wrapping up summer work

README.md

@@ -15,10 +15,7 @@ Hux - An x86 32-bit single-CPU toy operating system kernel built from scratch, f
 
 ## Tutorial / Development Doc
 
-I document the whole development process of Hux - its skeleton, related theories, practice pitfalls, plus everything I reckon important as a complete set of tutorials. They can be found at:
-
-- The [**WIKI pages 📝**](https://github.com/josehu07/hux-kernel/wiki) of this repo ✭
-- The Hux kernel dev doc PDF (identical, WIP)
+I document the whole development process of Hux as a complete set of tutorials. They can be found at the [**WIKI pages 📝**](https://github.com/josehu07/hux-kernel/wiki) of this GitHub repository ✭.
 
 If there are any typos / mistakes / errors, please raise an issue!
 
@@ -30,23 +27,20 @@ Requires a Linux host development environment. Tested on Ubuntu Xenial, Bionic,
 Clone the repo, set up a development cross-compilation toolchain following [this wiki page](https://github.com/josehu07/hux-kernel/wiki/02.-The-Very-First-Skeleton), then build Hux by:
 
 ```bash
+$ make clean
 $ make
 ```
 
-Or, if you just want to try out Hux without a development toolchain, download both the released kernel image `hux.iso` and the initial file system image `vsfs.img` to the folder.
-
-(The images have bot been uploaded yet. The first release of Hux is coming soon.)
+Or, if you just want to try out Hux without a development toolchain, download both the released kernel image `hux.iso` and the initial file system image `vsfs.img` to the folder. (The images have bot been uploaded yet. The first release of Hux is coming soon.)
 
-To run Hux in QEMU, do:
+To run Hux in QEMU (currently only supports GUI VGA mode, "nographics" mode is coming soon), do:
 
 ```bash
 $ make qemu
 ```
 
 You will see the QEMU GUI popping up with GRUB loaded. Choose the "`Hux`" option with <kbd>Enter</kbd> to boot into Hux.
 
-A random screenshot of the system at current progress:
-
 <p align=center> <img src="README-demo.gif" width=720px align=center /> </p>
 
 For development setup & instructions, please check out the wiki pages (recommended). I have every single detail documented there.
@@ -99,11 +93,12 @@ Check the "References" section [here](https://github.com/josehu07/hux-kernel/wik
 - [x] Essential system calls
 - [x] Time-sharing scheduler
 - [x] Basic IDE disk driver
-- [ ] Very simple file system
+- [x] Very simple file system
+- [ ] More user-level utilities
+- [ ] Thorough user-level tests
 - [ ] Caching, swapping, & logging
-- [ ] Multi-threading concurrency
 - [x] Synchronization primitives
+- [ ] Multi-threading concurrency
 - [ ] Move to APIC & IOAPIC
 - [ ] Direct memory access
-- [ ] Summary of current flaws
 - [ ] Extend Hux to Rux with Rust

src/common/printf.c

@@ -896,6 +896,8 @@ _vsnprintf(char *buf, size_t count, const char *fmt, va_list va)
         seg_end++;
         fmt++;
     }
+
+    *buf = '\0';
 }
 
 

src/filesys/exec.c

@@ -175,18 +175,19 @@ exec_program(mem_inode_t *inode, char *filename, char **argv)
             goto fail;
         sp = sp - (strlen(argv[argc]) + 1);
         sp &= 0xFFFFFFFC;   /** Align to 32-bit words. */
-        memcpy((char *) (paddr_top - (USER_MAX - sp)), argv[argc],
+        memcpy((char *) (paddr_top + PAGE_SIZE - (USER_MAX - sp)), argv[argc],
                strlen(argv[argc]) + 1);
         ustack[3 + argc] = sp;
     }
     ustack[3 + argc] = 0;       /** End of argv list. */
 
     ustack[2] = sp - (argc + 1) * 4;       /** `argv` */
-    ustack[1] = argc;                      /** `argv` */
+    ustack[1] = argc;                      /** `argc` */
     ustack[0] = 0x0000DEAD;  /** Fake return address. */
 
     sp -= (3 + argc + 1) * 4;
-    memcpy((char *) (paddr_top - (USER_MAX - sp)), ustack, (3 + argc + 1) * 4);
+    memcpy((char *) (paddr_top + PAGE_SIZE - (USER_MAX - sp)), ustack,
+           (3 + argc + 1) * 4);
 
