remove support for processes returning strings on exit

This isn't really all that useful, it doesn't enable anything that
wasn't possible before. With it removed I'll be able to implement
process_exit() in a much simpler way.

3 files changed, 12 insertions, 25 deletions

diff --git a/src/kernel/proc.c b/src/kernel/proc.c
index b9f96c8..b1dc5c1 100644
--- a/src/kernel/proc.c
+++ b/src/kernel/proc.c
@@ -115,16 +115,12 @@ int process_try2collect(struct process *dead) {
 			dead->state = PS_DEADER;
 			parent->state = PS_RUNNING;
 
-			len = min(parent->death_msg.len, dead->death_msg.len);
-			res = virt_cpy(
-					parent->pages, parent->death_msg.buf,
-					dead->pages, dead->death_msg.buf, len);
-
-			ret = res ? len : 0;
+			ret = dead->death_msg;
 			regs_savereturn(&parent->regs, ret);
 			return ret;
 
 		default:
-			return -1;
+			return -1; // this return value isn't used anywhere
+			           // TODO enforce that, somehow? idk
 	}
 }
diff --git a/src/kernel/proc.h b/src/kernel/proc.h
index 82bb59a..592451c 100644
--- a/src/kernel/proc.h
+++ b/src/kernel/proc.h
@@ -26,10 +26,7 @@ struct process {
 
 	// saved value, meaning depends on .state
 	union {
-		struct { // PS_DEAD, PS_WAITS4CHILDDEATH
-			char __user *buf;
-			size_t len;
-		} death_msg;
+		int death_msg; // PS_DEAD
 		struct vfs_request pending_req; // PS_WAITS4FS
 		struct {
 			char __user *buf;
diff --git a/src/kernel/syscalls.c b/src/kernel/syscalls.c
index 1b91eb7..c89efc7 100644
--- a/src/kernel/syscalls.c
+++ b/src/kernel/syscalls.c
@@ -8,28 +8,22 @@
 #include <shared/syscalls.h>
 #include <stdint.h>
 
-_Noreturn void _syscall_exit(const char __user *msg, size_t len) {
+_Noreturn void _syscall_exit(int ret) {
 	process_current->state = PS_DEAD;
-	process_current->death_msg.buf = (userptr_t) msg; // discarding const
-	process_current->death_msg.len = len;
+	process_current->death_msg = ret;
 	process_try2collect(process_current);
 	process_switch_any();
 }
 
-int _syscall_await(char __user *buf, int len) {
+int _syscall_await(void) {
 	bool has_children = false;
 	process_current->state = PS_WAITS4CHILDDEATH;
-	process_current->death_msg.buf = buf;
-	process_current->death_msg.len = len;
 
 	// find any already dead children
 	for (struct process *iter = process_current->child;
 			iter; iter = iter->sibling) {
-		if (iter->state == PS_DEAD) {
-			int ret = process_try2collect(iter);
-			assert(ret >= 0);
-			return ret;
-		}
+		if (iter->state == PS_DEAD)
+			return process_try2collect(iter);
 		if (iter->state != PS_DEADER)
 			has_children = true;
 	}
@@ -38,7 +32,7 @@ int _syscall_await(char __user *buf, int len) {
 		process_switch_any(); // wait until a child dies
 	else {
 		process_current->state = PS_RUNNING;
-		return -1; // error
+		return ~0; // TODO errno
 	}
 }
 
@@ -276,9 +270,9 @@ int _syscall_memflag(void __user *addr, size_t len, int flags) {
 int _syscall(int num, int a, int b, int c, int d) {
 	switch (num) {
 		case _SYSCALL_EXIT:
-			_syscall_exit((userptr_t)a, b);
+			_syscall_exit(a);
 		case _SYSCALL_AWAIT:
-			return _syscall_await((userptr_t)a, b);
+			return _syscall_await();
 		case _SYSCALL_FORK:
 			return _syscall_fork();
 		case _SYSCALL_OPEN: