https://bugs.gentoo.org/972401
https://github.com/lxc/lxc/issues/4710
https://github.com/lxc/lxc/pull/4711
https://github.com/lxc/lxc/commit/c2809b067bbd5c63f0f78a5acd6f7af4e77e584c

From c2809b067bbd5c63f0f78a5acd6f7af4e77e584c Mon Sep 17 00:00:00 2001
From: Adrian Ratiu <adrian.ratiu@collabora.com>
Date: Sat, 18 Jul 2026 23:11:52 +0300
Subject: [PATCH] tree-wide: fix const-correctness issues exposed by glibc 2.43

glibc 2.43 implements strchr(3), strrchr(3) and strstr(3) as
C23-style _Generic macros which propagate the const qualifier
of the input string to the return type.

For example, a 'const char *' input now produces 'const char *'
output types and vice-versa (non-const -> non-const).

Building with clang and -Werror=incompatible-pointer-types fails:

  src/lxc/confile.c:2690:4: error: assigning to 'char *' from
      'const char *' discards qualifiers
      [-Werror,-Wincompatible-pointer-types-discards-qualifiers]

Constify the result pointers where they are only read. Where the
code intentionally writes through the result into caller-owned
writable storage, drop the bogus const from the parameter instead
of casting it away: update_hwaddr() (and thus its caller
append_unexp_config_line()) modify the string in-place via
rand_complete_hwaddr(), so 'char *' is the honest type. The two
call sites already pass writable buffers (a strdup()'d line and an
internally built one), so no cast is needed.

The one remaining cast is in cgroup1-only pam_cgfs code
(cgv1_handle_cpuset_hierarchy) where the writable buffer is passed
down through a const 'cgroup' parameter; that hierarchy is slated
for removal, so the minimal cast is kept there.

This is just a build fix, the runtime behavior is unchanged.

Fixes: #4710
Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
--- a/src/lxc/confile.c
+++ b/src/lxc/confile.c
@@ -2675,7 +2675,7 @@ static int set_config_console_size(const char *key, const char *value,
  * lxc.include.
  * 'x' and 'X' are substituted in-place.
  */
-static void update_hwaddr(const char *line)
+static void update_hwaddr(char *line)
 {
 	char *p;
 
@@ -2701,7 +2701,7 @@ static void update_hwaddr(const char *line)
 	rand_complete_hwaddr(p);
 }
 
-int append_unexp_config_line(const char *line, struct lxc_conf *conf)
+int append_unexp_config_line(char *line, struct lxc_conf *conf)
 {
 	size_t linelen;
 	size_t len = conf->unexpanded_len;
@@ -4213,7 +4213,7 @@ static int get_config_uts_name(const char *key, char *retv, int inlen,
 static int get_config_hooks(const char *key, char *retv, int inlen,
 			    struct lxc_conf *c, void *data)
 {
-	char *subkey;
+	const char *subkey;
 	int len, fulllen = 0, found = -1;
 	struct string_entry *entry;
 	int i;
--- a/src/lxc/confile.h
+++ b/src/lxc/confile.h
@@ -75,7 +75,7 @@ __hidden extern int lxc_list_net(struct lxc_conf *c, const char *key, char *retv
 
 __hidden extern int lxc_config_read(const char *file, struct lxc_conf *conf, bool from_include);
 
-__hidden extern int append_unexp_config_line(const char *line, struct lxc_conf *conf);
+__hidden extern int append_unexp_config_line(char *line, struct lxc_conf *conf);
 
 extern int lxc_config_define_add(struct lxc_list *defines, char *arg);
 
--- a/src/lxc/confile_utils.c
+++ b/src/lxc/confile_utils.c
@@ -903,7 +903,7 @@ int lxc_inherit_namespace(const char *nsfd_path, const char *lxcpath,
 {
 	__do_free char *dup = NULL;
 	int fd, pid;
-	char *lastslash;
+	const char *lastslash;
 
 	if (nsfd_path[0] == '/') {
 		return open(nsfd_path, O_RDONLY | O_CLOEXEC);
--- a/src/lxc/pam/pam_cgfs.c
+++ b/src/lxc/pam/pam_cgfs.c
@@ -362,7 +362,7 @@ static char *copy_to_eol(char *s)
 /* Check if given entry under /proc/<pid>/mountinfo is a fuse.lxcfs mount. */
 static bool is_lxcfs(const char *line)
 {
-	char *p = strstr(line, " - ");
+	const char *p = strstr(line, " - ");
 	if (!p)
 		return false;
 
@@ -1914,7 +1914,7 @@ static bool cgv1_handle_cpuset_hierarchy(struct cgv1_hierarchy *h,
 
 	if (*cgroup == '/')
 		cgroup++;
-	slash = strchr(cgroup, '/');
+	slash = (char *)strchr(cgroup, '/');
 	if (slash)
 		*slash = '\0';
 
--- a/src/lxc/storage/nbd.c
+++ b/src/lxc/storage/nbd.c
@@ -291,7 +291,7 @@ static void nbd_detach(const char *path)
  */
 static int nbd_get_partition(const char *src)
 {
-	char *p = strchr(src, ':');
+	const char *p = strchr(src, ':');
 	if (!p)
 		return 0;
 
--- a/src/lxc/storage/zfs.c
+++ b/src/lxc/storage/zfs.c
@@ -461,7 +461,7 @@ int zfs_clonepaths(struct lxc_storage *orig, struct lxc_storage *new,
 			orig_src = cmd_output;
 		}
 
-		tmp = strrchr(orig_src, '/');
+		tmp = (char *)strrchr(orig_src, '/');
 		if (!tmp) {
 			ERROR("Failed to detect \"/\" in \"%s\"", orig_src);
 			return -1;