| /* |
| * seq_buf.c |
| * |
| * Copyright (C) 2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com> |
| * |
| * The seq_buf is a handy tool that allows you to pass a descriptor around |
| * to a buffer that other functions can write to. It is similar to the |
| * seq_file functionality but has some differences. |
| * |
| * To use it, the seq_buf must be initialized with seq_buf_init(). |
| * This will set up the counters within the descriptor. You can call |
| * seq_buf_init() more than once to reset the seq_buf to start |
| * from scratch. |
| */ |
| #include <linux/uaccess.h> |
| #include <linux/seq_file.h> |
| #include <linux/seq_buf.h> |
| |
| /** |
| * seq_buf_can_fit - can the new data fit in the current buffer? |
| * @s: the seq_buf descriptor |
| * @len: The length to see if it can fit in the current buffer |
| * |
| * Returns true if there's enough unused space in the seq_buf buffer |
| * to fit the amount of new data according to @len. |
| */ |
| static bool seq_buf_can_fit(struct seq_buf *s, size_t len) |
| { |
| return s->len + len <= s->size; |
| } |
| |
| /** |
| * seq_buf_print_seq - move the contents of seq_buf into a seq_file |
| * @m: the seq_file descriptor that is the destination |
| * @s: the seq_buf descriptor that is the source. |
| * |
| * Returns zero on success, non zero otherwise |
| */ |
| int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s) |
| { |
| unsigned int len = seq_buf_used(s); |
| |
| return seq_write(m, s->buffer, len); |
| } |
| |
| /** |
| * seq_buf_vprintf - sequence printing of information. |
| * @s: seq_buf descriptor |
| * @fmt: printf format string |
| * @args: va_list of arguments from a printf() type function |
| * |
| * Writes a vnprintf() format into the sequencce buffer. |
| * |
| * Returns zero on success, -1 on overflow. |
| */ |
| int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args) |
| { |
| int len; |
| |
| WARN_ON(s->size == 0); |
| |
| if (s->len < s->size) { |
| len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args); |
| if (s->len + len < s->size) { |
| s->len += len; |
| return 0; |
| } |
| } |
| seq_buf_set_overflow(s); |
| return -1; |
| } |
| |
| /** |
| * seq_buf_printf - sequence printing of information |
| * @s: seq_buf descriptor |
| * @fmt: printf format string |
| * |
| * Writes a printf() format into the sequence buffer. |
| * |
| * Returns zero on success, -1 on overflow. |
| */ |
| int seq_buf_printf(struct seq_buf *s, const char *fmt, ...) |
| { |
| va_list ap; |
| int ret; |
| |
| va_start(ap, fmt); |
| ret = seq_buf_vprintf(s, fmt, ap); |
| va_end(ap); |
| |
| return ret; |
| } |
| |
| #ifdef CONFIG_BINARY_PRINTF |
| /** |
| * seq_buf_bprintf - Write the printf string from binary arguments |
| * @s: seq_buf descriptor |
| * @fmt: The format string for the @binary arguments |
| * @binary: The binary arguments for @fmt. |
| * |
| * When recording in a fast path, a printf may be recorded with just |
| * saving the format and the arguments as they were passed to the |
| * function, instead of wasting cycles converting the arguments into |
| * ASCII characters. Instead, the arguments are saved in a 32 bit |
| * word array that is defined by the format string constraints. |
| * |
| * This function will take the format and the binary array and finish |
| * the conversion into the ASCII string within the buffer. |
| * |
| * Returns zero on success, -1 on overflow. |
| */ |
| int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary) |
| { |
| unsigned int len = seq_buf_buffer_left(s); |
| int ret; |
| |
| WARN_ON(s->size == 0); |
| |
| if (s->len < s->size) { |
| ret = bstr_printf(s->buffer + s->len, len, fmt, binary); |
| if (s->len + ret < s->size) { |
| s->len += ret; |
| return 0; |
| } |
| } |
| seq_buf_set_overflow(s); |
| return -1; |
| } |
| #endif /* CONFIG_BINARY_PRINTF */ |
| |
| /** |
| * seq_buf_puts - sequence printing of simple string |
| * @s: seq_buf descriptor |
| * @str: simple string to record |
| * |
| * Copy a simple string into the sequence buffer. |
| * |
| * Returns zero on success, -1 on overflow |
| */ |
| int seq_buf_puts(struct seq_buf *s, const char *str) |
| { |
| unsigned int len = strlen(str); |
| |
| WARN_ON(s->size == 0); |
| |
| if (seq_buf_can_fit(s, len)) { |
| memcpy(s->buffer + s->len, str, len); |
| s->len += len; |
| return 0; |
| } |
| seq_buf_set_overflow(s); |
| return -1; |
| } |
| |
| /** |
| * seq_buf_putc - sequence printing of simple character |
