include/linux/seq_file.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_SEQ_FILE_H
   3 #define _LINUX_SEQ_FILE_H
   4
   5 #include <linux/types.h>
   6 #include <linux/string.h>
   7 #include <linux/string_helpers.h>
   8 #include <linux/bug.h>
   9 #include <linux/mutex.h>
  10 #include <linux/nodemask.h>
  11 #include <linux/fs.h>
  12 #include <linux/cred.h>
  13
  14 struct seq_operations;
  15
  16 struct seq_file {
  17         char *buf;
  18         size_t size;
  19         size_t from;
  20         size_t count;
  21         size_t pad_until;
  22         loff_t index;
  23         loff_t read_pos;
  24         struct mutex lock;
  25         const struct seq_operations *op;
  26         int poll_event;
  27         const struct file *file;
  28         void *private;
  29 };
  30
  31 struct seq_operations {
  32         void * (*start) (struct seq_file *m, loff_t *pos);
  33         void (*stop) (struct seq_file *m, void *v);
  34         void * (*next) (struct seq_file *m, void *v, loff_t *pos);
  35         int (*show) (struct seq_file *m, void *v);
  36 };
  37
  38 #define SEQ_SKIP 1
  39
  40 /**
  41  * seq_has_overflowed - check if the buffer has overflowed
  42  * @m: the seq_file handle
  43  *
  44  * seq_files have a buffer which may overflow. When this happens a larger
  45  * buffer is reallocated and all the data will be printed again.
  46  * The overflow state is true when m->count == m->size.
  47  *
  48  * Returns true if the buffer received more than it can hold.
  49  */
  50 static inline bool seq_has_overflowed(struct seq_file *m)
  51 {
  52         return m->count == m->size;
  53 }
  54
  55 /**
  56  * seq_get_buf - get buffer to write arbitrary data to
  57  * @m: the seq_file handle
  58  * @bufp: the beginning of the buffer is stored here
  59  *
  60  * Return the number of bytes available in the buffer, or zero if
  61  * there's no space.
  62  */
  63 static inline size_t seq_get_buf(struct seq_file *m, char **bufp)
  64 {
  65         BUG_ON(m->count > m->size);
  66         if (m->count < m->size)
  67                 *bufp = m->buf + m->count;
  68         else
  69                 *bufp = NULL;
  70
  71         return m->size - m->count;
  72 }
  73
  74 /**
  75  * seq_commit - commit data to the buffer
  76  * @m: the seq_file handle
  77  * @num: the number of bytes to commit
  78  *
  79  * Commit @num bytes of data written to a buffer previously acquired
  80  * by seq_buf_get.  To signal an error condition, or that the data
  81  * didn't fit in the available space, pass a negative @num value.
  82  */
  83 static inline void seq_commit(struct seq_file *m, int num)
  84 {
  85         if (num < 0) {
  86                 m->count = m->size;
  87         } else {
  88                 BUG_ON(m->count + num > m->size);
  89                 m->count += num;
  90         }
  91 }
  92
  93 /**
  94  * seq_setwidth - set padding width
  95  * @m: the seq_file handle
  96  * @size: the max number of bytes to pad.
  97  *
  98  * Call seq_setwidth() for setting max width, then call seq_printf() etc. and
  99  * finally call seq_pad() to pad the remaining bytes.
 100  */
 101 static inline void seq_setwidth(struct seq_file *m, size_t size)
 102 {
 103         m->pad_until = m->count + size;
 104 }
 105 void seq_pad(struct seq_file *m, char c);
 106
 107 char *mangle_path(char *s, const char *p, const char *esc);
 108 int seq_open(struct file *, const struct seq_operations *);
 109 ssize_t seq_read(struct file *, char __user *, size_t, loff_t *);
 110 ssize_t seq_read_iter(struct kiocb *iocb, struct iov_iter *iter);
 111 loff_t seq_lseek(struct file *, loff_t, int);
 112 int seq_release(struct inode *, struct file *);
 113 int seq_write(struct seq_file *seq, const void *data, size_t len);
 114
 115 __printf(2, 0)
 116 void seq_vprintf(struct seq_file *m, const char *fmt, va_list args);
 117 __printf(2, 3)
 118 void seq_printf(struct seq_file *m, const char *fmt, ...);
 119 void seq_putc(struct seq_file *m, char c);
 120 void __seq_puts(struct seq_file *m, const char *s);
 121
 122 static __always_inline void seq_puts(struct seq_file *m, const char *s)
 123 {
 124         if (!__builtin_constant_p(*s))
 125                 __seq_puts(m, s);
 126         else if (s[0] && !s[1])
 127                 seq_putc(m, s[0]);
 128         else
 129                 seq_write(m, s, __builtin_strlen(s));
 130 }
 131
 132 void seq_put_decimal_ull_width(struct seq_file *m, const char *delimiter,
 133                                unsigned long long num, unsigned int width);
 134 void seq_put_decimal_ull(struct seq_file *m, const char *delimiter,
 135                          unsigned long long num);
 136 void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num);
 137 void seq_put_hex_ll(struct seq_file *m, const char *delimiter,
 138                     unsigned long long v, unsigned int width);
 139
 140 void seq_escape_mem(struct seq_file *m, const char *src, size_t len,
 141                     unsigned int flags, const char *esc);
 142
 143 static inline void seq_escape_str(struct seq_file *m, const char *src,
 144                                   unsigned int flags, const char *esc)
 145 {
 146         seq_escape_mem(m, src, strlen(src), flags, esc);
 147 }
 148
 149 /**
 150  * seq_escape - print string into buffer, escaping some characters
 151  * @m: target buffer
 152  * @s: NULL-terminated string
 153  * @esc: set of characters that need escaping
 154  *
 155  * Puts string into buffer, replacing each occurrence of character from
 156  * @esc with usual octal escape.
 157  *
 158  * Use seq_has_overflowed() to check for errors.
 159  */
 160 static inline void seq_escape(struct seq_file *m, const char *s, const char *esc)
 161 {
 162         seq_escape_str(m, s, ESCAPE_OCTAL, esc);
 163 }
 164
 165 void seq_hex_dump(struct seq_file *m, const char *prefix_str, int prefix_type,
 166                   int rowsize, int groupsize, const void *buf, size_t len,
 167                   bool ascii);
 168
 169 int seq_path(struct seq_file *, const struct path *, const char *);
 170 int seq_file_path(struct seq_file *, struct file *, const char *);
 171 int seq_dentry(struct seq_file *, struct dentry *, const char *);
 172 int seq_path_root(struct seq_file *m, const struct path *path,
 173                   const struct path *root, const char *esc);
 174
 175 void *single_start(struct seq_file *, loff_t *);
 176 int single_open(struct file *, int (*)(struct seq_file *, void *), void *);
 177 int single_open_size(struct file *, int (*)(struct seq_file *, void *), void *, size_t);
 178 int single_release(struct inode *, struct file *);
 179 void *__seq_open_private(struct file *, const struct seq_operations *, int);
 180 int seq_open_private(struct file *, const struct seq_operations *, int);
 181 int seq_release_private(struct inode *, struct file *);
 182
 183 #ifdef CONFIG_BINARY_PRINTF
 184 void seq_bprintf(struct seq_file *m, const char *f, const u32 *binary);
 185 #endif
 186
 187 #define DEFINE_SEQ_ATTRIBUTE(__name)                                    \
 188 static int __name ## _open(struct inode *inode, struct file *file)      \
 189 {                                                                       \
 190         int ret = seq_open(file, &__name ## _sops);                     \
 191         if (!ret && inode->i_private) {                                 \
 192                 struct seq_file *seq_f = file->private_data;            \
 193                 seq_f->private = inode->i_private;                      \
 194         }                                                               \
 195         return ret;                                                     \
 196 }                                                                       \
 197                                                                         \
 198 static const struct file_operations __name ## _fops = {                 \
 199         .owner          = THIS_MODULE,                                  \
 200         .open           = __name ## _open,                              \
 201         .read           = seq_read,                                     \
 202         .llseek         = seq_lseek,                                    \
 203         .release        = seq_release,                                  \
 204 }
 205
 206 #define DEFINE_SHOW_ATTRIBUTE(__name)                                   \
 207 static int __name ## _open(struct inode *inode, struct file *file)      \
 208 {                                                                       \
 209         return single_open(file, __name ## _show, inode->i_private);    \
 210 }                                                                       \
 211                                                                         \
 212 static const struct file_operations __name ## _fops = {                 \
 213         .owner          = THIS_MODULE,                                  \
 214         .open           = __name ## _open,                              \
