libbpf: Fix -Wdiscarded-qualifiers under C23

glibc ≥ 2.42 (GCC 15) defaults to -std=gnu23, which promotes
-Wdiscarded-qualifiers to an error.

In C23, strstr() and strchr() return "const char *".

Change variable types to const char * where the pointers are never
modified (res, sym_sfx, next_path).

Suggested-by: Florian Weimer <fweimer@redhat.com>
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Link: https://lore.kernel.org/r/20251206092825.1471385-1-mikhail.v.gavrilov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 3dc8a807881551bae23447033f8a7ed276a8e269..f4dfd23148a55fc4fe589154d21603c37af4a619 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -8484,7 +8484,7 @@ static int kallsyms_cb(unsigned long long sym_addr, char sym_type,
        struct bpf_object *obj = ctx;
        const struct btf_type *t;
        struct extern_desc *ext;
-       char *res;
+       const char *res;
 
        res = strstr(sym_name, ".llvm.");
        if (sym_type == 'd' && res)
@@ -11818,7 +11818,8 @@ static int avail_kallsyms_cb(unsigned long long sym_addr, char sym_type,
                 *
                 *   [0] fb6a421fb615 ("kallsyms: Match symbols exactly with CONFIG_LTO_CLANG")
                 */
-               char sym_trim[256], *psym_trim = sym_trim, *sym_sfx;
+               char sym_trim[256], *psym_trim = sym_trim;
+               const char *sym_sfx;
 
                if (!(sym_sfx = strstr(sym_name, ".llvm.")))
                        return 0;
@@ -12401,7 +12402,7 @@ static int resolve_full_path(const char *file, char *result, size_t result_sz)
                if (!search_paths[i])
                        continue;
                for (s = search_paths[i]; s != NULL; s = strchr(s, ':')) {
-                       char *next_path;
+                       const char *next_path;
                        int seg_len;
 
                        if (s[0] == ':')