From e8fe9f96356a6b19ec907ea30cffc829c539a7ff Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Wed, 27 Jan 2021 11:19:14 +0000
Subject: [PATCH] awk: allow printf('%c') to output NUL, closes 13486

Treat the output of printf as binary rather than a null-terminated
string so that NUL characters can be output.

This is considered to be a GNU extension, though it's also available
in mawk and FreeBSD's awk.

function                                             old     new   delta
evaluate                                            3487    3504     +17
awk_printf                                           504     519     +15
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 32/0)               Total: 32 bytes

Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
---
 editors/awk.c       | 18 +++++++++++++++---
 testsuite/awk.tests |  5 +++++
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/editors/awk.c b/editors/awk.c
index 2c15f9e4e..b4f6a3741 100644
--- a/editors/awk.c
+++ b/editors/awk.c
@@ -2155,7 +2155,10 @@ static int fmt_num(char *b, int size, const char *format, double n, int int_as_i
 }
 
 /* formatted output into an allocated buffer, return ptr to buffer */
-static char *awk_printf(node *n)
+#if !ENABLE_FEATURE_AWK_GNU_EXTENSIONS
+# define awk_printf(a, b) awk_printf(a)
+#endif
+static char *awk_printf(node *n, int *len)
 {
 	char *b = NULL;
 	char *fmt, *s, *f;
@@ -2209,6 +2212,10 @@ static char *awk_printf(node *n)
 	nvfree(v);
 	b = xrealloc(b, i + 1);
 	b[i] = '\0';
+#if ENABLE_FEATURE_AWK_GNU_EXTENSIONS
+	if (len)
+		*len = i;
+#endif
 	return b;
 }
 
@@ -2666,6 +2673,7 @@ static var *evaluate(node *op, var *res)
 		case XC( OC_PRINT ):
 		case XC( OC_PRINTF ): {
 			FILE *F = stdout;
+			IF_FEATURE_AWK_GNU_EXTENSIONS(int len;)
 
 			if (op->r.n) {
 				rstream *rsm = newfile(R.s);
@@ -2703,8 +2711,12 @@ static var *evaluate(node *op, var *res)
 				fputs(getvar_s(intvar[ORS]), F);
 
 			} else {	/* OC_PRINTF */
-				char *s = awk_printf(op1);
+				char *s = awk_printf(op1, &len);
+#if ENABLE_FEATURE_AWK_GNU_EXTENSIONS
+				fwrite(s, len, 1, F);
+#else
 				fputs(s, F);
+#endif
 				free(s);
 			}
 			fflush(F);
@@ -2978,7 +2990,7 @@ static var *evaluate(node *op, var *res)
 			break;
 
 		case XC( OC_SPRINTF ):
-			setvar_p(res, awk_printf(op1));
+			setvar_p(res, awk_printf(op1, NULL));
 			break;
 
 		case XC( OC_UNARY ): {
diff --git a/testsuite/awk.tests b/testsuite/awk.tests
index 92c83d719..cf9b722dc 100755
--- a/testsuite/awk.tests
+++ b/testsuite/awk.tests
@@ -383,6 +383,11 @@ testing "awk errors on missing delete arg" \
 	"awk -e '{delete}' 2>&1" "awk: cmd. line:1: Too few arguments\n" "" ""
 SKIP=
 
+optional FEATURE_AWK_GNU_EXTENSIONS
+testing "awk printf('%c') can output NUL" \
+	"awk '{printf(\"hello%c null\n\", 0)}'" "hello\0 null\n" "" "\n"
+SKIP=
+
 # testing "description" "command" "result" "infile" "stdin"
 testing 'awk negative field access' \
 	'awk 2>&1 -- '\''{ $(-1) }'\' \