in subject strings. This could now    * Option to use NUL as a line terminator in subject strings. This could now
261      be done relatively easily since the extension to support LF, CR, and CRLF.      be done relatively easily since the extension to support LF, CR, and CRLF.
262      If this is done, a suitable option for pcregrep is also required.      If it is done, a suitable option for pcregrep is also required.
263    
264  . Option to provide the pattern with a length instead of with a NUL terminator.  . Option to provide the pattern with a length instead of with a NUL terminator.
265    This probably affects quite a few places in the code.    This affects quite a few places in the code and is not trivial.
266    
267  . Catch SIGSEGV for stack overflows?  . Catch SIGSEGV for stack overflows?
268    
# Line 221  others are relatively new. Line 277  others are relatively new.
277    preceded by a blank line, instead of adding it to every matched line, and (b)    preceded by a blank line, instead of adding it to every matched line, and (b)
278    support --outputfile=name.    support --outputfile=name.
279    
280  . Consider making UTF-8 and UCP the default for PCRE n.0 for some n > 7.  . Consider making UTF-8 and UCP the default for PCRE n.0 for some n > 8.
281      (And now presumably UTF-16 and UCP for the 16-bit library.)
282    
283  . 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
284    needed to retain backward compatibility.    needed to retain backward compatibility.
# Line 236  others are relatively new. Line 293  others are relatively new.
293  . 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
294    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
295    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.
296      This is probably obsolete now that we have the JIT support.
297    
298  . Should pcretest have some private locale data, to avoid relying on the  . Should pcretest have some private locale data, to avoid relying on the
299    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 246  others are relatively new. Line 304  others are relatively new.
304    
305  . Someone suggested --disable-callout to save code space when callouts are  . Someone suggested --disable-callout to save code space when callouts are
306    never wanted. This seems rather marginal.    never wanted. This seems rather marginal.
307    
308  . 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
309    Python, etc?    Python, etc?
310    
311    . A user suggested a parameter to limit the length of string matched, for
312      example if the parameter is N, the current match should fail if the matched
313      substring exceeds N. This could apply to both match functions. The value
314      could be a new field in the extra block.
315    
316    . Callouts with arguments: (?Cn:ARG) for instance.
317    
318    . A user is going to supply a patch to generalize the API for user-specific
319      memory allocation so that it is more flexible in threaded environments. This
320      was promised a long time ago, and never appeared. However, this is a live
321      issue not only for threaded environments, but for libraries that use PCRE and
322      want not to be beholden to their caller's memory allocation.
323    
324    . Write a wrapper to maintain a structure with specified runtime parameters,
325      such as recurse limit, and pass these to PCRE each time it is called. Also
326      maybe malloc and free. A user sent a prototype. This relates the the previous
327      item.
328    
329    . Write a function that generates random matching strings for a compiled regex.
330    
331    . Pcregrep: an option to specify the output line separator, either as a string
332      or select from a fixed list. This is not dead easy, because at the moment it
333      outputs whatever is in the input file.
334    
335    . Improve the code for duplicate checking in pcre_dfa_exec(). An incomplete,
336      non-thread-safe patch showed that this can help performance for patterns
337      where there are many alternatives. However, a simple thread-safe
338      implementation that I tried made things worse in many simple cases, so this
339      is not an obviously good thing.
340    
341    . Make the longest lookbehind available via pcre_fullinfo(). This is not
342      straightforward because lookbehinds can be nested inside lookbehinds. This
343      case will have to be identified, and the amounts added. This should then give
344      the maximum possible lookbehind length. The reason for wanting this is to
345      help when implementing multi-segment matching using pcre_exec() with partial
346      matching and overlapping segments.
347    
348    . PCRE cannot at present distinguish between subpatterns with different names,
349      but the same number (created by the use of ?|). In order to do so, a way of
350      remembering *which* subpattern numbered n matched is needed. Bugzilla #760.
351      Now that (*MARK) has been implemented, it can perhaps be used as a way round
352      this problem.
353    
354    . Instead of having #ifdef HAVE_CONFIG_H in each module, put #include
355      "something" and the the #ifdef appears only in one place, in "something".
356    
357  Philip Hazel  Philip Hazel
358  Email local part: ph10  Email local part: ph10
359  Email domain: cam.ac.uk  Email domain: cam.ac.uk
360  Last updated: 02 July 2008  Last updated: 18 June 2012

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