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Initialize Objective-C classes before fork() for macOS 13 

Since macOS 13, CFString family API used in
`rb_str_append_normalized_ospath` may internally use Objective-C classes
(`NSTaggedPointerString` and `NSPlaceholderMutableString`) for small strings.

On the other hand, Objective-C classes should not be used for the first
time in a `fork()`'ed but not `exec()`'ed process. Violations for this rule
can result deadlock during class initialization, so Objective-C runtime
conservatively crashes on such cases by default.

Therefore, we need to use CFString API to initialize Objective-C classes
used internally *before* `fork()`.

For more details, see https://bugs.ruby-lang.org/issues/18912
This commit is contained in:
Yuta Saito 2022-09-24 03:36:04 +09:00 committed by usa
parent 99735a8b29
commit 022aefb450
1 changed files with 44 additions and 0 deletions
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file.c
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@ -253,6 +253,46 @@ rb_str_encode_ospath(VALUE path)
#ifdef __APPLE__
# define NORMALIZE_UTF8PATH 1
# ifdef HAVE_WORKING_FORK
static void
rb_CFString_class_initialize_before_fork(void)
{
/*
* Since macOS 13, CFString family API used in
* rb_str_append_normalized_ospath may internally use Objective-C classes
* (NSTaggedPointerString and NSPlaceholderMutableString) for small strings.
*
* On the other hand, Objective-C classes should not be used for the first
* time in a fork()'ed but not exec()'ed process. Violations for this rule
* can result deadlock during class initialization, so Objective-C runtime
* conservatively crashes on such cases by default.
*
* Therefore, we need to use CFString API to initialize Objective-C classes
* used internally *before* fork().
*
* For future changes, please note that this initialization process cannot
* be done in ctor because NSTaggedPointerString in CoreFoundation is enabled
* after CFStringInitializeTaggedStrings(), which is called during loading
* Objective-C runtime after ctor.
* For more details, see https://bugs.ruby-lang.org/issues/18912
*/
/* Enough small but non-empty ASCII string to fit in NSTaggedPointerString. */
const char small_str[] = "/";
long len = sizeof(small_str) - 1;
const CFAllocatorRef alloc = kCFAllocatorDefault;
CFStringRef s = CFStringCreateWithBytesNoCopy(alloc,
(const UInt8 *)small_str,
len, kCFStringEncodingUTF8,
FALSE, kCFAllocatorNull);
CFMutableStringRef m = CFStringCreateMutableCopy(alloc, len, s);
CFRelease(m);
CFRelease(s);
}
# endif
static VALUE
rb_str_append_normalized_ospath(VALUE str, const char *ptr, long len)
{
@ -6455,6 +6495,10 @@ const char ruby_null_device[] =
void
Init_File(void)
{
#if defined(__APPLE__) && defined(HAVE_WORKING_FORK)
rb_CFString_class_initialize_before_fork();
#endif
VALUE separator;
rb_mFileTest = rb_define_module("FileTest");