| * @s: seq_buf descriptor |
| * @c: simple character to record |
| * |
| * Copy a single character into the sequence buffer. |
| * |
| * Returns zero on success, -1 on overflow |
| */ |
| int seq_buf_putc(struct seq_buf *s, unsigned char c) |
| { |
| WARN_ON(s->size == 0); |
| |
| if (seq_buf_can_fit(s, 1)) { |
| s->buffer[s->len++] = c; |
| return 0; |
| } |
| seq_buf_set_overflow(s); |
| return -1; |
| } |
| |
| /** |
| * seq_buf_putmem - write raw data into the sequenc buffer |
| * @s: seq_buf descriptor |
| * @mem: The raw memory to copy into the buffer |
| * @len: The length of the raw memory to copy (in bytes) |
| * |
| * There may be cases where raw memory needs to be written into the |
| * buffer and a strcpy() would not work. Using this function allows |
| * for such cases. |
| * |
| * Returns zero on success, -1 on overflow |
| */ |
| int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len) |
| { |
| WARN_ON(s->size == 0); |
| |
| if (seq_buf_can_fit(s, len)) { |
| memcpy(s->buffer + s->len, mem, len); |
| s->len += len; |
| return 0; |
| } |
| seq_buf_set_overflow(s); |
| return -1; |
| } |
| |
| #define MAX_MEMHEX_BYTES 8U |
| #define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1) |
| |
| /** |
| * seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex |
| * @s: seq_buf descriptor |
| * @mem: The raw memory to write its hex ASCII representation of |
| * @len: The length of the raw memory to copy (in bytes) |
| * |
| * This is similar to seq_buf_putmem() except instead of just copying the |
| * raw memory into the buffer it writes its ASCII representation of it |
| * in hex characters. |
| * |
| * Returns zero on success, -1 on overflow |
| */ |
| int seq_buf_putmem_hex(struct seq_buf *s, const void *mem, |
| unsigned int len) |
| { |
| unsigned char hex[HEX_CHARS]; |
| const unsigned char *data = mem; |
| unsigned int start_len; |
| int i, j; |
| |
| WARN_ON(s->size == 0); |
| |
| while (len) { |
| start_len = min(len, HEX_CHARS - 1); |
| #ifdef __BIG_ENDIAN |
| for (i = 0, j = 0; i < start_len; i++) { |
| #else |
| for (i = start_len-1, j = 0; i >= 0; i--) { |
| #endif |
| hex[j++] = hex_asc_hi(data[i]); |
| hex[j++] = hex_asc_lo(data[i]); |
| } |
| if (WARN_ON_ONCE(j == 0 || j/2 > len)) |
| break; |
| |
| /* j increments twice per loop */ |
| len -= j / 2; |
| hex[j++] = ' '; |
| |
| seq_buf_putmem(s, hex, j); |
| if (seq_buf_has_overflowed(s)) |
| return -1; |
| } |
| return 0; |
| } |
| |
| /** |
| * seq_buf_path - copy a path into the sequence buffer |
| * @s: seq_buf descriptor |
| * @path: path to write into the sequence buffer. |
| * @esc: set of characters to escape in the output |
| * |
| * Write a path name into the sequence buffer. |
| * |
| * Returns the number of written bytes on success, -1 on overflow |
| */ |
| int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc) |
| { |
| char *buf; |
| size_t size = seq_buf_get_buf(s, &buf); |
| int res = -1; |
| |
| WARN_ON(s->size == 0); |
| |
| if (size) { |
| char *p = d_path(path, buf, size); |
| if (!IS_ERR(p)) { |
| char *end = mangle_path(buf, p, esc); |
| if (end) |
| res = end - buf; |
| } |
| } |
| seq_buf_commit(s, res); |
| |
| return res; |
| } |
| |
| /** |
| * seq_buf_to_user - copy the squence buffer to user space |
| * @s: seq_buf descriptor |
| * @ubuf: The userspace memory location to copy to |
| * @cnt: The amount to copy |
| * |
| * Copies the sequence buffer into the userspace memory pointed to |
| * by @ubuf. It starts from the last read position (@s->readpos) |
| * and writes up to @cnt characters or till it reaches the end of |
| * the content in the buffer (@s->len), which ever comes first. |
| * |
| * On success, it returns a positive number of the number of bytes |
| * it copied. |
| * |
| * On failure it returns -EBUSY if all of the content in the |
| * sequence has been already read, which includes nothing in the |
| * sequence (@s->len == @s->readpos). |
| * |
| * Returns -EFAULT if the copy to userspace fails. |
| */ |
| int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt) |
| { |
| int len; |
| int ret; |
| |
| if (!cnt) |
| return 0; |
| |
| len = seq_buf_used(s); |
| |
| if (len <= s->readpos) |
| return -EBUSY; |
| |
| len -= s->readpos; |
| if (cnt > len) |
| cnt = len; |
| ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt); |
| if (ret == cnt) |
| return -EFAULT; |
| |
| cnt -= ret; |
| |
| s->readpos += cnt; |
| return cnt; |
| } |