Changeset 0cb6c26

Timestamp:

May 5, 2009, 1:30:07 AM (16 years ago)

Author:

Nelson Elhage <nelhage@mit.edu>

Branches:

master, release-1.10, release-1.4, release-1.5, release-1.6, release-1.7, release-1.8, release-1.9

Children:

1e6e74e

Parents:

e0473d2

Message:

Fix a race that could cause us to miss a SIGINT

When I refactored the previous commits to unmask SIGINT in
owl_global_is_interrupted, I accidentally opened a window for us to miss
a SIGINT for a cycle of the event loop if it arrived in owl_select()
between a call to that functuon and pselect().

Undo that refactoring to make is_interrupted() just poll the flag, add
owl_function_(un)mask_sigint() for convenience, and use them in the
relevant locations.

Files:

• functions.c (modified) (3 diffs)
• global.c (modified) (1 diff)
• select.c (modified) (3 diffs)

functions.c

@@ -2990 +2990 @@
   int viewsize, i, curmsg, start;
   owl_message *m;
-  sigset_t intr;
-  sigemptyset(&intr);
-  sigaddset(&intr, SIGINT);
 
   v=owl_global_get_current_view(&g);
@@ -3035 +3032 @@
       i--;
     }
-    sigprocmask(SIG_BLOCK, &intr, NULL);
+    owl_function_mask_sigint(NULL);
     if(owl_global_is_interrupted(&g)) {
       owl_global_unset_interrupted(&g);
+      owl_function_unmask_sigint(NULL);
       owl_function_makemsg("Search interrupted!");
       owl_mainwin_redisplay(owl_global_get_mainwin(&g));
       return;
     }
+    owl_function_unmask_sigint(NULL);
   }
   owl_mainwin_redisplay(owl_global_get_mainwin(&g));
@@ -3517 +3516 @@
      return COLORS;
 }
+
+void owl_function_mask_sigint(sigset_t *oldmask) {
+  sigset_t intr;
+
+  sigemptyset(&intr);
+  sigaddset(&intr, SIGINT);
+  sigprocmask(SIG_BLOCK, &intr, oldmask);
+}
+
+void owl_function_unmask_sigint(sigset_t *oldmask) {
+  sigset_t intr;
+
+  sigemptyset(&intr);
+  sigaddset(&intr, SIGINT);
+  sigprocmask(SIG_UNBLOCK, &intr, oldmask);
+}

global.c

@@ -936 +936 @@
 }
 
-/*
- * Note: This must be called with SIGINT masked in order to avoid
- * races. This will unset the interrupt flag and unblock SIGINT before
- * returning.
- */
 int owl_global_is_interrupted(owl_global *g) {
-  int interrupted;
-  sigset_t intr;
-  sigemptyset(&intr);
-  sigaddset(&intr, SIGINT);
-
-  interrupted = g->interrupted;
-  g->interrupted = 0;
-
-  sigprocmask(SIG_UNBLOCK, &intr, NULL);
-  return interrupted;
+  return g->interrupted;
 }
 

select.c

@@ -290 +290 @@
 {
   owl_input in;
+
+  owl_global_unset_interrupted(&g);
+  owl_function_unmask_sigint(NULL);
+
   in.ch = in.uch = owl_global_get_startup_tio(&g)->c_cc[VINTR];
   owl_process_input_char(in);
@@ -301 +305 @@
   fd_set aim_rfds, aim_wfds;
   struct timespec timeout;
-  sigset_t mask, intr;
-
-  sigemptyset(&intr);
-  sigaddset(&intr, SIGINT);
+  sigset_t mask;
 
   owl_select_process_timers(&timeout);
 
-  sigprocmask(SIG_BLOCK, &intr, &mask);
+  owl_function_mask_sigint(&mask);
   if(owl_global_is_interrupted(&g)) {
-     owl_select_handle_intr();
+    owl_select_handle_intr();
     return;
   }
@@ -352 +353 @@
   }
 
-  sigprocmask(SIG_UNBLOCK, &intr, NULL);
+  owl_function_unmask_sigint(NULL);
 
   if(ret > 0) {