7 files changed, 20 insertions, 13 deletions

diff --git a/src/kernel/arch/amd64/driver/fsroot.c b/src/kernel/arch/amd64/driver/fsroot.c
index c4c3de4..2feaf67 100644
--- a/src/kernel/arch/amd64/driver/fsroot.c
+++ b/src/kernel/arch/amd64/driver/fsroot.c
@@ -94,6 +94,8 @@ static int handle(struct vfs_request *req) {
 			switch (id) {
 				case HANDLE_VGA: {
 					void *vga = (void*)0xB8000;
+					if (req->flags)
+						return -1;
 					fs_normslice(&req->offset, &req->input.len, 80*25*2, false);
 					if (!virt_cpy_from(req->caller->pages, vga + req->offset,
 							req->input.buf, req->input.len))
diff --git a/src/kernel/arch/amd64/driver/serial.c b/src/kernel/arch/amd64/driver/serial.c
index 6dda657..93202c2 100644
--- a/src/kernel/arch/amd64/driver/serial.c
+++ b/src/kernel/arch/amd64/driver/serial.c
@@ -93,7 +93,7 @@ static void accept(struct vfs_request *req) {
 			}
 			break;
 		case VFSOP_WRITE:
-			if (req->caller) {
+			if (req->caller && !req->flags) {
 				struct virt_iter iter;
 				virt_iter_new(&iter, req->input.buf, req->input.len,
 						req->caller->pages, true, false);
diff --git a/src/kernel/syscalls.c b/src/kernel/syscalls.c
index 0dec4c5..4537ff5 100644
--- a/src/kernel/syscalls.c
+++ b/src/kernel/syscalls.c
@@ -233,7 +233,7 @@ long _syscall_read(handle_t handle_num, void __user *buf, size_t len, long offse
 long _syscall_write(handle_t handle_num, const void __user *buf, size_t len, long offset, int flags) {
 	struct handle *h = process_handle_get(process_current, handle_num);
 	if (!h) SYSCALL_RETURN(-1);
-	if (flags != 0)
+	if (flags & ~(WRITE_TRUNCATE))
 		SYSCALL_RETURN(-ENOSYS);
 	switch (h->type) {
 		case HANDLE_FILE:
diff --git a/src/shared/include/camellia/syscalls.h b/src/shared/include/camellia/syscalls.h
index 67bd713..84af276 100644
--- a/src/shared/include/camellia/syscalls.h
+++ b/src/shared/include/camellia/syscalls.h
@@ -4,6 +4,7 @@
 
 #define FORK_NOREAP 1
 #define FORK_NEWFS 2
+#define WRITE_TRUNCATE 1
 #define OPEN_CREATE 1
 #define FSR_DELEGATE 1
 
diff --git a/src/user/app/init/driver/ansiterm.c b/src/user/app/init/driver/ansiterm.c
index 5daab41..0c720eb 100644
--- a/src/user/app/init/driver/ansiterm.c
+++ b/src/user/app/init/driver/ansiterm.c
@@ -84,10 +84,14 @@ void ansiterm_drv(void) {
 				break;
 
 			case VFSOP_WRITE:
-				for (size_t i = 0; i < res.len; i++)
-					in_char(buf[i]);
-				/* if (pendingFlush) */ flush();
-				_syscall_fs_respond(NULL, res.len, 0);
+				if (res.flags) {
+					_syscall_fs_respond(NULL, -1, 0);
+				} else {
+					for (size_t i = 0; i < res.len; i++)
+						in_char(buf[i]);
+					/* if (pendingFlush) */ flush();
+					_syscall_fs_respond(NULL, res.len, 0);
+				}
 				break;
 
 			default:
diff --git a/src/user/app/init/driver/tmpfs.c b/src/user/app/init/driver/tmpfs.c
index e4c079c..7bda37f 100644
--- a/src/user/app/init/driver/tmpfs.c
+++ b/src/user/app/init/driver/tmpfs.c
@@ -99,11 +99,7 @@ void tmpfs_drv(void) {
 					_syscall_fs_respond(NULL, -1, 0);
 					break;
 				}
-				if (res.len == 0) {
-					_syscall_fs_respond(NULL, 0, 0);
-					break;
-				}
-				if (!ptr->buf) {
+				if (res.len > 0 && !ptr->buf) {
 					ptr->buf = malloc(256);
 					if (!ptr->buf) {
 						_syscall_fs_respond(NULL, -1, 0);
@@ -121,8 +117,9 @@ void tmpfs_drv(void) {
 				}
 
 				memcpy(ptr->buf + res.offset, buf, res.len);
-				if (ptr->size < res.offset + res.len)
+				if ((res.flags & WRITE_TRUNCATE) || ptr->size < res.offset + res.len) {
 					ptr->size = res.offset + res.len;
+				}
 				_syscall_fs_respond(NULL, res.len, 0);
 				break;
 
diff --git a/src/user/lib/file.c b/src/user/lib/file.c
index b7e70e6..bd8cb76 100644
--- a/src/user/lib/file.c
+++ b/src/user/lib/file.c
@@ -17,13 +17,16 @@ FILE *fopen(const char *path, const char *mode) {
 	int flags = 0;
 	if (mode[0] == 'w' || mode[0] == 'a')
 		flags |= OPEN_CREATE;
-	// TODO truncate on w
 
 	h = _syscall_open(path, strlen(path), flags);
 	if (h < 0) {
 		errno = -h;
 		return NULL;
 	}
+
+	if (mode[0] == 'w')
+		_syscall_write(h, NULL, 0, 0, WRITE_TRUNCATE);
+
 	f = fdopen(h, mode);
 	if (!f) close(h);
 	return f;