mmap.c

来自「klibc精简化的c程序库」· C语言 代码 · 共 75 行

#include <errno.h>
#include <sys/types.h>
#include <linux/unistd.h>

struct mmap_arg_struct {
	unsigned long addr;
	unsigned long len;
	unsigned long prot;
	unsigned long flags;
	unsigned long fd;
	unsigned long offset;
};

#ifndef __s390x__

void *__mmap2(void *addr, size_t len, int prot, int flags, int fd, long offset)
{
	struct mmap_arg_struct args = {
		.addr	= (unsigned long)addr,
		.len	= (unsigned long)len,
		.prot	= (unsigned long)prot,
		.flags	= (unsigned long)flags,
		.fd	= (unsigned long)fd,
		.offset = (unsigned long)offset,
	};

	register struct mmap_arg_struct *__arg1 asm("2") = &args;
	register long __svcres asm("2");
	unsigned long __res;

	__asm__ __volatile__("    svc %b1\n"
			     : "=d"(__svcres)
			     : "i"(__NR_mmap2), "0"(__arg1)
			     : "1", "cc", "memory");
	__res = __svcres;
	if (__res >= (unsigned long)-4095) {
		errno = -__res;
		__res = -1;
	}
	return (void *)__res;
}

#else /* __s390x__ */

void *mmap(void *addr, size_t len, int prot, int flags, int fd, off_t offset)
{
	struct mmap_arg_struct args = {
		.addr	= (unsigned long)addr,
		.len	= (unsigned long)len,
		.prot	= (unsigned long)prot,
		.flags	= (unsigned long)flags,
		.fd	= (unsigned long)fd,
		.offset = (unsigned long)offset,
	};

	register struct mmap_arg_struct *__arg1 asm("2") = &args;
	register long __svcres asm("2");
	unsigned long __res;

	__asm__ __volatile__ (
		"    svc %b1\n"
		: "=d" (__svcres)
		: "i" (__NR_mmap),
		  "0" (__arg1)
		: "1", "cc", "memory");
	__res = __svcres;
	if (__res >= (unsigned long)-4095) {
		errno = -__res;
		__res = -1;
	}
	return (void *)__res;
}

#endif /* __s390x__ */