FOLLY_SAFE_PCHECK

Summary: [Folly] `FOLLY_SAFE_PCHECK`, for reporting errors from C standard library functions which may set errno from within code which must be reentrant.

Reviewed By: nbronson

Differential Revision: D19222785

fbshipit-source-id: 532ccee39c9d180b9b17edbd31517c09024539d7

folly/lang/SafeAssert.h

@@ -16,23 +16,28 @@
 
 #pragma once
 
+#include <cerrno>
+
 #include <folly/Portability.h>
 #include <folly/Preprocessor.h>
 
+#define FOLLY_SAFE_CHECK_IMPL(expr, expr_s, msg, error) \
+  ((expr) ? static_cast<void>(0)                        \
+          : ::folly::detail::assertionFailure(          \
+                FB_STRINGIZE(expr_s),                   \
+                (msg),                                  \
+                __FILE__,                               \
+                __LINE__,                               \
+                __PRETTY_FUNCTION__,                    \
+                error))
+
 /**
  * Verify that the expression is true. If not, prints an error message
  * (containing msg) to stderr and abort()s. Just like CHECK(), but only
  * logs to stderr and only does async-signal-safe calls.
  */
-#define FOLLY_SAFE_CHECK_IMPL(expr, expr_s, msg) \
-  ((expr) ? static_cast<void>(0)                 \
-          : ::folly::detail::assertionFailure(   \
-                FB_STRINGIZE(expr_s),            \
-                (msg),                           \
-                __FILE__,                        \
-                __LINE__,                        \
-                __PRETTY_FUNCTION__))
-#define FOLLY_SAFE_CHECK(expr, msg) FOLLY_SAFE_CHECK_IMPL((expr), (expr), (msg))
+#define FOLLY_SAFE_CHECK(expr, msg) \
+  FOLLY_SAFE_CHECK_IMPL((expr), (expr), (msg), 0)
 
 /**
  * In debug mode, verify that the expression is true. Otherwise, do nothing
@@ -40,7 +45,13 @@
  * only does async-signal-safe calls.
  */
 #define FOLLY_SAFE_DCHECK(expr, msg) \
-  FOLLY_SAFE_CHECK_IMPL(!::folly::kIsDebug || (expr), (expr), (msg))
+  FOLLY_SAFE_CHECK_IMPL(!::folly::kIsDebug || (expr), (expr), (msg), 0)
+
+/**
+ * Like FOLLY_SAFE_CHECK, but also prints errno.
+ */
+#define FOLLY_SAFE_PCHECK(expr, msg) \
+  FOLLY_SAFE_CHECK_IMPL((expr), (expr), (msg), errno)
 
 namespace folly {
 namespace detail {
@@ -50,6 +61,7 @@ namespace detail {
     const char* msg,
     const char* file,
     unsigned int line,
-    const char* function);
+    const char* function,
+    int error);
 } // namespace detail
 } // namespace folly

folly/lang/test/SafeAssertTest.cpp

@@ -19,6 +19,7 @@
 #include <glog/logging.h>
 
 #include <folly/Benchmark.h>
+#include <folly/Conv.h>
 #include <folly/portability/GTest.h>
 
 // clang-format off
@@ -36,3 +37,12 @@ TEST(SafeAssert, AssertionFailure) {
   EXPECT_DEATH(fail(), "Assertion failure: 0 \\+ 0");
   EXPECT_DEATH(fail(), "Message: hello");
 }
+
+TEST(SafeAssert, AssertionFailureErrno) {
+  EXPECT_DEATH(
+      FOLLY_SAFE_PCHECK((errno = EINVAL) && false, "hello"),
+      folly::to<std::string>("Error: ", EINVAL, " \\(EINVAL\\)"));
+  EXPECT_DEATH(
+      FOLLY_SAFE_PCHECK((errno = 999) && false, "hello"),
+      folly::to<std::string>("Error: 999 \\(<unknown>\\)"));
+}