/* SPDX-License-Identifier: GPL-2.0 *//* * Lightweight buffered reading library. * * Copyright 2019 Google LLC. */#ifndef __API_IO__#define __API_IO__ #include <stdlib.h>#include <unistd.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;	/* 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->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 = 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;	}} #endif /* __API_IO__ */