     /** Change process name. */
     strncpy(proc->name, filename, strlen(filename));

src/filesys/file.c

@@ -10,6 +10,7 @@
 #include "file.h"
 #include "block.h"
 #include "vsfs.h"
+#include "sysfile.h"
 
 #include "../common/debug.h"
 #include "../common/string.h"
@@ -521,3 +522,17 @@ file_put(file_t *file)
     /** Actually closing, put inode. */
     inode_put(inode);
 }
+
+
+/** Get metadata information of a file. */
+void
+file_stat(file_t *file, file_stat_t *stat)
+{
+    inode_lock(file->inode);
+
+    stat->inumber = file->inode->inumber;
+    stat->type = file->inode->d_inode.type;
+    stat->size = file->inode->d_inode.size;
+
+    inode_unlock(file->inode);
+}

src/filesys/file.h

@@ -12,6 +12,7 @@
 #include <stddef.h>
 
 #include "vsfs.h"
+#include "sysfile.h"
 
 #include "../common/spinlock.h"
 #include "../common/parklock.h"
@@ -73,5 +74,7 @@ file_t *file_get();
 void file_ref(file_t *file);
 void file_put(file_t *file);
 
+void file_stat(file_t *file, file_stat_t *stat);
+
 
 #endif

src/filesys/sysfile.c

@@ -193,3 +193,20 @@ syscall_exec(void)
     }
     return SYS_FAIL_RC;
 }
+
+/** int32_t fstat(int32_t fd, file_stat_t *stat); */
+int32_t
+syscall_fstat(void)
+{
+    int32_t fd;
+    file_stat_t *stat;
+
+    if (!sysarg_get_int(0, &fd))
+        return SYS_FAIL_RC;
+    if (!sysarg_get_mem(1, (char **) &stat, sizeof(file_stat_t)))
+        return SYS_FAIL_RC;
+
+    if (!filesys_fstat(fd, stat))
+        return SYS_FAIL_RC;
+    return 0;
+}

src/filesys/sysfile.h

@@ -19,6 +19,15 @@
 #define CREATE_DIR  0x2
 
 
+/** For the `fstat()` syscall. */
+struct file_stat {
+    uint32_t inumber;
+    uint32_t type;
+    uint32_t size;
+};
+typedef struct file_stat file_stat_t;
+
+
 int32_t syscall_open();
 int32_t syscall_close();
 int32_t syscall_create();
@@ -28,6 +37,7 @@ int32_t syscall_write();
 int32_t syscall_chdir();
 int32_t syscall_getcwd();
 int32_t syscall_exec();
+int32_t syscall_fstat();
 
 
 #endif

src/filesys/vsfs.c

@@ -664,6 +664,21 @@ filesys_exec(char *path, char **argv)
 }
 
 
+/** Get metadata information about an open file. */
+bool
+filesys_fstat(int8_t fd, file_stat_t *stat)
+{
+    file_t *file = _find_process_file(fd);
+    if (file == NULL) {
+        warn("fstat: cannot find file for fd %d", fd);
+        return false;
+    }
+
+    file_stat(file, stat);
+    return true;
+}
+
+
 /** Flush the in-memory modified bitmap block to disk. */
 bool
 inode_bitmap_update(uint32_t slot_no)

src/filesys/vsfs.h

@@ -13,6 +13,8 @@
 #include <stdbool.h>
 #include <stddef.h>
 
+#include "sysfile.h"
+
 #include "../common/bitmap.h"
 
 
@@ -126,6 +128,8 @@ bool filesys_getcwd(char *buf, size_t limit);
 
 bool filesys_exec(char *path, char **argv);
 
