[libc] [clang] [llvm] [flang] [compiler-rt] [clang-tools-extra] [flang] use setsid to assign the child to prevent zombie as it will be clean up by init process (PR #77944)

[Yi Wu via cfe-commits]

https://github.com/yi-wu-arm updated https://github.com/llvm/llvm-project/pull/77944

>From b51f293d57a1ae96fab5d3b2a529186a78643c8c Mon Sep 17 00:00:00 2001
From: Yi Wu <yi.wu2 at arm.com>
Date: Fri, 12 Jan 2024 16:44:21 +0000
Subject: [PATCH 1/4] use setsid to assign the child to prevent zombie as it
 will be clean up by init process

---
 flang/runtime/execute.cpp | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/flang/runtime/execute.cpp b/flang/runtime/execute.cpp
index 48773ae8114b0b..1bd5bb81ec8461 100644
--- a/flang/runtime/execute.cpp
+++ b/flang/runtime/execute.cpp
@@ -180,8 +180,6 @@ void RTNAME(ExecuteCommandLine)(const Descriptor &command, bool wait,
     }
     FreeMemory((void *)wcmd);
 #else
-    // terminated children do not become zombies
-    signal(SIGCHLD, SIG_IGN);
     pid_t pid{fork()};
     if (pid < 0) {
       if (!cmdstat) {
@@ -191,6 +189,18 @@ void RTNAME(ExecuteCommandLine)(const Descriptor &command, bool wait,
         CheckAndCopyCharsToDescriptor(cmdmsg, "Fork failed");
       }
     } else if (pid == 0) {
+      if (setsid() == -1) {
+        if (!cmdstat) {
+          terminator.Crash(
+              "setsid() failed with errno: %d, asynchronous process initiation failed.",
+              errno);
+        } else {
+          StoreIntToDescriptor(cmdstat, ASYNC_NO_SUPPORT_ERR, terminator);
+          CheckAndCopyCharsToDescriptor(
+              cmdmsg, "setsid() failed, asynchronous process initiation failed.");
+        }
+        exit(EXIT_FAILURE);
+      }
       int status{std::system(newCmd)};
       TerminationCheck(status, cmdstat, cmdmsg, terminator);
       exit(status);

>From 9682eb49bcd77e70439accd2eaa4524fea5cdfe5 Mon Sep 17 00:00:00 2001
From: Yi Wu <yi.wu2 at arm.com>
Date: Fri, 12 Jan 2024 16:58:29 +0000
Subject: [PATCH 2/4] clang-format

---
 flang/runtime/execute.cpp | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/flang/runtime/execute.cpp b/flang/runtime/execute.cpp
index 1bd5bb81ec8461..d149b5d47ef754 100644
--- a/flang/runtime/execute.cpp
+++ b/flang/runtime/execute.cpp
@@ -191,13 +191,13 @@ void RTNAME(ExecuteCommandLine)(const Descriptor &command, bool wait,
     } else if (pid == 0) {
       if (setsid() == -1) {
         if (!cmdstat) {
-          terminator.Crash(
-              "setsid() failed with errno: %d, asynchronous process initiation failed.",
+          terminator.Crash("setsid() failed with errno: %d, asynchronous "
+                           "process initiation failed.",
               errno);
         } else {
           StoreIntToDescriptor(cmdstat, ASYNC_NO_SUPPORT_ERR, terminator);
-          CheckAndCopyCharsToDescriptor(
-              cmdmsg, "setsid() failed, asynchronous process initiation failed.");
+          CheckAndCopyCharsToDescriptor(cmdmsg,
+              "setsid() failed, asynchronous process initiation failed.");
         }
         exit(EXIT_FAILURE);
       }

>From b8f4db41db6ceb10897f113243d4a0954d727dc7 Mon Sep 17 00:00:00 2001
From: Yi Wu <yi.wu2 at arm.com>
Date: Fri, 12 Jan 2024 17:01:48 +0000
Subject: [PATCH 3/4] add comment

---
 flang/runtime/execute.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/flang/runtime/execute.cpp b/flang/runtime/execute.cpp
index d149b5d47ef754..f455cf8b0e88ca 100644
--- a/flang/runtime/execute.cpp
+++ b/flang/runtime/execute.cpp
@@ -189,6 +189,7 @@ void RTNAME(ExecuteCommandLine)(const Descriptor &command, bool wait,
         CheckAndCopyCharsToDescriptor(cmdmsg, "Fork failed");
       }
     } else if (pid == 0) {
+      // Create a new session, let init process take care of zombie child
       if (setsid() == -1) {
         if (!cmdstat) {
           terminator.Crash("setsid() failed with errno: %d, asynchronous "

>From bd3279c5a4686f3aa5e7949dc0952c3fad34852e Mon Sep 17 00:00:00 2001
From: Yi Wu <yi.wu2 at arm.com>
Date: Thu, 18 Jan 2024 15:07:18 +0000
Subject: [PATCH 4/4] add tests

---
 flang/unittests/Runtime/CommandTest.cpp | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/flang/unittests/Runtime/CommandTest.cpp b/flang/unittests/Runtime/CommandTest.cpp
index 5ae0f1c72f92c3..3fd2667e2930ed 100644
--- a/flang/unittests/Runtime/CommandTest.cpp
+++ b/flang/unittests/Runtime/CommandTest.cpp
@@ -404,6 +404,24 @@ TEST_F(ZeroArguments, ECLInvalidCommandParentNotTerminatedAsync) {
   CheckDescriptorEqStr(cmdMsg.get(), "No change");
 }
 
+TEST_F(ZeroArguments, ECLInvalidCommandAsyncDontAffectSync) {
+  OwningPtr<Descriptor> command{CharDescriptor("echo hi")};
+
+  EXPECT_NO_FATAL_FAILURE(RTNAME(ExecuteCommandLine)(
+      *command.get(), false, nullptr, nullptr, nullptr));
+  EXPECT_NO_FATAL_FAILURE(RTNAME(ExecuteCommandLine)(
+      *command.get(), true, nullptr, nullptr, nullptr));
+}
+
+TEST_F(ZeroArguments, ECLInvalidCommandAsyncDontAffectAsync) {
+  OwningPtr<Descriptor> command{CharDescriptor("echo hi")};
+
+  EXPECT_NO_FATAL_FAILURE(RTNAME(ExecuteCommandLine)(
+      *command.get(), false, nullptr, nullptr, nullptr));
+  EXPECT_NO_FATAL_FAILURE(RTNAME(ExecuteCommandLine)(
+      *command.get(), false, nullptr, nullptr, nullptr));
+}
+
 static const char *oneArgArgv[]{"aProgram", "anArgumentOfLength20"};
 class OneArgument : public CommandFixture {
 protected: