linux-kernel - [PATCH 2/4] tools/bpf: musl compat: do not use DEFFILEMODE

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Message-Id: <20220424051022.2619648-3-asmadeus@codewreck.org>
Date:   Sun, 24 Apr 2022 14:10:20 +0900
From:   Dominique Martinet <asmadeus@...ewreck.org>
To:     bpf@...r.kernel.org
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        KP Singh <kpsingh@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        Yonghong Song <yhs@...com>, Song Liu <songliubraving@...com>,
        Martin KaFai Lau <kafai@...com>,
        Andrii Nakryiko <andrii@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Dominique Martinet <asmadeus@...ewreck.org>
Subject: [PATCH 2/4] tools/bpf: musl compat: do not use DEFFILEMODE

DEFFILEMODE is not defined on musl libc.

Linus has expressed preference towards using explicit octal value in
the past over combinaisons of S_Ix{USR,GRP,OTH}, so just replace it
with 0666 directly

Signed-off-by: Dominique Martinet <asmadeus@...ewreck.org>
---

I wanted to link to the Linus mail that said this, but it turns out
there weren't any list in Cc... I could be making this up but here's the
relevant part of his mail, which I hope is acceptable to forward as
there's nothing personal in it:
----
Date: Sat, 27 Feb 2021 11:29:31 -0800
From: Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [RFC][PATCHSET] inode type bits fixes
Message-ID: <CAHk-=whRkLinjW3gRJQ=fWHZcFP5iy37+4VVr38TzSXEwZrZGg@...l.gmail.com>

[...]

Finally, I absolutely _abhor_ the crazy "S_%&^%&^$" macros. They are
completely illegible garbage, imnsho. I'm looking at that

+                       mode = stat->st_mode & S_IALLUGO;
+                       mode |= inode->i_mode & ~S_IALLUGO;

and I'm like "WTF is that random character sequence again".

In this case, it's everything but the format.  I think it would be
more legible written the other way around, ie

+                       mode = stat->st_mode & ~S_IFMT;
+                       mode |= inode->i_mode & S_IFMT;

because at least that one has _less_ of the stupid random-generated letters.

Every single one of the "UGO" things are pure and utter crap. The
octal representation of the actual permissions masks are _way_ more
legible than the insane "standard" names for them.
----


 tools/bpf/bpf_jit_disasm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/bpf/bpf_jit_disasm.c b/tools/bpf/bpf_jit_disasm.c
index c8ae95804728..f748863e294c 100644
--- a/tools/bpf/bpf_jit_disasm.c
+++ b/tools/bpf/bpf_jit_disasm.c
@@ -303,7 +303,7 @@ int main(int argc, char **argv)
 		goto done;
 	}
 
-	ofd = open(ofile, O_WRONLY | O_CREAT | O_TRUNC, DEFFILEMODE);
+	ofd = open(ofile, O_WRONLY | O_CREAT | O_TRUNC, 0666);
 	if (ofd < 0) {
 		fprintf(stderr, "Could not open file %s for writing: ", ofile);
 		perror(NULL);
-- 
2.35.1