linux/fs/seq_file.c

// SPDX-License-Identifier: GPL-2.0
/*
 * linux/fs/seq_file.c
 *
 * helper functions for making synthetic files from sequences of records.
 * initial implementation -- AV, Oct 2001.
 */

#define pr_fmt(fmt) …

#include <linux/cache.h>
#include <linux/fs.h>
#include <linux/export.h>
#include <linux/seq_file.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/cred.h>
#include <linux/mm.h>
#include <linux/printk.h>
#include <linux/string_helpers.h>
#include <linux/uio.h>

#include <linux/uaccess.h>
#include <asm/page.h>

static struct kmem_cache *seq_file_cache __ro_after_init;

static void seq_set_overflow(struct seq_file *m)
{ … }

static void *seq_buf_alloc(unsigned long size)
{ … }

/**
 *	seq_open -	initialize sequential file
 *	@file: file we initialize
 *	@op: method table describing the sequence
 *
 *	seq_open() sets @file, associating it with a sequence described
 *	by @op.  @op->start() sets the iterator up and returns the first
 *	element of sequence. @op->stop() shuts it down.  @op->next()
 *	returns the next element of sequence.  @op->show() prints element
 *	into the buffer.  In case of error ->start() and ->next() return
 *	ERR_PTR(error).  In the end of sequence they return %NULL. ->show()
 *	returns 0 in case of success and negative number in case of error.
 *	Returning SEQ_SKIP means "discard this element and move on".
 *	Note: seq_open() will allocate a struct seq_file and store its
 *	pointer in @file->private_data. This pointer should not be modified.
 */
int seq_open(struct file *file, const struct seq_operations *op)
{ … }
EXPORT_SYMBOL(…);

static int traverse(struct seq_file *m, loff_t offset)
{ … }

/**
 *	seq_read -	->read() method for sequential files.
 *	@file: the file to read from
 *	@buf: the buffer to read to
 *	@size: the maximum number of bytes to read
 *	@ppos: the current position in the file
 *
 *	Ready-made ->f_op->read()
 */
ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{ … }
EXPORT_SYMBOL(…);

/*
 * Ready-made ->f_op->read_iter()
 */
ssize_t seq_read_iter(struct kiocb *iocb, struct iov_iter *iter)
{ … }
EXPORT_SYMBOL(…);

/**
 *	seq_lseek -	->llseek() method for sequential files.
 *	@file: the file in question
 *	@offset: new position
 *	@whence: 0 for absolute, 1 for relative position
 *
 *	Ready-made ->f_op->llseek()
 */
loff_t seq_lseek(struct file *file, loff_t offset, int whence)
{ … }
EXPORT_SYMBOL(…);

/**
 *	seq_release -	free the structures associated with sequential file.
 *	@file: file in question
 *	@inode: its inode
 *
 *	Frees the structures associated with sequential file; can be used
 *	as ->f_op->release() if you don't have private data to destroy.
 */
int seq_release(struct inode *inode, struct file *file)
{ … }
EXPORT_SYMBOL(…);

/**
 * seq_escape_mem - print data into buffer, escaping some characters
 * @m: target buffer
 * @src: source buffer
 * @len: size of source buffer
 * @flags: flags to pass to string_escape_mem()
 * @esc: set of characters that need escaping
 *
 * Puts data into buffer, replacing each occurrence of character from
 * given class (defined by @flags and @esc) with printable escaped sequence.
 *
 * Use seq_has_overflowed() to check for errors.
 */
void seq_escape_mem(struct seq_file *m, const char *src, size_t len,
		    unsigned int flags, const char *esc)
{ … }
EXPORT_SYMBOL(…);

void seq_vprintf(struct seq_file *m, const char *f, va_list args)
{ … }
EXPORT_SYMBOL(…);

void seq_printf(struct seq_file *m, const char *f, ...)
{ … }
EXPORT_SYMBOL(…);

#ifdef CONFIG_BINARY_PRINTF
void seq_bprintf(struct seq_file *m, const char *f, const u32 *binary)
{ … }
EXPORT_SYMBOL(…);
#endif /* CONFIG_BINARY_PRINTF */

/**
 *	mangle_path -	mangle and copy path to buffer beginning
 *	@s: buffer start
 *	@p: beginning of path in above buffer
 *	@esc: set of characters that need escaping
 *
 *      Copy the path from @p to @s, replacing each occurrence of character from
 *      @esc with usual octal escape.
 *      Returns pointer past last written character in @s, or NULL in case of
 *      failure.
 */
char *mangle_path(char *s, const char *p, const char *esc)
{ … }
EXPORT_SYMBOL(…);

