[PATCH] tools/resolve_btfids: Fix 'variable' may be used uninitialized warnings

[Eder Zulian]

- tools/bpf/resolve_btfids/main.c: Initialize 'set' and 'set8' pointers
  to NULL in to fix compiler warnings.

- tools/lib/bpf/btf_dump.c: Initialize 'new_off' and 'pad_bits' to 0 and
  'pad_type' to  NULL to prevent compiler warnings.

- tools/lib/subcmd/parse-options.c: Initiazlide pointer 'o' to NULL
  avoiding a compiler warning.

Tested on x86_64 with clang version 17.0.6 and gcc (GCC) 13.3.1.

$ cd tools/bpf/resolve_btfids
$ for c in gcc clang; do \
for o in fast g s z $(seq 0 3); do \
make clean && \
make HOST_CC=${c} "HOSTCFLAGS=-O${o} -Wall" 2>&1 | tee ${c}-O${o}.out; \
done; done && grep 'warning:\|error:' *.out

[...]
clang-O1.out:main.c:163:9: warning: ‘set8’ may be used uninitialized [-Wmaybe-uninitialized]
clang-O1.out:main.c:163:9: warning: ‘set’ may be used uninitialized [-Wmaybe-uninitialized]
clang-O2.out:main.c:163:9: warning: ‘set8’ may be used uninitialized [-Wmaybe-uninitialized]
clang-O2.out:main.c:163:9: warning: ‘set’ may be used uninitialized [-Wmaybe-uninitialized]
clang-O3.out:main.c:163:9: warning: ‘set8’ may be used uninitialized [-Wmaybe-uninitialized]
clang-O3.out:main.c:163:9: warning: ‘set’ may be used uninitialized [-Wmaybe-uninitialized]
clang-Ofast.out:main.c:163:9: warning: ‘set8’ may be used uninitialized [-Wmaybe-uninitialized]
clang-Ofast.out:main.c:163:9: warning: ‘set’ may be used uninitialized [-Wmaybe-uninitialized]
clang-Og.out:btf_dump.c:903:42: error: ‘new_off’ may be used uninitialized [-Werror=maybe-uninitialized]
clang-Og.out:btf_dump.c:917:25: error: ‘pad_type’ may be used uninitialized [-Werror=maybe-uninitialized]
clang-Og.out:btf_dump.c:930:20: error: ‘pad_bits’ may be used uninitialized [-Werror=maybe-uninitialized]
clang-Os.out:parse-options.c:832:9: error: ‘o’ may be used uninitialized [-Werror=maybe-uninitialized]
clang-Oz.out:parse-options.c:832:9: error: ‘o’ may be used uninitialized [-Werror=maybe-uninitialized]
gcc-O1.out:main.c:163:9: warning: ‘set8’ may be used uninitialized [-Wmaybe-uninitialized]
gcc-O1.out:main.c:163:9: warning: ‘set’ may be used uninitialized [-Wmaybe-uninitialized]
gcc-O2.out:main.c:163:9: warning: ‘set8’ may be used uninitialized [-Wmaybe-uninitialized]
gcc-O2.out:main.c:163:9: warning: ‘set’ may be used uninitialized [-Wmaybe-uninitialized]
gcc-O3.out:main.c:163:9: warning: ‘set8’ may be used uninitialized [-Wmaybe-uninitialized]
gcc-O3.out:main.c:163:9: warning: ‘set’ may be used uninitialized [-Wmaybe-uninitialized]
gcc-Ofast.out:main.c:163:9: warning: ‘set8’ may be used uninitialized [-Wmaybe-uninitialized]
gcc-Ofast.out:main.c:163:9: warning: ‘set’ may be used uninitialized [-Wmaybe-uninitialized]
gcc-Og.out:btf_dump.c:903:42: error: ‘new_off’ may be used uninitialized [-Werror=maybe-uninitialized]
gcc-Og.out:btf_dump.c:917:25: error: ‘pad_type’ may be used uninitialized [-Werror=maybe-uninitialized]
gcc-Og.out:btf_dump.c:930:20: error: ‘pad_bits’ may be used uninitialized [-Werror=maybe-uninitialized]
gcc-Os.out:parse-options.c:832:9: error: ‘o’ may be used uninitialized [-Werror=maybe-uninitialized]
gcc-Oz.out:parse-options.c:832:9: error: ‘o’ may be used uninitialized [-Werror=maybe-uninitialized]

The above warnings and/or errors are not observed after applying this
patch.

Signed-off-by: Eder Zulian <ezulian@xxxxxxxxxx>
---
 tools/bpf/resolve_btfids/main.c  | 4 ++--
 tools/lib/bpf/btf_dump.c         | 4 ++--
 tools/lib/subcmd/parse-options.c | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
index d54aaa0619df..bd9f960bce3d 100644
--- a/tools/bpf/resolve_btfids/main.c
+++ b/tools/bpf/resolve_btfids/main.c
@@ -679,8 +679,8 @@ static int sets_patch(struct object *obj)
 
 	next = rb_first(&obj->sets);
 	while (next) {
-		struct btf_id_set8 *set8;
-		struct btf_id_set *set;
+		struct btf_id_set8 *set8 = NULL;
+		struct btf_id_set *set = NULL;
 		unsigned long addr, off;
 		struct btf_id *id;
 
diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index 8440c2c5ad3e..468392f9882d 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -867,8 +867,8 @@ static void btf_dump_emit_bit_padding(const struct btf_dump *d,
 	} pads[] = {
 		{"long", d->ptr_sz * 8}, {"int", 32}, {"short", 16}, {"char", 8}
 	};
-	int new_off, pad_bits, bits, i;
-	const char *pad_type;
+	int new_off = 0, pad_bits = 0, bits, i;
+	const char *pad_type = NULL;
 
 	if (cur_off >= next_off)
 		return; /* no gap */
diff --git a/tools/lib/subcmd/parse-options.c b/tools/lib/subcmd/parse-options.c
index eb896d30545b..555d617c1f50 100644
--- a/tools/lib/subcmd/parse-options.c
+++ b/tools/lib/subcmd/parse-options.c
@@ -807,7 +807,7 @@ static int option__cmp(const void *va, const void *vb)
 static struct option *options__order(const struct option *opts)
 {
 	int nr_opts = 0, nr_group = 0, nr_parent = 0, len;
-	const struct option *o, *p = opts;
+	const struct option *o = NULL, *p = opts;
 	struct option *opt, *ordered = NULL, *group;
 
 	/* flatten the options that have parents */
-- 
2.46.2