[6s] Allow 6s to know about filesystems

Added a j6_proto_vfs_tag/_get_tag pair of messages to the VFS protocol
to allow filesystems to label themselves, and gave 6s the concept of
current fs and current working directory.

src/libraries/j6/include/j6/protocols/vfs.h

@@ -8,4 +8,6 @@ enum j6_proto_vfs_tag
 {
     j6_proto_vfs_load = j6_proto_base_first_proto_id,
     j6_proto_vfs_file,
+    j6_proto_vfs_get_tag,
+    j6_proto_vfs_tag,
 };

src/libraries/j6/include/j6/protocols/vfs.hh

@@ -13,7 +13,13 @@ class API client
 public:
     /// Constructor.
     /// \arg vfs_mb  Handle to the VFS service's mailbox
-    client(j6_handle_t vfs_mb);
+    client(j6_handle_t vfs_mb = 0);
+
+    /// Copy constructor
+    client(const client& c);
+
+    /// Check if this client's handle is valid
+    inline bool valid() const { return m_service != j6_handle_invalid; }
 
     /// Load a file into a VMA
     /// \arg path  Path of the file to load
@@ -21,6 +27,11 @@ public:
     /// \arg size  [out] Size of the file
     j6_status_t load_file(char *path, j6_handle_t &vma, size_t &size);
 
+    /// Get fs tag
+    /// \arg tag   [out] The filesystem's tag
+    /// \arg size  [inout] Size of the input buffer, length of the returned string
+    j6_status_t get_tag(char *tag, size_t &len);
+
 private:
     j6_handle_t m_service;
 };

src/libraries/j6/protocols/vfs.cpp

@@ -1,3 +1,4 @@
+#include "j6/types.h"
 #include <j6/errors.h>
 #include <j6/protocols/vfs.hh>
 #include <j6/syscalls.h>
@@ -12,6 +13,11 @@ client::client(j6_handle_t vfs_mb) :
 {
 }
 
+client::client(const client& c) :
+    m_service {c.m_service}
+{
+}
+
 inline size_t simple_strlen(const char *s) { size_t n = 0; while (s && *s) s++, n++; return n; }
 
 j6_status_t
@@ -61,5 +67,31 @@ client::load_file(char *path, j6_handle_t &vma, size_t &size)
 }
 
 
+j6_status_t
+client::get_tag(char *tag, size_t &len)
+{
+    if (len < sizeof(j6_status_t))
+        return j6_err_insufficient;
+
+    uint64_t message_tag = j6_proto_vfs_get_tag;
+    size_t handle_count = 0;
+
+    size_t in_len = 0;
+    j6_status_t s = j6_mailbox_call(m_service, &message_tag,
+        tag, &in_len, len, nullptr, &handle_count, 0);
+
+    if (s != j6_status_ok)
+        return s;
+
+    if (message_tag == j6_proto_base_status)
+        return *reinterpret_cast<j6_status_t*>(tag); // contains a status
+
+    if (message_tag != j6_proto_vfs_tag)
+        return j6_err_unexpected;
+
+    len = in_len;
+    return j6_status_ok; // data is now in `tag` and `len`
+}
+
 } // namespace j6::proto::vfs
 #endif // __j6kernel

src/user/6s/6s.module

@@ -7,4 +7,5 @@ module("6s",
     sources = [
         "commands.cpp",
         "main.cpp",
+        "shell.cpp",
     ])

src/user/6s/commands.cpp

@@ -1,23 +1,45 @@
 #include <edit/line.h>
 #include <util/format.h>
 #include "commands.h"
+#include "shell.h"
 
 static void
-help(edit::source &s)
+fslist(shell &s)
 {
-    for (unsigned i = 0; i < g_builtins_count; ++i) {
     char line[100];
     util::counted<char> output { line, sizeof(line) };
 
-        builtin &cmd = g_builtins[i];
+    for (auto &f : s.filesystems()) {
+        size_t len = util::format(output, "%s\r\n", f.tag);
+        s.write(line, len);
+    }
+}
 
+static void
+help(shell &s)
+{
+    char line[100];
+    util::counted<char> output { line, sizeof(line) };
+
+    for (unsigned i = 0; i < g_builtins_count; ++i) {
+        builtin &cmd = g_builtins[i];
         size_t len = util::format(output, "%20s - %s\r\n", cmd.name(), cmd.description());
         s.write(line, len);
     }
 }
 
 static void
-version(edit::source &s)
+pwd(shell &s)
+{
+    char line[100];
+    util::counted<char> output { line, sizeof(line) };
+
+    size_t len = util::format(output, "%s:%s\r\n", s.cfs(), s.cwd());
+    s.write(line, len);
+}
+
+static void
+version(shell &s)
 {
     static const char *gv = GIT_VERSION;
 
