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/bug.h>
   8 #include <linux/mutex.h>
   9 #include <linux/cpumask.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         u64 version;
  25         struct mutex lock;
  26         const struct seq_operations *op;
  27         int poll_event;
  28         const struct file *file;
  29         void *private;
  30 };
  31
  32 struct seq_operations {
  33         void * (*start) (struct seq_file *m, loff_t *pos);
  34         void (*stop) (struct seq_file *m, void *v);
  35         void * (*next) (struct seq_file *m, void *v, loff_t *pos);
  36         int (*show) (struct seq_file *m, void *v);
  37 };
  38
  39 #define SEQ_SKIP 1
  40
  41 /**
  42  * seq_has_overflowed - check if the buffer has overflowed
  43  * @m: the seq_file handle
  44  *
  45  * seq_files have a buffer which may overflow. When this happens a larger
  46  * buffer is reallocated and all the data will be printed again.
  47  * The overflow state is true when m->count == m->size.
  48  *
  49  * Returns true if the buffer received more than it can hold.
  50  */
  51 static inline bool seq_has_overflowed(struct seq_file *m)
  52 {
  53         return m->count == m->size;
  54 }
  55
  56 /**
  57  * seq_get_buf - get buffer to write arbitrary data to
  58  * @m: the seq_file handle
  59  * @bufp: the beginning of the buffer is stored here
  60  *
  61  * Return the number of bytes available in the buffer, or zero if
  62  * there's no space.
  63  */
  64 static inline size_t seq_get_buf(struct seq_file *m, char **bufp)
  65 {
  66         BUG_ON(m->count > m->size);
  67         if (m->count < m->size)
  68                 *bufp = m->buf + m->count;
  69         else
  70                 *bufp = NULL;
  71
  72         return m->size - m->count;
  73 }
  74
  75 /**
  76  * seq_commit - commit data to the buffer
  77  * @m: the seq_file handle
  78  * @num: the number of bytes to commit
  79  *
  80  * Commit @num bytes of data written to a buffer previously acquired
  81  * by seq_buf_get.  To signal an error condition, or that the data
  82  * didn't fit in the available space, pass a negative @num value.
  83  */
  84 static inline void seq_commit(struct seq_file *m, int num)
  85 {
  86         if (num < 0) {
  87                 m->count = m->size;
  88         } else {
  89                 BUG_ON(m->count + num > m->size);
  90                 m->count += num;
  91         }
  92 }
  93
  94 /**
  95  * seq_setwidth - set padding width
  96  * @m: the seq_file handle
  97  * @size: the max number of bytes to pad.
  98  *
  99  * Call seq_setwidth() for setting max width, then call seq_printf() etc. and
 100  * finally call seq_pad() to pad the remaining bytes.
 101  */
 102 static inline void seq_setwidth(struct seq_file *m, size_t size)
 103 {
 104         m->pad_until = m->count + size;
 105 }
 106 void seq_pad(struct seq_file *m, char c);
 107
 108 char *mangle_path(char *s, const char *p, const char *esc);
 109 int seq_open(struct file *, const struct seq_operations *);
 110 ssize_t seq_read(struct file *, char __user *, size_t, loff_t *);
 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 void seq_put_decimal_ull_width(struct seq_file *m, const char *delimiter,
 122                                unsigned long long num, unsigned int width);
 123 void seq_put_decimal_ull(struct seq_file *m, const char *delimiter,
 124                          unsigned long long num);
 125 void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num);
 126 void seq_put_hex_ll(struct seq_file *m, const char *delimiter,
 127                     unsigned long long v, unsigned int width);
 128
 129 void seq_escape(struct seq_file *m, const char *s, const char *esc);
 130
 131 void seq_hex_dump(struct seq_file *m, const char *prefix_str, int prefix_type,
 132                   int rowsize, int groupsize, const void *buf, size_t len,
 133                   bool ascii);
 134
 135 int seq_path(struct seq_file *, const struct path *, const char *);
 136 int seq_file_path(struct seq_file *, struct file *, const char *);
 137 int seq_dentry(struct seq_file *, struct dentry *, const char *);
 138 int seq_path_root(struct seq_file *m, const struct path *path,
 139                   const struct path *root, const char *esc);
 140
 141 int single_open(struct file *, int (*)(struct seq_file *, void *), void *);
 142 int single_open_size(struct file *, int (*)(struct seq_file *, void *), void *, size_t);
 143 int single_release(struct inode *, struct file *);
