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Bug #63380: Use PHP's allocator for libxml #223

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Bug #63380: Use PHP's allocator for libxml #223

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140 changes: 138 additions & 2 deletions ext/libxml/libxml.c
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Original file line number Diff line number Diff line change
Expand Up @@ -42,8 +42,17 @@
#include <libxml/uri.h>
#include <libxml/xmlerror.h>
#include <libxml/xmlsave.h>
#include <libxml/dict.h>
#include <libxml/nanohttp.h>
#include <libxml/nanoftp.h>

#ifdef LIBXML_SCHEMAS_ENABLED
#include <libxml/relaxng.h>
#include <libxml/xmlschemastypes.h>
#endif

#ifdef LIBXML_CATALOG_ENABLED
#include <libxml/catalog.h>
#endif

#include "php_libxml.h"
Expand All @@ -57,6 +66,13 @@ static int _php_libxml_initialized = 0;
static int _php_libxml_per_request_initialization = 1;
static xmlExternalEntityLoader _php_libxml_default_entity_loader;

#ifndef LIBXML_THREAD_ALLOC_ENABLED
static xmlFreeFunc _php_libxml_original_free;
static xmlMallocFunc _php_libxml_original_malloc;
static xmlReallocFunc _php_libxml_original_realloc;
static xmlStrdupFunc _php_libxml_original_strdup;
#endif

typedef struct _php_libxml_func_handler {
php_libxml_export_node export_func;
} php_libxml_func_handler;
Expand Down Expand Up @@ -263,6 +279,61 @@ static void php_libxml_node_free_list(xmlNodePtr node TSRMLS_DC)

/* }}} */

/** {{{ allocation hooks
*
* During xmlInitParser(), libxml allocates memory using xmlMalloc() etc., and
* stores the resulting pointers to true (thread-independent) global variables.
* Then in xmlCleanupParser(), this memory is freed using xmlFree(). The same
* functions are used for allocating memory to be stored in per-request state,
* such as document objects.
*
* We want memory allocated for the per-request state to be allocated from
* PHP's per-request pool, so that memory_limit and memory_get_usage() will
* work. So our approach is to use the time of call to distinguish between
* memory that needs to persist between requests (allocated from MINIT), and
* per-request memory.
*
* This will work if:
* 1. libxml doesn't lazy-initialise any global variables
* 2. PHP doesn't explicitly initialise libxml global variables after RINIT
*
* The second one generally seems to be a safe assumption. The first requires
* some care.
*/
static inline int _php_libxml_persistent()
{
#ifdef LIBXML_THREAD_ALLOC_ENABLED
/* If the hook function is set in LIBXML_THREAD_ALLOC_ENABLED mode, then
* we must be between RINIT and post_deactivate */
return 0;
#else
TSRMLS_FETCH();
return !LIBXML(use_emalloc);
#endif
}

static void _php_libxml_free_hook(void *mem)
{
pefree(mem, _php_libxml_persistent());
}

static void *_php_libxml_malloc_hook(size_t size)
{
return pemalloc(size, _php_libxml_persistent());
}

static void *_php_libxml_realloc_hook(void *mem, size_t size)
{
return perealloc(mem, size, _php_libxml_persistent());
}

static char *_php_libxml_strdup_hook(const char *str)
{
return pestrdup(str, _php_libxml_persistent());
}

/* }}} */

/* {{{ startup, shutdown and info functions */
static PHP_GINIT_FUNCTION(libxml)
{
Expand Down Expand Up @@ -726,13 +797,38 @@ PHP_LIBXML_API void php_libxml_error_handler(void *ctx, const char *msg, ...)
va_end(args);
}


PHP_LIBXML_API void php_libxml_initialize(void)
{
if (!_php_libxml_initialized) {
/* we should be the only one's to ever init!! */
xmlInitParser();


/* We need to explicitly initialise some things to avoid them being
* lazy-initialised the first time they are used, which would cause
* the memory to be allocated from the per-request pool. */
#if defined(LIBXML_SCHEMAS_ENABLED)
xmlSchemaInitTypes();
#endif
xmlRelaxNGInitTypes();

#if defined(LIBXML_CATALOG_ENABLED)
xmlInitializeCatalog();
/* The catalog system is not request-local, and it would break our
* memory management system if someone tried to use it, so we will
* just disable it. */
xmlCatalogSetDefaults(XML_CATA_ALLOW_NONE);
#endif
/* The initialisation function for the dict global mutex is static, so
* we have to trigger lazy initialisation indirectly. */
xmlDictFree(xmlDictCreate());