 215         .read           = seq_read,                                     \
 216         .llseek         = seq_lseek,                                    \
 217         .release        = single_release,                               \
 218 }
 219
 220 #define DEFINE_SHOW_STORE_ATTRIBUTE(__name)                             \
 221 static int __name ## _open(struct inode *inode, struct file *file)      \
 222 {                                                                       \
 223         return single_open(file, __name ## _show, inode->i_private);    \
 224 }                                                                       \
 225                                                                         \
 226 static const struct file_operations __name ## _fops = {                 \
 227         .owner          = THIS_MODULE,                                  \
 228         .open           = __name ## _open,                              \
 229         .read           = seq_read,                                     \
 230         .write          = __name ## _write,                             \
 231         .llseek         = seq_lseek,                                    \
 232         .release        = single_release,                               \
 233 }
 234
 235 #define DEFINE_PROC_SHOW_ATTRIBUTE(__name)                              \
 236 static int __name ## _open(struct inode *inode, struct file *file)      \
 237 {                                                                       \
 238         return single_open(file, __name ## _show, pde_data(inode));     \
 239 }                                                                       \
 240                                                                         \
 241 static const struct proc_ops __name ## _proc_ops = {                    \
 242         .proc_open      = __name ## _open,                              \
 243         .proc_read      = seq_read,                                     \
 244         .proc_lseek     = seq_lseek,                                    \
 245         .proc_release   = single_release,                               \
 246 }
 247
 248 static inline struct user_namespace *seq_user_ns(struct seq_file *seq)
 249 {
 250 #ifdef CONFIG_USER_NS
 251         return seq->file->f_cred->user_ns;
 252 #else
 253         extern struct user_namespace init_user_ns;
 254         return &init_user_ns;
 255 #endif
 256 }
 257
 258 /**
 259  * seq_show_options - display mount options with appropriate escapes.
 260  * @m: the seq_file handle
 261  * @name: the mount option name
 262  * @value: the mount option name's value, can be NULL
 263  */
 264 static inline void seq_show_option(struct seq_file *m, const char *name,
 265                                    const char *value)
 266 {
 267         seq_putc(m, ',');
 268         seq_escape(m, name, ",= \t\n\\");
 269         if (value) {
 270                 seq_putc(m, '=');
 271                 seq_escape(m, value, ", \t\n\\");
 272         }
 273 }
 274
 275 /**
 276  * seq_show_option_n - display mount options with appropriate escapes
 277  *                     where @value must be a specific length (i.e.
 278  *                     not NUL-terminated).
 279  * @m: the seq_file handle
 280  * @name: the mount option name
 281  * @value: the mount option name's value, cannot be NULL
 282  * @length: the exact length of @value to display, must be constant expression
 283  *
 284  * This is a macro since this uses "length" to define the size of the
 285  * stack buffer.
 286  */
 287 #define seq_show_option_n(m, name, value, length) {     \
 288         char val_buf[length + 1];                       \
 289         memcpy(val_buf, value, length);                 \
 290         val_buf[length] = '\0';                         \
 291         seq_show_option(m, name, val_buf);              \
 292 }
 293
 294 #define SEQ_START_TOKEN ((void *)1)
 295 /*
 296  * Helpers for iteration over list_head-s in seq_files
 297  */
 298
 299 extern struct list_head *seq_list_start(struct list_head *head,
 300                 loff_t pos);
 301 extern struct list_head *seq_list_start_head(struct list_head *head,
 302                 loff_t pos);
 303 extern struct list_head *seq_list_next(void *v, struct list_head *head,
 304                 loff_t *ppos);
 305
 306 extern struct list_head *seq_list_start_rcu(struct list_head *head, loff_t pos);
 307 extern struct list_head *seq_list_start_head_rcu(struct list_head *head, loff_t pos);
 308 extern struct list_head *seq_list_next_rcu(void *v, struct list_head *head, loff_t *ppos);
 309
 310 /*
 311  * Helpers for iteration over hlist_head-s in seq_files
 312  */
 313
 314 extern struct hlist_node *seq_hlist_start(struct hlist_head *head,
 315                                           loff_t pos);
 316 extern struct hlist_node *seq_hlist_start_head(struct hlist_head *head,
 317                                                loff_t pos);
 318 extern struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
 319                                          loff_t *ppos);
 320
 321 extern struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
 322                                               loff_t pos);
 323 extern struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
 324                                                    loff_t pos);
 325 extern struct hlist_node *seq_hlist_next_rcu(void *v,
 326                                                    struct hlist_head *head,
 327                                                    loff_t *ppos);
 328
 329 /* Helpers for iterating over per-cpu hlist_head-s in seq_files */
 330 extern struct hlist_node *seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos);
 331
 332 extern struct hlist_node *seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head, int *cpu, loff_t *pos);
 333
 334 void seq_file_init(void);
 335 #endif