Begin GDB stub

CMakeLists.txt

@@ -4,6 +4,7 @@ set(BINARY_NAME gbac CACHE INTERNAL "Name of output binaries")
 set(CMAKE_C_FLAGS_DEBUG "-g -Wall -Wextra --std=gnu99")
 set(CMAKE_C_FLAGS_RELEASE "-O3 -Wall -Wextra --std=gnu99")
 set(USE_CLI_DEBUGGER ON CACHE BOOL "Whether or not to enable the CLI-mode ARM debugger")
+set(USE_GDB_STUB ON CACHE BOOL "Whether or not to enable the GDB stub ARM debugger")
 set(BUILD_SDL ON CACHE BOOL "Build SDL frontend")
 set(BUILD_PERF ON CACHE BOOL "Build performance profiling tool")
 file(GLOB ARM_SRC ${CMAKE_SOURCE_DIR}/src/arm/*.c)
@@ -37,6 +38,10 @@ if(USE_CLI_DEBUGGER)
 else()
 	set(DEBUGGER_LIB "")
 endif()
+
+if(USE_GDB_STUB)
+	set(DEBUGGER_SRC "${DEBUGGER_SRC};${CMAKE_SOURCE_DIR}/src/debugger/gdb-stub.c")
+endif()
 source_group("ARM debugger" FILES ${DEBUGGER_SRC})
 
 add_library(${BINARY_NAME} SHARED ${ARM_SRC} ${GBA_SRC} ${DEBUGGER_SRC} ${RENDERER_SRC} ${UTIL_SRC} ${OS_SRC})

src/debugger/debugger.c

@@ -29,7 +29,9 @@ void ARMDebuggerInit(struct ARMDebugger* debugger, struct ARMCore* cpu) {
 	debugger->breakpoints = 0;
 	debugger->memoryShim.p = debugger;
 	debugger->memoryShim.watchpoints = 0;
-	debugger->init(debugger);
+	if (debugger->init) {
+		debugger->init(debugger);
+	}
 }
 
 void ARMDebuggerDeinit(struct ARMDebugger* debugger) {
@@ -56,7 +58,11 @@ void ARMDebuggerRun(struct ARMDebugger* debugger) {
 		case DEBUGGER_RUNNING:
 			break;
 		case DEBUGGER_PAUSED:
-			debugger->paused(debugger);
+			if (debugger->paused) {
+				debugger->paused(debugger);
+			} else {
+				debugger->state = DEBUGGER_RUNNING;
+			}
 			break;
 		case DEBUGGER_EXITING:
 		case DEBUGGER_SHUTDOWN:

src/debugger/gdb-stub.c

@@ -0,0 +1,118 @@
+#include "gdb-stub.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+void _gdbStubDeinit(struct ARMDebugger* debugger) {
+	struct GDBStub* stub = (struct GDBStub*) debugger;
+	if (stub->socket >= 0) {
+		GDBStubShutdown(stub);
+	}
+}
+
+void GDBStubCreate(struct GDBStub* stub) {
+	stub->socket = -1;
+	stub->connection = -1;
+	stub->d.init = 0;
+	stub->d.deinit = _gdbStubDeinit;
+	stub->d.paused = 0;
+}
+
+int GDBStubListen(struct GDBStub* stub, int port, uint32_t bindAddress) {
+	if (stub->socket >= 0) {
+		GDBStubShutdown(stub);
+	}
+	// TODO: support IPv6
+	stub->socket = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
+	if (stub->socket < 0) {
+		printf("Couldn't open socket\n");
+		return 0;
+	}
+
+	struct sockaddr_in bindInfo = {
+		.sin_family = AF_INET,
+		.sin_port = htons(port),
+		.sin_addr = {
+			.s_addr = htonl(bindAddress)
+		}
+	};
+	int err = bind(stub->socket, (const struct sockaddr*) &bindInfo, sizeof(struct sockaddr_in));
+	if (err) {
+		goto cleanup;
+	}
+	err = listen(stub->socket, 1);
+	if (err) {
+		goto cleanup;
+	}
+	int flags = fcntl(stub->socket, F_GETFL);
+	if (flags == -1) {
+		goto cleanup;
+	}
+	flags |= O_NONBLOCK;
+	fcntl(stub->socket, F_SETFL, flags | O_NONBLOCK);
+
+	return 1;
+
+cleanup:
+	close(stub->socket);
+	stub->socket = -1;
+	return 0;
+}
+
+void GDBStubHangup(struct GDBStub* stub) {
+	if (stub->connection >= 0) {
+		close(stub->connection);
+		stub->connection = -1;
+	}
+}
+
+void GDBStubShutdown(struct GDBStub* stub) {
+	GDBStubHangup(stub);
+	if (stub->socket >= 0) {
+		close(stub->socket);
+		stub->socket = -1;
+	}
+}
+
+void GDBStubUpdate(struct GDBStub* stub) {
+	if (stub->connection == -1) {
+		stub->connection = accept(stub->socket, 0, 0);
+		if (errno == EWOULDBLOCK || errno == EAGAIN) {
+			return;
+		}
+		if (stub->connection >= 0) {
+			int flags = fcntl(stub->connection, F_GETFL);
+			if (flags == -1) {
+				goto connectionLost;
+			}
+			flags |= O_NONBLOCK;
+			fcntl(stub->connection, F_SETFL, flags | O_NONBLOCK);
+		} else {
+			goto connectionLost;
+		}
+	}
+	while (1) {
+		ssize_t messageLen = recv(stub->connection, stub->line, GDB_STUB_MAX_LINE - 1, 0);
+		if (messageLen == 0) {
+			goto connectionLost;
+		}
+		if (messageLen == -1) {
+			if (errno == EWOULDBLOCK || errno == EAGAIN) {
+				return;
+			}
+			goto connectionLost;
+		}
+		stub->line[messageLen] = '\0';
+		printf("Received message: %s\n", stub->line);
+	}
+	return;
+
+connectionLost:
+	// TODO: add logging support to the debugging interface
+	printf("Connection lost\n");
+	GDBStubHangup(stub);
+}

src/debugger/gdb-stub.h

@@ -0,0 +1,25 @@
+#ifndef GDB_STUB_H
+#define GDB_STUB_H
+
+#include "debugger.h"
+
+#define GDB_STUB_MAX_LINE 256
+
+struct GDBStub {
+	struct ARMDebugger d;
+
+	char line[GDB_STUB_MAX_LINE];
+
+	int socket;
+	int connection;
+};
+
+void GDBStubCreate(struct GDBStub*);
+int GDBStubListen(struct GDBStub*, int port, uint32_t bindAddress);
+
+void GDBStubHangup(struct GDBStub*);
+void GDBStubShutdown(struct GDBStub*);
+
+void GDBStubUpdate(struct GDBStub*);
+
+#endif