On 12/9/22 12:05 PM, Xin Liu wrote:
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.
nit: $subject line got corrupted?
Signed-off-by: Xin Liu <liuxin350@xxxxxxxxxx>
---
v2:
Check the return value of snprintf to determine whether the buffer is
too small.
v1:
https://lore.kernel.org/bpf/20221209084047.229525-1-liuxin350@xxxxxxxxxx/T/#t
tools/lib/bpf/libbpf_errno.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/tools/lib/bpf/libbpf_errno.c b/tools/lib/bpf/libbpf_errno.c
index 96f67a772a1b..6240c7cb7472 100644
--- a/tools/lib/bpf/libbpf_errno.c
+++ b/tools/lib/bpf/libbpf_errno.c
@@ -39,14 +39,13 @@ static const char *libbpf_strerror_table[NR_ERRNO] = {
int libbpf_strerror(int err, char *buf, size_t size)
{
+ int ret;
nit: newline after declaration
if (!buf || !size)
return libbpf_err(-EINVAL);
err = err > 0 ? err : -err;
if (err < __LIBBPF_ERRNO__START) {
- int ret;
-
ret = strerror_r(err, buf, size);
buf[size - 1] = '\0';
return libbpf_err_errno(ret);
@@ -56,12 +55,20 @@ int libbpf_strerror(int err, char *buf, size_t size)
const char *msg;
msg = libbpf_strerror_table[ERRNO_OFFSET(err)];
- snprintf(buf, size, "%s", msg);
+ ret = snprintf(buf, size, "%s", msg);
buf[size - 1] = '\0';
+ if (ret < 0)
+ return libbpf_err_errno(ret);
This would pass in ret == -1 and then eventually return 1 which
is misleading, no?
We have buf and msg non-NULL and a positive size, afaik, the only
case where you could get a negative error now is when you pass in
a buf with size exceeding INT_MAX..
+ if (ret >= size)
+ return libbpf_err(-ERANGE);
return 0;
}
- snprintf(buf, size, "Unknown libbpf error %d", err);
+ ret = snprintf(buf, size, "Unknown libbpf error %d", err);
buf[size - 1] = '\0';
+ if (ret < 0)
+ return libbpf_err_errno(ret);
+ if (ret >= size)
+ return libbpf_err(-ERANGE);
return libbpf_err(-ENOENT);
}
