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 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 33 seq_buf_init(struct seq_buf *s, unsigned 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 45 seq_buf_has_overflowed(struct seq_buf *s) 46 { 47 return s->len > s->size; 48 } 49 50 static inline void 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 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? */ 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 */ 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 */ 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