linux-kernel - [PATCH bpf-next] libbpf: Optimized return value in libbpf

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Date:   Sat, 3 Dec 2022 17:37:40 +0800
From:   Xin Liu <liuxin350@...wei.com>
To:     <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>
CC:     <bpf@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <yanan@...wei.com>, <wuchangye@...wei.com>,
        <xiesongyang@...wei.com>, <kongweibin2@...wei.com>,
        <liuxin350@...wei.com>, <zhangmingyi5@...wei.com>
Subject: [PATCH bpf-next] libbpf: Optimized return value in libbpf_strerror when errno is libbpf errno

This is a small improvement in libbpf_strerror. When libbpf_strerror
is used to obtain the system error description, if the length of the
buf is insufficient, libbpf_sterror returns ERANGE and sets errno to
ERANGE.

However, this processing is not performed when the error code
customized by libbpf is obtained. Make some minor improvements here,
return -ERANGE and set errno to ERANGE when buf is not enough for
custom description.

Signed-off-by: Xin Liu <liuxin350@...wei.com>
---
 tools/lib/bpf/libbpf_errno.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/lib/bpf/libbpf_errno.c b/tools/lib/bpf/libbpf_errno.c
index 96f67a772a1b..48ce7d5b5bf9 100644
--- a/tools/lib/bpf/libbpf_errno.c
+++ b/tools/lib/bpf/libbpf_errno.c
@@ -54,10 +54,16 @@ int libbpf_strerror(int err, char *buf, size_t size)
 
 	if (err < __LIBBPF_ERRNO__END) {
 		const char *msg;
+		size_t msg_size;
 
 		msg = libbpf_strerror_table[ERRNO_OFFSET(err)];
 		snprintf(buf, size, "%s", msg);
 		buf[size - 1] = '\0';
+
+		msg_size = strlen(msg);
+		if (msg_size >= size)
+			return libbpf_err(-ERANGE);
+
 		return 0;
 	}
 
-- 
2.33.0