From 7389a3ba16731345713638aad3e74f952392eee1 Mon Sep 17 00:00:00 2001
From: Andy Keep <andy.keep@gmail.com>
Date: Fri, 5 Aug 2016 00:04:00 -0400
Subject: [PATCH] - reworked the S_create_thread_object to print an error and
 exit when   allocating the thread context fails from Sactivate_thread. 
 before   this change, the error was raised on the main thread, which resulted
   in strange behavior at best.  also added who argument to  
 S_create_thread_object to allow it to report either Sactivate_thread   or
 fork-thread led to the error.     externs.h, schsig.c, scheme.c, thread.c

original commit: 89691cee27ee7d5e9bffae530b6346e96f8cc7ad
---
 LOG         |  7 +++++++
 c/externs.h |  2 +-
 c/scheme.c  |  4 +++-
 c/schsig.c  |  2 +-
 c/thread.c  | 14 ++++++--------
 5 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/LOG b/LOG
index 59bb0a3b42..d34fbb6c05 100644
--- a/LOG
+++ b/LOG
@@ -273,3 +273,10 @@
   change to compile on windows.  unicode is not yet supported in the windows
   version of the repl.
     c/expeditor.c
+- reworked the S_create_thread_object to print an error and exit when
+  allocating the thread context fails from Sactivate_thread.  before
+  this change, the error was raised on the main thread, which resulted
+  in strange behavior at best.  also added who argument to
+  S_create_thread_object to allow it to report either Sactivate_thread
+  or fork-thread led to the error.
+    externs.h, schsig.c, scheme.c, thread.c
diff --git a/c/externs.h b/c/externs.h
index 5696a10e59..a0fbbc92c6 100644
--- a/c/externs.h
+++ b/c/externs.h
@@ -195,7 +195,7 @@ extern void S_new_io_init PROTO((void));
 
 /* thread.c */
 extern void S_thread_init PROTO((void));
-extern ptr S_create_thread_object PROTO((void));
+extern ptr S_create_thread_object PROTO((const char *who, ptr p_tc));
 #ifdef PTHREADS
 extern ptr S_fork_thread PROTO((ptr thunk));
 extern scheme_mutex_t *S_make_mutex PROTO((void));
diff --git a/c/scheme.c b/c/scheme.c
index 205596b453..15084b3ca7 100644
--- a/c/scheme.c
+++ b/c/scheme.c
@@ -1053,7 +1053,9 @@ extern void Sbuild_heap(kernel, custom_init) const char *kernel; void (*custom_i
     S_threads = Snil;
     S_nthreads = 0;
     S_set_symbol_value(S_G.active_threads_id, FIX(0));
-    tc = (ptr)THREADTC(S_create_thread_object());
+    /* pass a parent tc of Svoid, since this call establishes the initial
+     * thread context and hence there is no parent thread context.  */
+    tc = (ptr)THREADTC(S_create_thread_object("startup", tc));
 #ifdef PTHREADS
     s_thread_setspecific(S_tc_key, tc);
 #endif
diff --git a/c/schsig.c b/c/schsig.c
index 90145389c3..fbebe09ae3 100644
--- a/c/schsig.c
+++ b/c/schsig.c
@@ -373,7 +373,7 @@ void S_boot_error(ptr who, ptr msg, ptr args) {
 static void do_error(type, who, s, args) iptr type; const char *who, *s; ptr args; {
     ptr tc = get_thread_context();
 
-    if (S_errors_to_console || CCHAIN(tc) == Snil) {
+    if (S_errors_to_console || tc == (ptr)0 || CCHAIN(tc) == Snil) {
         if (strlen(who) == 0)
           printf("Error: %s\n", s);
         else
diff --git a/c/thread.c b/c/thread.c
index 0ca73c8dcf..7e56dd04a9 100644
--- a/c/thread.c
+++ b/c/thread.c
@@ -47,7 +47,7 @@ void S_thread_init() {
    thread_find_room.  main.c does part of the initialization of the
    base thread (e.g., parameters, current input/output ports) in one
    or more places. */
-ptr S_create_thread_object() {
+ptr S_create_thread_object(who, p_tc) const char *who; ptr p_tc; {
   ptr thread, tc;
   INT i;
 
@@ -56,7 +56,6 @@ ptr S_create_thread_object() {
   if (S_threads == Snil) {
     tc = (ptr)S_G.thread_context;
   } else { /* clone parent */
-    ptr p_tc = get_thread_context();
     ptr p_v = PARAMETERS(p_tc);
     iptr i, n = Svector_length(p_v);
    /* use S_vector_in to avoid thread-local allocation */
@@ -64,7 +63,7 @@ ptr S_create_thread_object() {
 
     tc = (ptr)malloc(size_tc);
     if (tc == (ptr)0)
-      S_error("fork-thread", "unable to malloc thread data structure");
+      S_error(who, "unable to malloc thread data structure");
     memcpy((void *)tc, (void *)p_tc, size_tc);
 
     for (i = 0; i < n; i += 1)
@@ -130,14 +129,12 @@ ptr S_create_thread_object() {
 #ifdef PTHREADS
 IBOOL Sactivate_thread() { /* create or reactivate current thread */
   ptr tc = get_thread_context();
+
   if (tc == (ptr)0) { /* thread created by someone else */
     ptr thread;
 
    /* borrow base thread for now */
-    tc = (ptr)S_G.thread_context;
-    s_thread_setspecific(S_tc_key, tc);
-
-    thread = S_create_thread_object();
+    thread = S_create_thread_object("Sactivate_thread", S_G.thread_context);
     s_thread_setspecific(S_tc_key, (ptr)THREADTC(thread));
     return 1;
   } else {
@@ -199,7 +196,8 @@ ptr S_fork_thread(thunk) ptr thunk; {
   ptr thread;
   int status;
 
-  thread = S_create_thread_object();
+  /* pass the current thread's context as the parent thread */
+  thread = S_create_thread_object("fork-thread", get_thread_context());
   CP(THREADTC(thread)) = thunk;
 
   if ((status = s_thread_create(start_thread, (void *)THREADTC(thread))) != 0) {