Document the secondary expansion method. Also, some other documentation

cleanups.

If we find a make error (invalid makefile syntax or something like that)
write back any tokens we have before we exit.

If we have waiting jobs (using -j + -l) set an alarm before we sleep on
the read() system call, so we can wake up to check the load and start
waiting jobs, if there are long-running jobs we would otherwise be
waiting for.  Suggested by Grant Taylor.

1 files changed, 24 insertions, 8 deletions

diff --git a/main.c b/main.c
index be0bac5..5536190 100644
--- a/main.c
+++ b/main.c
@@ -1076,7 +1076,7 @@ main (int argc, char **argv, char **envp)
 #endif
     {
 #ifdef	HAVE_GETCWD
-      perror_with_name ("getcwd: ", "");
+      perror_with_name ("getcwd", "");
 #else
       error (NILF, "getwd: %s", current_directory);
 #endif
@@ -1409,7 +1409,7 @@ main (int argc, char **argv, char **envp)
 #endif
 	{
 #ifdef	HAVE_GETCWD
-	  perror_with_name ("getcwd: ", "");
+	  perror_with_name ("getcwd", "");
 #else
 	  error (NILF, "getwd: %s", current_directory);
 #endif
@@ -2938,6 +2938,7 @@ die (int status)
 
   if (!dying)
     {
+      char token = '+';
       int err;
 
       dying = 1;
@@ -2958,18 +2959,33 @@ die (int status)
       if (print_data_base_flag)
 	print_data_base ();
 
-      /* Sanity: have we written all our jobserver tokens back?  */
+      /* Sanity: have we written all our jobserver tokens back?  If our
+         exit status is 2 that means some kind of syntax error; we might not
+         have written all our tokens so do that now.  If tokens are left
+         after any other error code, that's bad.  */
+
+      if (job_fds[0] != -1 && jobserver_tokens)
+        {
+          if (status != 2)
+            error (NILF,
+                   "INTERNAL: Exiting with %u jobserver tokens (should be 0)!",
+                   jobserver_tokens);
+          else
+            while (jobserver_tokens--)
+              {
+                int r;
+
+                EINTRLOOP (r, write (job_fds[1], &token, 1));
+                if (r != 1)
+                  perror_with_name ("write", "");
+              }
+        }
 
-      if (jobserver_tokens)
-        error (NILF,
-               "INTERNAL: Exiting with %u jobserver tokens (should be 0)!",
-               jobserver_tokens);
 
       /* Sanity: If we're the master, were all the tokens written back?  */
 
       if (master_job_slots)
         {
-          char token;
           /* We didn't write one for ourself, so start at 1.  */
           unsigned int tcnt = 1;