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Blame SOURCES/0122-util.h-add-new-UNPROTECT_ERRNO-macro.patch

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From b05795bd3d8afcdcb765639a636ada8d36a2ee79 Mon Sep 17 00:00:00 2001
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From: Lennart Poettering <lennart@poettering.net>
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Date: Fri, 18 Jan 2019 20:04:13 +0100
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Subject: [PATCH] util.h: add new UNPROTECT_ERRNO macro
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THis is inspired by #11395, but much simpler.
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(cherry picked from commit 840f606d88fef2f5d240b2d759ce7b951354d5bb)
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Resolves: #1691691
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---
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 src/basic/util.h        |  9 +++++++++
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 src/test/test-fs-util.c |  6 +++---
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 src/test/test-util.c    | 25 +++++++++++++++++++++++++
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 3 files changed, 37 insertions(+), 3 deletions(-)
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diff --git a/src/basic/util.h b/src/basic/util.h
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index 9699d228f9..27b5a09782 100644
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--- a/src/basic/util.h
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+++ b/src/basic/util.h
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@@ -134,11 +134,20 @@ static inline void *mempset(void *s, int c, size_t n) {
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 }
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 static inline void _reset_errno_(int *saved_errno) {
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+        if (*saved_errno < 0) /* Invalidated by UNPROTECT_ERRNO? */
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+                return;
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+
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         errno = *saved_errno;
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 }
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 #define PROTECT_ERRNO _cleanup_(_reset_errno_) __attribute__((unused)) int _saved_errno_ = errno
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+#define UNPROTECT_ERRNO                         \
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+        do {                                    \
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+                errno = _saved_errno_;          \
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+                _saved_errno_ = -1;             \
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+        } while (false)
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+
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 static inline int negative_errno(void) {
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         /* This helper should be used to shut up gcc if you know 'errno' is
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          * negative. Instead of "return -errno;", use "return negative_errno();"
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diff --git a/src/test/test-fs-util.c b/src/test/test-fs-util.c
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index fc650b513e..7b7990bb70 100644
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--- a/src/test/test-fs-util.c
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+++ b/src/test/test-fs-util.c
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@@ -322,11 +322,11 @@ static void test_unlink_noerrno(void) {
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         {
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                 PROTECT_ERRNO;
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-                errno = -42;
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+                errno = 42;
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                 assert_se(unlink_noerrno(name) >= 0);
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-                assert_se(errno == -42);
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+                assert_se(errno == 42);
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                 assert_se(unlink_noerrno(name) < 0);
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-                assert_se(errno == -42);
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+                assert_se(errno == 42);
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         }
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 }
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diff --git a/src/test/test-util.c b/src/test/test-util.c
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index 4d3e5c5b94..df60d89115 100644
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--- a/src/test/test-util.c
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+++ b/src/test/test-util.c
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@@ -164,6 +164,30 @@ static void test_protect_errno(void) {
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         assert_se(errno == 12);
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 }
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+static void test_unprotect_errno_inner_function(void) {
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+        PROTECT_ERRNO;
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+
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+        errno = 2222;
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+}
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+
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+static void test_unprotect_errno(void) {
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+        log_info("/* %s */", __func__);
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+
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+        errno = 4711;
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+
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+        PROTECT_ERRNO;
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+
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+        errno = 815;
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+
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+        UNPROTECT_ERRNO;
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+
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+        assert_se(errno == 4711);
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+
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+        test_unprotect_errno_inner_function();
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+
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+        assert_se(errno == 4711);
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+}
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+
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 static void test_in_set(void) {
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         assert_se(IN_SET(1, 1));
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         assert_se(IN_SET(1, 1, 2, 3, 4));
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@@ -307,6 +331,7 @@ int main(int argc, char *argv[]) {
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         test_div_round_up();
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         test_u64log2();
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         test_protect_errno();
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+        test_unprotect_errno();
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         test_in_set();
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         test_log2i();
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         test_raw_clone();