allocate file test

allocate-file-test.c

#define _GNU_SOURCE

#ifdef _WIN32
#include <windows.h>
#endif

#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>

static int allocate_file(int fd, uint64_t length)
{
#ifdef _WIN32
    HANDLE file = (HANDLE)_get_osfhandle(fd);
    if (file == INVALID_HANDLE_VALUE) {
        return EBADF;
    }

    int status = 0;

    LARGE_INTEGER size;
    size.HighPart = (uint32_t)((length & 0xFFFFFFFF00000000LL) >> 32);
    size.LowPart = (uint32_t)(length & 0xFFFFFFFFLL);

    if (!SetFilePointerEx(file, size, 0, FILE_BEGIN)) {
        status = GetLastError();
        goto win_finished;
    }

    if (!SetEndOfFile(file)) {
        status = GetLastError();
        goto win_finished;
    }

win_finished:

    CloseHandle(file);
    return status;

#elif __APPLE__
    fstore_t store = {F_ALLOCATECONTIG, F_PEOFPOSMODE, 0, length, 0};
    // Try to get a continous chunk of disk space
    int ret = fcntl(fd, F_PREALLOCATE, &store);
    if (-1 == ret) {
        // OK, perhaps we are too fragmented, allocate non-continuous
        store.fst_flags = F_ALLOCATEALL;
        ret = fcntl(fd, F_PREALLOCATE, &store);
        if ( -1 == ret) {
            return -1;
        }
    }
    return ftruncate(fd, length);
#else
    return fallocate(fd, FALLOC_FL_ZERO_RANGE, 0, length);
#endif
}

int main()
{
    FILE *fp = fopen("./test.data", "w+");
    if (!fp) {
        printf("Unable to open file: %s\n", strerror(errno));
        return 1;
    }
    int fd = fileno(fp);

    allocate_file(fd, 1024 * 10);

    fclose(fp);
}