/**
 * seq_path - seq_file interface to print a pathname
 * @m: the seq_file handle
 * @path: the struct path to print
 * @esc: set of characters to escape in the output
 *
 * return the absolute path of 'path', as represented by the
 * dentry / mnt pair in the path parameter.
 */
int seq_path(struct seq_file *m, const struct path *path, const char *esc)
{ … }
EXPORT_SYMBOL(…);

/**
 * seq_file_path - seq_file interface to print a pathname of a file
 * @m: the seq_file handle
 * @file: the struct file to print
 * @esc: set of characters to escape in the output
 *
 * return the absolute path to the file.
 */
int seq_file_path(struct seq_file *m, struct file *file, const char *esc)
{ … }
EXPORT_SYMBOL(…);

/*
 * Same as seq_path, but relative to supplied root.
 */
int seq_path_root(struct seq_file *m, const struct path *path,
		  const struct path *root, const char *esc)
{ … }

/*
 * returns the path of the 'dentry' from the root of its filesystem.
 */
int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc)
{ … }
EXPORT_SYMBOL(…);

void *single_start(struct seq_file *p, loff_t *pos)
{ … }

static void *single_next(struct seq_file *p, void *v, loff_t *pos)
{ … }

static void single_stop(struct seq_file *p, void *v)
{ … }

int single_open(struct file *file, int (*show)(struct seq_file *, void *),
		void *data)
{ … }
EXPORT_SYMBOL(…);

int single_open_size(struct file *file, int (*show)(struct seq_file *, void *),
		void *data, size_t size)
{ … }
EXPORT_SYMBOL(…);

int single_release(struct inode *inode, struct file *file)
{ … }
EXPORT_SYMBOL(…);

int seq_release_private(struct inode *inode, struct file *file)
{ … }
EXPORT_SYMBOL(…);

void *__seq_open_private(struct file *f, const struct seq_operations *ops,
		int psize)
{ … }
EXPORT_SYMBOL(…);

int seq_open_private(struct file *filp, const struct seq_operations *ops,
		int psize)
{ … }
EXPORT_SYMBOL(…);

void seq_putc(struct seq_file *m, char c)
{ … }
EXPORT_SYMBOL(…);

void __seq_puts(struct seq_file *m, const char *s)
{ … }
EXPORT_SYMBOL(…);

/**
 * seq_put_decimal_ull_width - A helper routine for putting decimal numbers
 * 			       without rich format of printf().
 * only 'unsigned long long' is supported.
 * @m: seq_file identifying the buffer to which data should be written
 * @delimiter: a string which is printed before the number
 * @num: the number
 * @width: a minimum field width
 *
 * This routine will put strlen(delimiter) + number into seq_filed.
 * This routine is very quick when you show lots of numbers.
 * In usual cases, it will be better to use seq_printf(). It's easier to read.
 */
void seq_put_decimal_ull_width(struct seq_file *m, const char *delimiter,
			 unsigned long long num, unsigned int width)
{ … }

void seq_put_decimal_ull(struct seq_file *m, const char *delimiter,
			 unsigned long long num)
{ … }
EXPORT_SYMBOL(…);

/**
 * seq_put_hex_ll - put a number in hexadecimal notation
 * @m: seq_file identifying the buffer to which data should be written
 * @delimiter: a string which is printed before the number
 * @v: the number
 * @width: a minimum field width
 *
 * seq_put_hex_ll(m, "", v, 8) is equal to seq_printf(m, "%08llx", v)
 *
 * This routine is very quick when you show lots of numbers.
 * In usual cases, it will be better to use seq_printf(). It's easier to read.
 */
void seq_put_hex_ll(struct seq_file *m, const char *delimiter,
				unsigned long long v, unsigned int width)
{ … }

void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num)
{ … }
EXPORT_SYMBOL(…);

/**
 * seq_write - write arbitrary data to buffer
 * @seq: seq_file identifying the buffer to which data should be written
 * @data: data address
 * @len: number of bytes
 *
 * Return 0 on success, non-zero otherwise.
 */
int seq_write(struct seq_file *seq, const void *data, size_t len)
{ … }
EXPORT_SYMBOL(…);