@@ -29,7 +51,9 @@ version(edit::source &s)
 }
 
 builtin g_builtins[] = {
-    { "help",       "list availble commands",               help },
+    { "fslist",     "list available filesystems",           fslist },
+    { "help",       "list available commands",              help },
+    { "pwd",        "print current working directory",      pwd },
     { "version",    "print current jsix version",           version },
 };
 size_t g_builtins_count = sizeof(g_builtins) / sizeof(g_builtins[0]);

src/user/6s/commands.h

@@ -2,15 +2,12 @@
 
 #include <stddef.h>
 
-namespace edit {
+struct shell;
-    class source;
-}
-
 
 class builtin
 {
 public:
-    using runf = void (*)(edit::source &);
+    using runf = void (*)(shell &);
 
     builtin(const char *name, const char *desc, runf func) :
         m_name {name}, m_desc {desc}, m_func {func} {}
@@ -18,7 +15,7 @@ public:
     const char * name() const { return m_name; }
     const char * description() const { return m_desc; }
 
-    void run(edit::source &s) { m_func(s); }
+    void run(shell &s) { m_func(s); }
 
 private:
     const char *m_name;

src/user/6s/main.cpp

@@ -11,13 +11,13 @@
 #include <j6/types.h>
 #include <edit/line.h>
 
-#include "commands.h"
+#include "shell.h"
 
 extern "C" {
     int main(int, const char **);
 }
 
-j6_handle_t g_handle_sys = j6_handle_invalid;
+//j6_handle_t g_handle_sys = j6_handle_invalid;
 
 const char prompt[] = "\x1b[1;32mj6> \x1b[0m";
 static constexpr size_t prompt_len = sizeof(prompt) - 1;
@@ -31,7 +31,6 @@ const char greeting[] = "\x1b[2J\x1b[H\x1b[1;30m\
 
 static constexpr size_t greeting_len = sizeof(greeting) - 1;
 
-void handle_command(edit::source &s, const char *command, size_t len);
 
 class channel_source :
     public edit::source
@@ -47,9 +46,13 @@ public:
 
     void write(char const *data, size_t len) override {
         uint8_t *outp;
-        m_chan.reserve(len, &outp);
+        while (len) {
-        memcpy(outp, data, len);
+            size_t size = m_chan.reserve(len, &outp);
-        m_chan.commit(len);
+            size_t n = len < size ? len : size;
+            memcpy(outp, data, n);
+            m_chan.commit(n);
+            len -= n;
+        }
     }
 
 private:
@@ -63,14 +66,20 @@ main(int argc, const char **argv)
     j6_handle_t event = j6_handle_invalid;
     j6_status_t result = j6_status_ok;
 
+    /*
     g_handle_sys = j6_find_init_handle(0);
     if (g_handle_sys == j6_handle_invalid)
         return 1;
+    */
 
     j6_handle_t slp = j6_find_init_handle(j6::proto::sl::id);
     if (slp == j6_handle_invalid)
         return 3;
 
+    j6_handle_t vfs = j6_find_init_handle(j6::proto::vfs::id);
+    if (vfs == j6_handle_invalid)
+        return 4;
+
     uint64_t proto_id = "jsix.protocol.stream.ouput"_id;
     j6::proto::sl::client slp_client {slp};
 
@@ -95,6 +104,9 @@ main(int argc, const char **argv)
     channel_source source {*cout};
     edit::line editor {source};
 
+    shell sh { source };
+    sh.add_filesystem(vfs);
+
     static constexpr size_t bufsize = 256;
     char buffer [bufsize];
 
