Add new interface gpgrt_get_syscall_clamp.

* src/visibility.c (gpgrt_get_syscall_clamp): New.
* src/gpg-error.vers, src/gpg-error.def.in: Add function.
* src/gpg-error.h.in: Ditto.
* src/estream.c (_gpgrt_get_syscall_clamp): New.
--

This function can be used by other libraries to set their own system
clamp functions.

Signed-off-by: Werner Koch <wk@gnupg.org>

8 files changed, 27 insertions, 0 deletions

diff --git a/NEWS b/NEWS
index b1c8c6c..3b373c5 100644
--- a/NEWS
+++ b/NEWS
@@ -12,6 +12,7 @@ Noteworthy changes in version 1.25 (unreleased) [C19/A19/R_)
  GPG_ERR_DUP_NAME                 NEW.
  GPG_ERR_TOO_OLD                  NEW.
  GPG_ERR_TOO_YOUNG                NEW.
+ gpgrt_get_syscall_clamp          NEW.
 
 
 Noteworthy changes in version 1.24 (2016-07-14) [C19/A19/R1)
diff --git a/src/estream.c b/src/estream.c
index d0f0ba9..752d22e 100644
--- a/src/estream.c
+++ b/src/estream.c
@@ -605,6 +605,17 @@ _gpgrt_set_syscall_clamp (void (*pre)(void), void (*post)(void))
   _gpgrt_lock_set_lock_clamp (pre, post);
 }
 
+/*
+ * Return the current sycall clamp functions.  This can be used by
+ * other libraries which have blocking functions.
+ */
+void
+_gpgrt_get_syscall_clamp (void (**r_pre)(void), void (**r_post)(void))
+{
+  *r_pre  = pre_syscall_func;
+  *r_post = post_syscall_func;
+}
+
 
 
 /*
diff --git a/src/gpg-error.def.in b/src/gpg-error.def.in
index 1fa8866..19e87fa 100644
--- a/src/gpg-error.def.in
+++ b/src/gpg-error.def.in
@@ -150,4 +150,6 @@ EXPORTS
  gpgrt_w32_iconv              @111
 #endif
 
+ gpgrt_get_syscall_clamp      @112
+
 ;; end of file with public symbols for Windows.
diff --git a/src/gpg-error.h.in b/src/gpg-error.h.in
index a79f6ba..86f3241 100644
--- a/src/gpg-error.h.in
+++ b/src/gpg-error.h.in
@@ -303,6 +303,9 @@ void gpg_err_deinit (int mode);
 /* Register blocking system I/O clamping functions.  */
 void gpgrt_set_syscall_clamp (void (*pre)(void), void (*post)(void));
 
+/* Get current I/O clamping functions.  */
+void gpgrt_get_syscall_clamp (void (**r_pre)(void), void (**r_post)(void));
+
 /* Register a custom malloc/realloc/free function.  */
 void gpgrt_set_alloc_func  (void *(*f)(void *a, size_t n));
 
diff --git a/src/gpg-error.vers b/src/gpg-error.vers
index cdff0e3..802ff3d 100644
--- a/src/gpg-error.vers
+++ b/src/gpg-error.vers
@@ -39,6 +39,7 @@ GPG_ERROR_1.0 {
     gpgrt_lock_trylock;
 
     gpgrt_set_syscall_clamp;
+    gpgrt_get_syscall_clamp;
 
     gpgrt_fopen;
     gpgrt_mopen;
diff --git a/src/gpgrt-int.h b/src/gpgrt-int.h
index d69fe2c..b2b553b 100644
--- a/src/gpgrt-int.h
+++ b/src/gpgrt-int.h
@@ -53,6 +53,7 @@ gpg_err_code_t _gpgrt_yield (void);
 /* Local prototypes for estream.  */
 int _gpgrt_es_init (void);
 void _gpgrt_set_syscall_clamp (void (*pre)(void), void (*post)(void));
+void _gpgrt_get_syscall_clamp (void (**r_pre)(void), void (**r_post)(void));
 
 gpgrt_stream_t _gpgrt_fopen (const char *_GPGRT__RESTRICT path,
                              const char *_GPGRT__RESTRICT mode);
diff --git a/src/visibility.c b/src/visibility.c
index e3ac8a7..89b5623 100644
--- a/src/visibility.c
+++ b/src/visibility.c
@@ -97,6 +97,12 @@ gpgrt_set_syscall_clamp (void (*pre)(void), void (*post)(void))
 }
 
 void
+gpgrt_get_syscall_clamp (void (**r_pre)(void), void (**r_post)(void))
+{
+  _gpgrt_get_syscall_clamp (r_pre, r_post);
+}
+
+void
 gpgrt_set_alloc_func (void *(*f)(void *a, size_t n))
 {
   _gpgrt_set_alloc_func (f);
diff --git a/src/visibility.h b/src/visibility.h
index 1de6c62..479186f 100644
--- a/src/visibility.h
+++ b/src/visibility.h
@@ -142,6 +142,7 @@ MARK_VISIBLE (gpgrt_vbsprintf)
 MARK_VISIBLE (gpgrt_snprintf)
 MARK_VISIBLE (gpgrt_vsnprintf)
 MARK_VISIBLE (gpgrt_set_syscall_clamp)
+MARK_VISIBLE (gpgrt_get_syscall_clamp)
 MARK_VISIBLE (gpgrt_set_alloc_func)
 
 #undef MARK_VISIBLE
@@ -251,6 +252,7 @@ MARK_VISIBLE (gpgrt_set_alloc_func)
 #define gpgrt_vsnprintf             _gpgrt_USE_UNDERSCORED_FUNCTION
 
 #define gpgrt_set_syscall_clamp     _gpgrt_USE_UNDERSCORED_FUNCTION
+#define gpgrt_get_syscall_clamp     _gpgrt_USE_UNDERSCORED_FUNCTION
 #define gpgrt_set_alloc_func        _gpgrt_USE_UNDERSCORED_FUNCTION