2 files changed, 360 insertions, 1 deletions
diff --git a/lib/Makefile b/lib/Makefile
index 0211d2bd5e1..923a191eaf7 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -13,7 +13,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
 	 sha1.o md5.o irq_regs.o argv_split.o \
 	 proportions.o flex_proportions.o ratelimit.o show_mem.o \
 	 is_single_threaded.o plist.o decompress.o kobject_uevent.o \
-	 earlycpio.o
+	 earlycpio.o seq_buf.o
 
 obj-$(CONFIG_ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS) += usercopy.o
 lib-$(CONFIG_MMU) += ioremap.o
diff --git a/lib/seq_buf.c b/lib/seq_buf.c
new file mode 100644
index 00000000000..4eedfedb9e3
--- /dev/null
+++ b/lib/seq_buf.c
@@ -0,0 +1,359 @@
+/*
+ * 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/uaccess.h>
+#include <linux/seq_file.h>
+#include <linux/seq_buf.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_print_seq - move the contents of seq_buf into a seq_file
+ * @m: the seq_file descriptor that is the destination
+ * @s: the seq_buf descriptor that is the source.
+ *
+ * Returns zero on success, non zero otherwise
+ */
+int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s)
+{
+	unsigned int len = seq_buf_used(s);
+
+	return seq_write(m, s->buffer, len);
+}
+
+/**
+ * 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 (seq_buf_can_fit(s, len)) {
+			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_bitmask - write a bitmask array in its ASCII representation
+ * @s:		seq_buf descriptor
+ * @maskp:	points to an array of unsigned longs that represent a bitmask
+ * @nmaskbits:	The number of bits that are valid in @maskp
+ *
+ * Writes a ASCII representation of a bitmask string into @s.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
+		    int nmaskbits)
+{
+	unsigned int len = seq_buf_buffer_left(s);
+	int ret;
+
+	WARN_ON(s->size == 0);
+
+	/*
+	 * Note, because bitmap_scnprintf() only returns the number of bytes
+	 * written and not the number that would be written, we use the last
+	 * byte of the buffer to let us know if we overflowed. There's a small
+	 * chance that the bitmap could have fit exactly inside the buffer, but
+	 * it's not that critical if that does happen.
+	 */
+	if (len > 1) {
+		ret = bitmap_scnprintf(s->buffer + s->len, len, maskp, nmaskbits);
+		if (ret < len) {
+			s->len += ret;
+			return 0;
+		}
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}
+
+#ifdef CONFIG_BINARY_PRINTF
+/**
+ * seq_buf_bprintf - Write the printf string from binary arguments
+ * @s: seq_buf descriptor
+ * @fmt: The format string for the @binary arguments
+ * @binary: The binary arguments for @fmt.
+ *
+ * When recording in a fast path, a printf may be recorded with just
+ * saving the format and the arguments as they were passed to the
+ * function, instead of wasting cycles converting the arguments into
+ * ASCII characters. Instead, the arguments are saved in a 32 bit
+ * word array that is defined by the format string constraints.
+ *
+ * This function will take the format and the binary array and finish
+ * the conversion into the ASCII string within the buffer.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
+{
+	unsigned int len = seq_buf_buffer_left(s);
+	int ret;
+
+	WARN_ON(s->size == 0);
+
+	if (s->len < s->size) {
+		ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
+		if (seq_buf_can_fit(s, ret)) {
+			s->len += ret;
+			return 0;
+		}
+	}
+	seq_buf_set_overflow(s);
+	return -1;
+}
+#endif /* CONFIG_BINARY_PRINTF */
+
+/**
+ * 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)
+{
+	unsigned int len = strlen(str);
+
+	WARN_ON(s->size == 0);
+
+	if (seq_buf_can_fit(s, len)) {
+		memcpy(s->buffer + s->len, str, len);
+		s->len += len;
+		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;
+}
+
+#define MAX_MEMHEX_BYTES	8U
+#define HEX_CHARS		(MAX_MEMHEX_BYTES*2 + 1)
+
+/**
+ * seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex
+ * @s: seq_buf descriptor
+ * @mem: The raw memory to write its hex ASCII representation of
+ * @len: The length of the raw memory to copy (in bytes)
+ *
+ * This is similar to seq_buf_putmem() except instead of just copying the
+ * raw memory into the buffer it writes its ASCII representation of it
+ * in hex characters.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
+		       unsigned int len)
+{
+	unsigned char hex[HEX_CHARS];
+	const unsigned char *data = mem;
+	unsigned int start_len;
+	int i, j;
+
+	WARN_ON(s->size == 0);
+
+	while (len) {
+		start_len = min(len, HEX_CHARS - 1);
+#ifdef __BIG_ENDIAN
+		for (i = 0, j = 0; i < start_len; i++) {
+#else
+		for (i = start_len-1, j = 0; i >= 0; i--) {
+#endif
+			hex[j++] = hex_asc_hi(data[i]);
+			hex[j++] = hex_asc_lo(data[i]);
+		}
+		if (WARN_ON_ONCE(j == 0 || j/2 > len))
+			break;
+
+		/* j increments twice per loop */
+		len -= j / 2;
+		hex[j++] = ' ';
+
+		seq_buf_putmem(s, hex, j);
+		if (seq_buf_has_overflowed(s))
+			return -1;
+	}
+	return 0;
+}
+
+/**
+ * seq_buf_path - copy a path into the sequence buffer
+ * @s: seq_buf descriptor
+ * @path: path to write into the sequence buffer.
+ * @esc: set of characters to escape in the output
+ *
+ * Write a path name into the sequence buffer.
+ *
+ * Returns the number of written bytes on success, -1 on overflow
+ */
+int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
+{
+	char *buf;
+	size_t size = seq_buf_get_buf(s, &buf);
+	int res = -1;
+
+	WARN_ON(s->size == 0);
+
+	if (size) {
+		char *p = d_path(path, buf, size);
+		if (!IS_ERR(p)) {
+			char *end = mangle_path(buf, p, esc);
+			if (end)
+				res = end - buf;
+		}
+	}
+	seq_buf_commit(s, res);
+
+	return res;
+}
+
+/**
+ * seq_buf_to_user - copy the squence buffer to user space
+ * @s: seq_buf descriptor
+ * @ubuf: The userspace memory location to copy to
+ * @cnt: The amount to copy
+ *
+ * Copies the sequence buffer into the userspace memory pointed to
+ * by @ubuf. It starts from the last read position (@s->readpos)
+ * and writes up to @cnt characters or till it reaches the end of
+ * the content in the buffer (@s->len), which ever comes first.
+ *
+ * On success, it returns a positive number of the number of bytes
+ * it copied.
+ *
+ * On failure it returns -EBUSY if all of the content in the
+ * sequence has been already read, which includes nothing in the
+ * sequence (@s->len == @s->readpos).
+ *
+ * Returns -EFAULT if the copy to userspace fails.
+ */
+int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
+{
+	int len;
+	int ret;
+
+	if (!cnt)
+		return 0;
+
+	if (s->len <= s->readpos)
+		return -EBUSY;
+
+	len = seq_buf_used(s) - s->readpos;
+	if (cnt > len)
+		cnt = len;
+	ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
+	if (ret == cnt)
+		return -EFAULT;
+
+	cnt -= ret;
+
+	s->readpos += cnt;
+	return cnt;
+}