fseek64, fs_total64, ftell64, fread, fwrite

[BB Hood]

I was trying to get TinyXML2 running and the example included with the library failed on me. I was using libfatfs and thought id try and use the above functions but they don't compile(undefined reference).

fs.h says:

/* 64-bit file access functions. Generally, you should only define one of
the 64-bit or 32-bit versions of these functions.*/

so lets say I ONLY have the 64 bit file access functions defined, will fs_total() call the 64 bit version since the 32-bit version isn't defined?

I tried to compile ext2 example by calling fs_total64() and I get the same compile error.

How do we call the 64-bit versions?

[BlueCrab]

I was trying to get TinyXML2 running and the example included with the library failed on me. I was using libfatfs and thought id try and use the above functions but they don't compile(undefined reference).

Can you actually give the full error? The fs_seek64, fs_total64, and fs_tell64 functions should all be defined. fseek64 and ftell64 are not part of KOS (they'd be in newlib, if anywhere).

fs.h says:

/* 64-bit file access functions. Generally, you should only define one of
the 64-bit or 32-bit versions of these functions.*/

so lets say I ONLY have the 64 bit file access functions defined, will fs_total() call the 64 bit version since the 32-bit version isn't defined?

Correct. fs_total will prefer the 32-bit version, but fall-back to the 64-bit version if needed. fs_total64 does the opposite (prefers 64-bit, falls back to 32-bit). See the following code snippet from fs.c:

Code: Select all

size_t fs_total(file_t fd) {
    fs_hnd_t *h = fs_map_hnd(fd);

    if(h == NULL) return -1;

    if(h->handler == NULL) {
        errno = EINVAL;
        return -1;
    }

    /* Prefer the 32-bit version, but fall back if needed to the 64-bit one. */
    if(h->handler->total)
        return h->handler->total(h->hnd);
    else if(h->handler->total64)
        return (size_t)h->handler->total64(h->hnd);

    errno = EINVAL;
    return -1;
}

uint64 fs_total64(file_t fd) {
    fs_hnd_t *h = fs_map_hnd(fd);

    if(h == NULL) return -1;

    if(h->handler == NULL) {
        errno = EINVAL;
        return -1;
    }

    /* Prefer the 64-bit version, but fall back if needed to the 32-bit one. */
    if(h->handler->total64)
        return h->handler->total64(h->hnd);
    else if(h->handler->total)
        return (uint64)h->handler->total(h->hnd);

    errno = EINVAL;
    return -1;
}

I tried to compile ext2 example by calling fs_total64() and I get the same compile error.

How do we call the 64-bit versions?

fs_total64 shouldn't give you any problems. The other two functions in the topic title aren't in KOS -- they're newlib's responsibility. I dunno if newlib even provides them (it probably doesn't, as they aren't standard functions, IIRC).

[BB Hood]

ugh looks like KallistiOS just needed a good cleaning and recompile. As for fseek64 and ftell64. There are actually supposed to be fseeko and ftello.

More about those functions are explained here: http://man7.org/linux/man-pages/man3/fseeko.3.html

Thanks again BlueCrab.

EDIT: So it seems fs_total()/fs_total64() only works for file descriptors and not file pointers?

Also fread() and (most likely; didnt test yet) fwrite() work differently than read() and write() for some reason.

When I use read(file descriptor) it reads the amount of bytes I tell it to in one go. When I use fread(file pointer) it reads in multiplies of 1024 bytes(repeat calls). For example:

Code: Select all

fread(buf, 1, 10, fp );

the debug output I put into fs_read() says that I want to read 1024 bytes instead of 10. Another example:

Code: Select all

fread( buf, 1, 1025, fp );

the debug output I put into fs_read() says that I want to read 1024 bytes instead of 1025. However, fs_read() is (automatically) called again reading another 1024 bytes starting from ptr = 1024.

read(file descriptor) doesn't do this. It reads it in one go (the right amount of bytes asked for) instead of being called again.