diff mbox series

[v6,bpf-next,2/4] bpf: Support "%c" in bpf_bprintf_prepare().

Message ID 20210814015718.42704-3-kuniyu@amazon.co.jp
State New
Headers show
Series BPF iterator for UNIX domain socket. | expand

Commit Message

Kuniyuki Iwashima Aug. 14, 2021, 1:57 a.m. UTC 
/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: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Acked-by: Yonghong Song <yhs@fb.com>
---
 kernel/bpf/helpers.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
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Patch

diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index 32761be48143..4e8540716187 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -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;
 		}