libc/stdio/local.h

/*	$OpenBSD: local.h,v 1.12 2005/10/10 17:37:44 espie Exp $	*/

/*-
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#pragma once

#include <pthread.h>
#include <stdbool.h>
#include <wchar.h>

#if defined(__cplusplus) // Until we fork all of stdio...
#include "private/bionic_fortify.h"
#endif

#include "wcio.h"

/*
 * Information local to this implementation of stdio,
 * in particular, macros and private variables.
 */

__BEGIN_DECLS

struct __sbuf {
  unsigned char* _base;
#if defined(__LP64__)
  size_t _size;
#else
  int _size;
#endif
};

struct __sFILE {
	unsigned char *_p;	/* current position in (some) buffer */
	int	_r;		/* read space left for getc() */
	int	_w;		/* write space left for putc() */
#if defined(__LP64__)
	int	_flags;		/* flags, below; this FILE is free if 0 */
	int	_file;		/* fileno, if Unix descriptor, else -1 */
#else
	short	_flags;		/* flags, below; this FILE is free if 0 */
	short	_file;		/* fileno, if Unix descriptor, else -1 */
#endif
	struct	__sbuf _bf;	/* the buffer (at least 1 byte, if !NULL) */
	int	_lbfsize;	/* 0 or -_bf._size, for inline putc */

	// Function pointers used by `funopen`.
	// Note that `_seek` is ignored if `_seek64` (in __sfileext) is set.
	// TODO: NetBSD has `funopen2` which corrects the `int`s to `size_t`s.
	// TODO: glibc has `fopencookie` which passes the function pointers in a struct.
	void* _cookie;	/* cookie passed to io functions */
	int (*_close)(void*);
	int (*_read)(void*, char*, int);
	fpos_t (*_seek)(void*, fpos_t, int);
	int (*_write)(void*, const char*, int);

	/* extension data, to avoid further ABI breakage */
	struct	__sbuf _ext;
	/* data for long sequences of ungetc() */
	unsigned char *_up;	/* saved _p when _p is doing ungetc data */
	int	_ur;		/* saved _r when _r is counting ungetc data */

	/* tricks to meet minimum requirements even when malloc() fails */
	unsigned char _ubuf[3];	/* guarantee an ungetc() buffer */
	unsigned char _nbuf[1];	/* guarantee a getc() buffer */

	/* separate buffer for fgetln() when line crosses buffer boundary */
	struct	__sbuf _lb;	/* buffer for fgetln() */

	/* Unix stdio files get aligned to block boundaries on fseek() */
	int	_blksize;	/* stat.st_blksize (may be != _bf._size) */

	fpos_t _unused_0; // This was the `_offset` field (see below).

	// Do not add new fields here. (Or remove or change the size of any above.)
	// Although bionic currently exports `stdin`, `stdout`, and `stderr` symbols,
	// that still hasn't made it to the NDK. All NDK-built apps index directly
	// into an array of this struct (which was in <stdio.h> historically), so if
	// you need to make any changes, they need to be in the `__sfileext` struct
	// below, and accessed via `_EXT`.
};

struct __sfileext {
  // ungetc buffer.
  struct __sbuf _ub;

  // Wide char io status.
  struct wchar_io_data _wcio;

  // File lock.
  pthread_mutex_t _lock;

  // __fsetlocking support.
  bool _caller_handles_locking;

  // Equivalent to `_seek` but for _FILE_OFFSET_BITS=64.
  // Callers should use this but fall back to `__sFILE::_seek`.
  off64_t (*_seek64)(void*, off64_t, int);
};

// Values for `__sFILE::_flags`.
#define __SLBF 0x0001  // Line buffered.
#define __SNBF 0x0002  // Unbuffered.
// __SRD and __SWR are mutually exclusive because they indicate what we did last.
// If you want to know whether we were opened read-write, check __SRW instead.
#define __SRD  0x0004  // Last operation was read.
#define __SWR  0x0008  // Last operation was write.
#define __SRW  0x0010  // Was opened for reading & writing.
#define __SEOF 0x0020  // Found EOF.
#define __SERR 0x0040  // Found error.
#define __SMBF 0x0080  // `_buf` is from malloc.
// #define __SAPP 0x0100 --- historical (fdopen()ed in append mode).
#define __SSTR 0x0200  // This is an sprintf/snprintf string.
// #define __SOPT 0x0400 --- historical (do fseek() optimization).
// #define __SNPT 0x0800 --- historical (do not do fseek() optimization).
// #define __SOFF 0x1000 --- historical (set iff _offset is in fact correct).
// #define __SMOD 0x2000 --- historical (set iff fgetln modified _p text).
#define __SALC 0x4000  // Allocate string space dynamically.
#define __SIGN 0x8000  // Ignore this file in _fwalk.

