[mirror_ubuntu-bionic-kernel.git] / lib / seq_buf.c

// 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/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 (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;
}

#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 (s->len + ret < s->size) {
			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);

	/* 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;
}

#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;

	len = seq_buf_used(s);

	if (len <= s->readpos)
		return -EBUSY;

	len -= 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;
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
3a161d99 SRRH	2	/*
	3	* seq_buf.c
	4	*
	5	* Copyright (C) 2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
	6	*
	7	* The seq_buf is a handy tool that allows you to pass a descriptor around
	8	* to a buffer that other functions can write to. It is similar to the
	9	* seq_file functionality but has some differences.
	10	*
	11	* To use it, the seq_buf must be initialized with seq_buf_init().
	12	* This will set up the counters within the descriptor. You can call
	13	* seq_buf_init() more than once to reset the seq_buf to start
	14	* from scratch.
	15	*/
	16	#include <linux/uaccess.h>
	17	#include <linux/seq_file.h>
	18	#include <linux/seq_buf.h>
	19
9b772153 SRRH	20	/**
	21	* seq_buf_can_fit - can the new data fit in the current buffer?
	22	* @s: the seq_buf descriptor
	23	* @len: The length to see if it can fit in the current buffer
	24	*
	25	* Returns true if there's enough unused space in the seq_buf buffer
	26	* to fit the amount of new data according to @len.
	27	*/
	28	static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
	29	{
8cd709ae	30	return s->len + len <= s->size;
9b772153 SRRH	31	}
9b772153 SRRH	32
3a161d99 SRRH	33	/**
	34	* seq_buf_print_seq - move the contents of seq_buf into a seq_file
	35	* @m: the seq_file descriptor that is the destination
	36	* @s: the seq_buf descriptor that is the source.
	37	*
	38	* Returns zero on success, non zero otherwise
	39	*/
	40	int seq_buf_print_seq(struct seq_file m, struct seq_buf s)
	41	{
eeab9815	42	unsigned int len = seq_buf_used(s);
3a161d99 SRRH	43
	44	return seq_write(m, s->buffer, len);
	45	}
	46
	47	/**
	48	* seq_buf_vprintf - sequence printing of information.
	49	* @s: seq_buf descriptor
	50	* @fmt: printf format string
	51	* @args: va_list of arguments from a printf() type function
	52	*
	53	* Writes a vnprintf() format into the sequencce buffer.
	54	*
	55	* Returns zero on success, -1 on overflow.
	56	*/
	57	int seq_buf_vprintf(struct seq_buf s, const char fmt, va_list args)
	58	{
	59	int len;
	60
	61	WARN_ON(s->size == 0);
	62
	63	if (s->len < s->size) {
	64	len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args);
4a8fe4e1	65	if (s->len + len < s->size) {
3a161d99 SRRH	66	s->len += len;
	67	return 0;
	68	}
	69	}
	70	seq_buf_set_overflow(s);
	71	return -1;
	72	}
	73
	74	/**
	75	* seq_buf_printf - sequence printing of information
	76	* @s: seq_buf descriptor
	77	* @fmt: printf format string
	78	*
	79	* Writes a printf() format into the sequence buffer.
	80	*
	81	* Returns zero on success, -1 on overflow.
	82	*/
	83	int seq_buf_printf(struct seq_buf s, const char fmt, ...)
	84	{
	85	va_list ap;
	86	int ret;
	87
	88	va_start(ap, fmt);
	89	ret = seq_buf_vprintf(s, fmt, ap);
	90	va_end(ap);
	91
	92	return ret;
	93	}
	94
2448913e	95	#ifdef CONFIG_BINARY_PRINTF
3a161d99 SRRH	96	/**
	97	* seq_buf_bprintf - Write the printf string from binary arguments
