From b9d8de574326e600755c28e36850f294aeb1277e Mon Sep 17 00:00:00 2001
From: Falk Werner <falk.werner@gmx.net>
Date: Tue, 22 Nov 2022 19:36:26 +0100
Subject: [PATCH] added description of most data types

---
 doc/protocol.md | 130 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 126 insertions(+), 4 deletions(-)

diff --git a/doc/protocol.md b/doc/protocol.md
index 23763cf..cd15349 100644
--- a/doc/protocol.md
+++ b/doc/protocol.md
@@ -11,10 +11,132 @@ For instance, the uint32 value 1 will be transferred as
 
 ### Basic data types
 
-| Data | Width  | Description |
-| ---- | ------ | ----------- |
-| bool |  8 bit | Represents a boolean value |
-| i32  | 32 bit |
+| Data Type | Width  | Description |
+| --------- | ------ | ----------- |
+| bool      |  8 bit | boolean value |
+| u8        |  8 bit | 8 bit unsigned integer |
+| u32       | 32 bit | 32 bit unsigned integer |
+| u64       | 64 bit | 64 bit unsigned integer | 
+| i32       | 32 bit | 32 bit signed integer |
+
+### Derrived integral types
+
+| Data Type | Base Type | Description |
+| --------- | --------- | ----------- |
+| uid       | u32       | user ID     |
+| gid       | u32       | group ID    |
+| dev       | u64       | device ID   |
+| handle    | u64       | file handle |
+
+### Flags and Enums
+
+| Data Type    | Base Type | Description               |
+| ------------ | --------- | ------------------------- |
+| result       | i32       | result type of methods    |
+| access_mode  | u32       | mode of `access` method   |
+| mode         | u32       | file type and permissions |
+| open_flags   | i32       | flags of `open` method    |
+| rename_flags | u8        | flags of `rename` method  |
+
+#### result
+
+| Value Range    | Description            |
+| -------------- | ---------------------- |
+| 0              | method call succeed    |
+| negative value | error code (see below) |
+| positive value | amount of bytes read or written (`read` and `write` only) |
+
+| Error Code   | Value | Description |
+| ------------ | ----- | ----------- |
+| E2BIG        |   -7  | argument list too long |
+| EACCES       |  -13  | permission denied |
+| EAGAIN       |  -11  | resource temporarily unavailable |
+| EBADF        |   -9  | bad file descriptor |
+| EBUSY        |  -16  | device or resource busy |
+| EDESTADDRREQ |  -89  | destination address required |
+| EDQUOT       | -122  | disk quota exceeded |
+| EEXIST       |  -17  | file exists |
+| EFAULT       |  -14  | bad address |
+| EFBIG        |  -27  | file too large |
+| EINTR        |   -4  | interrupt function call |
+| EINVAL       |  -22  | invalid argument |
+| EIO          |   -5  | input / output error |
+| EISDIR       |  -21  | is a directory
+| ELOOP        |  -40  | too many levels of symbolic links |
+| EMFILE       |  -24  | too many open files |
+| EMLINK       |  -31  | too many links |
+| ENAMETOOLONG |  -36  | filename too long |
+| ENFILE       |  -23  | too many open files in system |
+| ENODATA      |  -61  | the named attribute does not exist, or the process has not access to this attribute |
+| ENODEV       |  -19  | no such device |
+| ENOENT       |   -2  | no such file or directory |
+| ENOMEM       |  -12  | not enough space / cannot allocate memory |
+| ENOSPC       |  -28  | no space left on device |
+| ENOSYS       |  -38  | function not implemented |
+| ENOTDIR      |  -20  | not a directory |
+| ENOTEMPTY    |  -39  | directory not empty |
+| ENOTSUP      |  -95  | operation not supported |
+| ENXIO        |   -6  | no such device or address |
+| EOVERFLOW    |  -75  | value too large to be stored in data type |
+| EPERM        |   -1  | operation not permitted |
+| EPIPE        |  -32  | broken pipe |
+| ERANGE       |  -34  | result too large |
+| EROFS        |  -30  | read-only filesystem |
+| ETXTBSY      |  -26  | text file busy |
+| EXDEV        |  -18  | improper link |
+| EWOULDBLOCK  |  -11  | resource temporarily unavailable |
+
+
+
+### Complex Types
+
+| Data Type  | Description           |
+| ---------- | --------------------- |
+| string     | UTF-8 string          |
+| bytes      | array of bytes        |
+| timestamp  | date and time         |
+| attributes | file attributes       |
+| statistics | filesystem statistics |
+
+#### string
+
+| Field | Data Type | Description                   |
+| ----- | --------- | ----------------------------- |
+| size  | u32       | length of the string in bytes |
+| data  | u8[]      | string data (UTF-8)           |
+
+#### bytes
+
+| Field | Data Type | Description              |
+| ----- | --------- | ------------------------ |
+| size  | u32       | length of the byte array |
+| data  | u8[]      | array data               |
+
+#### timestamp
+
+| Field   | Data Type | Description                   |
+| ------- | --------- | ----------------------------- |
+| seconds | u64       | seconds sind epoch (1.1.1970) |
+| nsec    | u32       | nano seconds                  |
+
+#### attributes
+
+| Field  | Data Type  | Description                |
+| ------ | ---------- | -------------------------- |
+| inode  | u64        | Inode value                |
+| nlink  | u64        | Number of hard links       |
+| mode   | mode (u32) | file mode flags            |
+| uid    | uid (u32)  | user ID                    |
+| gid    | gid (u32)  | group ID                   |
+| rdev   | dev (u64)  | device ID                  |
+| size   | u64        | file size                  |
+| blocks | u64        | number 512-byte blocks     |
+| atime  | timestamp  | time of last access        |
+| mtime  | timestamp  | time of last modification  |
+| ctime  | timestamp  | time of last status change |
+
+#### statistics
+
 
 ## Message