// TODO: remove remaining references to these obsolete flags (see above).
#define __SMOD 0
#define __SNPT 0
#define __SOPT 0

#define _EXT(fp) __BIONIC_CAST(reinterpret_cast, struct __sfileext*, (fp)->_ext._base)

#define _UB(fp) _EXT(fp)->_ub
#define _FLOCK(fp)  _EXT(fp)->_lock

#define _FILEEXT_SETUP(fp, fext) \
  do { \
    (fp)->_ext._base = __BIONIC_CAST(reinterpret_cast, unsigned char*, fext); \
    memset(_EXT(fp), 0, sizeof(struct __sfileext)); \
    _EXT(fp)->_caller_handles_locking = true; \
  } while (0)

// Android <= 19 had getc/putc macros in <stdio.h> that referred
// to __srget/__swbuf, so those symbols need to be public for LP32
// but can be hidden for LP64. Moreover, the NDK continued to ship
// those macros until r15 made unified headers the default.
__LIBC32_LEGACY_PUBLIC__ int __srget(FILE*);
__LIBC32_LEGACY_PUBLIC__ int __swbuf(int, FILE*);
__LIBC32_LEGACY_PUBLIC__ int __srefill(FILE*);

/* This was referenced by the apportable middleware for LP32. */
__LIBC32_LEGACY_PUBLIC__ int __swsetup(FILE*);

/* These were referenced by a couple of different pieces of middleware and the Crystax NDK. */
__LIBC32_LEGACY_PUBLIC__ int __sflags(const char*, int*);
__LIBC32_LEGACY_PUBLIC__ FILE* __sfp(void);
__LIBC32_LEGACY_PUBLIC__ void __smakebuf(FILE*);

/* These are referenced by the Greed for Glory franchise. */
__LIBC32_LEGACY_PUBLIC__ int __sflush(FILE *);
__LIBC32_LEGACY_PUBLIC__ int __sread(void *, char *, int);
__LIBC32_LEGACY_PUBLIC__ int __swrite(void *, const char *, int);
__LIBC32_LEGACY_PUBLIC__ fpos_t __sseek(void *, fpos_t, int);
__LIBC32_LEGACY_PUBLIC__ int __sclose(void *);
__LIBC32_LEGACY_PUBLIC__ int _fwalk(int (*)(FILE *));

off64_t __sseek64(void*, off64_t, int);
int	__sflush_locked(FILE *);
int	__swhatbuf(FILE *, size_t *, int *);
wint_t __fgetwc_unlock(FILE *);
wint_t	__ungetwc(wint_t, FILE *);
int	__vfprintf(FILE *, const char *, va_list);
int	__svfscanf(FILE *, const char *, va_list);
int	__vfwprintf(FILE *, const wchar_t *, va_list);
int	__vfwscanf(FILE *, const wchar_t *, va_list);

/*
 * Return true if the given FILE cannot be written now.
 */
#define	cantwrite(fp) \
	((((fp)->_flags & __SWR) == 0 || (fp)->_bf._base == NULL) && \
	 __swsetup(fp))

/*
 * Test whether the given stdio file has an active ungetc buffer;
 * release such a buffer, without restoring ordinary unread data.
 */
#define	HASUB(fp) (_UB(fp)._base != NULL)
#define	FREEUB(fp) { \
	if (_UB(fp)._base != (fp)->_ubuf) \
		free(_UB(fp)._base); \
	_UB(fp)._base = NULL; \
}

#define FLOCKFILE(fp)   if (!_EXT(fp)->_caller_handles_locking) flockfile(fp)
#define FUNLOCKFILE(fp) if (!_EXT(fp)->_caller_handles_locking) funlockfile(fp)

#define NO_PRINTF_PERCENT_N

/* OpenBSD exposes these in <stdio.h>, but we only want them exposed to the implementation. */
#define __sferror(p)   (((p)->_flags & __SERR) != 0)
#define __sclearerr(p) ((void)((p)->_flags &= ~(__SERR|__SEOF)))
#define __sgetc(p) (--(p)->_r < 0 ? __srget(p) : (int)(*(p)->_p++))

/* OpenBSD declares these in fvwrite.h, but we share them with C++ parts of the implementation. */
struct __siov {
  void* iov_base;
  size_t iov_len;
};
struct __suio {
  struct __siov* uio_iov;
  int uio_iovcnt;
  size_t uio_resid;
};
int __sfvwrite(FILE*, struct __suio*);
wint_t __fputwc_unlock(wchar_t wc, FILE* fp);

/* Remove the if (!__sdidinit) __sinit() idiom from untouched upstream stdio code. */
extern void __sinit(void); // Not actually implemented.
#define __sdidinit 1

size_t parsefloat(FILE*, char*, char*);
size_t wparsefloat(FILE*, wchar_t*, wchar_t*);

// Sanity check a FILE* for nullptr, so we can emit a message while crashing
// instead of doing a blind null-dereference.
#define CHECK_FP(fp) if (fp == nullptr) __fortify_fatal("%s: null FILE*", __FUNCTION__)

/*
 * Floating point scanf/printf (input/output) definitions.
 */

/* 11-bit exponent (VAX G floating point) is 308 decimal digits */
#define MAXEXP 308
/* 128 bit fraction takes up 39 decimal digits; max reasonable precision */
#define MAXFRACT 39

/*
 * MAXEXPDIG is the maximum number of decimal digits needed to store a
 * floating point exponent in the largest supported format.  It should
 * be ceil(log10(LDBL_MAX_10_EXP)) or, if hexadecimal floating point
 * conversions are supported, ceil(log10(LDBL_MAX_EXP)).  But since it
 * is presently never greater than 5 in practice, we fudge it.
 */
#define MAXEXPDIG 6
#if LDBL_MAX_EXP > 999999
#error "floating point buffers too small"
#endif

char* __hdtoa(double, const char*, int, int*, int*, char**);
char* __hldtoa(long double, const char*, int, int*, int*, char**);
char* __ldtoa(long double*, int, int, int*, int*, char**);

__END_DECLS