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  * @readpos:	The next position to read in the buffer.
18  */
19 struct seq_buf {
20 	char			*buffer;
21 	size_t			size;
22 	size_t			len;
23 	loff_t			readpos;
24 };
25 
seq_buf_clear(struct seq_buf * s)26 static inline void seq_buf_clear(struct seq_buf *s)
27 {
28 	s->len = 0;
29 	s->readpos = 0;
30 }
31 
32 static inline void
seq_buf_init(struct seq_buf * s,char * buf,unsigned int size)33 seq_buf_init(struct seq_buf *s, char *buf, unsigned int size)
34 {
35 	s->buffer = buf;
36 	s->size = size;
37 	seq_buf_clear(s);
38 }
39 
40 /*
41  * seq_buf have a buffer that might overflow. When this happens
42  * the len and size are set to be equal.
43  */
44 static inline bool
seq_buf_has_overflowed(struct seq_buf * s)45 seq_buf_has_overflowed(struct seq_buf *s)
46 {
47 	return s->len > s->size;
48 }
49 
50 static inline void
seq_buf_set_overflow(struct seq_buf * s)51 seq_buf_set_overflow(struct seq_buf *s)
52 {
53 	s->len = s->size + 1;
54 }
55 
56 /*
57  * How much buffer is left on the seq_buf?
58  */
59 static inline unsigned int
seq_buf_buffer_left(struct seq_buf * s)60 seq_buf_buffer_left(struct seq_buf *s)
61 {
62 	if (seq_buf_has_overflowed(s))
63 		return 0;
64 
65 	return s->size - s->len;
66 }
67 
68 /* How much buffer was written? */
seq_buf_used(struct seq_buf * s)69 static inline unsigned int seq_buf_used(struct seq_buf *s)
70 {
71 	return min(s->len, s->size);
72 }
73 
74 /**
75  * seq_buf_get_buf - get buffer to write arbitrary data to
76  * @s: the seq_buf handle
77  * @bufp: the beginning of the buffer is stored here
78  *
79  * Return the number of bytes available in the buffer, or zero if
80  * there's no space.
81  */
seq_buf_get_buf(struct seq_buf * s,char ** bufp)82 static inline size_t seq_buf_get_buf(struct seq_buf *s, char **bufp)
83 {
84 	WARN_ON(s->len > s->size + 1);
85 
86 	if (s->len < s->size) {
87 		*bufp = s->buffer + s->len;
88 		return s->size - s->len;
89 	}
90 
91 	*bufp = NULL;
92 	return 0;
93 }
94 
95 /**
96  * seq_buf_commit - commit data to the buffer
97  * @s: the seq_buf handle
98  * @num: the number of bytes to commit
99  *
100  * Commit @num bytes of data written to a buffer previously acquired
101  * by seq_buf_get.  To signal an error condition, or that the data
102  * didn't fit in the available space, pass a negative @num value.
103  */
seq_buf_commit(struct seq_buf * s,int num)104 static inline void seq_buf_commit(struct seq_buf *s, int num)
105 {
106 	if (num < 0) {
107 		seq_buf_set_overflow(s);
108 	} else {
109 		/* num must be negative on overflow */
110 		BUG_ON(s->len + num > s->size);
111 		s->len += num;
112 	}
113 }
114 
115 extern __printf(2, 3)
116 int seq_buf_printf(struct seq_buf *s, const char *fmt, ...);
117 extern __printf(2, 0)
118 int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args);
119 extern int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s);
120 extern int seq_buf_to_user(struct seq_buf *s, char __user *ubuf,
121 			   int cnt);
122 extern int seq_buf_puts(struct seq_buf *s, const char *str);
123 extern int seq_buf_putc(struct seq_buf *s, unsigned char c);
124 extern int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len);
125 extern int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
126 			      unsigned int len);
127 extern int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc);
128 
129 #ifdef CONFIG_BINARY_PRINTF
130 extern int
131 seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary);
132 #endif
133 
134 #endif /* _LINUX_SEQ_BUF_H */
135