From 499fd07a44d35aabe7ff02275bd9907bab93893a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Gallet?= <clement.gallet@ens-lyon.org>
Date: Tue, 4 Aug 2020 18:41:03 +0200
Subject: [PATCH] Print forked processes and prevent closing the socket

---
 src/library/checkpoint/Checkpoint.cpp |  3 ++-
 src/library/global.cpp                |  1 +
 src/library/global.h                  |  3 +++
 src/library/logging.cpp               | 12 ++++++++----
 src/library/main.cpp                  |  8 +++++---
 src/library/systemwrappers.cpp        | 18 ++++++++++++++++++
 src/library/systemwrappers.h          |  7 ++++++-
 7 files changed, 43 insertions(+), 9 deletions(-)

diff --git a/src/library/checkpoint/Checkpoint.cpp b/src/library/checkpoint/Checkpoint.cpp
index cdaaf13b..1b04e501 100644
--- a/src/library/checkpoint/Checkpoint.cpp
+++ b/src/library/checkpoint/Checkpoint.cpp
@@ -753,7 +753,8 @@ static void readAnArea(SaveState &saved_state, int spmfd, SaveState &parent_stat
 static void writeAllAreas(bool base)
 {
     if (shared_config.savestate_settings & SharedConfig::SS_FORK) {
-        pid_t pid = fork();
+        pid_t pid;
+        NATIVECALL(pid = fork());
         if (pid != 0)
             return;
 
diff --git a/src/library/global.cpp b/src/library/global.cpp
index 9e990520..05ea5109 100644
--- a/src/library/global.cpp
+++ b/src/library/global.cpp
@@ -24,6 +24,7 @@ namespace libtas {
 SharedConfig shared_config;
 GameInfo game_info;
 volatile bool is_exiting = false;
+volatile bool is_fork = false;
 bool skipping_draw = false;
 Display* gameDisplays[GAMEDISPLAYNUM] = {};
 xcb_connection_t* gameConnections[GAMEDISPLAYNUM] = {};
diff --git a/src/library/global.h b/src/library/global.h
index 1add8df7..8e920ac4 100644
--- a/src/library/global.h
+++ b/src/library/global.h
@@ -50,6 +50,9 @@ namespace libtas {
     /* Indicate if the game is exiting. It helps avoiding some invalid or blocking calls */
     extern volatile bool is_exiting;
 
+    /* Indicate if this is a forked process. We should not use socket on forked processes */
+    extern volatile bool is_fork;
+
     /* Do we skip all rendering functions for the current frame */
     extern bool skipping_draw;
 
diff --git a/src/library/logging.cpp b/src/library/logging.cpp
index 97089daa..9d4aa6be 100644
--- a/src/library/logging.cpp
+++ b/src/library/logging.cpp
@@ -79,11 +79,15 @@ void debuglogstdio(LogCategoryFlag lcf, const char* fmt, ...)
     snprintf(s + size, maxsize-size-1, "[libTAS f:%" PRIu64 "] ", framecount);
     size = strlen(s);
 
-    pid_t tid = ThreadManager::getThreadTid();
-    if (ThreadManager::isMainThread())
-        snprintf(s + size, maxsize-size-1, "Thread %d (main) ", tid);
+    pid_t tid;
+    if (is_fork)
+        /* For forked processes, the thread manager have wrong pid values (those of parent process) */
+        NATIVECALL(tid = getpid());
     else
-        snprintf(s + size, maxsize-size-1, "Thread %d        ", tid);
+        tid = ThreadManager::getThreadTid();
+
+    snprintf(s + size, maxsize-size-1, "Thread %d %s ", tid, is_fork?"(fork)":(ThreadManager::isMainThread()?"(main)":""));
+
     size = strlen(s);
 
     if (isTerm) {
diff --git a/src/library/main.cpp b/src/library/main.cpp
index 4038a174..759bd3a9 100644
--- a/src/library/main.cpp
+++ b/src/library/main.cpp
@@ -180,10 +180,12 @@ void __attribute__((constructor)) init(void)
 void __attribute__((destructor)) term(void)
 {
     if (is_inited) {
-        ThreadManager::deallocateThreads();
-        sendMessage(MSGB_QUIT);
-        closeSocket();
+        if (!is_fork) {
+            sendMessage(MSGB_QUIT);
+            closeSocket();
+        }
         debuglog(LCF_SOCKET, "Exiting.");
+        ThreadManager::deallocateThreads();
     }
 }
 
diff --git a/src/library/systemwrappers.cpp b/src/library/systemwrappers.cpp
index 6ed24bb7..d6ba5a80 100644
--- a/src/library/systemwrappers.cpp
+++ b/src/library/systemwrappers.cpp
@@ -27,6 +27,7 @@
 namespace libtas {
 
 DEFINE_ORIG_POINTER(getpid);
+DEFINE_ORIG_POINTER(fork);
 
 /* Override */ pid_t getpid (void) throw()
 {
@@ -54,4 +55,21 @@ DEFINE_ORIG_POINTER(getpid);
     return pid;
 }
 
+/* Override */  pid_t fork(void) __THROWNL
+{
+    LINK_NAMESPACE_GLOBAL(fork);
+    pid_t pid = orig::fork();
+
+    if (GlobalState::isNative()) {
+        return pid;
+    }
+
+    DEBUGLOGCALL(LCF_SYSTEM);
+
+    if (pid == 0) {
+        is_fork = true;
+    }
+    return pid;
+}
+
 }
diff --git a/src/library/systemwrappers.h b/src/library/systemwrappers.h
index 70983724..2313462e 100644
--- a/src/library/systemwrappers.h
+++ b/src/library/systemwrappers.h
@@ -27,7 +27,12 @@
 namespace libtas {
 
 /* Get the process ID of the calling process.  */
-OVERRIDE pid_t getpid (void) throw();
+OVERRIDE pid_t getpid (void) __THROWNL;
+
+/* Clone the calling process, creating an exact copy.
+   Return -1 for errors, 0 to the new process,
+   and the process ID of the new process to the old process.  */
+OVERRIDE pid_t fork(void) __THROWNL;
 
 }