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crt/stdio/fseeki64: Copy-n-paste from f{tell,seek}o64()
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The old implementation of `_ftelli64()` was introduced in 518dd33 in
2007. However it sometimes reports incorrect values. This program, after
being compiled with `i686-w64-mingw32-gcc`, outputs `-15` on the second
line on my Windows 7 Professional:

    #include <stdio.h>
    #include <assert.h>

    int main(void)
      {
        FILE* fp = fopen(__FILE__, "rb");
        assert(fp);
        printf("offset = %lld\n", (long long)_ftelli64(fp));

        char buf[1];
        ssize_t nread = fread(&buf, 1, 1, fp);
        assert(nread == 1);
        printf("offset = %lld\n", (long long)_ftelli64(fp));

        fclose(fp);
      }

This is apparently incorrect, as file offsets can't be negative.

If it was compiled with `x86_64-w64-mingw32-gcc`, it however outputs `1`
as expected.

Since 4d3b28a, we have had 64-bit tell/seek functions. They should be
used to de-duplicate these implementations.

Signed-off-by: Liu Hao <[email protected]>
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@lhmouse
lhmouse committed Jul 22, 2020
1 parent df6c08b commit edeeef2
Showing 1 changed file with 30 additions and 157 deletions.
187 changes: 30 additions & 157 deletions mingw-w64-crt/stdio/fseeki64.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6,172 +6,45 @@
#include <stdio.h>
#include <io.h>
#include <errno.h>
#include <internal.h>

#define _IOYOURBUF 0x0100
#define _IOSETVBUF 0x0400
#define _IOFEOF 0x0800
#define _IOFLRTN 0x1000
#define _IOCTRLZ 0x2000
#define _IOCOMMIT 0x4000

/* General use macros */

#define inuse(s) ((s)->_flag & (_IOREAD|_IOWRT|_IORW))
#define mbuf(s) ((s)->_flag & _IOMYBUF)
#define nbuf(s) ((s)->_flag & _IONBF)
#define ybuf(s) ((s)->_flag & _IOYOURBUF)
#define bigbuf(s) ((s)->_flag & (_IOMYBUF|_IOYOURBUF))
#define anybuf(s) ((s)->_flag & (_IOMYBUF|_IONBF|_IOYOURBUF))

#define _INTERNAL_BUFSIZ 4096
#define _SMALL_BUFSIZ 512

#define FOPEN 0x01 /* file handle open */
#define FEOFLAG 0x02 /* end of file has been encountered */
#define FCRLF 0x04 /* CR-LF across read buffer (in text mode) */
#define FPIPE 0x08 /* file handle refers to a pipe */
#define FNOINHERIT 0x10 /* file handle opened _O_NOINHERIT */
#define FAPPEND 0x20 /* file handle opened O_APPEND */
#define FDEV 0x40 /* file handle refers to device */
#define FTEXT 0x80 /* file handle is in text mode */

_CRTIMP __int64 __cdecl _lseeki64(int fh,__int64 pos,int mthd);
__int64 __cdecl _ftelli64(FILE *str);

#if !defined(__arm__) && !defined(__aarch64__) /* we have F_ARM_ANY(_fseeki64) in msvcrt.def.in */
int __cdecl _flush (FILE *str);

int __cdecl _flush (FILE *str)
int __cdecl _fseeki64(FILE* stream, __int64 offset, int whence)
{
FILE *stream;
int rc = 0; /* assume good return */
__int64 nchar;

stream = str;
if ((stream->_flag & (_IOREAD | _IOWRT)) == _IOWRT && bigbuf(stream)
&& (nchar = (__int64) (stream->_ptr - stream->_base)) > 0ll)
{
if ( _write(_fileno(stream), stream->_base, nchar) == nchar) {
if (_IORW & stream->_flag)
stream->_flag &= ~_IOWRT;
} else {
stream->_flag |= _IOERR;
rc = EOF;
fpos_t pos;
if (whence == SEEK_CUR)
{
/* If stream is invalid, fgetpos sets errno. */
if (fgetpos (stream, &pos))
return (-1);
pos += (fpos_t) offset;
}
}
stream->_ptr = stream->_base;
stream->_cnt = 0ll;
return rc;
}

int __cdecl _fseeki64(FILE *str,__int64 offset,int whence)
{
FILE *stream;
/* Init stream pointer */
stream = str;
errno=0;
if(!stream || ((whence != SEEK_SET) && (whence != SEEK_CUR) && (whence != SEEK_END)))
{
errno=EINVAL;
return -1;
}
/* Clear EOF flag */
stream->_flag &= ~_IOEOF;

if (whence == SEEK_CUR) {
offset += _ftelli64(stream);
whence = SEEK_SET;
}
/* Flush buffer as necessary */
_flush(stream);

