//================================================
// Read noBytes into buffer from the file fHandle
//================================================
long ReadFromFile(struct FCB *fHandle, char *buffer, long noBytes)
{
long retval = 0;
long bytesRead = 0;
char done = 0;
char *buff;
struct Message *FSMsg;
if (noBytes == 0)
return 0;
buff = AllocKMem(PageSize);
FSMsg = ALLOCMSG;
while (noBytes > PageSize)
{
FSMsg->nextMessage = 0;
FSMsg->byte = READFILE;
FSMsg->quad1 = (long) fHandle;
FSMsg->quad2 = (long) buff;
FSMsg->quad3 = PageSize;
SendReceiveMessage(FSPort, FSMsg);
copyMem(buff, buffer + bytesRead, (size_t) (FSMsg->quad1));
bytesRead += FSMsg->quad1;
noBytes -= PageSize;
if (FSMsg->quad1 < PageSize)
done = 1;
}
if (!done)
{
FSMsg->nextMessage = 0;
FSMsg->byte = READFILE;
FSMsg->quad1 = (long) fHandle;
FSMsg->quad2 = (long) buff;
FSMsg->quad3 = noBytes;
SendReceiveMessage(FSPort, FSMsg);
copyMem(buff, buffer + bytesRead, (size_t) (FSMsg->quad1));
bytesRead += FSMsg->quad1;
}
retval = bytesRead;
DeallocMem(buff);
DeallocMem(FSMsg);
return (retval);
}
//===============================================================================
// This loads the program "name" into memory, if it exists.
//===============================================================================
long DoExec(char *name, char *environment)
{
struct FCB *fHandle;
long argv, argc;
int retval = -ENOEXEC;
struct Message *FSMsg = ALLOCMSG;
char *kname = AllocKMem((size_t) strlen(name) + 6); // Enough space for "/bin" + name
strcpy(kname, "/bin/");
strcat(kname, name);
// Open file
FSMsg->nextMessage = 0;
FSMsg->byte = OPENFILE;
FSMsg->quad1 = (long) kname;
FSMsg->quad2 = (long) fHandle;
SendReceiveMessage(FSPort, FSMsg);
fHandle = (struct FCB *) FSMsg->quad1;
if ((long) fHandle > 0)
{
char magic[5];
char executable = 0;
(void) SeekFile(FSMsg, fHandle, 10, SEEK_SET);
(void) ReadFromFile(fHandle, magic, 4);
magic[4] = 0;
if (!strcmp(magic, "IJ64"))
{
(void) SeekFile(FSMsg, fHandle, 0, SEEK_SET);
LoadFlat(fHandle);
executable = 1;
}
else
{
(void) SeekFile(FSMsg, fHandle, 0, SEEK_SET);
(void) ReadFromFile(fHandle, magic, 4);
if (magic[0] == 0x7F)
{
(void) SeekFile(FSMsg, fHandle, 0, SEEK_SET);
LoadElf(FSMsg, fHandle);
executable = 1;
}
}
//Close file and deallocate memory for structures
FSMsg->nextMessage = 0;
FSMsg->byte = CLOSEFILE;
FSMsg->quad1 = (long) fHandle;
SendReceiveMessage(FSPort, FSMsg);
DeallocMem(kname);
DeallocMem(FSMsg);
if (executable)
{
long *l;
// Process the arguments for argc and argv
// Copy environment string to user data space
// It occupies the 81 bytes after the current first free memory
currentTask->environment = (void *) currentTask->firstfreemem;
memcpy(currentTask->environment, environment, 80);
currentTask->firstfreemem += 80;
argv = (long) currentTask->environment;
argc = ParseEnvironmentString(&argv);
argv += 80;
// Adjust firstfreemem to point to the first free memory location.
currentTask->firstfreemem += argc * sizeof(char *);
// Build the first MemStruct struct. Is all this necessary? User tasks don't use the kernel memory allocation, do they?
l = (long *) (currentTask->firstfreemem);
*l = 0;
*(l + 1) = -(long) (((sizeof(struct MemStruct)
+ currentTask->firstfreemem)) % PageSize);
asm("mov %0,%%rdi;" "mov %1,%%rsi":
: "r"(argc), "r"(argv):"%rax", "%rdi");
return 0;
}
else
return retval;