--- /dev/null
+/*
+ Device File Virtualization Guest Preload Library
+
+ (c) Akhil Guliani and William Gross, 2015
+
+ Adapted from MPI module (c) 2012 Peter Dinda
+
+*/
+
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <errno.h>
+
+
+
+#include "devfile_hc.h"
+#include "devfile_guest_fd_tracker.h"
+
+static int __LocalFD = 0;
+static int __last_open_index = -1;
+
+
+unsigned long long syscall();
+
+int touch_ptr(volatile char* ptr, int size)
+{
+ int i;
+ for(i=0;i<size;i+=4096){
+ ptr[i] = ptr[i];
+ }
+ return 0;
+}
+
+int open(const char *path, int flags, mode_t mode)
+{
+
+ DEBUG_PRINT("path %s %d %d\n", path, flags, mode);
+
+ __last_open_index = check_name(path,dtrack);
+
+ if (__last_open_index>=0) {
+ DEBUG_PRINT("In our file, \n");
+ __LocalFD = dtrack[__last_open_index].devFD;
+ if(__LocalFD >= 0) {
+ return __LocalFD;
+ } else {
+ // Execute open hypercall here
+ char buf[8192];
+ char* my_path;
+ int path_length = strlen(path)+1;
+ //check if path is across a page boundary
+ //if so try to copy into a local buffer, that doesn't cross a page boundary
+ //if its greater than 4k, fail
+ if (path_length > 4096){
+ DEBUG_PRINT("Path greater than 4k, failing open\n");
+ return -1;
+ }
+ //forcing path to be in a single page
+ my_path = (char*)((((unsigned long long)buf+4096)/4096)*4096);
+ strcpy(my_path,path); // my_path is touched via this
+ long long sys_errno;
+ int rcFD = dev_file_syscall_hcall(SYS64_OPEN,(long long)my_path,flags,0 ,0,0,0,&sys_errno);
+ DEBUG_PRINT(" ReturnFD : %d; \n", rcFD);
+ __LocalFD = rcFD;
+ // set global errno so caller can see
+ errno=sys_errno;
+ return rcFD;
+ }
+ } else {
+ DEBUG_PRINT("performing original open\n");
+
+ return syscall(SYS64_OPEN, path, flags, mode);
+ }
+}
+
+size_t read(int fd, void *buf, size_t count)
+{
+ //does buf+count extend pass page boundary?
+ //if so, only do up to page boundary
+ // if( (buf%4096)+count <= 4096)
+ // normal
+
+ if (fd == __LocalFD || (check_fd(fd,dtrack)>=0)){
+ long long sys_errno;
+ //Need to handle only up to a page boundary, can't handle contiguous pages right now
+ count = MIN(count,4096-((unsigned long long)buf%4096));
+ touch_ptr(buf,count);
+ int ret = dev_file_syscall_hcall(SYS64_READ,fd,(long long)buf,count,0,0,0,&sys_errno);
+ DEBUG_PRINT("Read of %lu bytes returned %d (errno %lld)\n",count,ret,sys_errno);
+ errno = sys_errno;
+ return ret;
+ } else {
+ DEBUG_PRINT("performing original read\n");
+ return syscall(SYS64_READ,fd, buf, count);
+ }
+}
+
+ssize_t write(int fd, const void *buf, size_t count)
+{
+ if (fd == __LocalFD || (check_fd(fd,dtrack)>=0)) {
+ long long sys_errno;
+ //Need to handle only up to a page boundary, can't handle contiguous pages right now
+ count = MIN(count,4096-((unsigned long long)buf%4096));
+ touch_ptr((char*)buf,count);
+ int ret = dev_file_syscall_hcall(SYS64_WRITE,fd, (long long)buf,count,0,0,0,&sys_errno);
+ DEBUG_PRINT("Write of %lu bytes returned %d (errno %lld)\n",count,ret,sys_errno);
+ errno=sys_errno;
+ return ret;
+ } else {
+ DEBUG_PRINT("performing original write\n");
+ return syscall(SYS64_WRITE,fd, buf, count);
+ }
+}
+
+int close(int fd)
+{
+ int index = check_fd(fd,dtrack);
+ if (fd == __LocalFD || (index>=0)) {
+ long long sys_errno;
+ int ret = dev_file_syscall_hcall(SYS64_CLOSE,fd,0,0,0,0,0,&sys_errno);
+ if (ret >=0) {
+ dtrack[index].devFD = -1;
+ __LocalFD = -1;
+ }
+ DEBUG_PRINT("Close returned %d (errno %lld)\n",ret, sys_errno);
+ errno=sys_errno;
+ return ret;
+ } else {
+ DEBUG_PRINT("performing original close\n");
+ return syscall(SYS64_CLOSE,fd);
+ }
+}
+
+
+int ioctl(int fd, int request, void* data) {
+ //int sign_post;
+ int index = check_fd(fd,dtrack);
+
+ // this is where a careful, device-specific decode is needed
+ // to figure out whether the argument or anything it points
+ // is a pointer.
+ if (fd == __LocalFD || (index>=0)) {
+ long long sys_errno=0;
+ int ret;
+ // First cut for just the data pointer:
+ // if (data > &sign_post){
+ //probably on stack
+ // }
+ // if (data < brk()
+ ret = dev_file_syscall_hcall(SYS64_IOCTL,fd,request,(unsigned long long)data,0,0,0,&sys_errno);
+
+ DEBUG_PRINT("ioctl(%d) returned %d (errno %lld)\n",request,ret, sys_errno);
+ errno=sys_errno;
+ return ret;
+ }
+ else{
+ return syscall(SYS64_IOCTL,fd,request,data);
+ }
+ return -1;
+
+}
+