	98	* @s: seq_buf descriptor
	99	* @fmt: The format string for the @binary arguments
	100	* @binary: The binary arguments for @fmt.
	101	*
	102	* When recording in a fast path, a printf may be recorded with just
	103	* saving the format and the arguments as they were passed to the
	104	* function, instead of wasting cycles converting the arguments into
	105	* ASCII characters. Instead, the arguments are saved in a 32 bit
	106	* word array that is defined by the format string constraints.
	107	*
	108	* This function will take the format and the binary array and finish
	109	* the conversion into the ASCII string within the buffer.
	110	*
	111	* Returns zero on success, -1 on overflow.
	112	*/
	113	int seq_buf_bprintf(struct seq_buf s, const char fmt, const u32 *binary)
	114	{
	115	unsigned int len = seq_buf_buffer_left(s);
	116	int ret;
	117
	118	WARN_ON(s->size == 0);
	119
	120	if (s->len < s->size) {
	121	ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
4d4eb4d4	122	if (s->len + ret < s->size) {
3a161d99 SRRH	123	s->len += ret;
	124	return 0;
	125	}
	126	}
	127	seq_buf_set_overflow(s);
	128	return -1;
	129	}
2448913e	130	#endif /* CONFIG_BINARY_PRINTF */
3a161d99 SRRH	131
	132	/**
	133	* seq_buf_puts - sequence printing of simple string
	134	* @s: seq_buf descriptor
	135	* @str: simple string to record
	136	*
	137	* Copy a simple string into the sequence buffer.
	138	*
	139	* Returns zero on success, -1 on overflow
	140	*/
	141	int seq_buf_puts(struct seq_buf s, const char str)
	142	{
	143	unsigned int len = strlen(str);
	144
	145	WARN_ON(s->size == 0);
	146
afc6cb38 ME	147	/* Add 1 to len for the trailing null byte which must be there */
	148	len += 1;
	149
9b772153	150	if (seq_buf_can_fit(s, len)) {
3a161d99	151	memcpy(s->buffer + s->len, str, len);
afc6cb38 ME	152	/* Don't count the trailing null byte against the capacity */
afc6cb38 ME	153	s->len += len - 1;
3a161d99 SRRH	154	return 0;
	155	}
	156	seq_buf_set_overflow(s);
	157	return -1;
	158	}
	159
	160	/**
	161	* seq_buf_putc - sequence printing of simple character
	162	* @s: seq_buf descriptor
	163	* @c: simple character to record
	164	*
	165	* Copy a single character into the sequence buffer.
	166	*
	167	* Returns zero on success, -1 on overflow
	168	*/
	169	int seq_buf_putc(struct seq_buf *s, unsigned char c)
	170	{
	171	WARN_ON(s->size == 0);
	172
9b772153	173	if (seq_buf_can_fit(s, 1)) {
3a161d99 SRRH	174	s->buffer[s->len++] = c;
	175	return 0;
	176	}
	177	seq_buf_set_overflow(s);
	178	return -1;
	179	}
	180
	181	/**
	182	* seq_buf_putmem - write raw data into the sequenc buffer
	183	* @s: seq_buf descriptor
	184	* @mem: The raw memory to copy into the buffer
	185	* @len: The length of the raw memory to copy (in bytes)
	186	*
	187	* There may be cases where raw memory needs to be written into the
	188	* buffer and a strcpy() would not work. Using this function allows
	189	* for such cases.
	190	*
	191	* Returns zero on success, -1 on overflow
	192	*/
	193	int seq_buf_putmem(struct seq_buf s, const void mem, unsigned int len)
	194	{
	195	WARN_ON(s->size == 0);
	196
9b772153	197	if (seq_buf_can_fit(s, len)) {
3a161d99 SRRH	198	memcpy(s->buffer + s->len, mem, len);
	199	s->len += len;
	200	return 0;
	201	}
	202	seq_buf_set_overflow(s);
	203	return -1;
	204	}
	205
	206	#define MAX_MEMHEX_BYTES 8U
	207	#define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1)
	208
	209	/**
	210	* seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex
	211	* @s: seq_buf descriptor
