From 206ca77636cca94d14d7486a7a0e2679bf107a28 Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Thu, 16 Sep 2021 06:33:26 +0000
Subject: fs_read stub, basic implementation in userland
---
src/init/main.c | 13 +++++++++++++
src/kernel/syscalls.c | 17 ++++++++++++++---
src/shared/flags.h | 1 +
3 files changed, 28 insertions(+), 3 deletions(-)
diff --git a/src/init/main.c b/src/init/main.c
index 15afaf5..bed9ddb 100644
--- a/src/init/main.c
+++ b/src/init/main.c
@@ -43,6 +43,14 @@ void fs_test(void) {
file = _syscall_open(argify("/mnt/tty"));
log("open returned. ");
_syscall_write(file, argify("hello"));
+
+ // try reading
+ char buf[8];
+ int len;
+ for (int i = 0; i < 8; i++)
+ buf[i] = '.';
+ len = _syscall_read(file, buf, len);
+ _syscall_write(tty_fd, buf, len + 1); // read 1 byte past, should be a dot
}
void fs_server(handle_t back) {
@@ -57,6 +65,11 @@ void fs_server(handle_t back) {
_syscall_fs_respond(NULL, 32); // doesn't check the path yet
break;
+ case VFSOP_READ:
+ // all reads output "world"
+ _syscall_fs_respond("world", 5);
+ break;
+
case VFSOP_WRITE:
// uppercase the buffer
for (int i = 0; i < len; i++) buf[i] &= ~id; // id == 32
diff --git a/src/kernel/syscalls.c b/src/kernel/syscalls.c
index 48e67db..d39aed9 100644
--- a/src/kernel/syscalls.c
+++ b/src/kernel/syscalls.c
@@ -135,9 +135,20 @@ fail:
return -1;
}
-int _syscall_read(handle_t handle, char __user *buf, int len) {
- if (handle < 0 || handle >= HANDLE_MAX) return -1;
- return -1;
+int _syscall_read(handle_t handle_num, char __user *buf, int len) {
+ struct handle *handle = &process_current->handles[handle_num];
+ if (handle_num < 0 || handle_num >= HANDLE_MAX) return -1;
+ if (handle->type != HANDLE_FILE) return -1;
+ return vfs_request_create((struct vfs_request) {
+ .type = VFSOP_READ,
+ .output = {
+ .buf = (userptr_t) buf,
+ .len = len,
+ },
+ .id = handle->file.id,
+ .caller = process_current,
+ .backend = handle->file.backend,
+ });
}
int _syscall_write(handle_t handle_num, const char __user *buf, int len) {
diff --git a/src/shared/flags.h b/src/shared/flags.h
index 3f182b9..eced61f 100644
--- a/src/shared/flags.h
+++ b/src/shared/flags.h
@@ -2,6 +2,7 @@
enum vfs_operation {
VFSOP_OPEN,
+ VFSOP_READ,
VFSOP_WRITE,
};
--
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