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authorTom Tromey <tom@tromey.com>2019-03-04 15:12:04 -0700
committerTom Tromey <tom@tromey.com>2019-11-26 14:02:57 -0700
commit3b3978bca2a204a772563c8e121e4a02be72e802 (patch)
tree70076c2fc0433920de0b7a71ae12b34311a5fdfa /gdb/event-top.h
parent9411c49ecc09df989ecddb05e1756e0a9da0d1c8 (diff)
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Introduce thread-safe way to handle SIGSEGV
The gdb demangler installs a SIGSEGV handler in order to protect gdb from demangler bugs. However, this is not thread-safe, as signal handlers are global to the process. This patch changes gdb to always install a global SIGSEGV handler, and then lets threads indicate their interest in handling the signal by setting a thread-local variable. This patch then arranges for the demangler code to use this; being sure to arrange for calls to warning and the like to be done on the main thread. One thing I wondered while writing this patch is if there are any systems that do not have "sigaction". If gdb could assume this, it would simplify this code. gdb/ChangeLog 2019-11-26 Tom Tromey <tom@tromey.com> * event-top.h (thread_local_segv_handler): Declare. * event-top.c (thread_local_segv_handler): New global. (install_handle_sigsegv, handle_sigsegv): New functions. (async_init_signals): Install SIGSEGV handler. * cp-support.c (gdb_demangle_jmp_buf): Change type. Now thread-local. (report_failed_demangle): New function. (gdb_demangle): Make core_dump_allowed atomic. Remove signal handler-setting code, instead use segv_handler. Run warning code on main thread. Change-Id: Ic832bbb033b64744e4b44f14b41db7e4168ce427
Diffstat (limited to 'gdb/event-top.h')
-rw-r--r--gdb/event-top.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/gdb/event-top.h b/gdb/event-top.h
index 1dc7b13..e844125 100644
--- a/gdb/event-top.h
+++ b/gdb/event-top.h
@@ -70,4 +70,10 @@ extern void gdb_rl_callback_handler_install (const char *prompt);
currently installed. */
extern void gdb_rl_callback_handler_reinstall (void);
+/* The SIGSEGV handler for this thread, or NULL if there is none. GDB
+ always installs a global SIGSEGV handler, and then lets threads
+ indicate their interest in handling the signal by setting this
+ thread-local variable. */
+extern thread_local void (*thread_local_segv_handler) (int);
+
#endif