linux-kernel - [PATCH] bootconfig: do not put quotes on cmdline items unless necessary

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Message-Id: <20240306122452.1664709-1-linux@rasmusvillemoes.dk>
Date: Wed,  6 Mar 2024 13:24:52 +0100
From: Rasmus Villemoes <linux@...musvillemoes.dk>
To: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] bootconfig: do not put quotes on cmdline items unless necessary

When trying to migrate to using bootconfig to embed the kernel's and
PID1's command line with the kernel image itself, and so allowing
changing that without modifying the bootloader, I noticed that
/proc/cmdline changed from e.g.

  console=ttymxc0,115200n8 cma=128M quiet -- --log-level=notice

to

  console="ttymxc0,115200n8" cma="128M" quiet -- --log-level="notice"

The kernel parameters are parsed just fine, and the quotes are indeed
stripped from the actual argv[] given to PID1. However, the quoting
doesn't really serve any purpose and looks excessive, and might
confuse some (naive) userspace tool trying to parse /proc/cmdline. So
do not quote the value unless it contains whitespace.

Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
---
 init/main.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/init/main.c b/init/main.c
index e24b0780fdff..a658c00a0208 100644
--- a/init/main.c
+++ b/init/main.c
@@ -319,12 +319,20 @@ static char xbc_namebuf[XBC_KEYLEN_MAX] __initdata;
 
 #define rest(dst, end) ((end) > (dst) ? (end) - (dst) : 0)
 
+static int has_space(const char *v)
+{
+	for (; *v; v++)
+		if (isspace(*v))
+			return 1;
+	return 0;
+}
+
 static int __init xbc_snprint_cmdline(char *buf, size_t size,
 				      struct xbc_node *root)
 {
 	struct xbc_node *knode, *vnode;
 	char *end = buf + size;
-	const char *val;
+	const char *val, *q;
 	int ret;
 
 	xbc_node_for_each_key_value(root, knode, val) {
@@ -342,8 +350,9 @@ static int __init xbc_snprint_cmdline(char *buf, size_t size,
 			continue;
 		}
 		xbc_array_for_each_value(vnode, val) {
-			ret = snprintf(buf, rest(buf, end), "%s=\"%s\" ",
-				       xbc_namebuf, val);
+			q = has_space(val) ? "\"" : "";
+			ret = snprintf(buf, rest(buf, end), "%s=%s%s%s ",
+				       xbc_namebuf, q, val, q);
 			if (ret < 0)
 				return ret;
 			buf += ret;
-- 
2.40.1.1.g1c60b9335d