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Getting started with PHP core development - PHP...

Getting started with PHP core development - PHP Serbia 2018

Video recording: https://youtu.be/DNAJXROxQ8g
Joind.in: https://joind.in/talk/7d50f

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!

Arnout Boks

May 27, 2018
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  1. @arnoutboks #phpsrb PHP Open Source projects 4175 contributors 418 contributors

    689 contributors 1497 contributors 497 contributors?
  2. @arnoutboks #phpsrb Once upon a time… <something xmlns:foo="http://www.example.com"> <foo:bar />

    <bar /> </something> <?php $doc = /* … (DOMDocument) */; $doc->getElementsByTagName( "bar" )->length;
  3. @arnoutboks #phpsrb Once upon a time… <something xmlns:foo="http://www.example.com"> <foo:bar />

    <bar /> </something> <?php $doc = /* … (DOMDocument) */; $doc->getElementsByTagName( "bar" )->length; // returns 2
  4. @arnoutboks #phpsrb 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;
  5. @arnoutboks #phpsrb 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
  6. @arnoutboks #phpsrb Once upon a time… <something xmlns:foo="http://www.example.com"> <foo:bar />

    <bar /> </something> <?php $doc = /* … (DOMDocument) */; $doc->getElementsByTagNameNS( "", "bar" )->length;
  7. @arnoutboks #phpsrb Once upon a time… <something xmlns:foo="http://www.example.com"> <foo:bar />

    <bar /> </something> <?php $doc = /* … (DOMDocument) */; $doc->getElementsByTagNameNS( "", "bar" )->length; // returns 0!
  8. @arnoutboks #phpsrb Sharpen bug details Report different platform/version: Don’t post

    “me too” comments – Do post other relevant details
  9. @arnoutboks #phpsrb 1. Install dependencies • git • build-essential •

    autoconf • automake • libtool • re2c • bison • libxml2-dev Using apt-get, yum or similar
  10. @arnoutboks #phpsrb 3. Generate ./configure script $ ./buildconf Uses autoconf

    to build ./configure from: • configure.ac • acinclude.m4 • sapi/*/config.m4 • ext/*/config.m4
  11. @arnoutboks #phpsrb 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
  12. @arnoutboks #phpsrb 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
  13. @arnoutboks #phpsrb 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
  14. @arnoutboks #phpsrb 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
  15. @arnoutboks #phpsrb 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…]
  16. @arnoutboks #phpsrb 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
  17. @arnoutboks #phpsrb 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- [email protected] later. Do you want to send this report now? [Yns]:|
  18. @arnoutboks #phpsrb 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
  19. @arnoutboks #phpsrb 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
  20. @arnoutboks #phpsrb Testing tools Typical PHP project: • Written in

    PHP • Tests written in PHP (PHPUnit, PHPSpec, CodeCeption) The PHP core: • Written in C • Tests written in …
  21. @arnoutboks #phpsrb PHPT tests • Basically plaintext with sections •

    Some sections (can) contain PHP code • Let PHP print some output… • …and check against expected output
  22. @arnoutboks #phpsrb Very simple PHPT test --TEST-- Basic arithmetic -

    addition --FILE-- <?php var_dump(42 + 1); ?> --EXPECT-- int(43)
  23. @arnoutboks #phpsrb Very simple PHPT test --TEST-- Basic arithmetic -

    addition --FILE-- <?php var_dump(42 + 1); ?> --EXPECT-- int(43)
  24. @arnoutboks #phpsrb Folder structure tests/ and Zend/tests/ tests for the

    Zend engine ext/standard/tests /<group>/ tests for ‘standard’ extension (array, string, filesystem functions, etc.) ext/<name>/tests/ tests for extensions sapi/<name>/tests/ tests for specific SAPI’s (CGI, CLI, PHP-FPM, etc.)
  25. @arnoutboks #phpsrb Naming PHPT files bug<bugid>.phpt tests for bugs <func>_basic[<no>].phpt