/**
 * seq_pad - write padding spaces to buffer
 * @m: seq_file identifying the buffer to which data should be written
 * @c: the byte to append after padding if non-zero
 */
void seq_pad(struct seq_file *m, char c)
{ … }
EXPORT_SYMBOL(…);

/* A complete analogue of print_hex_dump() */
void seq_hex_dump(struct seq_file *m, const char *prefix_str, int prefix_type,
		  int rowsize, int groupsize, const void *buf, size_t len,
		  bool ascii)
{ … }
EXPORT_SYMBOL(…);

struct list_head *seq_list_start(struct list_head *head, loff_t pos)
{ … }
EXPORT_SYMBOL(…);

struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
{ … }
EXPORT_SYMBOL(…);

struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
{ … }
EXPORT_SYMBOL(…);

struct list_head *seq_list_start_rcu(struct list_head *head, loff_t pos)
{ … }
EXPORT_SYMBOL(…);

struct list_head *seq_list_start_head_rcu(struct list_head *head, loff_t pos)
{ … }
EXPORT_SYMBOL(…);

struct list_head *seq_list_next_rcu(void *v, struct list_head *head,
				    loff_t *ppos)
{ … }
EXPORT_SYMBOL(…);

/**
 * seq_hlist_start - start an iteration of a hlist
 * @head: the head of the hlist
 * @pos:  the start position of the sequence
 *
 * Called at seq_file->op->start().
 */
struct hlist_node *seq_hlist_start(struct hlist_head *head, loff_t pos)
{ … }
EXPORT_SYMBOL(…);

/**
 * seq_hlist_start_head - start an iteration of a hlist
 * @head: the head of the hlist
 * @pos:  the start position of the sequence
 *
 * Called at seq_file->op->start(). Call this function if you want to
 * print a header at the top of the output.
 */
struct hlist_node *seq_hlist_start_head(struct hlist_head *head, loff_t pos)
{ … }
EXPORT_SYMBOL(…);

/**
 * seq_hlist_next - move to the next position of the hlist
 * @v:    the current iterator
 * @head: the head of the hlist
 * @ppos: the current position
 *
 * Called at seq_file->op->next().
 */
struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
				  loff_t *ppos)
{ … }
EXPORT_SYMBOL(…);

/**
 * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
 * @head: the head of the hlist
 * @pos:  the start position of the sequence
 *
 * Called at seq_file->op->start().
 *
 * This list-traversal primitive may safely run concurrently with
 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
 * as long as the traversal is guarded by rcu_read_lock().
 */
struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
				       loff_t pos)
{ … }
EXPORT_SYMBOL(…);

/**
 * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
 * @head: the head of the hlist
 * @pos:  the start position of the sequence
 *
 * Called at seq_file->op->start(). Call this function if you want to
 * print a header at the top of the output.
 *
 * This list-traversal primitive may safely run concurrently with
 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
 * as long as the traversal is guarded by rcu_read_lock().
 */
struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
					    loff_t pos)
{ … }
EXPORT_SYMBOL(…);

/**
 * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
 * @v:    the current iterator
 * @head: the head of the hlist
 * @ppos: the current position
 *
 * Called at seq_file->op->next().
 *
 * This list-traversal primitive may safely run concurrently with
 * the _rcu list-mutation primitives such as hlist_add_head_rcu()
 * as long as the traversal is guarded by rcu_read_lock().
 */
struct hlist_node *seq_hlist_next_rcu(void *v,
				      struct hlist_head *head,
				      loff_t *ppos)
{ … }
EXPORT_SYMBOL(…);

/**
 * seq_hlist_start_percpu - start an iteration of a percpu hlist array
 * @head: pointer to percpu array of struct hlist_heads
 * @cpu:  pointer to cpu "cursor"
 * @pos:  start position of sequence
 *
 * Called at seq_file->op->start().
 */
struct hlist_node *
seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos)
{ … }
EXPORT_SYMBOL(…);

/**
 * seq_hlist_next_percpu - move to the next position of the percpu hlist array
 * @v:    pointer to current hlist_node
 * @head: pointer to percpu array of struct hlist_heads
 * @cpu:  pointer to cpu "cursor"
 * @pos:  start position of sequence
 *
 * Called at seq_file->op->next().
 */
struct hlist_node *
seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head,
			int *cpu, loff_t *pos)
{ … }
EXPORT_SYMBOL(…);

void __init seq_file_init(void)
{ … }