Getting started with PHP core development - Dutch PHP Conference 2018

Joind.in: https://joind.in/talk/4783a

While PHP’s open source community is thriving, only a relatively small number of PHP developers contribute to the number one tool they use on a daily basis: PHP itself. Although it may seem daunting to help out on a project written in C, requiring compilation and linking, getting started is actually pretty easy. In this talk I would like to share my own recent experiences of beginning to contribute to PHP itself. We will see different ways to contribute and cover some practical tips, workflows and resources, so you can start giving back to your programming language straight away!

Transcript

1. Getting started with PHP core development @arnoutboks Arnout Boks #dpc18 08-06-2018
2. @arnoutboks #dpc18 PHP Open Source projects
3. @arnoutboks #dpc18 PHP Open Source projects 4175 contributors 418 contributors 689 contributors 1497 contributors
4. @arnoutboks #dpc18 PHP Open Source projects 4175 contributors 418 contributors 689 contributors 1497 contributors
5. @arnoutboks #dpc18 PHP Open Source projects 4175 contributors 418 contributors 689 contributors 1497 contributors 497 contributors?
6. @arnoutboks #dpc18 We all use PHP intensively Why not contribute something back?
7. @arnoutboks #dpc18 The catch
8. @arnoutboks #dpc18 The catch
9. @arnoutboks #dpc18 The core
10. @arnoutboks #dpc18 The core
11. @arnoutboks #dpc18 My own journey to the core
12. @arnoutboks #dpc18 Once upon a time… <something xmlns:foo="http://www.example.com"> <foo:bar /> <bar /> </something> <?php $doc = /* … (DOMDocument) */; $doc->getElementsByTagName( "bar" )->length;
13. @arnoutboks #dpc18 Once upon a time… <something xmlns:foo="http://www.example.com"> <foo:bar /> <bar /> </something> <?php $doc = /* … (DOMDocument) */; $doc->getElementsByTagName( "bar" )->length; // returns 2
14. @arnoutboks #dpc18 Once upon a time… <something xmlns:foo="http://www.example.com"> <foo:bar /> <bar /> </something> <?php $doc = /* … (DOMDocument) */; $doc->getElementsByTagNameNS( "http://www.example.com", "bar" )->length;
15. @arnoutboks #dpc18 Once upon a time… <something xmlns:foo="http://www.example.com"> <foo:bar /> <bar /> </something> <?php $doc = /* … (DOMDocument) */; $doc->getElementsByTagNameNS( "http://www.example.com", "bar" )->length; // returns 1
16. @arnoutboks #dpc18 Once upon a time… <something xmlns:foo="http://www.example.com"> <foo:bar /> <bar /> </something> <?php $doc = /* … (DOMDocument) */; $doc->getElementsByTagNameNS( "", "bar" )->length;
17. @arnoutboks #dpc18 Once upon a time… <something xmlns:foo="http://www.example.com"> <foo:bar /> <bar /> </something> <?php $doc = /* … (DOMDocument) */; $doc->getElementsByTagNameNS( "", "bar" )->length; // returns 0!
