Function solana_rbpf::helpers::memfrob

pub fn memfrob(
    addr: u64, 
    len: u64, 
    unused3: u64, 
    unused4: u64, 
    unused5: u64, 
    _context: &mut HelperContext, 
    _ro_regions: &[MemoryRegion], 
    rw_regions: &[MemoryRegion]
) -> Result<u64, Error>

Same as void *memfrob(void *s, size_t n); in string.h in C. See the GNU manual page (in section 3) for memfrob. The memory is directly modified, and the helper returns 0 in all cases. Arguments 3 to 5 are unused.

Examples

use solana_rbpf::helpers;
use solana_rbpf::memory_region::MemoryRegion;

let val = vec![0x00, 0x00, 0x00, 0x00, 0x00, 0x11, 0x22, 0x33];
let val_va = 0x1000;
let regions = [MemoryRegion::new_from_slice(&val, val_va)];

helpers::memfrob(val_va, 8, 0, 0, 0, &mut None, &regions, &regions);
assert_eq!(val, vec![0x2a, 0x2a, 0x2a, 0x2a, 0x2a, 0x3b, 0x08, 0x19]);
helpers::memfrob(val_va, 8, 0, 0, 0, &mut None, &regions, &regions);
assert_eq!(val, vec![0x00, 0x00, 0x00, 0x00, 0x00, 0x11, 0x22, 0x33]);