@@ -102,25 +114,6 @@ main(int argc, const char **argv)
 
     while (true) {
         size_t len = editor.read(buffer, bufsize, prompt, prompt_len);
-        handle_command(source, buffer, len);
+        sh.handle_command(buffer, len);
     }
 }
-
-void
-handle_command(edit::source &s, const char *command, size_t len)
-{
-    j6::syslog(j6::logs::app, j6::log_level::info, "Command: %s", command);
-    if (len == 0)
-        return;
-
-    for (unsigned i = 0; i < g_builtins_count; ++i) {
-        builtin &cmd = g_builtins[i];
-        if (strncmp(command, cmd.name(), len) == 0) {
-            cmd.run(s);
-            return;
-        }
-    }
-
-    static const char unknown[] = "\x1b[1;33mUnknown command.\x1b[0m\r\n";
-    s.write(unknown, sizeof(unknown)-1);
-}

src/user/6s/shell.cpp

@@ -0,0 +1,43 @@
+#include <string.h>
+#include <j6/errors.h>
+#include <j6/syslog.hh>
+#include "commands.h"
+#include "shell.h"
+
+void
+shell::add_filesystem(j6_handle_t mb)
+{
+    char tag_buf [100];
+    size_t size = sizeof(tag_buf);
+    j6::proto::vfs::client c {mb};
+    j6_status_t s = c.get_tag(tag_buf, size);
+    if (s != j6_status_ok)
+        return;
+
+    char *name = new char [size + 1];
+    memcpy(name, tag_buf, size);
+    name[size] = 0;
+
+    m_fs.push_back({name, c});
+    if (!m_cfs)
+        m_cfs = name;
+}
+
+void
+shell::handle_command(const char *command, size_t len)
+{
+    j6::syslog(j6::logs::app, j6::log_level::info, "Command: %s", command);
+    if (len == 0)
+        return;
+
+    for (unsigned i = 0; i < g_builtins_count; ++i) {
+        builtin &cmd = g_builtins[i];
+        if (strncmp(command, cmd.name(), len) == 0) {
+            cmd.run(*this);
+            return;
+        }
+    }
+
+    static const char unknown[] = "\x1b[1;33mUnknown command.\x1b[0m\r\n";
+    write(unknown, sizeof(unknown)-1);
+}

src/user/6s/shell.h

@@ -0,0 +1,38 @@
+#pragma once
+
+#include <vector>
+#include <j6/protocols/vfs.hh>
+#include <edit/line.h>
+
+/// Shell state
+class shell
+{
+public:
+    struct fs {
+        const char *tag;
+        j6::proto::vfs::client client;
+    };
+    using fs_list = std::vector<fs>;
+
+    shell(edit::source &source) : m_source {source}, m_cwd {"/"}, m_cfs {nullptr} {}
+
+    const char * cwd() const { return m_cwd; }
+    const char * cfs() const { return m_cfs; }
+
+    // Transparently use source read/write functions
+    inline void consume(size_t len) { m_source.consume(len); }
+    inline void write(char const *data, size_t len) { m_source.write(data, len); }
+    inline size_t read(char const **data) { return m_source.read(data); }
+
+    void add_filesystem(j6_handle_t mb);
+    inline const fs_list & filesystems() const { return m_fs; }
+
+    void handle_command(const char *command, size_t len);
+
+private:
+    edit::source &m_source;
+
+    char m_cwd [256];
+    char const *m_cfs;
+    fs_list m_fs;
+};

src/user/srv.init/initfs.cpp

@@ -1,6 +1,7 @@
 #include <stdint.h>
 #include <j6/flags.h>
 #include <j6/errors.h>
+#include <j6/memutils.h>
 #include <j6/protocols/vfs.h>
 #include <j6/syscalls.h>
 #include <j6/syslog.hh>
@@ -11,6 +12,9 @@
 static uint64_t initfs_running = 1;
 static constexpr size_t buffer_size = 2048;
 
+static char fs_tag[] = "init";
+static constexpr size_t fs_tag_len = sizeof(fs_tag) - 1;
+
 j6_status_t
 handle_load_request(j6romfs::fs &fs, const char *path, j6_handle_t &vma)
 {
@@ -82,6 +86,14 @@ initfs_start(j6romfs::fs &fs, j6_handle_t mb)
             tag = j6_proto_vfs_file;
             break;
 
+        case j6_proto_vfs_get_tag:
+            out_len = fs_tag_len;
+            handles_count = 0;
+            tag = j6_proto_vfs_tag;
+            memcpy(buffer, fs_tag, fs_tag_len);
+            break;
+
+
         default:
             tag = j6_proto_base_status;
             *reinterpret_cast<j6_status_t*>(buffer) = j6_err_invalid_arg;
@@ -90,7 +102,6 @@ initfs_start(j6romfs::fs &fs, j6_handle_t mb)
             handles_count = 0;
         }
 
-        out_len = buffer_size;
         s = j6_mailbox_respond(mb, &tag,
                 buffer, &out_len, buffer_size,
                 &give_handle, &handles_count, max_handles,