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Safely recognize when fork is running from main thread or another pthread 

* child_info.h (struct child_info): Add member from_main.
        * fork.cc (frok::child): Check from_main rather than stackaddr.
        (frok::parent): Set ch.from_main if running in the main thread.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
This commit is contained in:
Corinna Vinschen 2015-12-03 12:38:19 +01:00
parent 8974e06da3
commit 89e86492b3
3 changed files with 10 additions and 2 deletions
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6
winsup/cygwin/ChangeLog
View File

@ -1,3 +1,9 @@
2015-12-03 Corinna Vinschen <corinna@vinschen.de>
* child_info.h (struct child_info): Add member from_main.
* fork.cc (frok::child): Check from_main rather than stackaddr.
(frok::parent): Set ch.from_main if running in the main thread.
2015-12-02 Corinna Vinschen <corinna@vinschen.de>
* child_info.h (CURR_CHILD_INFO_MAGIC): Align to below change.

3
winsup/cygwin/child_info.h
View File

@ -39,7 +39,7 @@ enum child_status
#define EXEC_MAGIC_SIZE sizeof(child_info)
/* Change this value if you get a message indicating that it is out-of-sync. */
#define CURR_CHILD_INFO_MAGIC 0xc96f5e9U
#define CURR_CHILD_INFO_MAGIC 0x30ea98f6U
#define NPROCS 256
@ -109,6 +109,7 @@ public:
void *stackbase; // StackBase of parent thread
size_t guardsize; // size of POSIX guard region or (size_t) -1 if
// user stack
bool from_main; // true if started from parent's main thread
char filler[4];
child_info_fork ();
void __reg1 handle_fork ();

3
winsup/cygwin/fork.cc
View File

@ -149,7 +149,7 @@ frok::child (volatile char * volatile here)
/* If we've played with the stack, stacksize != 0. That means that
fork() was invoked from other than the main thread. Make sure that
the threadinfo information is properly set up. */
if (fork_info->stackaddr)
if (!fork_info->from_main)
{
_main_tls = &_my_tls;
_main_tls->init_thread (NULL, NULL);
@ -307,6 +307,7 @@ frok::parent (volatile char * volatile stack_here)
ch.forker_finished = forker_finished;
ch.from_main = &_my_tls == _main_tls;
ch.stackbase = NtCurrentTeb()->Tib.StackBase;
ch.stackaddr = NtCurrentTeb ()->DeallocationStack;
if (!ch.stackaddr)