How do you get the file size for an open file?

[Member 4194593]

I have the following code:

FILE \*fp = stdin;

if ((fp = fopen(argv\[optind\], "rb")) == NULL) {
     printf("Cannot open file %s\\n", argv\[optind\]);
     return 2;
}

It executes correctly and the correct file is accessed. I added the following to get the file size:

SizeLow = GetFileSize(\_fileno(fp), & SizeHigh);
if ((SizeLow == 0xFFFFFFFF) && ((Error = GetLastError()) != NO\_ERROR)) {
     printf("Cannot read file size for %s, error %d\\n", argv\[optind\], Error);
     help();
     return 2;
}
if (binary && (SizeHigh > 0x70000000)) {
    printf("File too big for Binary Mode\\n");
    help();
    return 2;
}
\_\_asm {
          mov   eax,SizeLow
          mov   edx,SizeHigh
          cmp   binary,TRUE
          jnz   Bytes
          shld  edx,eax,3
          shl   eax,3
      Bytes:
          mov   DWORD PTR totalc,eax
          mov   DWORD PTR totalc+4,edx
      }

When I execute I get the following:

ent.exe f:\tst1.tst >ent1.txt
Cannot read file size for f:\tst1.tst, error 6

What am I doing wrong with the the GetFileSize call? In case you are wondering, this is a modification to John Walker's ENT to speed up execution for huge files. Dave.

[Jochen Arndt]

GetFileSize() expects a file HANDLE but you are passing a file descriptor returned by _fileno(). This is indicated by the error code 6 ERROR_INVALID_HANDLE. See A Handy Guide To Handling Handles[^] for the differences and how to convert between the various file handle types.

[Member 4194593]

Jochen, Thank you for the excellent reference. Just what I needed. Dave.

[Member 4194593]

Jochen, With this line, everything works correctly:

SizeLow = GetFileSize(\_get\_osfhandle(\_fileno(fp)), & SizeHigh);

Thanks for the pointer. Dave.