/* * 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;} #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;}