/* If file opened for read/write, clear flags since we don't know
what the user is going to do next. If the file was opened for
read access only, decrease _bufsiz so that the next _filbuf
won't cost quite so much */

if (stream->_flag & _IORW)
stream->_flag &= ~(_IOWRT|_IOREAD);
else if ( (stream->_flag & _IOREAD) && (stream->_flag & _IOMYBUF) &&
!(stream->_flag & _IOSETVBUF) )
stream->_bufsiz = _SMALL_BUFSIZ;

/* Seek to the desired locale and return. */

return (_lseeki64(_fileno(stream), offset, whence) == -1ll ? -1 : 0);
else if (whence == SEEK_END)
{
/* If writing, we need to flush before getting file length. */
fflush (stream);
pos = (fpos_t) (_filelengthi64 (_fileno (stream)) + offset);
}
else if (whence == SEEK_SET)
pos = (fpos_t) offset;
else
{
errno = EINVAL;
return (-1);
}
return fsetpos (stream, &pos);
}

int __cdecl (*__MINGW_IMP_SYMBOL(_fseeki64))(FILE *, __int64, int) = _fseeki64;
int __cdecl (*__MINGW_IMP_SYMBOL(_fseeki64))(FILE*, __int64, int) = _fseeki64;
#endif /* !defined(__arm__) && !defined(__aarch64__) */

__int64 __cdecl _ftelli64(FILE *str)
__int64 __cdecl _ftelli64(FILE* stream)
{
FILE *stream;
size_t offset;
__int64 filepos;
register char *p;
char *max;
int fd;
size_t rdcnt = 0;

errno=0;
stream = str;
fd = _fileno(stream);
if (stream->_cnt < 0ll) stream->_cnt = 0ll;
if ((filepos = _lseeki64(fd, 0ll, SEEK_CUR)) < 0L)
return -1ll;

if (!bigbuf(stream)) /* _IONBF or no buffering designated */
return (filepos - (__int64) stream->_cnt);

offset = (size_t)(stream->_ptr - stream->_base);

if (stream->_flag & (_IOWRT|_IOREAD))
{
if (_osfile(fd) & FTEXT)
for (p = stream->_base; p < stream->_ptr; p++)
if (*p == '\n') /* adjust for '\r' */
offset++;
}
else if (!(stream->_flag & _IORW)) {
errno=EINVAL;
return -1ll;
}
if (filepos == 0ll)
return ((__int64)offset);

if (stream->_flag & _IOREAD) /* go to preceding sector */
{
if (stream->_cnt == 0ll) /* filepos holds correct location */
offset = 0ll;
else
{
rdcnt = ((size_t) stream->_cnt) + ((size_t) (size_t)(stream->_ptr - stream->_base));
if (_osfile(fd) & FTEXT) {
if (_lseeki64(fd, 0ll, SEEK_END) == filepos) {
max = stream->_base + rdcnt;
for (p = stream->_base; p < max; p++)
if (*p == '\n') /* adjust for '\r' */
rdcnt++;
if (stream->_flag & _IOCTRLZ)
++rdcnt;
} else {
_lseeki64(fd, filepos, SEEK_SET);
if ( (rdcnt <= _SMALL_BUFSIZ) && (stream->_flag & _IOMYBUF) &&
!(stream->_flag & _IOSETVBUF))
rdcnt = _SMALL_BUFSIZ;
else
rdcnt = stream->_bufsiz;
if (_osfile(fd) & FCRLF)
++rdcnt;
}
} /* end if FTEXT */
}
filepos -= (__int64)rdcnt;
} /* end else stream->_cnt != 0 */
return (filepos + (__int64)offset);
fpos_t pos;
if (fgetpos (stream, &pos))
return -1LL;
else
return (__int64) pos;
}

__int64 __cdecl (*__MINGW_IMP_SYMBOL(_ftelli64))(FILE *) = _ftelli64;
__int64 __cdecl (*__MINGW_IMP_SYMBOL(_ftelli64))(FILE*) = _ftelli64;

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