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git.proxmox.com Git - mirror_ubuntu-jammy-kernel.git/blob - lib/seq_buf.c
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 (seq_buf_can_fit(s
, len
)) {
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
);
95 * seq_buf_bitmask - write a bitmask array in its ASCII representation
96 * @s: seq_buf descriptor
97 * @maskp: points to an array of unsigned longs that represent a bitmask
98 * @nmaskbits: The number of bits that are valid in @maskp
100 * Writes a ASCII representation of a bitmask string into @s.
102 * Returns zero on success, -1 on overflow.
104 int seq_buf_bitmask(struct seq_buf
*s
, const unsigned long *maskp
,
107 unsigned int len
= seq_buf_buffer_left(s
);
110 WARN_ON(s
->size
== 0);
113 * Note, because bitmap_scnprintf() only returns the number of bytes
114 * written and not the number that would be written, we use the last
115 * byte of the buffer to let us know if we overflowed. There's a small
116 * chance that the bitmap could have fit exactly inside the buffer, but
117 * it's not that critical if that does happen.
120 ret
= bitmap_scnprintf(s
->buffer
+ s
->len
, len
, maskp
, nmaskbits
);
126 seq_buf_set_overflow(s
);
130 #ifdef CONFIG_BINARY_PRINTF
132 * seq_buf_bprintf - Write the printf string from binary arguments
133 * @s: seq_buf descriptor
134 * @fmt: The format string for the @binary arguments
135 * @binary: The binary arguments for @fmt.
137 * When recording in a fast path, a printf may be recorded with just
138 * saving the format and the arguments as they were passed to the
139 * function, instead of wasting cycles converting the arguments into
140 * ASCII characters. Instead, the arguments are saved in a 32 bit
141 * word array that is defined by the format string constraints.
143 * This function will take the format and the binary array and finish
144 * the conversion into the ASCII string within the buffer.
146 * Returns zero on success, -1 on overflow.
148 int seq_buf_bprintf(struct seq_buf
*s
, const char *fmt
, const u32
*binary
)
150 unsigned int len
= seq_buf_buffer_left(s
);
153 WARN_ON(s
->size
== 0);
155 if (s
->len
< s
->size
) {
156 ret
= bstr_printf(s
->buffer
+ s
->len
, len
, fmt
, binary
);
157 if (seq_buf_can_fit(s
, ret
)) {
162 seq_buf_set_overflow(s
);
165 #endif /* CONFIG_BINARY_PRINTF */
168 * seq_buf_puts - sequence printing of simple string
169 * @s: seq_buf descriptor
170 * @str: simple string to record
172 * Copy a simple string into the sequence buffer.
174 * Returns zero on success, -1 on overflow
176 int seq_buf_puts(struct seq_buf
*s
, const char *str
)
178 unsigned int len
= strlen(str
);
180 WARN_ON(s
->size
== 0);
182 if (seq_buf_can_fit(s
, len
)) {
183 memcpy(s
->buffer
+ s
->len
, str
, len
);
187 seq_buf_set_overflow(s
);
192 * seq_buf_putc - sequence printing of simple character
193 * @s: seq_buf descriptor
194 * @c: simple character to record
196 * Copy a single character into the sequence buffer.
198 * Returns zero on success, -1 on overflow
200 int seq_buf_putc(struct seq_buf
*s
, unsigned char c
)
202 WARN_ON(s
->size
== 0);
204 if (seq_buf_can_fit(s
, 1)) {
205 s
->buffer
[s
->len
++] = c
;
208 seq_buf_set_overflow(s
);
213 * seq_buf_putmem - write raw data into the sequenc buffer
214 * @s: seq_buf descriptor
215 * @mem: The raw memory to copy into the buffer
216 * @len: The length of the raw memory to copy (in bytes)
218 * There may be cases where raw memory needs to be written into the
219 * buffer and a strcpy() would not work. Using this function allows
222 * Returns zero on success, -1 on overflow
224 int seq_buf_putmem(struct seq_buf
*s
, const void *mem
, unsigned int len
)
226 WARN_ON(s
->size
== 0);
228 if (seq_buf_can_fit(s
, len
)) {
229 memcpy(s
->buffer
+ s
->len
, mem
, len
);
233 seq_buf_set_overflow(s
);
237 #define MAX_MEMHEX_BYTES 8U
238 #define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1)
241 * seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex
242 * @s: seq_buf descriptor
243 * @mem: The raw memory to write its hex ASCII representation of
244 * @len: The length of the raw memory to copy (in bytes)
246 * This is similar to seq_buf_putmem() except instead of just copying the
247 * raw memory into the buffer it writes its ASCII representation of it
250 * Returns zero on success, -1 on overflow
252 int seq_buf_putmem_hex(struct seq_buf
*s
, const void *mem
,
255 unsigned char hex
[HEX_CHARS
];
256 const unsigned char *data
= mem
;
257 unsigned int start_len
;
260 WARN_ON(s
->size
== 0);
263 start_len
= min(len
, HEX_CHARS
- 1);
265 for (i
= 0, j
= 0; i
< start_len
; i
++) {
267 for (i
= start_len
-1, j
= 0; i
>= 0; i
--) {
269 hex
[j
++] = hex_asc_hi(data
[i
]);
270 hex
[j
++] = hex_asc_lo(data
[i
]);
272 if (WARN_ON_ONCE(j
== 0 || j
/2 > len
))
275 /* j increments twice per loop */
279 seq_buf_putmem(s
, hex
, j
);
280 if (seq_buf_has_overflowed(s
))
287 * seq_buf_path - copy a path into the sequence buffer
288 * @s: seq_buf descriptor
289 * @path: path to write into the sequence buffer.
290 * @esc: set of characters to escape in the output
292 * Write a path name into the sequence buffer.
294 * Returns the number of written bytes on success, -1 on overflow
296 int seq_buf_path(struct seq_buf
*s
, const struct path
*path
, const char *esc
)
299 size_t size
= seq_buf_get_buf(s
, &buf
);
302 WARN_ON(s
->size
== 0);
305 char *p
= d_path(path
, buf
, size
);
307 char *end
= mangle_path(buf
, p
, esc
);
312 seq_buf_commit(s
, res
);
318 * seq_buf_to_user - copy the squence buffer to user space
319 * @s: seq_buf descriptor
320 * @ubuf: The userspace memory location to copy to
321 * @cnt: The amount to copy
323 * Copies the sequence buffer into the userspace memory pointed to
324 * by @ubuf. It starts from the last read position (@s->readpos)
325 * and writes up to @cnt characters or till it reaches the end of
326 * the content in the buffer (@s->len), which ever comes first.
328 * On success, it returns a positive number of the number of bytes
331 * On failure it returns -EBUSY if all of the content in the
332 * sequence has been already read, which includes nothing in the
333 * sequence (@s->len == @s->readpos).
335 * Returns -EFAULT if the copy to userspace fails.
337 int seq_buf_to_user(struct seq_buf
*s
, char __user
*ubuf
, int cnt
)
345 if (s
->len
<= s
->readpos
)
348 len
= seq_buf_used(s
) - s
->readpos
;
351 ret
= copy_to_user(ubuf
, s
->buffer
+ s
->readpos
, cnt
);