1 /* SPDX-License-Identifier: GPL-2.0 */
3 * Lightweight buffered reading library.
5 * Copyright 2019 Google LLC.
14 /* File descriptor being read/ */
16 /* Size of the read buffer. */
18 /* Pointer to storage for buffering read. */
20 /* End of the storage. */
22 /* Currently accessed data pointer. */
24 /* Set true on when the end of file on read error. */
28 static inline void io__init(struct io *io, int fd,
29 char *buf, unsigned int buf_len)
32 io->buf_len = buf_len;
39 /* Reads one character from the "io" file with similar semantics to fgetc. */
40 static inline int io__get_char(struct io *io)
48 ssize_t n = read(io->fd, io->buf, io->buf_len);
55 io->end = &io->buf[n];
61 /* Read a hexadecimal value with no 0x prefix into the out argument hex. If the
62 * first character isn't hexadecimal returns -2, io->eof returns -1, otherwise
63 * returns the character after the hexadecimal value which may be -1 for eof.
64 * If the read value is larger than a u64 the high-order bits will be dropped.
66 static inline int io__get_hex(struct io *io, __u64 *hex)
68 bool first_read = true;
72 int ch = io__get_char(io);
76 if (ch >= '0' && ch <= '9')
77 *hex = (*hex << 4) | (ch - '0');
78 else if (ch >= 'a' && ch <= 'f')
79 *hex = (*hex << 4) | (ch - 'a' + 10);
80 else if (ch >= 'A' && ch <= 'F')
81 *hex = (*hex << 4) | (ch - 'A' + 10);
90 /* Read a positive decimal value with out argument dec. If the first character
91 * isn't a decimal returns -2, io->eof returns -1, otherwise returns the
92 * character after the decimal value which may be -1 for eof. If the read value
93 * is larger than a u64 the high-order bits will be dropped.
95 static inline int io__get_dec(struct io *io, __u64 *dec)
97 bool first_read = true;
101 int ch = io__get_char(io);
105 if (ch >= '0' && ch <= '9')
106 *dec = (*dec * 10) + ch - '0';
115 #endif /* __API_IO__ */