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  So do not
quote the value unless it contains whitespace.

Link: https://lkml.kernel.org/r/20240320101952.62135-1-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/init/main.c b/init/main.c
index 881f6230ee59e9675eb98b62adf761ee74823a16..6b4b656cef1d9f90cef99d86a9189c528ba64703 100644 (file)
--- a/init/main.c
+++ b/init/main.c
@@ -327,7 +327,7 @@ static int __init xbc_snprint_cmdline(char *buf, size_t size,
 {
        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) {
@@ -345,8 +345,14 @@ 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);
+                       /*
+                        * For prettier and more readable /proc/cmdline, only
+                        * quote the value when necessary, i.e. when it contains
+                        * whitespace.
+                        */
+                       q = strpbrk(val, " \t\r\n") ? "\"" : "";
+                       ret = snprintf(buf, rest(buf, end), "%s=%s%s%s ",
+                                      xbc_namebuf, q, val, q);
                        if (ret < 0)
                                return ret;
                        buf += ret;