private int handleJoin(int pid, int status) {
if (pid < 0 || status < 0) {
return -1;
}
// get the child process from our hashmap
childProcess childData;
if (map.containsKey(pid)) {
childData = map.get(pid);
} else {
return -1;
}
// join it
childData.child.thread.join();
// remove from hashmap
map.remove(pid);
// write the exit # to the address status
if (childData.status != -999) {
byte exitStatus[] = new byte[4];
exitStatus = Lib.bytesFromInt(childData.status);
int byteTransfered = writeVirtualMemory(status, exitStatus);
if (byteTransfered == 4) {
return 1;
} else {
return 0;
}
}
return 0;
}
/**
* Load the executable with the specified name into this process, and prepare to pass it the
* specified arguments. Opens the executable, reads its header information, and copies sections
* and arguments into this process's virtual memory.
*
* @param name the name of the file containing the executable.
* @param args the arguments to pass to the executable.
* @return <tt>true</tt> if the executable was successfully loaded.
*/
private boolean load(String name, String[] args) {
Lib.debug(dbgProcess, "UserProcess.load(\"" + name + "\")");
OpenFile executable = ThreadedKernel.fileSystem.open(name, false);
if (executable == null) {
Lib.debug(dbgProcess, "\topen failed");
return false;
}
try {
coff = new Coff(executable);
} catch (EOFException e) {
executable.close();
Lib.debug(dbgProcess, "\tcoff load failed");
return false;
}
// make sure the sections are contiguous and start at page 0
numPages = 0;
for (int s = 0; s < coff.getNumSections(); s++) {
CoffSection section = coff.getSection(s);
if (section.getFirstVPN() != numPages) {
coff.close();
Lib.debug(dbgProcess, "\tfragmented executable");
return false;
}
numPages += section.getLength();
}
// make sure the argv array will fit in one page
byte[][] argv = new byte[args.length][];
int argsSize = 0;
for (int i = 0; i < args.length; i++) {
argv[i] = args[i].getBytes();
// 4 bytes for argv[] pointer; then string plus one for null byte
argsSize += 4 + argv[i].length + 1;
}
if (argsSize > pageSize) {
coff.close();
Lib.debug(dbgProcess, "\targuments too long");
return false;
}
// program counter initially points at the program entry point
initialPC = coff.getEntryPoint();
// next comes the stack; stack pointer initially points to top of it
numPages += stackPages;
initialSP = numPages * pageSize;
// and finally reserve 1 page for arguments
numPages++;
if (!loadSections()) return false;
// store arguments in last page
int entryOffset = (numPages - 1) * pageSize;
int stringOffset = entryOffset + args.length * 4;
this.argc = args.length;
this.argv = entryOffset;
for (int i = 0; i < argv.length; i++) {
byte[] stringOffsetBytes = Lib.bytesFromInt(stringOffset);
Lib.assertTrue(writeVirtualMemory(entryOffset, stringOffsetBytes) == 4);
entryOffset += 4;
Lib.assertTrue(writeVirtualMemory(stringOffset, argv[i]) == argv[i].length);
stringOffset += argv[i].length;
Lib.assertTrue(writeVirtualMemory(stringOffset, new byte[] {0}) == 1);
stringOffset += 1;
}
return true;
}