minux的源代码,一个非常小的操作系统

				/* gethostname(2) system call emulation */
				
				#include 
				#include 
				#include 
				#include 
				#include 
				#include 
				
				#define HOSTNAME_FILE "/etc/hostname.file"
				
				int gethostname(char *buf, size_t len)
				{
					int fd;
					int r;
					char *nl;
				
					if ((fd= open(HOSTNAME_FILE, O_RDONLY)) < 0) return -1;
				
					r= read(fd, buf, len);
					close(fd);
					if (r == -1) return -1;
				
					buf[len-1]= '\0';
					if ((nl= strchr(buf, '\n')) != NULL) *nl= '\0';
					return 0;
				}