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Add file I/O primitives to UVM
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Lines changed: 507 additions & 11 deletions

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‎.github/workflows/test.yml‎

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@@ -22,6 +22,10 @@ jobs:
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working-directory: ./spec
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run: cargo build
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- name: Check generated bindings are up to date
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working-directory: ./spec
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run: cargo run && git diff --exit-code
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- name: Test VM
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working-directory: ./vm
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run: RUST_BACKTRACE=1 cargo test

‎docs/syscalls.md‎

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@@ -381,3 +381,79 @@ Close an open socket.
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File I/O and filesystem-related functionality. This subsystem is separated out from the general-purpose io subsystem for security reasons.
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## file_open
385+
386+
```
387+
u64 file_open(const char* path, u64 flags)
388+
```
389+
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**Returns:** `u64 handle`
391+
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Open the file at the given path. The flags argument is a bitfield combining OPEN_READ, OPEN_WRITE, OPEN_CREATE and OPEN_TRUNC. All access is binary (byte-exact) with no newline translation. Returns a nonzero file handle on success, or 0 on failure (for example if the path is rejected by the sandbox or does not exist).
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## file_close
395+
396+
```
397+
void file_close(u64 handle)
398+
```
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Close a file handle previously returned by file_open. Has no effect if the handle is not open.
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## file_read
403+
404+
```
405+
i64 file_read(u64 handle, u8* buf, u64 num_bytes)
406+
```
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**Returns:** `i64 num_bytes`
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Read up to num_bytes from the file into the buffer. Returns the number of bytes actually read, 0 at end of file, or -1 on error.
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## file_write
413+
414+
```
415+
i64 file_write(u64 handle, const u8* buf, u64 num_bytes)
416+
```
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**Returns:** `i64 num_bytes`
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Write num_bytes from the buffer to the file. Returns the number of bytes actually written, or -1 on error.
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## file_seek
423+
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```
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u64 file_seek(u64 handle, u64 pos)
426+
```
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**Returns:** `u64 new_pos`
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Seek to an absolute byte offset measured from the start of the file. Returns the new absolute position.
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## file_tell
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```
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u64 file_tell(u64 handle)
436+
```
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**Returns:** `u64 pos`
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Return the current absolute byte offset, measured from the start of the file.
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## file_size
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```
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u64 file_size(u64 handle)
446+
```
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**Returns:** `u64 num_bytes`
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Return the total size of the file in bytes. Does not change the current file position.
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## Constants
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These are the constants associated with the fs subsystem:
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- `u64 OPEN_READ = 1`
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- `u64 OPEN_WRITE = 2`
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- `u64 OPEN_CREATE = 4`
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- `u64 OPEN_TRUNC = 8`
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‎ncc/include/uvm/syscalls.h‎

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@@ -125,6 +125,34 @@
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// Close an open socket.
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#define net_close(__socket_id) asm (__socket_id) -> void { syscall net_close; }
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128+
// u64 file_open(const char* path, u64 flags)
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// Open the file at the given path. The flags argument is a bitfield combining OPEN_READ, OPEN_WRITE, OPEN_CREATE and OPEN_TRUNC. All access is binary (byte-exact) with no newline translation. Returns a nonzero file handle on success, or 0 on failure (for example if the path is rejected by the sandbox or does not exist).
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#define file_open(__path, __flags) asm (__path, __flags) -> u64 { syscall file_open; }
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// void file_close(u64 handle)
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// Close a file handle previously returned by file_open. Has no effect if the handle is not open.
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#define file_close(__handle) asm (__handle) -> void { syscall file_close; }
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// i64 file_read(u64 handle, u8* buf, u64 num_bytes)
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// Read up to num_bytes from the file into the buffer. Returns the number of bytes actually read, 0 at end of file, or -1 on error.
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#define file_read(__handle, __buf, __num_bytes) asm (__handle, __buf, __num_bytes) -> i64 { syscall file_read; }
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// i64 file_write(u64 handle, const u8* buf, u64 num_bytes)
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// Write num_bytes from the buffer to the file. Returns the number of bytes actually written, or -1 on error.
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#define file_write(__handle, __buf, __num_bytes) asm (__handle, __buf, __num_bytes) -> i64 { syscall file_write; }
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// u64 file_seek(u64 handle, u64 pos)
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// Seek to an absolute byte offset measured from the start of the file. Returns the new absolute position.
146+
#define file_seek(__handle, __pos) asm (__handle, __pos) -> u64 { syscall file_seek; }
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// u64 file_tell(u64 handle)
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// Return the current absolute byte offset, measured from the start of the file.
150+
#define file_tell(__handle) asm (__handle) -> u64 { syscall file_tell; }
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// u64 file_size(u64 handle)
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// Return the total size of the file in bytes. Does not change the current file position.