18. @arnoutboks #dpc18 Once upon a time…
19. Reporting bugs Gotta squash them all
20. @arnoutboks #dpc18 bugs.php.net PHP bug tracker
21. @arnoutboks #dpc18 Write good bug reports https://bugs.php.net/how-to-report.php
22. @arnoutboks #dpc18 Search for existing bugs
23. @arnoutboks #dpc18 Sharpen bug details Report different platform/version: Don’t post “me too” comments – Do post other relevant details
24. @arnoutboks #dpc18 Help triaging bugs! https://bugs.php.net/random
25. Building PHP from git Living on the edge
26. @arnoutboks #dpc18 1. Install dependencies • git • build-essential • autoconf • automake • libtool • re2c • bison • libxml2-dev Using apt-get, yum or similar
27. @arnoutboks #dpc18 2. Clone php-src $ git clone https://github.com/php/php- src.git
28. @arnoutboks #dpc18 3. Generate ./configure script $ ./buildconf Uses autoconf to build ./configure from: • configure.ac • acinclude.m4 • sapi/*/config.m4 • ext/*/config.m4
29. @arnoutboks #dpc18 4. Run ./configure script $ ./configure Configure a default PHP build: $ ./configure --disable-cgi --disable-dom --enable-opcache --with-sqlite3=/path /to/sqlite3 Customize extensions/SAPIs: $ ./configure --help See all options
30. @arnoutboks #dpc18 5. Compile $ make $ make –j`nproc` To use all available cores (faster):
31. @arnoutboks #dpc18 6. Run! $ sapi/cli/php --version Binaries are in sapi/cli/php and sapi/cgi/php-cgi:
32. @arnoutboks #dpc18 Subsequent builds $ make Just run Recompiles only files that have changed
33. @arnoutboks #dpc18 Cleanup scripts $ make clean # try again $ make distclean # try again $ ./buildconf –force $ ./configure # try again If compilation fails, try (subsequently): Might be needed after git pull/git checkout
34. @arnoutboks #dpc18 https://wiki.php.net/ internals/windows/stepbystepbuild Building for Windows
35. @arnoutboks #dpc18
36. @arnoutboks #dpc18 • ramsey/vagrant-php-src- dev • rlerdorf/php7dev Vagrant boxes for compiling PHP
37. @arnoutboks #dpc18 Or use Docker: aboks/php-src-devtools
38. @arnoutboks #dpc18 Using php-src-devtools $ composer global require aboks/php-src- devtools $ git clone https://github.com/php/php- src.git && cd php-src $ php-src-devtools build
39. Running tests for PHP Human-driven CI
40. @arnoutboks #dpc18 Running tests $ sapi/cli/php run-tests.php –p `pwd`/sapi/cli/php
41. @arnoutboks #dpc18 Running tests $ sapi/cli/php run-tests.php –p `pwd`/sapi/cli/php $ sapi/cli/php run-tests.php -P
42. @arnoutboks #dpc18 Running tests $ sapi/cli/php run-tests.php –p `pwd`/sapi/cli/php $ sapi/cli/php run-tests.php -P $ make test # (or, with php-src-devtools) $ php-src-devtools test
43. @arnoutboks #dpc18 Running tests $ make test […] PASS Trivial "Hello World" test [tests/basic/001.phpt] SKIP Check libcurl config on windows [ext/curl/tests/check_win_config.phpt] reason: for windows only FAIL Compiled regex cache limit [ext/pcre/tests/cache_limit.phpt] XFAIL Inconsistencies when accessing protected members [Zend/tests/access_modifiers_008.phpt] XFAIL REASON: Discussion: http://marc.info/?l=php- internals&m=120221184420957&w=2 […10000 more lines of output…]
44. @arnoutboks #dpc18 Running tests $ make test […] ========================================= TEST RESULT SUMMARY ----------------------------------------- Number of tests : 14896 12520 Tests skipped : 2376 ( 16.0%) -------- Tests warned : 2 ( 0.0%) ( 0.0%) Tests failed : 175 ( 1.2%) ( 1.4%) Expected fail : 44 ( 0.3%) ( 0.4%) Tests passed : 12299 ( 82.6%) ( 98.2%) ----------------------------------------- Time taken : 2937 seconds
45. @arnoutboks #dpc18 Running tests $ make test […] You may have found a problem in PHP. This report can be automatically sent to the PHP QA team at http://qa.php.net/reports and http://news.php.net/php.qa.reports This gives us a better understanding of PHP's behavior. If you don't want to send the report immediately you can choose option "s" to save it. You can then email it to qa- reports@lists.php.net later. Do you want to send this report now? [Yns]:|
