1 /* SPDX-License-Identifier: GPL-2.0 */
3 * Lightweight buffered reading library.
5 * Copyright 2019 Google LLC.
15 #include <linux/types.h>
18 /* File descriptor being read/ */
20 /* Size of the read buffer. */
22 /* Pointer to storage for buffering read. */
24 /* End of the storage. */
26 /* Currently accessed data pointer. */
28 /* Read timeout, 0 implies no timeout. */
30 /* Set true on when the end of file on read error. */
34 static inline void io__init(struct io *io, int fd,
35 char *buf, unsigned int buf_len)
38 io->buf_len = buf_len;
46 /* Read from fd filling the buffer. Called when io->data == io->end. */
47 static inline int io__fill_buffer(struct io *io)
54 if (io->timeout_ms != 0) {
55 struct pollfd pfds[] = {
62 n = poll(pfds, 1, io->timeout_ms);
65 if (n > 0 && !(pfds[0].revents & POLLIN)) {
74 n = read(io->fd, io->buf, io->buf_len);
80 io->data = &io->buf[0];
81 io->end = &io->buf[n];
85 /* Reads one character from the "io" file with similar semantics to fgetc. */
86 static inline int io__get_char(struct io *io)
88 if (io->data == io->end) {
89 int ret = io__fill_buffer(io);
97 /* Read a hexadecimal value with no 0x prefix into the out argument hex. If the
98 * first character isn't hexadecimal returns -2, io->eof returns -1, otherwise
99 * returns the character after the hexadecimal value which may be -1 for eof.
100 * If the read value is larger than a u64 the high-order bits will be dropped.
102 static inline int io__get_hex(struct io *io, __u64 *hex)
104 bool first_read = true;
108 int ch = io__get_char(io);
112 if (ch >= '0' && ch <= '9')
113 *hex = (*hex << 4) | (ch - '0');
114 else if (ch >= 'a' && ch <= 'f')
115 *hex = (*hex << 4) | (ch - 'a' + 10);
116 else if (ch >= 'A' && ch <= 'F')
117 *hex = (*hex << 4) | (ch - 'A' + 10);
126 /* Read a positive decimal value with out argument dec. If the first character
127 * isn't a decimal returns -2, io->eof returns -1, otherwise returns the
128 * character after the decimal value which may be -1 for eof. If the read value
129 * is larger than a u64 the high-order bits will be dropped.
131 static inline int io__get_dec(struct io *io, __u64 *dec)
133 bool first_read = true;
137 int ch = io__get_char(io);
141 if (ch >= '0' && ch <= '9')
142 *dec = (*dec * 10) + ch - '0';
151 /* Read up to and including the first delim. */
152 static inline ssize_t io__getdelim(struct io *io, char **line_out, size_t *line_len_out, int delim)
156 char *line = NULL, *temp;
160 /* TODO: reuse previously allocated memory. */
162 while (ch != delim) {
163 ch = io__get_char(io);
168 if (buf_pos == sizeof(buf)) {
169 temp = realloc(line, line_len + sizeof(buf));
173 memcpy(&line[line_len], buf, sizeof(buf));
174 line_len += sizeof(buf);
177 buf[buf_pos++] = (char)ch;
179 temp = realloc(line, line_len + buf_pos + 1);
183 memcpy(&line[line_len], buf, buf_pos);
184 line[line_len + buf_pos] = '\0';
187 *line_len_out = line_len;
196 static inline ssize_t io__getline(struct io *io, char **line_out, size_t *line_len_out)
198 return io__getdelim(io, line_out, line_len_out, /*delim=*/'\n');
201 #endif /* __API_IO__ */