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Date: Tue, 13 Sep 2022 10:55:42 +0800
From: wangyufen <wangyufen@...wei.com>
To: <sdf@...gle.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
在 2022/9/10 1:16, sdf@...gle.com 写道:
> 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;
>
Thanks for your comments.
Sure, my bad.
> 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? :-)
Ok. I will try. :-)
>
>
>> 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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