linux/tools/include/nolibc/stdio.h

/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
/*
 * minimal stdio function definitions for NOLIBC
 * Copyright (C) 2017-2021 Willy Tarreau <w@1wt.eu>
 */

#ifndef _NOLIBC_STDIO_H
#define _NOLIBC_STDIO_H

#include <stdarg.h>

#include "std.h"
#include "arch.h"
#include "errno.h"
#include "types.h"
#include "sys.h"
#include "stdlib.h"
#include "string.h"

#ifndef EOF
#define EOF (-1)
#endif

/* just define FILE as a non-empty type */
typedef struct FILE {
	char dummy[1];
} FILE;

/* We define the 3 common stdio files as constant invalid pointers that
 * are easily recognized.
 */
static __attribute__((unused)) FILE* const stdin  = (FILE*)-3;
static __attribute__((unused)) FILE* const stdout = (FILE*)-2;
static __attribute__((unused)) FILE* const stderr = (FILE*)-1;

/* getc(), fgetc(), getchar() */

#define getc(stream) fgetc(stream)

static __attribute__((unused))
int fgetc(FILE* stream)
{
	unsigned char ch;
	int fd;

	if (stream < stdin || stream > stderr)
		return EOF;

	fd = 3 + (long)stream;

	if (read(fd, &ch, 1) <= 0)
		return EOF;
	return ch;
}

static __attribute__((unused))
int getchar(void)
{
	return fgetc(stdin);
}


/* putc(), fputc(), putchar() */

#define putc(c, stream) fputc(c, stream)

static __attribute__((unused))
int fputc(int c, FILE* stream)
{
	unsigned char ch = c;
	int fd;

	if (stream < stdin || stream > stderr)
		return EOF;

	fd = 3 + (long)stream;

	if (write(fd, &ch, 1) <= 0)
		return EOF;
	return ch;
}

static __attribute__((unused))
int putchar(int c)
{
	return fputc(c, stdout);
}


/* fwrite(), puts(), fputs(). Note that puts() emits '\n' but not fputs(). */

/* internal fwrite()-like function which only takes a size and returns 0 on
 * success or EOF on error. It automatically retries on short writes.
 */
static __attribute__((unused))
int _fwrite(const void *buf, size_t size, FILE *stream)
{
	ssize_t ret;
	int fd;

	if (stream < stdin || stream > stderr)
		return EOF;

	fd = 3 + (long)stream;

	while (size) {
		ret = write(fd, buf, size);
		if (ret <= 0)
			return EOF;
		size -= ret;
		buf += ret;
	}
	return 0;
}

static __attribute__((unused))
size_t fwrite(const void *s, size_t size, size_t nmemb, FILE *stream)
{
	size_t written;

	for (written = 0; written < nmemb; written++) {
		if (_fwrite(s, size, stream) != 0)
			break;
		s += size;
	}
	return written;
}

static __attribute__((unused))
int fputs(const char *s, FILE *stream)
{
	return _fwrite(s, strlen(s), stream);
}

static __attribute__((unused))
int puts(const char *s)
{
	if (fputs(s, stdout) == EOF)
		return EOF;
	return putchar('\n');
}


/* fgets() */
static __attribute__((unused))
char *fgets(char *s, int size, FILE *stream)
{
	int ofs;
	int c;

	for (ofs = 0; ofs + 1 < size;) {
		c = fgetc(stream);
		if (c == EOF)
			break;
		s[ofs++] = c;
		if (c == '\n')
			break;
	}
	if (ofs < size)
		s[ofs] = 0;
	return ofs ? s : NULL;
}


/* minimal vfprintf(). It supports the following formats:
 *  - %[l*]{d,u,c,x,p}
 *  - %s
 *  - unknown modifiers are ignored.
 */
static __attribute__((unused))
int vfprintf(FILE *stream, const char *fmt, va_list args)
{
	char escape, lpref, c;
	unsigned long long v;
	unsigned int written;
	size_t len, ofs;
	char tmpbuf[21];
	const char *outstr;

	written = ofs = escape = lpref = 0;
	while (1) {
		c = fmt[ofs++];

		if (escape) {
			/* we're in an escape sequence, ofs == 1 */
			escape = 0;
			if (c == 'c' || c == 'd' || c == 'u' || c == 'x' || c == 'p') {
				char *out = tmpbuf;

				if (c == 'p')
					v = va_arg(args, unsigned long);
				else if (lpref) {
					if (lpref > 1)
						v = va_arg(args, unsigned long long);
					else
						v = va_arg(args, unsigned long);
				} else
					v = va_arg(args, unsigned int);

				if (c == 'd') {
					/* sign-extend the value */
					if (lpref == 0)
						v = (long long)(int)v;
					else if (lpref == 1)
						v = (long long)(long)v;
				}

				switch (c) {
				case 'c':
					out[0] = v;
					out[1] = 0;
					break;
				case 'd':
					i64toa_r(v, out);
					break;
				case 'u':
					u64toa_r(v, out);
					break;
				case 'p':
					*(out++) = '0';
					*(out++) = 'x';
					/* fall through */
				default: /* 'x' and 'p' above */
					u64toh_r(v, out);
					break;
				}
				outstr = tmpbuf;
			}
			else if (c == 's') {
				outstr = va_arg(args, char *);
				if (!outstr)
					outstr="(null)";
			}
			else if (c == '%') {
				/* queue it verbatim */
				continue;
			}
			else {
				/* modifiers or final 0 */
				if (c == 'l') {
					/* long format prefix, maintain the escape */
					lpref++;
				}
				escape = 1;
				goto do_escape;
			}
			len = strlen(outstr);
			goto flush_str;
		}

		/* not an escape sequence */
		if (c == 0 || c == '%') {
			/* flush pending data on escape or end */
			escape = 1;
			lpref = 0;
			outstr = fmt;
			len = ofs - 1;
		flush_str:
			if (_fwrite(outstr, len, stream) != 0)
				break;

			written += len;
		do_escape:
			if (c == 0)
				break;
			fmt += ofs;
			ofs = 0;
			continue;
		}

		/* literal char, just queue it */
	}
	return written;
}

static __attribute__((unused))
int fprintf(FILE *stream, const char *fmt, ...)
{
	va_list args;
	int ret;

	va_start(args, fmt);
	ret = vfprintf(stream, fmt, args);
	va_end(args);
	return ret;
}

static __attribute__((unused))
int printf(const char *fmt, ...)
{
	va_list args;
	int ret;

	va_start(args, fmt);
	ret = vfprintf(stdout, fmt, args);
	va_end(args);
	return ret;
}

static __attribute__((unused))
void perror(const char *msg)
{
	fprintf(stderr, "%s%serrno=%d\n", (msg && *msg) ? msg : "", (msg && *msg) ? ": " : "", errno);
}

#endif /* _NOLIBC_STDIO_H */