+bool filesys_fstat(int8_t fd, file_stat_t *stat);
+
 bool inode_bitmap_update(uint32_t slot_no);
 bool data_bitmap_update(uint32_t slot_no);
 

src/interrupt/syscall.c

@@ -46,7 +46,8 @@ static syscall_t syscall_handlers[] = {
     [SYSCALL_WRITE]     syscall_write,
     [SYSCALL_CHDIR]     syscall_chdir,
     [SYSCALL_GETCWD]    syscall_getcwd,
-    [SYSCALL_EXEC]      syscall_exec
+    [SYSCALL_EXEC]      syscall_exec,
+    [SYSCALL_FSTAT]     syscall_fstat
 };
 
 #define NUM_SYSCALLS ((int32_t) (sizeof(syscall_handlers) / sizeof(syscall_t)))

src/interrupt/syscall.h

@@ -37,6 +37,7 @@
 #define SYSCALL_CHDIR   17
 #define SYSCALL_GETCWD  18
 #define SYSCALL_EXEC    19
+#define SYSCALL_FSTAT   20
 
 
 /**

user/init.c

@@ -4,6 +4,7 @@
 
 
 #include <stdint.h>
+#include <stddef.h>
 
 #include "lib/syscall.h"
 #include "lib/debug.h"
@@ -22,8 +23,9 @@ main(void)
 
     if (shell_pid == 0) {
         /** Child: exec the command line shell. */
-        char *argv[1];
-        argv[0] = 0;
+        char *argv[2];
+        argv[0] = "shell";
+        argv[1] = NULL;
         exec("shell", argv);
         error("init: failed to exec the shell program");
 

user/lib/printf.c

@@ -632,6 +632,8 @@ _vsnprintf(char *buf, size_t count, const char *fmt, va_list va)
         seg_end++;
         fmt++;
     }
+
+    *buf = '\0';
 }
 
 /** Wrapper over string printing for `printf()` and `cprintf()`. */

user/lib/syscall.h

@@ -24,6 +24,29 @@
 #define CREATE_FILE 0x1
 #define CREATE_DIR  0x2
 
+/** Struct & type code for `fstat()`. */
+#define INODE_TYPE_EMPTY 0
+#define INODE_TYPE_FILE  1
+#define INODE_TYPE_DIR   2
+
+struct file_stat {
+    uint32_t inumber;
+    uint32_t type;
+    uint32_t size;
+};
+typedef struct file_stat file_stat_t;
+
+/** Struct of a directory entry, see `vsfs.h`. */
+#define DENTRY_SIZE 128
+#define MAX_FILENAME 100
+
+struct dentry {
+    uint32_t valid;
+    uint32_t inumber;
+    char filename[DENTRY_SIZE - 8];
+} __attribute__((packed));
+typedef struct dentry dentry_t;
+
 
 /**
  * Externed from ASM `syscall.s`.
@@ -50,6 +73,7 @@ extern int32_t write(int32_t fd, char *src, uint32_t len);
 extern int32_t chdir(char *path);
 extern int32_t getcwd(char *buf, uint32_t limit);
 extern int32_t exec(char *path, char **argv);
+extern int32_t fstat(int32_t fd, file_stat_t *stat);
 
 
 #endif

user/lib/syscall.s

@@ -39,3 +39,4 @@ SYSCALL_LIBGEN  write,   SYSCALL_WRITE
 SYSCALL_LIBGEN  chdir,   SYSCALL_CHDIR
 SYSCALL_LIBGEN  getcwd,  SYSCALL_GETCWD
 SYSCALL_LIBGEN  exec,    SYSCALL_EXEC
+SYSCALL_LIBGEN  fstat,   SYSCALL_FSTAT

user/lib/syslist.s

@@ -30,3 +30,4 @@ SYSCALL_WRITE   = 16
 SYSCALL_CHDIR   = 17
 SYSCALL_GETCWD  = 18
 SYSCALL_EXEC    = 19
+SYSCALL_FSTAT   = 20