In `elf_close`, we get this with GCC 15 -O3 (at least):
```
In function ‘elf_close’,
inlined from ‘elf_close’ at elf.c:53:6,
inlined from ‘elf_find_func_offset_from_file’ at elf.c:384:2:
elf.c:57:9: warning: ‘elf_fd.elf’ may be used uninitialized [-Wmaybe-uninitialized]
57 | elf_end(elf_fd->elf);
| ^~~~~~~~~~~~~~~~~~~~
elf.c: In function ‘elf_find_func_offset_from_file’:
elf.c:377:23: note: ‘elf_fd.elf’ was declared here
377 | struct elf_fd elf_fd;
| ^~~~~~
In function ‘elf_close’,
inlined from ‘elf_close’ at elf.c:53:6,
inlined from ‘elf_find_func_offset_from_file’ at elf.c:384:2:
elf.c:58:9: warning: ‘elf_fd.fd’ may be used uninitialized [-Wmaybe-uninitialized]
58 | close(elf_fd->fd);
| ^~~~~~~~~~~~~~~~~
elf.c: In function ‘elf_find_func_offset_from_file’:
elf.c:377:23: note: ‘elf_fd.fd’ was declared here
377 | struct elf_fd elf_fd;
| ^~~~~~
```
In reality, our use is fine, it's just that GCC doesn't model errno
here (see linked GCC bug). Suppress -Wmaybe-uninitialized accordingly
by initializing elf_fd.elf to -1.
I've done this in two other functions as well given it could easily
occur there too (same access/use pattern).
Link: https://gcc.gnu.org/PR114952
Signed-off-by: Sam James <sam@xxxxxxxxxx>
---
v3: Initialize to -1 instead of using a pragma.
Range-diff against v2:
1: 8f5c3b173e4cb < -: ------------- libbpf: workaround -Wmaybe-uninitialized false positive
-: ------------- > 1: 12cec1262be71 libbpf: workaround -Wmaybe-uninitialized false positive
tools/lib/bpf/elf.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/tools/lib/bpf/elf.c b/tools/lib/bpf/elf.c
index c92e02394159e..00ea3f867bbc8 100644
--- a/tools/lib/bpf/elf.c
+++ b/tools/lib/bpf/elf.c
@@ -374,7 +374,7 @@ long elf_find_func_offset(Elf *elf, const char *binary_path, const char *name)
*/
long elf_find_func_offset_from_file(const char *binary_path, const char *name)
{
- struct elf_fd elf_fd;
+ struct elf_fd elf_fd = { .fd = -1 };
long ret = -ENOENT;
ret = elf_open(binary_path, &elf_fd);
@@ -412,7 +412,7 @@ int elf_resolve_syms_offsets(const char *binary_path, int cnt,
int err = 0, i, cnt_done = 0;
unsigned long *offsets;
struct symbol *symbols;
- struct elf_fd elf_fd;
+ struct elf_fd elf_fd = { .fd = -1 };
err = elf_open(binary_path, &elf_fd);
if (err)
@@ -507,7 +507,7 @@ int elf_resolve_pattern_offsets(const char *binary_path, const char *pattern,
int sh_types[2] = { SHT_SYMTAB, SHT_DYNSYM };
unsigned long *offsets = NULL;
size_t cap = 0, cnt = 0;
- struct elf_fd elf_fd;
+ struct elf_fd elf_fd = { .fd = -1 };
int err = 0, i;
err = elf_open(binary_path, &elf_fd);
--
2.45.2
