1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_SEQ_BUF_H
3 #define _LINUX_SEQ_BUF_H
4
5 #include <linux/bug.h>
6 #include <linux/minmax.h>
7 #include <linux/seq_file.h>
8 #include <linux/types.h>
9
10 /*
11 * Trace sequences are used to allow a function to call several other functions
12 * to create a string of data to use.
13 */
14
15 /**
16 * struct seq_buf - seq buffer structure
17 * @buffer: pointer to the buffer
18 * @size: size of the buffer
19 * @len: the amount of data inside the buffer
20 */
21 struct seq_buf {
22 char *buffer;
23 size_t size;
24 size_t len;
25 };
26
27 #define DECLARE_SEQ_BUF(NAME, SIZE) \
28 struct seq_buf NAME = { \
29 .buffer = (char[SIZE]) { 0 }, \
30 .size = SIZE, \
31 }
32
seq_buf_clear(struct seq_buf * s)33 static inline void seq_buf_clear(struct seq_buf *s)
34 {
35 s->len = 0;
36 if (s->size)
37 s->buffer[0] = '\0';
38 }
39
40 static inline void
seq_buf_init(struct seq_buf * s,char * buf,unsigned int size)41 seq_buf_init(struct seq_buf *s, char *buf, unsigned int size)
42 {
43 s->buffer = buf;
44 s->size = size;
45 seq_buf_clear(s);
46 }
47
48 /*
49 * seq_buf have a buffer that might overflow. When this happens
50 * len is set to be greater than size.
51 */
52 static inline bool
seq_buf_has_overflowed(struct seq_buf * s)53 seq_buf_has_overflowed(struct seq_buf *s)
54 {
55 return s->len > s->size;
56 }
57
58 static inline void
seq_buf_set_overflow(struct seq_buf * s)59 seq_buf_set_overflow(struct seq_buf *s)
60 {
61 s->len = s->size + 1;
62 }
63
64 /*
65 * How much buffer is left on the seq_buf?
66 */
67 static inline unsigned int
seq_buf_buffer_left(struct seq_buf * s)68 seq_buf_buffer_left(struct seq_buf *s)
69 {
70 if (seq_buf_has_overflowed(s))
71 return 0;
72
73 return s->size - s->len;
74 }
75
76 /* How much buffer was written? */
seq_buf_used(struct seq_buf * s)77 static inline unsigned int seq_buf_used(struct seq_buf *s)
78 {
79 return min(s->len, s->size);
80 }
81
82 /**
83 * seq_buf_str - get NUL-terminated C string from seq_buf
84 * @s: the seq_buf handle
85 *
86 * This makes sure that the buffer in @s is NUL-terminated and
87 * safe to read as a string.
88 *
89 * Note, if this is called when the buffer has overflowed, then
90 * the last byte of the buffer is zeroed, and the len will still
91 * point passed it.
92 *
93 * After this function is called, s->buffer is safe to use
94 * in string operations.
95 *
96 * Returns: @s->buf after making sure it is terminated.
97 */
seq_buf_str(struct seq_buf * s)98 static inline const char *seq_buf_str(struct seq_buf *s)
99 {
100 if (WARN_ON(s->size == 0))
101 return "";
102
103 if (seq_buf_buffer_left(s))
104 s->buffer[s->len] = 0;
105 else
106 s->buffer[s->size - 1] = 0;
107
108 return s->buffer;
109 }
110
111 /**
112 * seq_buf_get_buf - get buffer to write arbitrary data to
113 * @s: the seq_buf handle
114 * @bufp: the beginning of the buffer is stored here
115 *
116 * Returns: the number of bytes available in the buffer, or zero if
117 * there's no space.
118 */
seq_buf_get_buf(struct seq_buf * s,char ** bufp)119 static inline size_t seq_buf_get_buf(struct seq_buf *s, char **bufp)
120 {
121 WARN_ON(s->len > s->size + 1);
122
123 if (s->len < s->size) {
124 *bufp = s->buffer + s->len;
125 return s->size - s->len;
126 }
127
128 *bufp = NULL;
129 return 0;
130 }
131
132 /**
133 * seq_buf_commit - commit data to the buffer
134 * @s: the seq_buf handle
135 * @num: the number of bytes to commit
136 *
137 * Commit @num bytes of data written to a buffer previously acquired
138 * by seq_buf_get_buf(). To signal an error condition, or that the data
139 * didn't fit in the available space, pass a negative @num value.
140 */
seq_buf_commit(struct seq_buf * s,int num)141 static inline void seq_buf_commit(struct seq_buf *s, int num)
142 {
143 if (num < 0) {
144 seq_buf_set_overflow(s);
145 } else {
146 /* num must be negative on overflow */
147 BUG_ON(s->len + num > s->size);
148 s->len += num;
149 }
150 }
151
152 /**
153 * seq_buf_pop - pop off the last written character
154 * @s: the seq_buf handle
155 *
156 * Removes the last written character to the seq_buf @s.
157 *
158 * Returns the last character or -1 if it is empty.
159 */
seq_buf_pop(struct seq_buf * s)160 static inline int seq_buf_pop(struct seq_buf *s)
161 {
162 if (!s->len)
163 return -1;
164
165 s->len--;
166 return (unsigned int)s->buffer[s->len];
167 }
168
169 extern __printf(2, 3)
170 int seq_buf_printf(struct seq_buf *s, const char *fmt, ...);
171 extern __printf(2, 0)
172 int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args);
173 extern int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s);
174 extern int seq_buf_to_user(struct seq_buf *s, char __user *ubuf,
175 size_t start, int cnt);
176 extern int seq_buf_puts(struct seq_buf *s, const char *str);
177 extern int seq_buf_putc(struct seq_buf *s, unsigned char c);
178 extern int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len);
179 extern int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
180 unsigned int len);
181 extern int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc);
182 extern int seq_buf_hex_dump(struct seq_buf *s, const char *prefix_str,
183 int prefix_type, int rowsize, int groupsize,
184 const void *buf, size_t len, bool ascii);
185
186 #ifdef CONFIG_BINARY_PRINTF
187 __printf(2, 0)
188 int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary);
189 #endif
190
191 void seq_buf_do_printk(struct seq_buf *s, const char *lvl);
192
193 #endif /* _LINUX_SEQ_BUF_H */
194