Commit 3478cfcf authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Andrii Nakryiko
Browse files

bpf: Support "%c" in bpf_bprintf_prepare(). 



/proc/net/unix uses "%c" to print a single-byte character to escape '\0' in
the name of the abstract UNIX domain socket.  The following selftest uses
it, so this patch adds support for "%c".  Note that it does not support
wide character ("%lc" and "%llc") for simplicity.

Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210814015718.42704-3-kuniyu@amazon.co.jp
parent 2c860a43

kernel/bpf/helpers.c

+14 −0
Original line number Diff line number Diff line
@@ -907,6 +907,20 @@ int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args, 
			tmp_buf += err;

			num_spec++;



			continue;

		} else if (fmt[i] == 'c') {

			if (!tmp_buf)

				goto nocopy_fmt;



			if (tmp_buf_end == tmp_buf) {

				err = -ENOSPC;

				goto out;

			}



			*tmp_buf = raw_args[num_spec];

			tmp_buf++;

			num_spec++;



			continue;

		}