Split out _xexit() from xexit() and give sigatexit() multiple callbacks.

3 files changed, 38 insertions, 5 deletions

diff --git a/lib/lib.c b/lib/lib.c
index 1c1f2248..200f77d6 100644
--- a/lib/lib.c
+++ b/lib/lib.c
@@ -757,11 +757,24 @@ void generic_signal(int sig)
   toys.signal = sig;
 }
 
-// Install the same handler on every signal that defaults to killing the process
+void exit_signal(int sig)
+{
+  toys.exitval = sig|128;
+  xexit();
+}
+
+// Install the same handler on every signal that defaults to killing the
+// process, and 
 void sigatexit(void *handler)
 {
+  struct arg_list *al = xmalloc(sizeof(struct arg_list));
   int i;
-  for (i=0; signames[i].num != SIGCHLD; i++) signal(signames[i].num, handler);
+
+  for (i=0; signames[i].num != SIGCHLD; i++)
+    signal(signames[i].num, exit_signal);
+  al->next = toys.xexit;
+  al->arg = handler;
+  toys.xexit = al;
 }
 
 // Convert name to signal number.  If name == NULL print names.
diff --git a/lib/lib.h b/lib/lib.h
index 917be0c1..b12a110b 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -96,6 +96,7 @@ void show_help(FILE *out);
 // xwrap.c
 void xstrncpy(char *dest, char *src, size_t size);
 void xstrncat(char *dest, char *src, size_t size);
+void _xexit(void) noreturn;
 void xexit(void) noreturn;
 void *xmalloc(size_t size);
 void *xzalloc(size_t size);
diff --git a/lib/xwrap.c b/lib/xwrap.c
index 78103555..0b1ab8e9 100644
--- a/lib/xwrap.c
+++ b/lib/xwrap.c
@@ -28,13 +28,32 @@ void xstrncat(char *dest, char *src, size_t size)
   strcpy(dest+len, src);
 }
 
+// We replaced exit(), _exit(), and atexit() with xexit(), _xexit(), and
+// sigatexit(). This gives _xexit() the option to siglongjmp(toys.rebound, 1)
+// instead of exiting, lets xexit() report stdout flush failures to stderr
+// and change the exit code to indicate error, lets our toys.exit function
+// change happen for signal exit paths and lets us remove the functions
+// after we've called them.
+
+void _xexit(void)
+{
+  if (toys.rebound) siglongjmp(*toys.rebound, 1);
+
+  _exit(toys.exitval);
+}
+
 void xexit(void)
 {
-  if (toys.rebound) longjmp(*toys.rebound, 1);
+  // Call toys.xexit functions in reverse order added.
+  while (toys.xexit) {
+    // This is typecasting xexit->arg to a function pointer,then calling it.
+    ((void (*)(void))(toys.xexit->arg))();
+
+    free(llist_pop(&toys.xexit));
+  }
   if (fflush(NULL) || ferror(stdout))
     if (!toys.exitval) perror_msg("write");
-
-  exit(toys.exitval);
+  _xexit();
 }
 
 // Die unless we can allocate memory.