include/linux/seq_buf.h

   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, 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_terminate - Make sure buffer is nul terminated
  76  * @s: the seq_buf descriptor to terminate.
  77  *
  78  * This makes sure that the buffer in @s is nul terminated and
  79  * safe to read as a string.
  80  *
  81  * Note, if this is called when the buffer has overflowed, then
  82  * the last byte of the buffer is zeroed, and the len will still
  83  * point passed it.
  84  *
  85  * After this function is called, s->buffer is safe to use
  86  * in string operations.
  87  */
  88 static inline void seq_buf_terminate(struct seq_buf *s)
  89 {
  90         if (WARN_ON(s->size == 0))
  91                 return;
  92
  93         if (seq_buf_buffer_left(s))
  94                 s->buffer[s->len] = 0;
  95         else
  96                 s->buffer[s->size - 1] = 0;
  97 }
  98
  99 /**
 100  * seq_buf_get_buf - get buffer to write arbitrary data to
 101  * @s: the seq_buf handle
 102  * @bufp: the beginning of the buffer is stored here
 103  *
 104  * Return the number of bytes available in the buffer, or zero if
 105  * there's no space.
 106  */
 107 static inline size_t seq_buf_get_buf(struct seq_buf *s, char **bufp)
 108 {
 109         WARN_ON(s->len > s->size + 1);
 110
 111         if (s->len < s->size) {
 112                 *bufp = s->buffer + s->len;
 113                 return s->size - s->len;
 114         }
 115
 116         *bufp = NULL;
 117         return 0;
 118 }
 119
 120 /**
 121  * seq_buf_commit - commit data to the buffer
 122  * @s: the seq_buf handle
 123  * @num: the number of bytes to commit
 124  *
 125  * Commit @num bytes of data written to a buffer previously acquired
 126  * by seq_buf_get.  To signal an error condition, or that the data
 127  * didn't fit in the available space, pass a negative @num value.
 128  */
 129 static inline void seq_buf_commit(struct seq_buf *s, int num)
 130 {
 131         if (num < 0) {
 132                 seq_buf_set_overflow(s);
 133         } else {
 134                 /* num must be negative on overflow */
 135                 BUG_ON(s->len + num > s->size);
 136                 s->len += num;
 137         }
 138 }
 139
 140 extern __printf(2, 3)
 141 int seq_buf_printf(struct seq_buf *s, const char *fmt, ...);
 142 extern __printf(2, 0)
 143 int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args);
 144 extern int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s);
 145 extern int seq_buf_to_user(struct seq_buf *s, char __user *ubuf,
 146                            int cnt);
 147 extern int seq_buf_puts(struct seq_buf *s, const char *str);
 148 extern int seq_buf_putc(struct seq_buf *s, unsigned char c);
 149 extern int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len);
 150 extern int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
 151                               unsigned int len);
 152 extern int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc);
 153 extern int seq_buf_hex_dump(struct seq_buf *s, const char *prefix_str,
 154                             int prefix_type, int rowsize, int groupsize,
 155                             const void *buf, size_t len, bool ascii);
 156
 157 #ifdef CONFIG_BINARY_PRINTF
 158 extern int
 159 seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary);
 160 #endif
 161
 162 #endif /* _LINUX_SEQ_BUF_H */