seq_file: Add a seq_bprintf function

Similarly to seq_buf_bprintf in lib/seq_buf.c, this function writes a
printf formatted string with arguments provided in a "binary
representation" built by functions such as vbin_printf.
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210427174313.860948-2-revest@chromium.org

fs/seq_file.c

@@ -412,6 +412,24 @@ void seq_printf(struct seq_file *m, const char *f, ...)
 }
 EXPORT_SYMBOL(seq_printf);
 
+#ifdef CONFIG_BINARY_PRINTF
+void seq_bprintf(struct seq_file *m, const char *f, const u32 *binary)
+{
+	int len;
+
+	if (m->count < m->size) {
+		len = bstr_printf(m->buf + m->count, m->size - m->count, f,
+				  binary);
+		if (m->count + len < m->size) {
+			m->count += len;
+			return;
+		}
+	}
+	seq_set_overflow(m);
+}
+EXPORT_SYMBOL(seq_bprintf);
+#endif /* CONFIG_BINARY_PRINTF */
+
 /**
  *	mangle_path -	mangle and copy path to buffer beginning
  *	@s: buffer start

include/linux/seq_file.h

@@ -146,6 +146,10 @@ void *__seq_open_private(struct file *, const struct seq_operations *, int);
 int seq_open_private(struct file *, const struct seq_operations *, int);
 int seq_release_private(struct inode *, struct file *);
 
+#ifdef CONFIG_BINARY_PRINTF
+void seq_bprintf(struct seq_file *m, const char *f, const u32 *binary);
+#endif
+
 #define DEFINE_SEQ_ATTRIBUTE(__name)					\
 static int __name ## _open(struct inode *inode, struct file *file)	\
 {									\