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Date: Wed, 21 Sep 2022 17:35:32 -0700
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Wang Yufen <wangyufen@...wei.com>
Cc: andrii@...nel.org, ast@...nel.org, daniel@...earbox.net,
martin.lau@...ux.dev, song@...nel.org, yhs@...com,
john.fastabend@...il.com, kpsingh@...nel.org, sdf@...gle.com,
haoluo@...gle.com, jolsa@...nel.org, paul.walmsley@...ive.com,
palmer@...belt.com, aou@...s.berkeley.edu, davem@...emloft.net,
kuba@...nel.org, hawk@...nel.org, nathan@...nel.org,
ndesaulniers@...gle.com, trix@...hat.com, bpf@...r.kernel.org,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
llvm@...ts.linux.dev
Subject: Re: [bpf-next v3 1/2] libbpf: Add pathname_concat() helper
On Sun, Sep 18, 2022 at 7:28 PM Wang Yufen <wangyufen@...wei.com> wrote:
>
> Move snprintf and len check to common helper pathname_concat() to make the
> code simpler.
>
> Signed-off-by: Wang Yufen <wangyufen@...wei.com>
> ---
> 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..43a530d 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, size_t buflen)
> +{
> + int len;
> +
> + len = snprintf(buf, buflen, "%s/%s", path, name);
> + if (len < 0)
> + return -EINVAL;
> + if (len >= buflen)
> + 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, PATH_MAX);
sizeof(buf) instead of PATH_MAX?
> + 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, PATH_MAX);
same, let's not hardcode constants we don't need to hardcode, just do
sizeof(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, PATH_MAX);
ditto here and all the cases below
> + 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, PATH_MAX);
> + 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, PATH_MAX))
> 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, PATH_MAX);
> + if (err)
> + return libbpf_err(err);
>
> err = bpf_program__unpin(prog, buf);
> if (err)
> --
> 1.8.3.1
>
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