nvme-print-stdout: change stdout_d() to not print all zeros

This is for the id-ns command empty vendor-specific fields.
  Note: This will change for other commands d() outputs.

Signed-off-by: Tokunori Ikegami <[email protected]>

Author: ikegami-t

nvme-print-stdout.c

@@ -4901,10 +4901,45 @@ static void stdout_lba_status_info(__u64 result)
 	       (__u32)NVME_FEAT_LBAS_LSIRI(result));
 }
 
+static bool is_all_zero(unsigned char *buf, int len, int width)
+{
+	int i;
+
+	if (len < width)
+		return false;
+
+	for (i = 0; i < width; i++) {
+		if (buf[i])
+			return false;
+	}
+
+	return true;
+}
+
+static bool is_ommit(unsigned char *buf, int len, int width, int offset)
+{
+	static bool all_zero;
+
+	if (!offset)
+		all_zero = false;
+
+	if (is_all_zero(&buf[offset], len - offset, width)) {
+		if (all_zero) {
+			return true;
+		}
+		all_zero = true;
+	} else {
+		all_zero = false;
+	}
+
+	return false;
+}
+
 void stdout_d(unsigned char *buf, int len, int width, int group)
 {
 	int i, offset = 0;
 	char ascii[32 + 1] = { 0 };
+	bool ommit = false;
 
 	assert(width < sizeof(ascii));
 
@@ -4914,8 +4949,21 @@ void stdout_d(unsigned char *buf, int len, int width, int group)
 		printf("%3x", i);
 
 	for (i = 0; i < len; i++) {
-		if (!(i % width))
+		if (!(i % width)) {
+			if (is_ommit(buf, len, width, offset)) {
+				if (!ommit) {
+					ommit = true;
+					printf("\n*");
+				}
+				offset += width;
+				continue;
+			} else if (ommit) {
+				ommit = false;
+			}
 			printf("\n%04x:", offset);
+		}
+		if (ommit)
+			continue;
 		if (i % group)
 			printf("%02x", buf[i]);
 		else
@@ -4927,6 +4975,8 @@ void stdout_d(unsigned char *buf, int len, int width, int group)
 			memset(ascii, 0, sizeof(ascii));
 		}
 	}
+	if (ommit)
+		printf("\n%04x:\n", offset);
 
 	if (strlen(ascii)) {
 		unsigned int b = width - (i % width);