46. @arnoutboks #dpc18 Options for running tests $ make test TESTS=path/to/my/test.phpt $ make test TESTS=ext/dom $ make test TESTS="--verbose ext/dom" $ make test TESTS=--help
47. Writing tests for PHP “the best bug report”
48. @arnoutboks #dpc18 Steps to reproduce for bug #67474 Test script: --------------- $doc = new DOMDocument(); $doc->loadXML('<root xmlns:x="x"><a/><x:a/></root>'); $list = $doc->getElementsByTagNameNS('', 'a'); echo $list->length; Expected result: ---------------- 1 Actual result: -------------- 0
49. @arnoutboks #dpc18 Testing tools Typical PHP project: • Written in PHP • Tests written in PHP (PHPUnit, PHPSpec, CodeCeption) The PHP core: • Written in C • Tests written in …
50. @arnoutboks #dpc18 PHP is tested using PHPT tests No C skills required
51. @arnoutboks #dpc18 PHPT tests • Basically plaintext with sections • Some sections (can) contain PHP code • Let PHP print some output… • …and check against expected output
52. @arnoutboks #dpc18 Very simple PHPT test --TEST-- Basic arithmetic - addition --FILE-- <?php var_dump(42 + 1); ?> --EXPECT-- int(43)
53. @arnoutboks #dpc18 Very simple PHPT test --TEST-- Basic arithmetic - addition --FILE-- <?php var_dump(42 + 1); ?> --EXPECT-- int(43)
54. @arnoutboks #dpc18 PHPT test for bug #67474 --TEST-- Bug #67474 getElementsByTagNameNS and default namespace --FILE-- <?php $doc = new DOMDocument(); $doc->loadXML('<root xmlns:x="x"><a/><x:a/></root>'); $list = $doc->getElementsByTagNameNS('', 'a'); var_dump($list->length); ?> --EXPECT-- int(1)
55. @arnoutboks #dpc18 Running our PHPT test $ make test TESTS=ext/dom/tests/bug67474.phpt […] ============================================= FAILED TEST SUMMARY --------------------------------------------- Bug #67474 getElementsByTagNameNS and default namespace [ext/dom/tests/bug67474.phpt] =============================================
56. @arnoutboks #dpc18 Running our PHPT test Files generated for our failing test: bug67474.php contents of the FILE section bug67474.sh shell script for running the .php file bug67474.exp expected output bug67474.out actual output bug67474.diff diff between expected and actual bug67474.log log file, including the expected and actual output
57. @arnoutboks #dpc18 Running our PHPT test $ cat ext/dom/tests/bug67474.log ---- EXPECTED OUTPUT int(1) ---- ACTUAL OUTPUT int(0) ---- FAILED
58. @arnoutboks #dpc18 Running our PHPT test
59. @arnoutboks #dpc18 Sections in PHPT files GET, POST, PUT, COOKIE, HEADERS: Simulate HTTP input to the PHP script in FILE --GET-- foo=bar&baz=qux --COOKIE-- foo=bar;baz=qux --FILE-- <?php var_dump($_GET['foo'] . $_COOKIE['foo']); ?> --EXPECT-- string(6) "barbar"
60. @arnoutboks #dpc18 Sections in PHPT files EXPECTF, EXPECTREGEX: Expect the output to match a certain format --FILE-- <?php $fp = fopen(__FILE__, 'r'); var_dump($fp); ?> --EXPECTF-- resource(%d) of type (stream)
61. @arnoutboks #dpc18 More sections in PHPT files SKIPIF: Skips the test if the code in SKIPIF generates output containing ‘skip’ somewhere CLEAN: Cleans up after the test INI: Specifies custom php.ini directives for the test XFAIL: Indicates the test is expected to fail, and gives an explanation why
62. @arnoutboks #dpc18 Easy way to get started without C skills
63. @arnoutboks #dpc18 Finding untested code gcov.php.net
64. @arnoutboks #dpc18 Resources • https://qa.php.net/write-test.php • https://www.sammyk.me/compiling-php-from-source- writing-tests-for-php-source • https://phptestfest.org/tutorials/ • http://www.phpinternalsbook.com/#testing-php- source • https://github.com/PHPTestFestBrasil/phptt • https://gist.github.com/SammyK/4a5cf70d0973731d0c 85b151a323ea2d
65. Editing the PHP source Your own custom PHP
66. @arnoutboks #dpc18 A shot at fixing #67474: recap <something xmlns:foo="http://www.example.com"> <foo:bar /> <bar /> </something> <?php $doc = /* … (DOMDocument) */; $doc->getElementsByTagNameNS( "", "bar" )->length; // returns 0!
