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authorPaul Pluzhnikov <ppluzhnikov@google.com>2013-12-18 15:07:11 -0800
committerPaul Pluzhnikov <ppluzhnikov@google.com>2013-12-18 15:07:11 -0800
commit69a17d9d245dc3551792e95e1823cc2d877592f3 (patch)
tree719f3789f573b05c6c168f3720048acd42420ea4 /sysdeps/unix/sysv/linux/dl-sysdep.c
parenta588438951a271ca10623fb8c7e25693c7ebea67 (diff)
downloadglibc-69a17d9d245dc3551792e95e1823cc2d877592f3.tar.gz
Patch [1/4] async-signal safe TLS.
2013-12-18 Andrew Hunter <ahh@google.com> * sysdeps/generic/ldsodefs.h (_dl_mask_all_signals): New prototype. (_dl_unmask_signals): Likewise. * sysdeps/mach/hurd/dl-sysdep.h (_dl_mask_all_signals): New stub. (_dl_unmask_all_signals): Likewise. * sysdeps/unix/sysv/linux/dl-sysdep.h (_dl_mask_all_signals): New prototype. (_dl_unmask_all_signals): Likewise. * sysdeps/unix/sysv/linux/dl-sysdep.c (_dl_mask_all_signals): New function. (_dl_unmask_signals): Likewise.
Diffstat (limited to 'sysdeps/unix/sysv/linux/dl-sysdep.c')
-rw-r--r--sysdeps/unix/sysv/linux/dl-sysdep.c46
1 files changed, 46 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/dl-sysdep.c b/sysdeps/unix/sysv/linux/dl-sysdep.c
index e80cb8d9f0..4b837acbc0 100644
--- a/sysdeps/unix/sysv/linux/dl-sysdep.c
+++ b/sysdeps/unix/sysv/linux/dl-sysdep.c
@@ -19,6 +19,7 @@
/* Linux needs some special initialization, but otherwise uses
the generic dynamic linker system interface code. */
+#include <assert.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
@@ -130,3 +131,48 @@ _dl_discover_osversion (void)
return version;
}
+
+/* Mask every signal, returning the previous sigmask in OLD. */
+void
+internal_function
+_dl_mask_all_signals (sigset_t *old)
+{
+ int ret;
+ sigset_t new;
+
+ sigfillset (&new);
+
+ /* This function serves as a replacement to pthread_sigmask, which
+ isn't available from within the dynamic linker since it would require
+ linking with libpthread. We duplicate some of the functionality here
+ to avoid requiring libpthread. This isn't quite identical to
+ pthread_sigmask in that we do not mask internal signals used for
+ cancellation and setxid handling. This disables asynchronous
+ cancellation for the duration the signals are disabled, but it's a
+ small window, and prevents any problems with the use of TLS variables
+ in the signal handlers that would have executed. */
+
+ /* It's very important we don't touch errno here, as that's TLS; since this
+ gets called from get_tls_addr we might end up recursing. */
+
+ INTERNAL_SYSCALL_DECL (err);
+
+ ret = INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, &new, old,
+ _NSIG / 8);
+
+ assert (ret == 0);
+}
+
+/* Return sigmask to what it was before a call to _dl_mask_all_signals. */
+void
+internal_function
+_dl_unmask_signals (sigset_t *old)
+{
+ int ret;
+ INTERNAL_SYSCALL_DECL (err);
+
+ ret = INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_SETMASK, old, NULL,
+ _NSIG / 8);
+
+ assert (ret == 0);
+}