libctru/libctru/include/3ds/services/soc.h

#pragma once

Result SOC_Initialize(u32 *context_addr, u32 context_size);//Example context_size: 0x48000. The specified context buffer can no longer be accessed by the process which called this function, since the userland permissions for this block are set to no-access.
Result SOC_Shutdown();
int SOC_GetErrno();

Result SOC_Shutdown(void);
int SOC_GetErrno(void);

/* this is supposed to be in unistd.h but newlib only puts it for cygwin */
long gethostid(void);