51faf04dbd
The TSRM keeps a hashtable mapping the thread IDs to the thread resource pointers. It's possible that the thread disappears without us knowing, and then another thread gets spawned some time later with the same ID as the disappeared thread. Note that since it's a new thread the TSRM key pointer and cached pointer will be NULL. The Apache request handler `php_handler()` will try to fetch some fields from the SAPI globals. It uses a lazy thread resource allocation by calling `ts_resource(0);`. This allocates a thread resource and sets up the TSRM pointers if they haven't been set up yet. At least, that's what's supposed to happen. But since we are in a situation where the thread ID still has the resources of the *old* thread associated in the hashtable, the loop in `ts_resource_ex` will find that thread resource and assume the thread has been setup already. But this is not the case since this thread is actually a new thread, just reusing the ID of the old one, without any relation whatsoever to the old thread. Because of this assumption, the TSRM pointers will not be setup, leading to a NULL pointer dereference when trying to access the SAPI globals. We can easily detect this scenario: if we're in the fallback path, and the pointer is NULL, and we're looking for our own thread resource, we know we're actually reusing a thread ID. In that case, we'll free up the old thread resources gracefully (gracefully because there might still be resources open like database connection which need to be shut down cleanly). After freeing the resources, we'll create the new resources for this thread as if the stale resources never existed in the first place. From that point forward, it is as if that situation never occurred. The fact that this situation happens isn't that bad because a child process containing threads will eventually be respawned anyway by the SAPI, so the stale thread resources won't remain forever. Note that we can't simply assign our own TSRM pointers to the existing thread resource for our ID, since it was actually from a different thread (just with the same ID!). Furthermore, the dynamically loaded extensions have their own pointer, which is only set when their constructor is called, so we'd have to call their constructor anyway... I also tried to call the dtor and then the ctor again for those resources on the pre-existing thread resource to reuse storage, but that didn't work properly because other code doesn't expect something like that to happen, which breaks assumptions, and this in turn caused Valgrind to (rightfully) complain about memory bugs. Note 2: I also had to fix a bug in the core globals destruction because it always assumed that the thread destroying them was the owning thread, which on TSRM shutdown isn't always the case. A similar bug was fixed recently with the JIT globals. Closes GH-10863. |
||
|---|---|---|
| .github | ||
| build | ||
| docs | ||
| ext | ||
| main | ||
| pear | ||
| sapi | ||
| scripts | ||
| tests | ||
| travis | ||
| TSRM | ||
| win32 | ||
| Zend | ||
| .appveyor.yml | ||
| .cirrus.yml | ||
| .editorconfig | ||
| .gdbinit | ||
| .gitattributes | ||
| .gitignore | ||
| .travis.yml | ||
| buildconf | ||
| buildconf.bat | ||
| CODING_STANDARDS.md | ||
| configure.ac | ||
| CONTRIBUTING.md | ||
| EXTENSIONS | ||
| LICENSE | ||
| NEWS | ||
| php.ini-development | ||
| php.ini-production | ||
| README.md | ||
| README.REDIST.BINS | ||
| run-tests.php | ||
| UPGRADING | ||
| UPGRADING.INTERNALS | ||
The PHP Interpreter
PHP is a popular general-purpose scripting language that is especially suited to web development. Fast, flexible and pragmatic, PHP powers everything from your blog to the most popular websites in the world. PHP is distributed under the PHP License v3.01.
Documentation
The PHP manual is available at php.net/docs.
Installation
Prebuilt packages and binaries
Prebuilt packages and binaries can be used to get up and running fast with PHP.
For Windows, the PHP binaries can be obtained from
windows.php.net. After extracting the archive the
*.exe files are ready to use.
For other systems, see the installation chapter.
Building PHP source code
For Windows, see Build your own PHP on Windows.
For a minimal PHP build from Git, you will need autoconf, bison, and re2c. For a default build, you will additionally need libxml2 and libsqlite3.
On Ubuntu, you can install these using:
sudo apt install -y pkg-config build-essential autoconf bison re2c \
libxml2-dev libsqlite3-dev
On Fedora, you can install these using:
sudo dnf install re2c bison autoconf make libtool ccache libxml2-devel sqlite-devel
Generate configure:
./buildconf
Configure your build. --enable-debug is recommended for development, see
./configure --help for a full list of options.
# For development
./configure --enable-debug
# For production
./configure
Build PHP. To speed up the build, specify the maximum number of jobs using -j:
make -j4
The number of jobs should usually match the number of available cores, which
can be determined using nproc.
Testing PHP source code
PHP ships with an extensive test suite, the command make test is used after
successful compilation of the sources to run this test suite.
It is possible to run tests using multiple cores by setting -jN in
TEST_PHP_ARGS:
make TEST_PHP_ARGS=-j4 test
Shall run make test with a maximum of 4 concurrent jobs: Generally the maximum
number of jobs should not exceed the number of cores available.
The qa.php.net site provides more detailed info about testing and quality assurance.
Installing PHP built from source
After a successful build (and test), PHP may be installed with:
make install
Depending on your permissions and prefix, make install may need super user
permissions.
PHP extensions
Extensions provide additional functionality on top of PHP. PHP consists of many essential bundled extensions. Additional extensions can be found in the PHP Extension Community Library - PECL.
Contributing
The PHP source code is located in the Git repository at github.com/php/php-src. Contributions are most welcome by forking the repository and sending a pull request.
Discussions are done on GitHub, but depending on the topic can also be relayed to the official PHP developer mailing list internals@lists.php.net.
New features require an RFC and must be accepted by the developers. See Request for comments - RFC and Voting on PHP features for more information on the process.
Bug fixes don't require an RFC. If the bug has a GitHub issue, reference it in
the commit message using GH-NNNNNN. Use #NNNNNN for tickets in the old
bugs.php.net bug tracker.
Fix GH-7815: php_uname doesn't recognise latest Windows versions
Fix #55371: get_magic_quotes_gpc() throws deprecation warning
See Git workflow for details on how pull requests are merged.
Guidelines for contributors
See further documents in the repository for more information on how to contribute:
Credits
For the list of people who've put work into PHP, please see the PHP credits page.