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#include <unistd.h>
#include <sys/mman.h>
#include <errno.h>
#include <stdint.h>
#include <limits.h>
#include <stdio.h>
#include <sys/syscall.h>
#define SYSCALL_MMAP2_UNIT 4096ULL
#define UNIT SYSCALL_MMAP2_UNIT
#define OFF_MASK ((-0x2000ULL << (8*sizeof(long)-1)) | (UNIT-1))
void *__mmap(void *start, size_t len, int prot, int flags, int fd, off_t off)
{
void* ret = (void*)-1;
if (off & OFF_MASK) {
errno = EINVAL;
return ret;
}
if (len >= PTRDIFF_MAX) {
errno = ENOMEM;
return ret;
}
#ifdef SYS_mmap2
ret = (void*)syscall(SYS_mmap2, start, len, prot, flags, fd, off/UNIT);
#else
ret = (void*)syscall(SYS_mmap, start, len, prot, flags, fd, off);
#endif
/* Fixup incorrect EPERM from kernel. */
if (ret == (void*)-1 && errno == EPERM && !start && (flags & MAP_ANON) && !(flags & MAP_FIXED)) {
errno = ENOMEM;
return (void*)-1;
}
return ret;
}
void *mmap(void *start, size_t len, int prot, int flags, int fd, off_t off)
{
auto res = __mmap(start, len, prot, flags, fd, off);
if (res == (void*) -1 && errno == ENOMEM) {
fprintf(stderr, "mmap failed with ENOMEM\n");
_exit(2);
}
return res;
}
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