 144 void *__seq_open_private(struct file *, const struct seq_operations *, int);
 145 int seq_open_private(struct file *, const struct seq_operations *, int);
 146 int seq_release_private(struct inode *, struct file *);
 147
 148 #define DEFINE_SHOW_ATTRIBUTE(__name)                                   \
 149 static int __name ## _open(struct inode *inode, struct file *file)      \
 150 {                                                                       \
 151         return single_open(file, __name ## _show, inode->i_private);    \
 152 }                                                                       \
 153                                                                         \
 154 static const struct file_operations __name ## _fops = {                 \
 155         .owner          = THIS_MODULE,                                  \
 156         .open           = __name ## _open,                              \
 157         .read           = seq_read,                                     \
 158         .llseek         = seq_lseek,                                    \
 159         .release        = single_release,                               \
 160 }
 161
 162 static inline struct user_namespace *seq_user_ns(struct seq_file *seq)
 163 {
 164 #ifdef CONFIG_USER_NS
 165         return seq->file->f_cred->user_ns;
 166 #else
 167         extern struct user_namespace init_user_ns;
 168         return &init_user_ns;
 169 #endif
 170 }
 171
 172 /**
 173  * seq_show_options - display mount options with appropriate escapes.
 174  * @m: the seq_file handle
 175  * @name: the mount option name
 176  * @value: the mount option name's value, can be NULL
 177  */
 178 static inline void seq_show_option(struct seq_file *m, const char *name,
 179                                    const char *value)
 180 {
 181         seq_putc(m, ',');
 182         seq_escape(m, name, ",= \t\n\\");
 183         if (value) {
 184                 seq_putc(m, '=');
 185                 seq_escape(m, value, ", \t\n\\");
 186         }
 187 }
 188
 189 /**
 190  * seq_show_option_n - display mount options with appropriate escapes
 191  *                     where @value must be a specific length.
 192  * @m: the seq_file handle
 193  * @name: the mount option name
 194  * @value: the mount option name's value, cannot be NULL
 195  * @length: the length of @value to display
 196  *
 197  * This is a macro since this uses "length" to define the size of the
 198  * stack buffer.
 199  */
 200 #define seq_show_option_n(m, name, value, length) {     \
 201         char val_buf[length + 1];                       \
 202         strncpy(val_buf, value, length);                \
 203         val_buf[length] = '\0';                         \
 204         seq_show_option(m, name, val_buf);              \
 205 }
 206
 207 #define SEQ_START_TOKEN ((void *)1)
 208 /*
 209  * Helpers for iteration over list_head-s in seq_files
 210  */
 211
 212 extern struct list_head *seq_list_start(struct list_head *head,
 213                 loff_t pos);
 214 extern struct list_head *seq_list_start_head(struct list_head *head,
 215                 loff_t pos);
 216 extern struct list_head *seq_list_next(void *v, struct list_head *head,
 217                 loff_t *ppos);
 218
 219 /*
 220  * Helpers for iteration over hlist_head-s in seq_files
 221  */
 222
 223 extern struct hlist_node *seq_hlist_start(struct hlist_head *head,
 224                                           loff_t pos);
 225 extern struct hlist_node *seq_hlist_start_head(struct hlist_head *head,
 226                                                loff_t pos);
 227 extern struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
 228                                          loff_t *ppos);
 229
 230 extern struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
 231                                               loff_t pos);
 232 extern struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
 233                                                    loff_t pos);
 234 extern struct hlist_node *seq_hlist_next_rcu(void *v,
 235                                                    struct hlist_head *head,
 236                                                    loff_t *ppos);
 237
 238 /* Helpers for iterating over per-cpu hlist_head-s in seq_files */
 239 extern struct hlist_node *seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos);
 240
 241 extern struct hlist_node *seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head, int *cpu, loff_t *pos);
 242
 243 void seq_file_init(void);
 244 #endif