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

/*
 * 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`.
};

/* minimal requirement of SUSv2 */
#define WCIO_UNGETWC_BUFSIZE 1

struct wchar_io_data {
  mbstate_t wcio_mbstate_in;
  mbstate_t wcio_mbstate_out;

  wchar_t wcio_ungetwc_buf[WCIO_UNGETWC_BUFSIZE];
  size_t wcio_ungetwc_inbuf;

  int wcio_mode; /* orientation */
};

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);

  // The pid of the child if this FILE* is from popen(3).
  pid_t _popen_pid;
};

// 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 _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)

/* 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) : __BIONIC_CAST(static_cast, 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*);

// Check a FILE* isn't nullptr, so we can emit a clear diagnostic message
// instead of just crashing with SIGSEGV.
#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**);

#define WCIO_GET(fp) (_EXT(fp) ? &(_EXT(fp)->_wcio) : NULL)

#define ORIENT_BYTES (-1)
#define ORIENT_UNKNOWN 0
#define ORIENT_CHARS 1

#define _SET_ORIENTATION(fp, mode)                                              \
  do {                                                                          \
    struct wchar_io_data* _wcio = WCIO_GET(fp);                                 \
    if (_wcio && _wcio->wcio_mode == ORIENT_UNKNOWN) _wcio->wcio_mode = (mode); \
  } while (0)

#define WCIO_FREE(fp)                           \
  do {                                          \
    struct wchar_io_data* _wcio = WCIO_GET(fp); \
    if (_wcio) {                                \
      _wcio->wcio_mode = ORIENT_UNKNOWN;        \
      _wcio->wcio_ungetwc_inbuf = 0;            \
    }                                           \
  } while (0)

__END_DECLS