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#define file_size(__handle) asm (__handle) -> u64 { syscall file_size; }
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128156
#define EVENT_QUIT 0
129157
#define EVENT_KEYDOWN 1
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#define EVENT_KEYUP 2
@@ -186,5 +214,9 @@
186214
#define KEY_DOWN 16004
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#define KEY_SHIFT 16005
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#define AUDIO_FORMAT_I16 0
217+
#define OPEN_READ 1
218+
#define OPEN_WRITE 2
219+
#define OPEN_CREATE 4
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#define OPEN_TRUNC 8
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#endif

‎spec/src/main.rs‎

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@@ -181,7 +181,7 @@ fn main()
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gen_rust_bindings("../vm/src/constants.rs", &subsystems, &idx_to_name);
183183
gen_c_bindings("../ncc/include/uvm/syscalls.h", &subsystems);
184-
gen_markdown("../doc/syscalls.md", &subsystems);
184+
gen_markdown("../docs/syscalls.md", &subsystems);
185185
}
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187187
fn gen_rust_bindings(out_file: &str, subsystems: &Vec<SubSystem>, idx_to_name: &Vec<Option<String>>)

‎spec/syscalls.json‎

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@@ -918,7 +918,165 @@
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{
919919
"subsystem": "fs",
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"description": "File I/O and filesystem-related functionality. This subsystem is separated out from the general-purpose io subsystem for security reasons.",
921-
"syscalls": [],
922-
"constants": []
921+
"syscalls": [
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{
923+
"name": "file_open",
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"args": [
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[
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"const char*",
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"path"
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],
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[
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"u64",
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"flags"
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]
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],
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"returns": [
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"u64",
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"handle"
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],
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"permission": "file_open",
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"const_idx": 15,
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"description": "Open the file at the given path. The flags argument is a bitfield combining OPEN_READ, OPEN_WRITE, OPEN_CREATE and OPEN_TRUNC. All access is binary (byte-exact) with no newline translation. Returns a nonzero file handle on success, or 0 on failure (for example if the path is rejected by the sandbox or does not exist)."
941+
},
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{
943+
"name": "file_close",
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"args": [
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[
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"u64",
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"handle"
948+
]
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],
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"returns": [
951+
"void",
952+
""
953+
],
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"permission": "file_io",
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"const_idx": 19,
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"description": "Close a file handle previously returned by file_open. Has no effect if the handle is not open."
957+
},
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{
959+
"name": "file_read",
960+
"args": [
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[
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"u64",
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"handle"
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],
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[
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"u8*",
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"buf"
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],
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[
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"u64",
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"num_bytes"
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]
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],
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"returns": [
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"i64",
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"num_bytes"
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],
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"permission": "file_io",
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"const_idx": 32,
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"description": "Read up to num_bytes from the file into the buffer. Returns the number of bytes actually read, 0 at end of file, or -1 on error."
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},
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{
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"name": "file_write",
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"args": [
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[
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"u64",
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"handle"
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],
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[
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"const u8*",
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"buf"
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],
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[
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"u64",
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"num_bytes"
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]
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],
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"returns": [
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"i64",
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"num_bytes"
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],
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"permission": "file_io",
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"const_idx": 33,
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"description": "Write num_bytes from the buffer to the file. Returns the number of bytes actually written, or -1 on error."
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},
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{
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"name": "file_seek",
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"args": [
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[
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"u64",
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"handle"
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],
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[
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"u64",
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"pos"
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]
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],
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"returns": [
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"u64",
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"new_pos"
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],
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"permission": "file_io",
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"const_idx": 34,
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"description": "Seek to an absolute byte offset measured from the start of the file. Returns the new absolute position."
1025+
},
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{
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"name": "file_tell",
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"args": [
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[
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"u64",
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"handle"
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]
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],
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"returns": [
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"u64",
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"pos"
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],
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"permission": "file_io",
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"const_idx": 35,
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"description": "Return the current absolute byte offset, measured from the start of the file."
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},
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{
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"name": "file_size",
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"args": [
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[
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"u64",
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"handle"
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]
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],
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"returns": [
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"u64",
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"num_bytes"
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],
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"permission": "file_io",
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"const_idx": 36,
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"description": "Return the total size of the file in bytes. Does not change the current file position."
