Fix various things about SIGINT handling:

* exception handlers are now run with interrupts disabled, which avoids
  many race conditions
* fix some cases where SIGINT only aborts one command and continues the
  script, in particular if a SIGINT causes an EINTR error which trumped the
  interrupt.

Example:
  sh -c 'echo < /some/fifo; echo This should not be printed'
The fifo should not have writers. When pressing ctrl+c to abort the open,
the shell used to continue with the next command.

Example:
  sh -c '/bin/echo < /some/fifo; echo This should not be printed'
Similar. Note, however, that this particular case did not and does not work
in interactive mode with job control enabled.

1 files changed, 5 insertions, 2 deletions

diff --git a/bin/sh/redir.c b/bin/sh/redir.c
index 695e150..08878f6 100644
--- a/bin/sh/redir.c
+++ b/bin/sh/redir.c
@@ -166,8 +166,11 @@ openredirect(union node *redir, char memory[10])
 
 	/*
 	 * We suppress interrupts so that we won't leave open file
-	 * descriptors around.  This may not be such a good idea because
-	 * an open of a device or a fifo can block indefinitely.
+	 * descriptors around.  Because the signal handler remains
+	 * installed and we do not use system call restart, interrupts
+	 * will still abort blocking opens such as fifos (they will fail
+	 * with EINTR). There is, however, a race condition if an interrupt
+	 * arrives after INTOFF and before open blocks.
 	 */
 	INTOFF;
 	memory[fd] = 0;