libstdc++: Make std::random_device throw std::system_error [PR105081]

This changes std::random_device constructors to throw std::system_error
(with EINVAL as the error code) when the constructor argument is
invalid. We can also throw std::system_error when read(2) fails so that
the exception includes the additional information provided by errno.

As noted in the PR, this is consistent with libc++, and doesn't break
any existing code which catches std::runtime_error, because those
handlers will still catch std::system_error.

libstdc++-v3/ChangeLog:

	PR libstdc++/105081
	* src/c++11/random.cc (__throw_syserr): New function.
	(random_device::_M_init, random_device::_M_init_pretr1): Use new
	function for bad tokens.
	(random_device::_M_getval): Use new function for read errors.
	* testsuite/util/testsuite_random.h (random_device_available):
	Change catch handler to use std::system_error.

2 files changed, 14 insertions, 7 deletions

diff --git a/libstdc++-v3/src/c++11/random.cc b/libstdc++-v3/src/c++11/random.cc
index ed2db4a..daf9348 100644
--- a/libstdc++-v3/src/c++11/random.cc
+++ b/libstdc++-v3/src/c++11/random.cc
@@ -26,6 +26,7 @@
 #define _CRT_RAND_S // define this before including <stdlib.h> to get rand_s
 
 #include <random>
+#include <system_error>
 
 #ifdef  _GLIBCXX_USE_C99_STDINT_TR1
 
@@ -94,6 +95,11 @@ namespace std _GLIBCXX_VISIBILITY(default)
 {
   namespace
   {
+    [[noreturn]]
+    inline void
+    __throw_syserr([[maybe_unused]] int e, [[maybe_unused]] const char* msg)
+    { _GLIBCXX_THROW_OR_ABORT(system_error(e, std::generic_category(), msg)); }
+
 #if USE_RDRAND
     unsigned int
     __attribute__ ((target("rdrnd")))
@@ -365,9 +371,9 @@ namespace std _GLIBCXX_VISIBILITY(default)
       which = prng;
 #endif
     else
-      std::__throw_runtime_error(
-	  __N("random_device::random_device(const std::string&):"
-	      " unsupported token"));
+      std::__throw_syserr(EINVAL, __N("random_device::random_device"
+				      "(const std::string&):"
+				      " unsupported token"));
 
 #ifdef _GLIBCXX_USE_CRT_RAND_S
     if (which & rand_s)
@@ -508,8 +514,8 @@ namespace std _GLIBCXX_VISIBILITY(default)
 	char* endptr;
 	seed = std::strtoul(nptr, &endptr, 0);
 	if (*nptr == '\0' || *endptr != '\0')
-	  std::__throw_runtime_error(__N("random_device::_M_init_pretr1"
-					 "(const std::string&)"));
+	  std::__throw_syserr(EINVAL, __N("random_device::_M_init_pretr1"
+					  "(const std::string&)"));
       }
     _M_mt.seed(seed);
 #else
@@ -582,7 +588,7 @@ namespace std _GLIBCXX_VISIBILITY(default)
 	    p = static_cast<char*>(p) + e;
 	  }
 	else if (e != -1 || errno != EINTR)
-	  __throw_runtime_error(__N("random_device could not be read"));
+	  __throw_syserr(errno, __N("random_device could not be read"));
       }
     while (n > 0);
 #else // USE_POSIX_FILE_IO
diff --git a/libstdc++-v3/testsuite/util/testsuite_random.h b/libstdc++-v3/testsuite/util/testsuite_random.h
index 840294d..763707b 100644
--- a/libstdc++-v3/testsuite/util/testsuite_random.h
+++ b/libstdc++-v3/testsuite/util/testsuite_random.h
@@ -26,6 +26,7 @@
 
 #include <cmath>
 #include <initializer_list>
+#include <system_error>
 #include <testsuite_hooks.h>
 
 namespace __gnu_test
@@ -204,7 +205,7 @@ namespace __gnu_test
     try {
       std::random_device dev(token);
       return true;
-    } catch (...) {
+    } catch (const std::system_error& /* See PR libstdc++/105081 */) {
       return false;
     }
   }