Enhance getline to return -2 when an I/O operation should be retried.

5 files changed, 79 insertions, 14 deletions

diff --git a/ChangeLog b/ChangeLog
index 78027810..9719effc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,20 @@
+2013-07-02         Andrew J. Schorr     <aschorr@telemetry-investments.com>
+
+	* eval.c (update_ERRNO_string): Set PROCINFO["errno"] to 0.
+	* io.c (inrec): Since get_a_record may now return -2, be sure
+	to throw an error in that case as well.
+	(wait_any): Fix what appears to be a bug.  The old logic repeatedly
+	called wait until it failed.  When a process has multiple children,
+	this causes it to stall until all of them have exited.  Instead,
+	we now exit the function after the first successful wait call.
+	(do_getline_redir, do_getline): Handle case where get_a_record
+	returns -2.
+	(errno_io_retry): New function to decide whether an I/O operation should
+	be retried.
+	(get_a_record): When read returns an error, call errno_io_retry to
+	decide whether the operation should be retried.  If so, return -2
+	instead of setting the IOP_AT_EOF flag.
+
 2013-07-01         Andrew J. Schorr     <aschorr@telemetry-investments.com>
 
 	* eval.c (update_ERRNO_int, unset_ERRNO): Update PROCINFO["errno"].
diff --git a/eval.c b/eval.c
index c1253f57..4ad5afe0 100644
--- a/eval.c
+++ b/eval.c
@@ -1012,6 +1012,7 @@ update_ERRNO_int(int errcode)
 void
 update_ERRNO_string(const char *string)
 {
+	update_PROCINFO_num("errno", 0);
 	unref(ERRNO_node->var_value);
 	ERRNO_node->var_value = make_string(string, strlen(string));
 }
diff --git a/extension/ChangeLog b/extension/ChangeLog
index 9218c744..d1ef7b4a 100644
--- a/extension/ChangeLog
+++ b/extension/ChangeLog
@@ -1,3 +1,9 @@
+2013-07-02         Andrew J. Schorr     <aschorr@telemetry-investments.com>
+
+	* select.c (set_non_blocking): New helper function to call fcntl.
+	(do_set_non_blocking): Add support for the case where there's a single
+	integer fd argument.
+
 2013-07-01         Andrew J. Schorr     <aschorr@telemetry-investments.com>
 
 	* select.c (do_set_non_blocking): Implement new set_non_blocking
diff --git a/extension/select.c b/extension/select.c
index 91898a20..c1b706fc 100644
--- a/extension/select.c
+++ b/extension/select.c
@@ -364,26 +364,36 @@ do_select(int nargs, awk_value_t *result)
 	return make_number(rc, result);
 }
 
+static int
+set_non_blocking(int fd)
+{
+	int flags = fcntl(fd, F_GETFL);
+	int rc = fcntl(fd, F_SETFL, (flags|O_NONBLOCK));
+	if (rc < 0)
+		update_ERRNO_int(errno);
+	return rc;
+}
+
 /*  do_set_non_blocking --- Set a file to be non-blocking */
 
 static awk_value_t *
 do_set_non_blocking(int nargs, awk_value_t *result)
 {
 	awk_value_t cmd, cmdtype;
+	int fd;
 