1057+
}
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],
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"constants": [
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[
1061+
"OPEN_READ",
1062+
"u64",
1063+
1
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],
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[
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"OPEN_WRITE",
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"u64",
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2
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],
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[
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"OPEN_CREATE",
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"u64",
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4
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],
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[
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"OPEN_TRUNC",
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"u64",
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8
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]
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]
9231081
}
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]

‎vm/src/constants.rs‎

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@@ -4,7 +4,7 @@
44

55
#![allow(unused)]
66

7-
pub const SYSCALL_TBL_LEN: usize = 32;
7+
pub const SYSCALL_TBL_LEN: usize = 37;
88

99
pub const TIME_CURRENT_MS: u16 = 0;
1010
pub const WINDOW_CREATE: u16 = 1;
@@ -21,9 +21,11 @@ pub const EXIT: u16 = 11;
2121
pub const AUDIO_OPEN_INPUT: u16 = 12;
2222
pub const AUDIO_READ_SAMPLES: u16 = 13;
2323
pub const VM_HEAP_SIZE: u16 = 14;
24+
pub const FILE_OPEN: u16 = 15;
2425
pub const MEMSET32: u16 = 16;
2526
pub const VM_GROW_HEAP: u16 = 17;
2627
pub const AUDIO_OPEN_OUTPUT: u16 = 18;
28+
pub const FILE_CLOSE: u16 = 19;
2729
pub const PRINT_F32: u16 = 20;
2830
pub const NET_LISTEN: u16 = 21;
2931
pub const NET_ACCEPT: u16 = 22;
@@ -36,6 +38,11 @@ pub const THREAD_ID: u16 = 28;
3638
pub const THREAD_SPAWN: u16 = 29;
3739
pub const THREAD_SLEEP: u16 = 30;
3840
pub const THREAD_JOIN: u16 = 31;
41+
pub const FILE_READ: u16 = 32;
42+
pub const FILE_WRITE: u16 = 33;
43+
pub const FILE_SEEK: u16 = 34;
44+
pub const FILE_TELL: u16 = 35;
45+
pub const FILE_SIZE: u16 = 36;
3946

4047
pub struct SysCallDesc
4148
{
@@ -61,11 +68,11 @@ pub const SYSCALL_DESCS: [Option<SysCallDesc>; SYSCALL_TBL_LEN] = [
6168
Some(SysCallDesc { name: "audio_open_input", const_idx: 12, argc: 4, has_ret: true }),
6269
Some(SysCallDesc { name: "audio_read_samples", const_idx: 13, argc: 2, has_ret: false }),
6370
Some(SysCallDesc { name: "vm_heap_size", const_idx: 14, argc: 0, has_ret: true }),
64-
None,
71+
Some(SysCallDesc { name: "file_open", const_idx: 15, argc: 2, has_ret: true }),
6572
Some(SysCallDesc { name: "memset32", const_idx: 16, argc: 3, has_ret: false }),
6673
Some(SysCallDesc { name: "vm_grow_heap", const_idx: 17, argc: 1, has_ret: true }),
6774
Some(SysCallDesc { name: "audio_open_output", const_idx: 18, argc: 4, has_ret: true }),
68-
None,
75+
Some(SysCallDesc { name: "file_close", const_idx: 19, argc: 1, has_ret: false }),
6976
Some(SysCallDesc { name: "print_f32", const_idx: 20, argc: 1, has_ret: false }),
7077
Some(SysCallDesc { name: "net_listen", const_idx: 21, argc: 2, has_ret: true }),
7178
Some(SysCallDesc { name: "net_accept", const_idx: 22, argc: 4, has_ret: true }),
@@ -78,6 +85,11 @@ pub const SYSCALL_DESCS: [Option<SysCallDesc>; SYSCALL_TBL_LEN] = [
7885
Some(SysCallDesc { name: "thread_spawn", const_idx: 29, argc: 2, has_ret: true }),
7986
Some(SysCallDesc { name: "thread_sleep", const_idx: 30, argc: 1, has_ret: false }),
8087
Some(SysCallDesc { name: "thread_join", const_idx: 31, argc: 1, has_ret: true }),
88+
Some(SysCallDesc { name: "file_read", const_idx: 32, argc: 3, has_ret: true }),
89+
Some(SysCallDesc { name: "file_write", const_idx: 33, argc: 3, has_ret: true }),
90+
Some(SysCallDesc { name: "file_seek", const_idx: 34, argc: 2, has_ret: true }),
91+
Some(SysCallDesc { name: "file_tell", const_idx: 35, argc: 1, has_ret: true }),
92+
Some(SysCallDesc { name: "file_size", const_idx: 36, argc: 1, has_ret: true }),
8193
];
8294

8395
pub const EVENT_QUIT: u16 = 0;
@@ -141,3 +153,7 @@ pub const KEY_UP: u16 = 16003;
141153
pub const KEY_DOWN: u16 = 16004;
142154
pub const KEY_SHIFT: u16 = 16005;
143155
pub const AUDIO_FORMAT_I16: u16 = 0;
156+
pub const OPEN_READ: u64 = 1;
157+
pub const OPEN_WRITE: u64 = 2;
158+
pub const OPEN_CREATE: u64 = 4;
159+
pub const OPEN_TRUNC: u64 = 8;

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