    <func>_variation[<no>].phpt <func>_error[<no>].phpt tests for specific function: basic behavior, variations (edge cases, etc.) and errors <extname><no>.phpt general tests for extension
  26. @arnoutboks #phpsrb 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)
  27. @arnoutboks #phpsrb 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] =============================================
  28. @arnoutboks #phpsrb 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
  29. @arnoutboks #phpsrb Running our PHPT test $ cat ext/dom/tests/bug67474.log ----

    EXPECTED OUTPUT int(1) ---- ACTUAL OUTPUT int(0) ---- FAILED
  30. @arnoutboks #phpsrb Sections in PHPT files SKIPIF: Skips the test

    if the code in SKIPIF generates output containing ‘skip’ somewhere --SKIPIF-- <?php if(!extension_loaded('dom')) { die('skip dom extension not available'); } ?>
  31. @arnoutboks #phpsrb Sections in PHPT files Tip: Extensions usually have

    a skipif.inc shared between tests: --SKIPIF-- <?php require_once('skipif.inc'); ?>
  32. @arnoutboks #phpsrb 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"
  33. @arnoutboks #phpsrb 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)
  34. @arnoutboks #phpsrb Sections in PHPT files CLEAN: Cleans up after

    the test --FILE-- <?php touch(__DIR__ . '/foo.tmp'); var_dump(file_exists(__DIR__ . '/foo.tmp')); ?> --EXPECT-- bool(true) --CLEAN-- <?php unlink(__DIR__ . '/foo.tmp'); ?>
  35. @arnoutboks #phpsrb Sections in PHPT files INI: Specifies custom php.ini

    directives for the test --INI-- precision=7 --FILE-- <?php var_dump(pi()); ?> --EXPECT-- float(3.141593)
  36. @arnoutboks #phpsrb Sections in PHPT files XFAIL: Indicates the test

    is expected to fail, and gives an explanation why This is usually used for hard-to-fix bugs or bugs in upstream code. --XFAIL-- See bug #xxxx
  37. @arnoutboks #phpsrb 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
  38. @arnoutboks #phpsrb 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!
  39. @arnoutboks #phpsrb 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 • …
  40. @arnoutboks #phpsrb 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 };
  41. @arnoutboks #phpsrb C macros #define MIN(a,b) a < b ?

    a : b int c = MIN(42,7) // ^ is converted into // int c = 42 < 7 ? 42 : 7
  42. @arnoutboks #phpsrb 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 };
  43. @arnoutboks #phpsrb 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); }
  44. @arnoutboks #phpsrb 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
  45. @arnoutboks #phpsrb 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
  46. @arnoutboks #phpsrb 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
  47. @arnoutboks #phpsrb 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); }
  48. @arnoutboks #phpsrb 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:
  49. @arnoutboks #phpsrb 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
  50. @arnoutboks #phpsrb 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”
  51. @arnoutboks #phpsrb 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”
  52. @arnoutboks #phpsrb 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”
  53. @arnoutboks #phpsrb 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%)
  54. @arnoutboks #phpsrb PR for #67474 Submit bug fixes to the

    oldest supported branch: http://php.net/supported-versions.php
  55. @arnoutboks #phpsrb 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
  56. @arnoutboks #phpsrb 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
  57. @arnoutboks #phpsrb 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
  58. @arnoutboks #phpsrb 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/
  59. @arnoutboks #phpsrb 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
  60. @arnoutboks #phpsrb 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
  61. @arnoutboks #phpsrb 1. Find the correct file Tip: Use the

    “edit” link from the documentation itself
  62. @arnoutboks #phpsrb Don’t like edit.php.net? Or set up your own

    development environment: https://www.sammyk.me/how-to-contribute-to-php- documentation
  63. @arnoutboks #phpsrb 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
  64. @arnoutboks #phpsrb Numerous ways to contribute • Bug reports •

    Bug triaging • Running tests • Writing tests • Bug fixes • New features • Documentation patches • Documentation translations • Tools
  65. @arnoutboks #phpsrb 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
  66. @arnoutboks #phpsrb Feedback & Questions @arnoutboks @arnoutboks @aboks Arnout Boks

    Please leave your feedback on joind.in: https://joind.in/talk/7d50f
  67. @arnoutboks #phpsrb 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