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Message-ID: <Yxt07BE7TOX6dGh2@google.com>
Date: Fri, 9 Sep 2022 10:16:28 -0700
From: sdf@...gle.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, 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 2/2] libbpf: Add pathname_concat() helper
On 09/09, Wang Yufen 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 | 74
> ++++++++++++++++++--------------------------------
> 1 file changed, 27 insertions(+), 47 deletions(-)
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 5854b92..238a03e 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -2096,20 +2096,31 @@ static bool get_map_field_int(const char
> *map_name, const struct btf *btf,
> return true;
> }
> -static int build_map_pin_path(struct bpf_map *map, const char *path)
> +static int pathname_concat(const char *path, const char *name, char *buf)
> {
> - char buf[PATH_MAX];
> int len;
> - if (!path)
> - path = "/sys/fs/bpf";
> -
> - len = snprintf(buf, PATH_MAX, "%s/%s", path, bpf_map__name(map));
> + len = snprintf(buf, PATH_MAX, "%s/%s", path, name);
> if (len < 0)
> return -EINVAL;
> else 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 err;
> +
> + if (!path)
> + path = "/sys/fs/bpf";
> +
> + err = pathname_concat(path, bpf_map__name(map), buf);
> + if (err)
> + return err;
> +
> return bpf_map__set_pin_path(map, buf);
> }
> @@ -7959,17 +7970,8 @@ 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;
[..]
> + if (pathname_concat(path, bpf_map__name(map), buf))
> goto err_unpin_maps;
> - }
You're breaking error reporting here and in a bunch of other places.
Should be:
err = pathname_concat();
if (err)
goto err_unpin_maps;
I have the same attitude towards this patch as the first one in the
series: not worth it. Nothing is currently broken, the code as is relatively
readable, this version is not much simpler, it just looks slightly different
taste-wise..
How about this: if you really want to push this kind of cleanup, send
selftests that exercise all these error cases? :-)
> sanitize_pin_path(buf);
> pin_path = buf;
> } else if (!map->pin_path) {
> @@ -8007,14 +8009,9 @@ 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) {
> @@ -8032,6 +8029,7 @@ 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)
> @@ -8043,17 +8041,8 @@ 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;
> + if (pathname_concat(path, prog->name, buf))
> goto err_unpin_programs;
> - } else if (len >= PATH_MAX) {
> - err = -ENAMETOOLONG;
> - goto err_unpin_programs;
> - }
> err = bpf_program__pin(prog, buf);
> if (err)
> @@ -8064,13 +8053,7 @@ 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);
> @@ -8089,13 +8072,10 @@ 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
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