tools/apps/busybox/akaros-patches/1.17.3/0007-echo-buffering.patch

diff -ru busybox-1.17.3-orig/coreutils/echo.c busybox-1.17.3-akaros/coreutils/echo.c
--- busybox-1.17.3-orig/coreutils/echo.c	2015-03-06 12:06:11.732280338 -0500
+++ busybox-1.17.3-akaros/coreutils/echo.c	2015-03-06 12:34:12.607118758 -0500
@@ -33,6 +33,12 @@
 {
 	int ret;
 	const char *arg;
+	/* In lieu of using fputs/fflush, Akaros works better with raw writes.  The
+	 * main issue is that we want to have the entire echo sent as one write.
+	 * using setvbuf for line buffered mode seems to work, but fflush won't
+	 * propagate errors from the kernel. */
+	char write_buf[4096];
+	size_t buf_idx = 0;
 #if !ENABLE_FEATURE_FANCY_ECHO
 	enum {
 		eflag = '\\',
@@ -100,12 +106,7 @@
 		/* arg is already == *argv and isn't NULL */
 		int c;
 
-		if (!eflag) {
-			/* optimization for very common case */
-			ret = fputs(arg, stdout);
-			if (ret == EOF)
-				perror("echo failed");
-		} else while ((c = *arg++)) {
+		while ((c = *arg++)) {
 			if (c == eflag) {	/* Check for escape seq. */
 				if (*arg == 'c') {
 					/* '\c' means cancel newline and
@@ -130,25 +131,27 @@
 					c = bb_process_escape_sequence(&arg);
 				}
 			}
-			bb_putchar(c);
+			write_buf[buf_idx++] = c;
 		}
 
 		arg = *++argv;
 		if (!arg)
 			break;
-		bb_putchar(' ');
+		write_buf[buf_idx++] = ' ';
 	}
 
  newline_ret:
 	if (nflag) {
-		bb_putchar('\n');
+		write_buf[buf_idx++] = '\n';
 	}
  ret:
-	errno = 0;
-	ret = fflush_all();
-	if (errno)
+	ret = write(1, write_buf, buf_idx);
+	if (ret == -1) {
 		perror("echo failed");
-	return ret;
+		return EOF;
+	} else {
+		return 0;
+	}
 }
 
 /*-