1 files changed, 152 insertions, 0 deletions
diff --git a/c_src/linux/seq_buf.c b/c_src/linux/seq_buf.c
new file mode 100644
index 00000000..cf8709ad
--- /dev/null
+++ b/c_src/linux/seq_buf.c
@@ -0,0 +1,152 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * seq_buf.c
+ *
+ * Copyright (C) 2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
+ *
+ * The seq_buf is a handy tool that allows you to pass a descriptor around
+ * to a buffer that other functions can write to. It is similar to the
+ * seq_file functionality but has some differences.
+ *
+ * To use it, the seq_buf must be initialized with seq_buf_init().
+ * This will set up the counters within the descriptor. You can call
+ * seq_buf_init() more than once to reset the seq_buf to start
+ * from scratch.
+ */
+#include <linux/seq_buf.h>
+#include <stdio.h>
+
+/**
+ * seq_buf_can_fit - can the new data fit in the current buffer?
+ * @s: the seq_buf descriptor
+ * @len: The length to see if it can fit in the current buffer
+ *
+ * Returns true if there's enough unused space in the seq_buf buffer
+ * to fit the amount of new data according to @len.
+ */
+static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
+{
+	return s->len + len <= s->size;
+}
+
+/**
+ * seq_buf_vprintf - sequence printing of information.
+ * @s: seq_buf descriptor
+ * @fmt: printf format string
+ * @args: va_list of arguments from a printf() type function
+ *
+ * Writes a vnprintf() format into the sequencce buffer.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args)
+{
+	int len;
+
+	WARN_ON(s->size == 0);
+
+	if (s->len < s->size) {
+		len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args);
+		if (s->len + len < s->size) {
+			s->len += len;
+			return 0;
+		}
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}
+
+/**
+ * seq_buf_printf - sequence printing of information
+ * @s: seq_buf descriptor
+ * @fmt: printf format string
+ *
+ * Writes a printf() format into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_printf(struct seq_buf *s, const char *fmt, ...)
+{
+	va_list ap;
+	int ret;
+
+	va_start(ap, fmt);
+	ret = seq_buf_vprintf(s, fmt, ap);
+	va_end(ap);
+
+	return ret;
+}
+
+/**
+ * seq_buf_puts - sequence printing of simple string
+ * @s: seq_buf descriptor
+ * @str: simple string to record
+ *
+ * Copy a simple string into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_puts(struct seq_buf *s, const char *str)
+{
+	size_t len = strlen(str);
+
+	WARN_ON(s->size == 0);
+
+	/* Add 1 to len for the trailing null byte which must be there */
+	len += 1;
+
+	if (seq_buf_can_fit(s, len)) {
+		memcpy(s->buffer + s->len, str, len);
+		/* Don't count the trailing null byte against the capacity */
+		s->len += len - 1;
+		return 0;
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}
+
+/**
+ * seq_buf_putc - sequence printing of simple character
+ * @s: seq_buf descriptor
+ * @c: simple character to record
+ *
+ * Copy a single character into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_putc(struct seq_buf *s, unsigned char c)
+{
+	WARN_ON(s->size == 0);
+
+	if (seq_buf_can_fit(s, 1)) {
+		s->buffer[s->len++] = c;
+		return 0;
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}
+
+/**
+ * seq_buf_putmem - write raw data into the sequenc buffer
+ * @s: seq_buf descriptor
+ * @mem: The raw memory to copy into the buffer
+ * @len: The length of the raw memory to copy (in bytes)
+ *
+ * There may be cases where raw memory needs to be written into the
+ * buffer and a strcpy() would not work. Using this function allows
+ * for such cases.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len)
+{
+	WARN_ON(s->size == 0);
+
+	if (seq_buf_can_fit(s, len)) {
+		memcpy(s->buffer + s->len, mem, len);
+		s->len += len;
+		return 0;
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}