From b05795bd3d8afcdcb765639a636ada8d36a2ee79 Mon Sep 17 00:00:00 2001

From: Lennart Poettering <lennart@poettering.net>

Date: Fri, 18 Jan 2019 20:04:13 +0100

Subject: [PATCH] util.h: add new UNPROTECT_ERRNO macro

THis is inspired by #11395, but much simpler.

(cherry picked from commit 840f606d88fef2f5d240b2d759ce7b951354d5bb)

Resolves: #1691691

---

 src/basic/util.h        |  9 +++++++++

 src/test/test-fs-util.c |  6 +++---

 src/test/test-util.c    | 25 +++++++++++++++++++++++++

 3 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/src/basic/util.h b/src/basic/util.h

index 9699d228f9..27b5a09782 100644

--- a/src/basic/util.h

+++ b/src/basic/util.h

@@ -134,11 +134,20 @@ static inline void *mempset(void *s, int c, size_t n) {

 }

 static inline void _reset_errno_(int *saved_errno) {

+        if (*saved_errno < 0) /* Invalidated by UNPROTECT_ERRNO? */

+                return;

+

         errno = *saved_errno;

 }

 #define PROTECT_ERRNO _cleanup_(_reset_errno_) __attribute__((unused)) int _saved_errno_ = errno

+#define UNPROTECT_ERRNO                         \

+        do {                                    \

+                errno = _saved_errno_;          \

+                _saved_errno_ = -1;             \

+        } while (false)

+

 static inline int negative_errno(void) {

         /* This helper should be used to shut up gcc if you know 'errno' is

          * negative. Instead of "return -errno;", use "return negative_errno();"

diff --git a/src/test/test-fs-util.c b/src/test/test-fs-util.c

index fc650b513e..7b7990bb70 100644

--- a/src/test/test-fs-util.c

+++ b/src/test/test-fs-util.c

@@ -322,11 +322,11 @@ static void test_unlink_noerrno(void) {

         {

                 PROTECT_ERRNO;

-                errno = -42;

+                errno = 42;

                 assert_se(unlink_noerrno(name) >= 0);

-                assert_se(errno == -42);

+                assert_se(errno == 42);

                 assert_se(unlink_noerrno(name) < 0);

-                assert_se(errno == -42);

+                assert_se(errno == 42);

         }

 }

diff --git a/src/test/test-util.c b/src/test/test-util.c

index 4d3e5c5b94..df60d89115 100644

--- a/src/test/test-util.c

+++ b/src/test/test-util.c

@@ -164,6 +164,30 @@ static void test_protect_errno(void) {

         assert_se(errno == 12);

 }

+static void test_unprotect_errno_inner_function(void) {

+        PROTECT_ERRNO;

+

+        errno = 2222;

+}

+

+static void test_unprotect_errno(void) {

+        log_info("/* %s */", __func__);

+

+        errno = 4711;

+

+        PROTECT_ERRNO;

+

+        errno = 815;

+

+        UNPROTECT_ERRNO;

+

+        assert_se(errno == 4711);

+

+        test_unprotect_errno_inner_function();

+

+        assert_se(errno == 4711);

+}

+

 static void test_in_set(void) {

         assert_se(IN_SET(1, 1));

         assert_se(IN_SET(1, 1, 2, 3, 4));

@@ -307,6 +331,7 @@ int main(int argc, char *argv[]) {

         test_div_round_up();

         test_u64log2();

         test_protect_errno();

+        test_unprotect_errno();

         test_in_set();

         test_log2i();

         test_raw_clone();