67. @arnoutboks #dpc18 A shot at fixing #67474 php-src/ext/dom/ • attr.c • document.c • dom_ce.h • dom_fe.h • element.c • node.c • php_dom.c • xpath.c • …
68. @arnoutboks #dpc18 A shot at fixing #67474 const zend_function_entry php_dom_document_class_functions[] = { // ... PHP_FALIAS(createAttributeNS, dom_document_create_attribute_ns, arginfo_dom_document_create_attribute_ns) PHP_FALIAS(getElementsByTagNameNS, dom_document_get_elements_by_tag_name_ns, arginfo_dom_document_get_elements_by_tag_name_ns) PHP_FALIAS(getElementById, dom_document_get_element_by_id, arginfo_dom_document_get_element_by_id) // ... PHP_ME(domdocument, __construct, arginfo_dom_document_construct, ZEND_ACC_PUBLIC) PHP_FE_END };
69. @arnoutboks #dpc18 C macros
70. @arnoutboks #dpc18 C macros #define MIN(a,b) a < b ? a : b int c = MIN(42,7) // ^ is converted into // int c = 42 < 7 ? 42 : 7
71. @arnoutboks #dpc18 A shot at fixing #67474 const zend_function_entry php_dom_document_class_functions[] = { // ... PHP_FALIAS(createAttributeNS, dom_document_create_attribute_ns, arginfo_dom_document_create_attribute_ns) PHP_FALIAS(getElementsByTagNameNS, dom_document_get_elements_by_tag_name_ns, arginfo_dom_document_get_elements_by_tag_name_ns) PHP_FALIAS(getElementById, dom_document_get_element_by_id, arginfo_dom_document_get_element_by_id) // ... PHP_ME(domdocument, __construct, arginfo_dom_document_construct, ZEND_ACC_PUBLIC) PHP_FE_END };
72. @arnoutboks #dpc18 A shot at fixing #67474 PHP_FUNCTION(dom_document_get_elements_by_tag_name_ns) { // ... if (zend_parse_method_parameters(ZEND_NUM_ARGS(), getThis(), "Oss", &id, dom_document_class_entry, &uri, &uri_len, &name, &name_len) == FAILURE) { return; } // ... local = xmlCharStrndup(name, name_len); nsuri = xmlCharStrndup(uri, uri_len); dom_namednode_iter(intern, 0, namednode, NULL, local, nsuri); }
73. @arnoutboks #dpc18 zend_parse_parameters (‘ZPP’) PHP_FUNCTION(dom_document_get_elements_by_tag_name_ns) { // ... if (zend_parse_method_parameters(ZEND_NUM_ARGS(), getThis(), "Oss", &id, dom_document_class_entry, &uri, &uri_len, &name, &name_len) == FAILURE) { return; } // ... local = xmlCharStrndup(name, name_len); nsuri = xmlCharStrndup(uri, uri_len); dom_namednode_iter(intern, 0, namednode, NULL, local, nsuri); } s: string s: string O: object of given class
74. @arnoutboks #dpc18 zend_parse_parameters (‘ZPP’) Specifier Type a array b boolean d double/float l long/int o object (any type) O object (specific type) r resource s string z mixed
75. @arnoutboks #dpc18 zend_parse_parameters (‘ZPP’) Modifier Effect * variable number of arguments (0 or more) + variable number of arguments (1 or more) ! optional argument | remaining arguments are optional See README.PARAMETER_PARSING_API
76. @arnoutboks #dpc18 A shot at fixing #67474 PHP_FUNCTION(dom_document_get_elements_by_tag_name_ns) { // ... if (zend_parse_method_parameters(ZEND_NUM_ARGS(), getThis(), "Oss", &id, dom_document_class_entry, &uri, &uri_len, &name, &name_len) == FAILURE) { return; } // ... local = xmlCharStrndup(name, name_len); nsuri = xmlCharStrndup(uri, uri_len); dom_namednode_iter(intern, 0, namednode, NULL, local, nsuri); }