 	if (do_lint && nargs > 2)
 		lintwarn(ext_id, _("set_non_blocking: called with too many arguments"));
-	if (get_argument(0, AWK_STRING, & cmd) &&
+	if (get_argument(0, AWK_NUMBER, & cmd) &&
+		(cmd.num_value == (fd = cmd.num_value)) && 
+		! get_argument(1, AWK_STRING, & cmdtype))
+		return make_number(set_non_blocking(fd), result);
+	else if (get_argument(0, AWK_STRING, & cmd) &&
 		get_argument(1, AWK_STRING, & cmdtype)) {
 		const awk_input_buf_t *buf;
-		if ((buf = get_file(cmd.str_value.str, cmd.str_value.len, cmdtype.str_value.str, cmdtype.str_value.len)) != NULL) {
-			int flags = fcntl(buf->fd, F_GETFL);
-			int rc = fcntl(buf->fd, F_SETFL, (flags|O_NONBLOCK));
-			if (rc < 0)
-				update_ERRNO_int(errno);
-			return make_number(rc, result);
-		} else
-			warning(ext_id, _("set_non_blocking: get_file(`%s', `%s') failed"), cmd.str_value.str, cmdtype.str_value.str);
+		if ((buf = get_file(cmd.str_value.str, cmd.str_value.len, cmdtype.str_value.str, cmdtype.str_value.len)) != NULL)
+			return make_number(set_non_blocking(buf->fd), result);
+		warning(ext_id, _("set_non_blocking: get_file(`%s', `%s') failed"), cmd.str_value.str, cmdtype.str_value.str);
 	} else if (do_lint) {
 		if (nargs < 2)
 			lintwarn(ext_id, _("set_non_blocking: called with too few arguments"));
diff --git a/io.c b/io.c
index 14b8df91..0ba36451 100644
--- a/io.c
+++ b/io.c
@@ -555,7 +555,7 @@ inrec(IOBUF *iop, int *errcode)
 	else 
 		cnt = get_a_record(& begin, iop, errcode);
 
-	if (cnt == EOF) {
+	if (cnt < 0) {
 		retval = 1;
 		if (*errcode > 0)
 			update_ERRNO_int(*errcode);
@@ -2210,12 +2210,13 @@ wait_any(int interesting)	/* pid of interest, if any */
 				if (pid == redp->pid) {
 					redp->pid = -1;
 					redp->status = status;
-					break;
+					goto finished;
 				}
 		}
 		if (pid == -1 && errno == ECHILD)
 			break;
 	}
+finished:
 	signal(SIGHUP, hstat);
 	signal(SIGQUIT, qstat);
 #endif
@@ -2439,7 +2440,7 @@ do_getline_redir(int into_variable, enum redirval redirtype)
 	if (errcode != 0) {
 		if (! do_traditional && (errcode != -1))
 			update_ERRNO_int(errcode);
-		return make_number((AWKNUM) -1.0);
+		return make_number((AWKNUM) cnt);
 	}
 
 	if (cnt == EOF) {
@@ -2489,7 +2490,7 @@ do_getline(int into_variable, IOBUF *iop)
 			update_ERRNO_int(errcode);
 		if (into_variable)
 			(void) POP_ADDRESS();
-		return make_number((AWKNUM) -1.0); 
+		return make_number((AWKNUM) cnt); 
 	}
 
 	if (cnt == EOF)
@@ -3427,6 +3428,32 @@ find_longest_terminator:
 	return REC_OK;
 }
 
+/* Does the I/O error indicate that the operation should be retried later? */
+
+static inline int
+errno_io_retry(void)
+{
+	switch (errno) {
+#ifdef EAGAIN
+	case EAGAIN:
+#endif
+#ifdef EWOULDBLOCK
+#if !defined(EAGAIN) || (EWOULDBLOCK != EAGAIN)
+	case EWOULDBLOCK:
+#endif
+#endif
+#ifdef EINTR
+	case EINTR:
+#endif
+#ifdef ETIMEDOUT
+	case ETIMEDOUT:
+#endif
+		return 1;
+	default:
+		return 0;
+	}
+}
+
 /*
  * get_a_record --- read a record from IOP into out,
  * return length of EOF, set RT.
@@ -3474,8 +3501,10 @@ get_a_record(char **out,        /* pointer to pointer to data */
 			iop->flag |= IOP_AT_EOF;
 			return EOF;
 		} else if (iop->count == -1) {
-			iop->flag |= IOP_AT_EOF; 
 			*errcode = errno;
+			if (errno_io_retry())
+				return -2;
+			iop->flag |= IOP_AT_EOF; 
 			return EOF;
 		} else {
 			iop->dataend = iop->buf + iop->count;
@@ -3540,6 +3569,8 @@ get_a_record(char **out,        /* pointer to pointer to data */
 		iop->count = iop->public.read_func(iop->public.fd, iop->dataend, amt_to_read);
 		if (iop->count == -1) {
 			*errcode = errno;
+			if (errno_io_retry())
+				return -2;
 			iop->flag |= IOP_AT_EOF;
 			break;
 		} else if (iop->count == 0) {