/* 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;} /* Read from fd filling the buffer. Called when io->data == io->end. */static inline int io__fill_buffer(struct io *io){	ssize_t n; 	if (io->eof)		return -1; 	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;	}	io->data = &io->buf[0];	io->end = &io->buf[n];	return 0;} /* Reads one character from the "io" file with similar semantics to fgetc. */static inline int io__get_char(struct io *io){	if (io->data == io->end) {		int ret = io__fill_buffer(io); 		if (ret)			return ret;	}	return *io->data++;} /* 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 delim. */static inline ssize_t io__getdelim(struct io *io, char **line_out, size_t *line_len_out, int delim){	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 != delim) {		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);	*line_out = NULL;	*line_len_out = 0;	return -ENOMEM;} static inline ssize_t io__getline(struct io *io, char **line_out, size_t *line_len_out){	return io__getdelim(io, line_out, line_len_out, /*delim=*/'\n');} #endif /* __API_IO__ */