77. @arnoutboks #dpc18 A shot at fixing #67474 xmlNode *dom_get_elements_by_tag_name_ns_raw( xmlNodePtr nodep, char *ns, char *local /* ... */ ) { // ... if ( ns == NULL || (nodep->ns != NULL && ( xmlStrEqual(nodep->ns->href, (xmlChar *)ns) || xmlStrEqual((xmlChar *)"*", (xmlChar *)ns) )) ) { /* namespace matches */ } // ... } Eventually:
78. @arnoutboks #dpc18 A shot at fixing #67474 xmlNode *dom_get_elements_by_tag_name_ns_raw( xmlNodePtr nodep, char *ns, char *local /* ... */ ) { // ... if ( ns == NULL || (nodep->ns != NULL && ( xmlStrEqual(nodep->ns->href, (xmlChar *)ns) || xmlStrEqual((xmlChar *)"*", (xmlChar *)ns) )) ) { /* namespace matches */ } // ... } Eventually: element to ‘test’ filter namespace and local name
79. @arnoutboks #dpc18 A shot at fixing #67474 xmlNode *dom_get_elements_by_tag_name_ns_raw( xmlNodePtr nodep, char *ns, char *local /* ... */ ) { // ... if ( ns == NULL || (nodep->ns != NULL && ( xmlStrEqual(nodep->ns->href, (xmlChar *)ns) || xmlStrEqual((xmlChar *)"*", (xmlChar *)ns) )) ) { /* namespace matches */ } // ... } Eventually: “no namespace filter”
80. @arnoutboks #dpc18 A shot at fixing #67474 xmlNode *dom_get_elements_by_tag_name_ns_raw( xmlNodePtr nodep, char *ns, char *local /* ... */ ) { // ... if ( ns == NULL || (nodep->ns != NULL && ( xmlStrEqual(nodep->ns->href, (xmlChar *)ns) || xmlStrEqual((xmlChar *)"*", (xmlChar *)ns) )) ) { /* namespace matches */ } // ... } Eventually: “node has a namespace”, and “it matches the filter” or “filter is a wildcard”
81. @arnoutboks #dpc18 A shot at fixing #67474 xmlNode *dom_get_elements_by_tag_name_ns_raw( xmlNodePtr nodep, char *ns, char *local /* ... */ ) { // ... if ( ns == NULL || (nodep->ns == NULL && !strcmp(ns, "")) || (nodep->ns != NULL && ( xmlStrEqual(nodep->ns->href, (xmlChar *)ns) || xmlStrEqual((xmlChar *)"*", (xmlChar *)ns) )) ) { /* namespace matches */ } // ... } Fix: “node has empty namespace”, and “filter is empty namespace”
82. @arnoutboks #dpc18 A shot at fixing #67474 $ make test TESTS=ext/dom/tests/bug67474.phpt […] ============================================= Running selected tests. PASS Bug #67474 getElementsByTagNameNS and default namespace [ext/dom/tests/bug67474.phpt] ============================================= Number of tests : 1 1 Tests passed : 1 (100.0%) (100.0%)
83. @arnoutboks #dpc18 PR for #67474 Submit bug fixes to the oldest supported branch: http://php.net/supported-versions.php
84. @arnoutboks #dpc18 The Release Managers PHP 7.1 Davey Shafik @dshafik Joe Watkins @krakjoe PHP 7.2 Remi Collet @RemiCollet Sara Golemon @SaraMG PHP 7.3 Christoph M. Becker @cmbecker69 Stanislav Malyshev @smalyshev
85. @arnoutboks #dpc18 PR for #67474: 2 hours later…
86. @arnoutboks #dpc18 It’s not THAT difficult • Read past the C details and macros • Focus on the logic • See where variables come from and go to • Try and see what happens • Rely on the tests
87. @arnoutboks #dpc18 You can do this!
