[PATCH v2] libbpf: Fix determine_ptr_size() guessing

From: Douglas RAILLARD
Date: Mon May 23 2022 - 06:31:41 EST


From: Douglas Raillard <douglas.raillard@xxxxxxx>

One strategy employed by libbpf to guess the pointer size is by finding
the size of "unsigned long" type. This is achieved by looking for a type
of with the expected name and checking its size.

Unfortunately, the C syntax is friendlier to humans than to computers
as there is some variety in how such a type can be named. Specifically,
gcc and clang do not use the same name in debug info.

Lookup all the names for such a type so that libbpf can hope to find the
information it wants.

Signed-off-by: Douglas Raillard <douglas.raillard@xxxxxxx>
---
tools/lib/bpf/btf.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)

CHANGELOG
v2:
* Added missing case for "long"

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 1383e26c5d1f..ab92b3bc2724 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -489,8 +489,19 @@ static int determine_ptr_size(const struct btf *btf)
if (!name)
continue;

- if (strcmp(name, "long int") == 0 ||
- strcmp(name, "long unsigned int") == 0) {
+ if (
+ strcmp(name, "long") == 0 ||
+ strcmp(name, "long int") == 0 ||
+ strcmp(name, "int long") == 0 ||
+ strcmp(name, "unsigned long") == 0 ||
+ strcmp(name, "long unsigned") == 0 ||
+ strcmp(name, "unsigned long int") == 0 ||
+ strcmp(name, "unsigned int long") == 0 ||
+ strcmp(name, "long unsigned int") == 0 ||
+ strcmp(name, "long int unsigned") == 0 ||
+ strcmp(name, "int unsigned long") == 0 ||
+ strcmp(name, "int long unsigned") == 0
+ ) {
if (t->size != 4 && t->size != 8)
continue;
return t->size;
--
2.25.1