syscalls: done with open, write, close syscalls

grubshit/aaa.asm

@@ -1,29 +1,33 @@
-section .text
-    global _start       ;must be declared for using gcc
-_start:                     ;tell linker entry point
-    mov edx, len    ;message length
-    mov ecx, msg    ;message to write
-    mov ebx, 1      ;file descriptor (stdout)
-    mov eax, 4      ;system call number (sys_write)
-    int 0x80        ;call kernel
-
-    mov eax, 1      ;system call number (sys_exit)
-    int 0x80        ;call kernel
-
-    mov eax, 4
-    mov ebx, 1
-    mov ecx, msg2
-    mov edx, len2
-    int 0x80
-
-    mov eax, 1
-    int 0x80
-
-    jmp $
-
 section .data
+    file_path db '/ebalo/huy.txt', 0        ; Specific file path, null-terminated
+    message   db 'Hello, World from KatauOS!', 10, 0    ; Message to write, with newline
+    message_len equ $ - message - 1        ; Length of message (14 bytes, excluding null)
 
-msg db  'Hello, world!',0x0 ;our dear string
-len equ $ - msg         ;length of our dear string
-msg2 db 'seems like KatauOS just executed this ELF-file!!',0x0
-len2 equ $ - msg2
+section .text
+    global _start
+
+_start:
+    ; Open the file
+    mov eax, 5              ; System call number for sys_open
+    mov ebx, file_path      ; Pointer to file path
+    mov ecx, 65             ; Flags: O_WRONLY (1) | O_CREAT (64)
+    mov edx, 0x1A4          ; Mode: 0644 (rw-r--r--)
+    int 0x80                ; Invoke system call
+    mov edi, eax            ; Save file descriptor in edi
+
+    ; Write to the file
+    mov eax, 4              ; System call number for sys_write
+    mov ebx, edi            ; File descriptor
+    mov ecx, message        ; Pointer to message
+    mov edx, message_len    ; Number of bytes to write
+    int 0x80                ; Invoke system call
+
+    ; Close the file
+    mov eax, 6              ; System call number for sys_close
+    mov ebx, edi            ; File descriptor
+    int 0x80                ; Invoke system call
+
+    ; Exit the program
+    mov eax, 1              ; System call number for sys_exit
+    xor ebx, ebx            ; Return status 0
+    int 0x80                ; Invoke system call

src/tasking/syscalls.c

@@ -1,13 +1,50 @@
 #include "../include/syscalls.h"
 #include <stddef.h>
 #include "../include/stdio.h"
+#include "../include/liballoc.h"
 
 #define STDIN_FILENO 0
 #define STDOUT_FILENO 1
 #define STDERR_FILENO 2
 
 #define EBADF 9
-typedef unsigned short umode_t
+
+const char* flags_to_mode_str(int flags) {
+    static char mode[4] = {0};
+    int accmode = flags & 3;
+
+    if (accmode == 0) {         // O_RDONLY
+        mode[0] = 'r';
+        mode[1] = '\0';
+    } else if (accmode == 1) {  // O_WRONLY
+        if (flags & 0x400) {    // O_APPEND
+            mode[0] = 'a';
+            mode[1] = '\0';
+        } else {
+            mode[0] = 'w';
+            mode[1] = '\0';
+        }
+    } else if (accmode == 2) {  // O_RDWR
+        if (flags & 0x400) {    // O_APPEND
+            mode[0] = 'a';
+            mode[1] = '+';
+            mode[2] = '\0';
+        } else if (flags & 0x200) { // O_TRUNC
+            mode[0] = 'w';
+            mode[1] = '+';
+            mode[2] = '\0';
+        } else {
+            mode[0] = 'r';
+            mode[1] = '+';
+            mode[2] = '\0';
+        }
+    } else {
+        mode[0] = 'r';
+        mode[1] = '\0';
+    }
+
+    return mode;
+}
 
 int sys_write(TrapFrame *tf)
 {
@@ -32,18 +69,30 @@ int sys_write(TrapFrame *tf)
 
 int sys_open(TrapFrame *tf)
 {
-    const char* filename = tf->ebx;
+    const char* filename = (const char*)tf->ebx;
     int flags = tf->ecx;
-    umode_t mode = tf->edx;
 
     int fd = -1;
+    const char* mode_str = flags_to_mode_str(flags);
+
+    debug_log("\n====filename: %s\n", filename);
+    debug_log("\n====mode_str: %s\n", mode_str);
 
     for(int i = 3; i < MAX_OPEN_FILES; i++)
     {
+        debug_log("\n====i: %X\n", i);
         if(current->file_descriptors[i] == NULL)
         {
-            fat_fopen(current->file_descriptors[i], filename, (char)mode);
+            current->file_descriptors[i] = malloc(sizeof(file_t));  // Kernel malloc
+            debug_log("\n====FILE_DESCRIPTOR: %X\n", i);
+            int result = fat_fopen(current->file_descriptors[i], filename, mode_str);
+            if (result < 0) {
+                free(current->file_descriptors[i]);  // Free on failure
+                current->file_descriptors[i] = NULL;
+                return result;
+            }
             fd = i;
+            break;
         }
     }
 
@@ -55,7 +104,10 @@ int sys_close(TrapFrame *tf)
     int fd = tf->ebx;
     if(current->file_descriptors[fd] != NULL)
     {
-        return fat_fclose(current->file_descriptors[fd]);
+        int result = fat_fclose(current->file_descriptors[fd]);
+        free(current->file_descriptors[fd]);
+        current->file_descriptors[fd] = NULL;
+        return result;
     }
     return -1;
 }