diff options
Diffstat (limited to 'tools/lib/api/io.h')
| -rw-r--r-- | tools/lib/api/io.h | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/tools/lib/api/io.h b/tools/lib/api/io.h new file mode 100644 index 0000000000..f4a9328035 --- /dev/null +++ b/tools/lib/api/io.h @@ -0,0 +1,187 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Lightweight buffered reading library. + * + * Copyright 2019 Google LLC. + */ +#ifndef __API_IO__ +#define __API_IO__ + +#include <errno.h> +#include <poll.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <linux/types.h> + +struct io { + /* File descriptor being read/ */ + int fd; + /* Size of the read buffer. */ + unsigned int buf_len; + /* Pointer to storage for buffering read. */ + char *buf; + /* End of the storage. */ + char *end; + /* Currently accessed data pointer. */ + char *data; + /* Read timeout, 0 implies no timeout. */ + int timeout_ms; + /* Set true on when the end of file on read error. */ + bool eof; +}; + +static inline void io__init(struct io *io, int fd, + char *buf, unsigned int buf_len) +{ + io->fd = fd; + io->buf_len = buf_len; + io->buf = buf; + io->end = buf; + io->data = buf; + io->timeout_ms = 0; + io->eof = false; +} + +/* Reads one character from the "io" file with similar semantics to fgetc. */ +static inline int io__get_char(struct io *io) +{ + char *ptr = io->data; + + if (io->eof) + return -1; + + if (ptr == io->end) { + ssize_t n; + + if (io->timeout_ms != 0) { + struct pollfd pfds[] = { + { + .fd = io->fd, + .events = POLLIN, + }, + }; + + n = poll(pfds, 1, io->timeout_ms); + if (n == 0) + errno = ETIMEDOUT; + if (n > 0 && !(pfds[0].revents & POLLIN)) { + errno = EIO; + n = -1; + } + if (n <= 0) { + io->eof = true; + return -1; + } + } + n = read(io->fd, io->buf, io->buf_len); + + if (n <= 0) { + io->eof = true; + return -1; + } + ptr = &io->buf[0]; + io->end = &io->buf[n]; + } + io->data = ptr + 1; + return *ptr; +} + +/* Read a hexadecimal value with no 0x prefix into the out argument hex. If the + * first character isn't hexadecimal returns -2, io->eof returns -1, otherwise + * returns the character after the hexadecimal value which may be -1 for eof. + * If the read value is larger than a u64 the high-order bits will be dropped. + */ +static inline int io__get_hex(struct io *io, __u64 *hex) +{ + bool first_read = true; + + *hex = 0; + while (true) { + int ch = io__get_char(io); + + if (ch < 0) + return ch; + if (ch >= '0' && ch <= '9') + *hex = (*hex << 4) | (ch - '0'); + else if (ch >= 'a' && ch <= 'f') + *hex = (*hex << 4) | (ch - 'a' + 10); + else if (ch >= 'A' && ch <= 'F') + *hex = (*hex << 4) | (ch - 'A' + 10); + else if (first_read) + return -2; + else + return ch; + first_read = false; + } +} + +/* Read a positive decimal value with out argument dec. If the first character + * isn't a decimal returns -2, io->eof returns -1, otherwise returns the + * character after the decimal value which may be -1 for eof. If the read value + * is larger than a u64 the high-order bits will be dropped. + */ +static inline int io__get_dec(struct io *io, __u64 *dec) +{ + bool first_read = true; + + *dec = 0; + while (true) { + int ch = io__get_char(io); + + if (ch < 0) + return ch; + if (ch >= '0' && ch <= '9') + *dec = (*dec * 10) + ch - '0'; + else if (first_read) + return -2; + else + return ch; + first_read = false; + } +} + +/* Read up to and including the first newline following the pattern of getline. */ +static inline ssize_t io__getline(struct io *io, char **line_out, size_t *line_len_out) +{ + char buf[128]; + int buf_pos = 0; + char *line = NULL, *temp; + size_t line_len = 0; + int ch = 0; + + /* TODO: reuse previously allocated memory. */ + free(*line_out); + while (ch != '\n') { + ch = io__get_char(io); + + if (ch < 0) + break; + + if (buf_pos == sizeof(buf)) { + temp = realloc(line, line_len + sizeof(buf)); + if (!temp) + goto err_out; + line = temp; + memcpy(&line[line_len], buf, sizeof(buf)); + line_len += sizeof(buf); + buf_pos = 0; + } + buf[buf_pos++] = (char)ch; + } + temp = realloc(line, line_len + buf_pos + 1); + if (!temp) + goto err_out; + line = temp; + memcpy(&line[line_len], buf, buf_pos); + line[line_len + buf_pos] = '\0'; + line_len += buf_pos; + *line_out = line; + *line_len_out = line_len; + return line_len; +err_out: + free(line); + return -ENOMEM; +} + +#endif /* __API_IO__ */ |