88. @arnoutboks #dpc18 Bug fixes vs. features • Bug fixes • PR against oldest supported branch • No RFC needed • Refer to bug in bug tracker • Features • PR against master • Formal RFC needed
89. @arnoutboks #dpc18 RFC Process • Introduce idea, measure initial reaction • Formal proposal • Discussion period • Voting See https://wiki.php.net/rfc/howto & https://benramsey.com/talks/2015/06/dpc-contributing-core/
90. @arnoutboks #dpc18 Resources • http://php.net/internals • https://wiki.php.net/internals • https://wiki.php.net/internals/references • http://www.phpinternalsbook.com/ • http://blog.jpauli.tech/ • https://nikic.github.io/ • https://blog.ircmaxell.com/search/label/PHP-Internals • https://www.sammyk.me/how-to-find-and-patch-a- bug-in-php-source-php-internals • https://externals.io
91. @arnoutboks #dpc18 Some time later…
92. Documentation for PHP Contributing to the manual
93. @arnoutboks #dpc18 edit.php.net PHP Docbook Online Editor ‘Easiest’ way to get started (if you can figure out how it works)
94. @arnoutboks #dpc18 edit.php.net
95. @arnoutboks #dpc18 edit.php.net
96. @arnoutboks #dpc18 edit.php.net
97. @arnoutboks #dpc18 1. Find the correct file Under “All files” in the left menu Top-level directory per language • reference/<ext|group>/ • functions/<function>.xml • <class>.xml • <class>/<method>.xml • language/<feature>.xml
98. @arnoutboks #dpc18 1. Find the correct file Tip: Use the “edit” link from the documentation itself
99. @arnoutboks #dpc18 2. Make your changes Documentation is written using DocBook XML http://tdg.docbook.org/tdg/5.2/
100. @arnoutboks #dpc18 2. Make your changes Documentation is written using DocBook XML (or just peek in other docs)
101. @arnoutboks #dpc18 3. Preview changes Seems broken at the moment
102. @arnoutboks #dpc18 4. Submit as patch
103. @arnoutboks #dpc18 Tip: submit a docs patch instead of user note
104. @arnoutboks #dpc18 Don’t like edit.php.net? Make it better!
105. @arnoutboks #dpc18 Don’t like edit.php.net? Or set up your own development environment: https://www.sammyk.me/how-to-contribute-to-php- documentation
106. @arnoutboks #dpc18 Where to help? • Bugs of type “Doc” in bug tracker • check-missing-docs.php • “Failures to meet strict standards” (in edit.php.net sidebar) • Translations • Missing translations • Out-of-date translations • Translations needing review • Translations with errors
107. @arnoutboks #dpc18 Where to help?
108. Recap Ways to contribute to PHP
109. @arnoutboks #dpc18 Numerous ways to contribute • Bug reports • Bug triaging • Running tests • Writing tests • Bug fixes • New features • Documentation patches • Documentation translations • Tools
110. @arnoutboks #dpc18 Why contribute? • Get ‘own’ bugs fixed • Fix ‘own’ bugs • Make PHP better • Make PHP more popular • Learn PHP • Learn C • Give back to the community
111. @arnoutboks #dpc18 You don’t have to be an expert to contribute to the PHP core
112. @arnoutboks #dpc18 Feedback & Questions @arnoutboks @arnoutboks @aboks Arnout Boks Please leave your feedback on joind.in: https://joind.in/talk/4783a
113. @arnoutboks #dpc18 Image Credits • https://photojournal.jpl.nasa.gov/jpeg/PIA19058.jpg • https://www.flickr.com/photos/vivianejl/22990832 • https://www.flickr.com/photos/dhuiz/13609080315/ • https://www.flickr.com/photos/gotovan/8671348572 • https://www.flickr.com/photos/sidelong/246816211 • https://www.flickr.com/photos/pezon64/23764268828 • https://www.flickr.com/photos/crdot/6855538268/ • https://www.flickr.com/photos/borkurdotnet/9682277597