1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_SEQ_BUF_H
3 #define _LINUX_SEQ_BUF_H
4
5 #include <linux/fs.h>
6
7 /*
8 * Trace sequences are used to allow a function to call several other functions
9 * to create a string of data to use.
10 */
11
12 /**
13 * seq_buf - seq buffer structure
14 * @buffer: pointer to the buffer
15 * @size: size of the buffer
16 * @len: the amount of data inside the buffer
17 */
18 struct seq_buf {
19 char *buffer;
20 size_t size;
21 size_t len;
22 };
23
24 #define DECLARE_SEQ_BUF(NAME, SIZE) \
25 struct seq_buf NAME = { \
26 .buffer = (char[SIZE]) { 0 }, \
27 .size = SIZE, \
28 }
29
seq_buf_clear(struct seq_buf * s)30 static inline void seq_buf_clear(struct seq_buf *s)
31 {
32 s->len = 0;
33 if (s->size)
34 s->buffer[0] = '\0';
35 }
36
37 static inline void
seq_buf_init(struct seq_buf * s,char * buf,unsigned int size)38 seq_buf_init(struct seq_buf *s, char *buf, unsigned int size)
39 {
40 s->buffer = buf;
41 s->size = size;
42 seq_buf_clear(s);
43 }
44
45 /*
46 * seq_buf have a buffer that might overflow. When this happens
47 * the len and size are set to be equal.
48 */
49 static inline bool
seq_buf_has_overflowed(struct seq_buf * s)50 seq_buf_has_overflowed(struct seq_buf *s)
51 {
52 return s->len > s->size;
53 }
54
55 static inline void
seq_buf_set_overflow(struct seq_buf * s)56 seq_buf_set_overflow(struct seq_buf *s)
57 {
58 s->len = s->size + 1;
59 }
60
61 /*
62 * How much buffer is left on the seq_buf?
63 */
64 static inline unsigned int
seq_buf_buffer_left(struct seq_buf * s)65 seq_buf_buffer_left(struct seq_buf *s)
66 {
67 if (seq_buf_has_overflowed(s))
68 return 0;
69
70 return s->size - s->len;
71 }
72
73 /* How much buffer was written? */
seq_buf_used(struct seq_buf * s)74 static inline unsigned int seq_buf_used(struct seq_buf *s)
75 {
76 return min(s->len, s->size);
77 }
78
79 /**
80 * seq_buf_str - get %NUL-terminated C string from seq_buf
81 * @s: the seq_buf handle
82 *
83 * This makes sure that the buffer in @s is nul terminated and
84 * safe to read as a string.
85 *
86 * Note, if this is called when the buffer has overflowed, then
87 * the last byte of the buffer is zeroed, and the len will still
88 * point passed it.
89 *
90 * After this function is called, s->buffer is safe to use
91 * in string operations.
92 *
93 * Returns @s->buf after making sure it is terminated.
94 */
seq_buf_str(struct seq_buf * s)95 static inline const char *seq_buf_str(struct seq_buf *s)
96 {
97 if (WARN_ON(s->size == 0))
98 return "";
99
100 if (seq_buf_buffer_left(s))
101 s->buffer[s->len] = 0;
102 else
103 s->buffer[s->size - 1] = 0;
104
105 return s->buffer;
106 }
107
108 /**
109 * seq_buf_get_buf - get buffer to write arbitrary data to
110 * @s: the seq_buf handle
111 * @bufp: the beginning of the buffer is stored here
112 *
113 * Return the number of bytes available in the buffer, or zero if
114 * there's no space.
115 */
seq_buf_get_buf(struct seq_buf * s,char ** bufp)116 static inline size_t seq_buf_get_buf(struct seq_buf *s, char **bufp)
117 {
118 WARN_ON(s->len > s->size + 1);
119
120 if (s->len < s->size) {
121 *bufp = s->buffer + s->len;
122 return s->size - s->len;
123 }
124
125 *bufp = NULL;
126 return 0;
127 }
128
129 /**
130 * seq_buf_commit - commit data to the buffer
131 * @s: the seq_buf handle
132 * @num: the number of bytes to commit
133 *
134 * Commit @num bytes of data written to a buffer previously acquired
135 * by seq_buf_get. To signal an error condition, or that the data
136 * didn't fit in the available space, pass a negative @num value.
137 */
seq_buf_commit(struct seq_buf * s,int num)138 static inline void seq_buf_commit(struct seq_buf *s, int num)
139 {
140 if (num < 0) {
141 seq_buf_set_overflow(s);
142 } else {
143 /* num must be negative on overflow */
144 BUG_ON(s->len + num > s->size);
145 s->len += num;
146 }
147 }
148
149 extern __printf(2, 3)
150 int seq_buf_printf(struct seq_buf *s, const char *fmt, ...);
151 extern __printf(2, 0)
152 int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args);
153 extern int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s);
154 extern int seq_buf_to_user(struct seq_buf *s, char __user *ubuf,
155 size_t start, int cnt);
156 extern int seq_buf_puts(struct seq_buf *s, const char *str);
157 extern int seq_buf_putc(struct seq_buf *s, unsigned char c);
158 extern int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len);
159 extern int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
160 unsigned int len);
161 extern int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc);
162 extern int seq_buf_hex_dump(struct seq_buf *s, const char *prefix_str,
163 int prefix_type, int rowsize, int groupsize,
164 const void *buf, size_t len, bool ascii);
165
166 #ifdef CONFIG_BINARY_PRINTF
167 extern int
168 seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary);
169 #endif
170
171 void seq_buf_do_printk(struct seq_buf *s, const char *lvl);
172
173 #endif /* _LINUX_SEQ_BUF_H */
174