	212	* @mem: The raw memory to write its hex ASCII representation of
	213	* @len: The length of the raw memory to copy (in bytes)
	214	*
	215	* This is similar to seq_buf_putmem() except instead of just copying the
	216	* raw memory into the buffer it writes its ASCII representation of it
	217	* in hex characters.
	218	*
	219	* Returns zero on success, -1 on overflow
	220	*/
	221	int seq_buf_putmem_hex(struct seq_buf s, const void mem,
	222	unsigned int len)
	223	{
	224	unsigned char hex[HEX_CHARS];
	225	const unsigned char *data = mem;
	226	unsigned int start_len;
	227	int i, j;
	228
	229	WARN_ON(s->size == 0);
	230
	231	while (len) {
	232	start_len = min(len, HEX_CHARS - 1);
	233	#ifdef __BIG_ENDIAN
	234	for (i = 0, j = 0; i < start_len; i++) {
	235	#else
	236	for (i = start_len-1, j = 0; i >= 0; i--) {
	237	#endif
	238	hex[j++] = hex_asc_hi(data[i]);
	239	hex[j++] = hex_asc_lo(data[i]);
	240	}
	241	if (WARN_ON_ONCE(j == 0 \|\| j/2 > len))
	242	break;
	243
	244	/* j increments twice per loop */
	245	len -= j / 2;
	246	hex[j++] = ' ';
	247
	248	seq_buf_putmem(s, hex, j);
	249	if (seq_buf_has_overflowed(s))
	250	return -1;
	251	}
	252	return 0;
	253	}
	254
	255	/**
	256	* seq_buf_path - copy a path into the sequence buffer
	257	* @s: seq_buf descriptor
	258	* @path: path to write into the sequence buffer.
dd23180a	259	* @esc: set of characters to escape in the output
3a161d99 SRRH	260	*
	261	* Write a path name into the sequence buffer.
	262	*
dd23180a	263	* Returns the number of written bytes on success, -1 on overflow
3a161d99	264	*/
dd23180a	265	int seq_buf_path(struct seq_buf s, const struct path path, const char *esc)
3a161d99	266	{
01cb06a4 SRRH	267	char *buf;
01cb06a4 SRRH	268	size_t size = seq_buf_get_buf(s, &buf);
dd23180a	269	int res = -1;
3a161d99 SRRH	270
	271	WARN_ON(s->size == 0);
	272
dd23180a SRRH	273	if (size) {
	274	char *p = d_path(path, buf, size);
	275	if (!IS_ERR(p)) {
	276	char *end = mangle_path(buf, p, esc);
	277	if (end)
	278	res = end - buf;
3a161d99 SRRH	279	}
3a161d99 SRRH	280	}
01cb06a4	281	seq_buf_commit(s, res);
dd23180a SRRH	282
dd23180a SRRH	283	return res;
3a161d99 SRRH	284	}
	285
	286	/**
	287	* seq_buf_to_user - copy the squence buffer to user space
	288	* @s: seq_buf descriptor
	289	* @ubuf: The userspace memory location to copy to
	290	* @cnt: The amount to copy
	291	*
	292	* Copies the sequence buffer into the userspace memory pointed to
	293	* by @ubuf. It starts from the last read position (@s->readpos)
	294	* and writes up to @cnt characters or till it reaches the end of
	295	* the content in the buffer (@s->len), which ever comes first.
	296	*
	297	* On success, it returns a positive number of the number of bytes
	298	* it copied.
	299	*
	300	* On failure it returns -EBUSY if all of the content in the
	301	* sequence has been already read, which includes nothing in the
	302	* sequence (@s->len == @s->readpos).
	303	*
	304	* Returns -EFAULT if the copy to userspace fails.
	305	*/
	306	int seq_buf_to_user(struct seq_buf s, char __user ubuf, int cnt)
	307	{
	308	int len;
	309	int ret;
	310
	311	if (!cnt)
	312	return 0;
	313
ff078d8f JS	314	len = seq_buf_used(s);
	315
	316	if (len <= s->readpos)
3a161d99 SRRH	317	return -EBUSY;
3a161d99 SRRH	318
ff078d8f	319	len -= s->readpos;
3a161d99 SRRH	320	if (cnt > len)
	321	cnt = len;
	322	ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
	323	if (ret == cnt)
	324	return -EFAULT;
	325
	326	cnt -= ret;
	327
	328	s->readpos += cnt;
	329	return cnt;
	330	}