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 /* Add 1 to len for the trailing null byte which must be there */
149 if (seq_buf_can_fit(s, len)) {
150 memcpy(s->buffer + s->len, str, len);
151 /* Don't count the trailing null byte against the capacity */
155 seq_buf_set_overflow(s);
160 * seq_buf_putc - sequence printing of simple character
161 * @s: seq_buf descriptor
162 * @c: simple character to record
164 * Copy a single character into the sequence buffer.
166 * Returns zero on success, -1 on overflow
168 int seq_buf_putc(struct seq_buf *s, unsigned char c)
170 WARN_ON(s->size == 0);
172 if (seq_buf_can_fit(s, 1)) {
173 s->buffer[s->len++] = c;
176 seq_buf_set_overflow(s);
181 * seq_buf_putmem - write raw data into the sequenc buffer
182 * @s: seq_buf descriptor
183 * @mem: The raw memory to copy into the buffer
184 * @len: The length of the raw memory to copy (in bytes)
186 * There may be cases where raw memory needs to be written into the
187 * buffer and a strcpy() would not work. Using this function allows
190 * Returns zero on success, -1 on overflow
192 int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len)
194 WARN_ON(s->size == 0);
196 if (seq_buf_can_fit(s, len)) {
197 memcpy(s->buffer + s->len, mem, len);
201 seq_buf_set_overflow(s);
205 #define MAX_MEMHEX_BYTES 8U
206 #define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1)
209 * seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex
210 * @s: seq_buf descriptor
211 * @mem: The raw memory to write its hex ASCII representation of
212 * @len: The length of the raw memory to copy (in bytes)
214 * This is similar to seq_buf_putmem() except instead of just copying the
215 * raw memory into the buffer it writes its ASCII representation of it
218 * Returns zero on success, -1 on overflow
220 int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
223 unsigned char hex[HEX_CHARS];
224 const unsigned char *data = mem;
225 unsigned int start_len;
228 WARN_ON(s->size == 0);
230 BUILD_BUG_ON(MAX_MEMHEX_BYTES * 2 >= HEX_CHARS);
233 start_len = min(len, MAX_MEMHEX_BYTES);
235 for (i = 0, j = 0; i < start_len; i++) {
237 for (i = start_len-1, j = 0; i >= 0; i--) {
239 hex[j++] = hex_asc_hi(data[i]);
240 hex[j++] = hex_asc_lo(data[i]);
242 if (WARN_ON_ONCE(j == 0 || j/2 > len))
245 /* j increments twice per loop */
248 seq_buf_putmem(s, hex, j);
249 if (seq_buf_has_overflowed(s))
259 * seq_buf_path - copy a path into the sequence buffer
260 * @s: seq_buf descriptor
261 * @path: path to write into the sequence buffer.
262 * @esc: set of characters to escape in the output
264 * Write a path name into the sequence buffer.
266 * Returns the number of written bytes on success, -1 on overflow
268 int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
271 size_t size = seq_buf_get_buf(s, &buf);
274 WARN_ON(s->size == 0);
277 char *p = d_path(path, buf, size);
279 char *end = mangle_path(buf, p, esc);
284 seq_buf_commit(s, res);
290 * seq_buf_to_user - copy the squence buffer to user space
291 * @s: seq_buf descriptor
292 * @ubuf: The userspace memory location to copy to
293 * @cnt: The amount to copy
295 * Copies the sequence buffer into the userspace memory pointed to
296 * by @ubuf. It starts from the last read position (@s->readpos)
297 * and writes up to @cnt characters or till it reaches the end of
298 * the content in the buffer (@s->len), which ever comes first.
300 * On success, it returns a positive number of the number of bytes
303 * On failure it returns -EBUSY if all of the content in the
304 * sequence has been already read, which includes nothing in the
305 * sequence (@s->len == @s->readpos).
307 * Returns -EFAULT if the copy to userspace fails.
309 int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
317 len = seq_buf_used(s);
319 if (len <= s->readpos)
325 ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);