[bpf-next v2 1/2] libbpf: Add pathname_concat() helper

From: Wang Yufen
Date: Fri Sep 16 2022 - 03:16:45 EST


Move snprintf and len check to common helper pathname_concat() to make the
code simpler.

Signed-off-by: Wang Yufen <wangyufen@xxxxxxxxxx>
---
tools/lib/bpf/libbpf.c | 76 +++++++++++++++++++-------------------------------
1 file changed, 29 insertions(+), 47 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 3ad1392..7ab977c 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2096,19 +2096,30 @@ static bool get_map_field_int(const char *map_name, const struct btf *btf,
return true;
}

+static int pathname_concat(const char *path, const char *name, char *buf)
+{
+ int len;
+
+ len = snprintf(buf, PATH_MAX, "%s/%s", path, name);
+ if (len < 0)
+ return -EINVAL;
+ if (len >= PATH_MAX)
+ return -ENAMETOOLONG;
+
+ return 0;
+}
+
static int build_map_pin_path(struct bpf_map *map, const char *path)
{
char buf[PATH_MAX];
- int len;
+ int err;

if (!path)
path = "/sys/fs/bpf";

- len = snprintf(buf, PATH_MAX, "%s/%s", path, bpf_map__name(map));
- if (len < 0)
- return -EINVAL;
- else if (len >= PATH_MAX)
- return -ENAMETOOLONG;
+ err = pathname_concat(path, bpf_map__name(map), buf);
+ if (err)
+ return err;

return bpf_map__set_pin_path(map, buf);
}
@@ -7961,17 +7972,9 @@ int bpf_object__pin_maps(struct bpf_object *obj, const char *path)
continue;

if (path) {
- int len;
-
- len = snprintf(buf, PATH_MAX, "%s/%s", path,
- bpf_map__name(map));
- if (len < 0) {
- err = -EINVAL;
- goto err_unpin_maps;
- } else if (len >= PATH_MAX) {
- err = -ENAMETOOLONG;
+ err = pathname_concat(path, bpf_map__name(map), buf);
+ if (err)
goto err_unpin_maps;
- }
sanitize_pin_path(buf);
pin_path = buf;
} else if (!map->pin_path) {
@@ -8009,14 +8012,9 @@ int bpf_object__unpin_maps(struct bpf_object *obj, const char *path)
char buf[PATH_MAX];

if (path) {
- int len;
-
- len = snprintf(buf, PATH_MAX, "%s/%s", path,
- bpf_map__name(map));
- if (len < 0)
- return libbpf_err(-EINVAL);
- else if (len >= PATH_MAX)
- return libbpf_err(-ENAMETOOLONG);
+ err = pathname_concat(path, bpf_map__name(map), buf);
+ if (err)
+ return err;
sanitize_pin_path(buf);
pin_path = buf;
} else if (!map->pin_path) {
@@ -8034,6 +8032,7 @@ int bpf_object__unpin_maps(struct bpf_object *obj, const char *path)
int bpf_object__pin_programs(struct bpf_object *obj, const char *path)
{
struct bpf_program *prog;
+ char buf[PATH_MAX];
int err;

if (!obj)
@@ -8045,17 +8044,9 @@ int bpf_object__pin_programs(struct bpf_object *obj, const char *path)
}

bpf_object__for_each_program(prog, obj) {
- char buf[PATH_MAX];
- int len;
-
- len = snprintf(buf, PATH_MAX, "%s/%s", path, prog->name);
- if (len < 0) {
- err = -EINVAL;
- goto err_unpin_programs;
- } else if (len >= PATH_MAX) {
- err = -ENAMETOOLONG;
+ err = pathname_concat(path, prog->name, buf);
+ if (err)
goto err_unpin_programs;
- }

err = bpf_program__pin(prog, buf);
if (err)
@@ -8066,13 +8057,7 @@ int bpf_object__pin_programs(struct bpf_object *obj, const char *path)

err_unpin_programs:
while ((prog = bpf_object__prev_program(obj, prog))) {
- char buf[PATH_MAX];
- int len;
-
- len = snprintf(buf, PATH_MAX, "%s/%s", path, prog->name);
- if (len < 0)
- continue;
- else if (len >= PATH_MAX)
+ if (pathname_concat(path, prog->name, buf))
continue;

bpf_program__unpin(prog, buf);
@@ -8091,13 +8076,10 @@ int bpf_object__unpin_programs(struct bpf_object *obj, const char *path)

bpf_object__for_each_program(prog, obj) {
char buf[PATH_MAX];
- int len;

- len = snprintf(buf, PATH_MAX, "%s/%s", path, prog->name);
- if (len < 0)
- return libbpf_err(-EINVAL);
- else if (len >= PATH_MAX)
- return libbpf_err(-ENAMETOOLONG);
+ err = pathname_concat(path, prog->name, buf);
+ if (err)
+ return libbpf_err(err);

err = bpf_program__unpin(prog, buf);
if (err)
--
1.8.3.1