#ifdef LIBXML_HTTP_ENABLED
xmlNanoHTTPInit();
#endif
#ifdef LIBXML_FTP_ENABLED
xmlNanoFTPInit();
#endif

_php_libxml_default_entity_loader = xmlGetExternalEntityLoader();
xmlSetExternalEntityLoader(_php_libxml_pre_ext_ent_loader);

Expand All @@ -747,8 +843,15 @@ PHP_LIBXML_API void php_libxml_shutdown(void)
if (_php_libxml_initialized) {
#if defined(LIBXML_SCHEMAS_ENABLED)
xmlRelaxNGCleanupTypes();
#endif
#ifdef LIBXML_HTTP_ENABLED
xmlNanoHTTPCleanup();
#endif
#ifdef LIBXML_FTP_ENABLED
xmlNanoFTPCleanup();
#endif
xmlCleanupParser();

zend_hash_destroy(&php_libxml_exports);

xmlSetExternalEntityLoader(_php_libxml_default_entity_loader);
Expand Down Expand Up @@ -839,19 +942,40 @@ static PHP_MINIT_FUNCTION(libxml)
xmlParserInputBufferCreateFilenameDefault(php_libxml_input_buffer_create_filename);
xmlOutputBufferCreateFilenameDefault(php_libxml_output_buffer_create_filename);
}

/* If LIBXML_THREAD_ALLOC_ENABLED is not defined, we need to set up the allocator
* like a true global. */
#ifndef LIBXML_THREAD_ALLOC_ENABLED
xmlMemGet(&_php_libxml_original_free, &_php_libxml_original_malloc,
&_php_libxml_original_realloc, &_php_libxml_original_strdup);
xmlMemSetup(_php_libxml_free_hook, _php_libxml_malloc_hook,
_php_libxml_realloc_hook, _php_libxml_strdup_hook);
#endif

return SUCCESS;
}


static PHP_RINIT_FUNCTION(libxml)
{
/* If LIBXML_THREAD_ALLOC_ENABLED is defined, then the allocator hooks are
* stored in thread-specific state, so we need to initialise them here */
#ifdef LIBXML_THREAD_ALLOC_ENABLED
xmlMemGet(&LIBXML(original_free), &LIBXML(original_malloc),
&LIBXML(original_realloc), &LIBXML(original_strdup));
xmlMemSetup(_php_libxml_free_hook, _php_libxml_malloc_hook,
_php_libxml_realloc_hook, _php_libxml_strdup_hook);
#else
LIBXML(use_emalloc) = 1;
#endif

if (_php_libxml_per_request_initialization) {
/* report errors via handler rather than stderr */
xmlSetGenericErrorFunc(NULL, php_libxml_error_handler);
xmlParserInputBufferCreateFilenameDefault(php_libxml_input_buffer_create_filename);
xmlOutputBufferCreateFilenameDefault(php_libxml_output_buffer_create_filename);
}

return SUCCESS;
}

Expand All @@ -865,6 +989,12 @@ static PHP_MSHUTDOWN_FUNCTION(libxml)
xmlParserInputBufferCreateFilenameDefault(NULL);
xmlOutputBufferCreateFilenameDefault(NULL);
}

#ifndef LIBXML_THREAD_ALLOC_ENABLED
xmlMemSetup(_php_libxml_original_free, _php_libxml_original_malloc,
_php_libxml_original_realloc, _php_libxml_original_strdup);
#endif

php_libxml_shutdown();

return SUCCESS;
Expand Down Expand Up @@ -897,6 +1027,12 @@ static int php_libxml_post_deactivate()

_php_libxml_destroy_fci(&LIBXML(entity_loader).fci);

#ifdef LIBXML_THREAD_ALLOC_ENABLED
xmlMemSetup(LIBXML(original_free), LIBXML(original_malloc),
LIBXML(original_realloc), LIBXML(original_strdup));
#else
LIBXML(use_emalloc) = 0;
#endif
return SUCCESS;
}

Expand Down
6 changes: 6 additions & 0 deletions ext/libxml/php_libxml.h
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Original file line number Diff line number Diff line change
Expand Up @@ -47,6 +47,12 @@ ZEND_BEGIN_MODULE_GLOBALS(libxml)
zend_fcall_info fci;
zend_fcall_info_cache fcc;
} entity_loader;

xmlFreeFunc original_free;
xmlMallocFunc original_malloc;
xmlReallocFunc original_realloc;
xmlStrdupFunc original_strdup;
int use_emalloc;
ZEND_END_MODULE_GLOBALS(libxml)

typedef struct _libxml_doc_props {
Expand Down