4 * Copyright (C) 2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
6 * The seq_buf is a handy tool that allows you to pass a descriptor around
7 * to a buffer that other functions can write to. It is similar to the
8 * seq_file functionality but has some differences.
10 * To use it, the seq_buf must be initialized with seq_buf_init().
11 * This will set up the counters within the descriptor. You can call
12 * seq_buf_init() more than once to reset the seq_buf to start
15 #include <linux/uaccess.h>
16 #include <linux/seq_file.h>
17 #include <linux/seq_buf.h>
20 * seq_buf_can_fit - can the new data fit in the current buffer?
21 * @s: the seq_buf descriptor
22 * @len: The length to see if it can fit in the current buffer
24 * Returns true if there's enough unused space in the seq_buf buffer
25 * to fit the amount of new data according to @len.
27 static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
29 return s->len + len <= s->size;
33 * seq_buf_print_seq - move the contents of seq_buf into a seq_file
34 * @m: the seq_file descriptor that is the destination
35 * @s: the seq_buf descriptor that is the source.
37 * Returns zero on success, non zero otherwise
39 int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s)
41 unsigned int len = seq_buf_used(s);
43 return seq_write(m, s->buffer, len);
47 * seq_buf_vprintf - sequence printing of information.
48 * @s: seq_buf descriptor
49 * @fmt: printf format string
50 * @args: va_list of arguments from a printf() type function
52 * Writes a vnprintf() format into the sequencce buffer.
54 * Returns zero on success, -1 on overflow.
56 int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args)
60 WARN_ON(s->size == 0);
62 if (s->len < s->size) {
63 len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args);
64 if (s->len + len < s->size) {
69 seq_buf_set_overflow(s);
74 * seq_buf_printf - sequence printing of information
75 * @s: seq_buf descriptor
76 * @fmt: printf format string
78 * Writes a printf() format into the sequence buffer.
80 * Returns zero on success, -1 on overflow.
82 int seq_buf_printf(struct seq_buf *s, const char *fmt, ...)
88 ret = seq_buf_vprintf(s, fmt, ap);
94 #ifdef CONFIG_BINARY_PRINTF
96 * seq_buf_bprintf - Write the printf string from binary arguments
97 * @s: seq_buf descriptor
98 * @fmt: The format string for the @binary arguments
99 * @binary: The binary arguments for @fmt.
101 * When recording in a fast path, a printf may be recorded with just
102 * saving the format and the arguments as they were passed to the
103 * function, instead of wasting cycles converting the arguments into
104 * ASCII characters. Instead, the arguments are saved in a 32 bit
105 * word array that is defined by the format string constraints.
107 * This function will take the format and the binary array and finish
108 * the conversion into the ASCII string within the buffer.
110 * Returns zero on success, -1 on overflow.
112 int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
114 unsigned int len = seq_buf_buffer_left(s);
117 WARN_ON(s->size == 0);
119 if (s->len < s->size) {
120 ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
121 if (s->len + ret < s->size) {
126 seq_buf_set_overflow(s);
129 #endif /* CONFIG_BINARY_PRINTF */
132 * seq_buf_puts - sequence printing of simple string
133 * @s: seq_buf descriptor
134 * @str: simple string to record
136 * Copy a simple string into the sequence buffer.
138 * Returns zero on success, -1 on overflow
140 int seq_buf_puts(struct seq_buf *s, const char *str)
142 unsigned int len = strlen(str);
144 WARN_ON(s->size == 0);
146 if (seq_buf_can_fit(s, len)) {
147 memcpy(s->buffer + s->len, str, len);
151 seq_buf_set_overflow(s);
156 * seq_buf_putc - sequence printing of simple character
157 * @s: seq_buf descriptor
158 * @c: simple character to record
160 * Copy a single character into the sequence buffer.
162 * Returns zero on success, -1 on overflow
164 int seq_buf_putc(struct seq_buf *s, unsigned char c)
166 WARN_ON(s->size == 0);
168 if (seq_buf_can_fit(s, 1)) {
169 s->buffer[s->len++] = c;
172 seq_buf_set_overflow(s);
177 * seq_buf_putmem - write raw data into the sequenc buffer
178 * @s: seq_buf descriptor
179 * @mem: The raw memory to copy into the buffer
180 * @len: The length of the raw memory to copy (in bytes)
182 * There may be cases where raw memory needs to be written into the
183 * buffer and a strcpy() would not work. Using this function allows
186 * Returns zero on success, -1 on overflow
188 int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len)
190 WARN_ON(s->size == 0);
192 if (seq_buf_can_fit(s, len)) {
193 memcpy(s->buffer + s->len, mem, len);
197 seq_buf_set_overflow(s);
201 #define MAX_MEMHEX_BYTES 8U
202 #define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1)
205 * seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex
206 * @s: seq_buf descriptor
207 * @mem: The raw memory to write its hex ASCII representation of
208 * @len: The length of the raw memory to copy (in bytes)
210 * This is similar to seq_buf_putmem() except instead of just copying the
211 * raw memory into the buffer it writes its ASCII representation of it
214 * Returns zero on success, -1 on overflow
216 int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
219 unsigned char hex[HEX_CHARS];
220 const unsigned char *data = mem;
221 unsigned int start_len;
224 WARN_ON(s->size == 0);
227 start_len = min(len, HEX_CHARS - 1);
229 for (i = 0, j = 0; i < start_len; i++) {
231 for (i = start_len-1, j = 0; i >= 0; i--) {
233 hex[j++] = hex_asc_hi(data[i]);
234 hex[j++] = hex_asc_lo(data[i]);
236 if (WARN_ON_ONCE(j == 0 || j/2 > len))
239 /* j increments twice per loop */
243 seq_buf_putmem(s, hex, j);
244 if (seq_buf_has_overflowed(s))
251 * seq_buf_path - copy a path into the sequence buffer
252 * @s: seq_buf descriptor
253 * @path: path to write into the sequence buffer.
254 * @esc: set of characters to escape in the output
256 * Write a path name into the sequence buffer.
258 * Returns the number of written bytes on success, -1 on overflow
260 int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
263 size_t size = seq_buf_get_buf(s, &buf);
266 WARN_ON(s->size == 0);
269 char *p = d_path(path, buf, size);
271 char *end = mangle_path(buf, p, esc);
276 seq_buf_commit(s, res);
282 * seq_buf_to_user - copy the squence buffer to user space
283 * @s: seq_buf descriptor
284 * @ubuf: The userspace memory location to copy to
285 * @cnt: The amount to copy
287 * Copies the sequence buffer into the userspace memory pointed to
288 * by @ubuf. It starts from the last read position (@s->readpos)
289 * and writes up to @cnt characters or till it reaches the end of
290 * the content in the buffer (@s->len), which ever comes first.
292 * On success, it returns a positive number of the number of bytes
295 * On failure it returns -EBUSY if all of the content in the
296 * sequence has been already read, which includes nothing in the
297 * sequence (@s->len == @s->readpos).
299 * Returns -EFAULT if the copy to userspace fails.
301 int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
309 len = seq_buf_used(s);
311 if (len <= s->readpos)
317 ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);