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, 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 */