From: Matt Birkholz <matt@birkholz.chandler.az.us>
Date: Fri, 19 Oct 2012 18:52:04 +0000 (-0700)
Subject: Fix test-select-descriptor, test-select-registry.
X-Git-Tag: mit-scheme-pucked-9.2.12~552
X-Git-Url: https://birchwood-abbey.net/git?a=commitdiff_plain;h=9d566d67fd3cfcc99752eea0519ad8451e584c71;p=mit-scheme.git

Fix test-select-descriptor, test-select-registry.

Both test-select- primitives (in uxio.c) now return 0 only if there
are no INTERRUPTs nor PROCESS-STATUS-CHANGEs pending.  A previous
attempt at this was incomplete or wrong (e.g. not spinning on
interrupted calls when interrupts are masked).
---

diff --git a/src/microcode/uxio.c b/src/microcode/uxio.c
index 35c8db642..625820af7 100644
--- a/src/microcode/uxio.c
+++ b/src/microcode/uxio.c
@@ -607,7 +607,7 @@ OS_test_select_registry (select_registry_t registry, int blockp)
   while (1)
     {
       int nfds = (safe_poll ((SR_ENTRIES (r)), (SR_N_FDS (r)), blockp));
-      if (nfds >= 0)
+      if (nfds > 0)
 	return (nfds);
       if (nfds < 0 && errno != EINTR)
 	error_system_call (errno, syscall_select);
@@ -615,6 +615,8 @@ OS_test_select_registry (select_registry_t registry, int blockp)
 	return (SELECT_PROCESS_STATUS_CHANGE);
       if (pending_interrupts_p ())
 	return (SELECT_INTERRUPT);
+      if (nfds == 0) /* and no status-change nor interrupts pending */
+	return (0);
     }
 }
 
@@ -635,8 +637,8 @@ OS_test_select_descriptor (int fd, int blockp, unsigned int mode)
 	return (SELECT_PROCESS_STATUS_CHANGE);
       if (pending_interrupts_p ())
 	return (SELECT_INTERRUPT);
-      /* nfds == 0, AND no status-change nor interrupts pending */
-      return (0);
+      if (nfds == 0) /* and no status-change nor interrupts pending */
+	return (0);
     }
 }
 
@@ -809,7 +811,7 @@ OS_test_select_registry (select_registry_t registry, int blockp)
 			       (SR_RREADERS (r)),
 			       (SR_RWRITERS (r)),
 			       blockp));
-      if (nfds >= 0)
+      if (nfds > 0)
 	return (nfds);
       if (nfds < 0 && errno != EINTR)
 	error_system_call (errno, syscall_select);
@@ -817,6 +819,8 @@ OS_test_select_registry (select_registry_t registry, int blockp)
 	return (SELECT_PROCESS_STATUS_CHANGE);
       if (pending_interrupts_p ())
 	return (SELECT_INTERRUPT);
+      if (nfds == 0) /* and no status-change nor interrupts pending */
+	return (0);
     }
 #else
   error_system_call (ENOSYS, syscall_select);
@@ -852,8 +856,8 @@ OS_test_select_descriptor (int fd, int blockp, unsigned int mode)
 	return (SELECT_PROCESS_STATUS_CHANGE);
       if (pending_interrupts_p ())
 	return (SELECT_INTERRUPT);
-      /* nfds == 0, AND no status-change nor interrupts pending */
-      return (0);
+      if (nfds == 0) /* and no status-change nor interrupts pending */
+	return (0);
     }
 #else
   error_system_call (ENOSYS, syscall_select);