* process.c: Fix minor off-by-one issues in descriptor counts.

This shouldn't fix any real bugs, but it cleans up the code a bit.
(max_process_desc, max_input_desc): -1, not 0, means none.
All uses changed.
(delete_input_desc): New function.
(delete_write_fd, delete_keyboard_wait_descriptor): Use it.
(deactivate_process): Scan backwards when recomuting max_process_desc;
that should be faster.
(init_process_emacs): Initialize max_input_desc.

1 files changed, 27 insertions, 27 deletions

diff --git a/src/process.c b/src/process.c
index d87a1803fe2..85d07028c59 100644
--- a/src/process.c
+++ b/src/process.c
@@ -323,10 +323,10 @@ static SELECT_TYPE connect_wait_mask;
 static int num_pending_connects;
 #endif  /* NON_BLOCKING_CONNECT */
 
-/* The largest descriptor currently in use for a process object.  */
+/* The largest descriptor currently in use for a process object; -1 if none.  */
 static int max_process_desc;
 
-/* The largest descriptor currently in use for input.  */
+/* The largest descriptor currently in use for input; -1 if none.  */
 static int max_input_desc;
 
 /* Indexed by descriptor, gives the process (if any) for that descriptor */
@@ -500,13 +500,27 @@ add_write_fd (int fd, fd_callback func, void *data)
   fd_callback_info[fd].condition |= FOR_WRITE;
 }
 
+/* FD is no longer an input descriptor; update max_input_desc accordingly.  */
+
+static void
+delete_input_desc (int fd)
+{
+  if (fd == max_input_desc)
+    {
+      do
+        fd--;
+      while (0 <= fd && ! (FD_ISSET (fd, &input_wait_mask)
+                           || FD_ISSET (fd, &write_mask)));
+
+      max_input_desc = fd;
+    }
+}
+
 /* Stop monitoring file descriptor FD for when write is possible.  */
 
 void
 delete_write_fd (int fd)
 {
-  int lim = max_input_desc;
-
   eassert (fd < MAXDESC);
   FD_CLR (fd, &write_mask);
   fd_callback_info[fd].condition &= ~FOR_WRITE;
@@ -514,15 +528,7 @@ delete_write_fd (int fd)
     {
       fd_callback_info[fd].func = 0;
       fd_callback_info[fd].data = 0;
-
-      if (fd == max_input_desc)
-        for (fd = lim; fd >= 0; fd--)
-          if (FD_ISSET (fd, &input_wait_mask) || FD_ISSET (fd, &write_mask))
-            {
-              max_input_desc = fd;
-              break;
-            }
-
+      delete_input_desc (fd);
     }
 }
 
@@ -3831,13 +3837,14 @@ deactivate_process (Lisp_Object proc)
 #endif
       if (inchannel == max_process_desc)
         {
-          int i;
           /* We just closed the highest-numbered process input descriptor,
              so recompute the highest-numbered one now.  */
-          max_process_desc = 0;
-          for (i = 0; i < MAXDESC; i++)
-            if (!NILP (chan_process[i]))
-              max_process_desc = i;
+          int i = inchannel;
+          do
+            i--;
+          while (0 <= i && NILP (chan_process[i]));
+
+          max_process_desc = i;
         }
     }
 }
@@ -6763,16 +6770,9 @@ void
 delete_keyboard_wait_descriptor (int desc)
 {
 #ifdef subprocesses
-  int fd;
-  int lim = max_input_desc;
-
   FD_CLR (desc, &input_wait_mask);
   FD_CLR (desc, &non_process_wait_mask);
-
-  if (desc == max_input_desc)
-    for (fd = 0; fd < lim; fd++)
-      if (FD_ISSET (fd, &input_wait_mask) || FD_ISSET (fd, &write_mask))
-        max_input_desc = fd;
+  delete_input_desc (desc);
 #endif
 }
 
@@ -7037,7 +7037,7 @@ init_process_emacs (void)
   FD_ZERO (&non_keyboard_wait_mask);
   FD_ZERO (&non_process_wait_mask);
   FD_ZERO (&write_mask);
-  max_process_desc = 0;
+  max_process_desc = max_input_desc = -1;
   memset (fd_callback_info, 0, sizeof (fd_callback_info));
 
 #ifdef NON_BLOCKING_CONNECT