posix_fallocate_mac.h

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 *   Taras Glek <tglek@mozilla.com>
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#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>

// 20150108 RJVB: created from the OSX-specific code from Mozilla's mozilla::fallocation() function
// of which the licensing information is copied above.

#ifdef cplusplus
extern "C" {
#endif

static int posix_fallocate(int fd, off_t offset, off_t len)
{
    fstore_t store = {F_ALLOCATECONTIG, F_PEOFPOSMODE, offset, len};
    // 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 false;
    }
    return 0 == ftruncate(fd, len);
}

#ifdef cplusplus
}
#endif