Added an considerable multitasking code, fixed some minor bugs, clean up existing code.

Author: pradosh-arduino

disk.img

@@ -269,6 +269,11 @@
     "file": "/home/pradosh/osdev/source/kernel/C/shell/commands/lspci.c",
     "command": "clang -std=gnu11 -ffreestanding -w -fno-common -fno-stack-protector -fno-stack-check -fno-lto -fno-builtin -fno-omit-frame-pointer -Og -g -fPIE -I includes -I src -m64 -march=x86-64 -mno-80387 -mno-mmx -mno-red-zone -mno-sse -mno-sse2 -MMD -MP -c /home/pradosh/osdev/source/kernel/C/shell/commands/lspci.c -o /dev/null"
   },
+  {
+    "directory": "/home/pradosh/osdev/source",
+    "file": "/home/pradosh/osdev/source/kernel/C/shell/commands/tasks.c",
+    "command": "clang -std=gnu11 -ffreestanding -w -fno-common -fno-stack-protector -fno-stack-check -fno-lto -fno-builtin -fno-omit-frame-pointer -Og -g -fPIE -I includes -I src -m64 -march=x86-64 -mno-80387 -mno-mmx -mno-red-zone -mno-sse -mno-sse2 -MMD -MP -c /home/pradosh/osdev/source/kernel/C/shell/commands/tasks.c -o /dev/null"
+  },
   {
     "directory": "/home/pradosh/osdev/source",
     "file": "/home/pradosh/osdev/source/kernel/C/shell/commands/shutdown.c",
@@ -339,6 +344,11 @@
     "file": "/home/pradosh/osdev/source/kernel/C/algorithms/hashing.c",
     "command": "clang -std=gnu11 -ffreestanding -w -fno-common -fno-stack-protector -fno-stack-check -fno-lto -fno-builtin -fno-omit-frame-pointer -Og -g -fPIE -I includes -I src -m64 -march=x86-64 -mno-80387 -mno-mmx -mno-red-zone -mno-sse -mno-sse2 -MMD -MP -c /home/pradosh/osdev/source/kernel/C/algorithms/hashing.c -o /dev/null"
   },
+  {
+    "directory": "/home/pradosh/osdev/source",
+    "file": "/home/pradosh/osdev/source/kernel/C/multitasking.c",
+    "command": "clang -std=gnu11 -ffreestanding -w -fno-common -fno-stack-protector -fno-stack-check -fno-lto -fno-builtin -fno-omit-frame-pointer -Og -g -fPIE -I includes -I src -m64 -march=x86-64 -mno-80387 -mno-mmx -mno-red-zone -mno-sse -mno-sse2 -MMD -MP -c /home/pradosh/osdev/source/kernel/C/multitasking.c -o /dev/null"
+  },
   {
     "directory": "/home/pradosh/osdev/source",
     "file": "/home/pradosh/osdev/source/kernel/C/debugger.c",

source/compile_commands.json

@@ -516,6 +516,8 @@ int fat16_read(fat16_file_t* f, uint8_t* out, uint32_t size) {
         f->fs->bs.sectors_per_cluster * 512;
     uint16_t cluster = f->entry.first_cluster;
 
+    printf("READ CALLED: pos=%u size=%u\n", f->pos, size);
+
     if (cluster_size == 0 || cluster < 2)
         return 0;
 

source/kernel/C/filesystems/fat16.c

@@ -328,6 +328,7 @@ int vfs_open(const char* path, int flags, vfs_file_t* out)
     if (vfs_resolve_mount(norm, &res) != 0)
         return -2;
 
+    printf("[OPEN] %s", norm);
 
     if (res.mnt->type == FS_PROC) {
         strncpy(out->rel_path, res.rel_path, sizeof(out->rel_path));
@@ -378,6 +379,11 @@ int vfs_open(const char* path, int flags, vfs_file_t* out)
 
         out->mnt   = res.mnt;
         out->flags = flags;
+        if (flags & VFS_APPEND) {
+            out->f.fat16.pos = out->f.fat16.entry.filesize;
+        } else {
+            out->f.fat16.pos = 0;
+        }
 
         return 0;
     } else if (res.mnt->type == FS_FAT32) {
@@ -411,6 +417,12 @@ int vfs_open(const char* path, int flags, vfs_file_t* out)
 
         out->mnt = res.mnt;
         out->flags = flags;
+
+        if (flags & VFS_APPEND) {
+            out->f.fat32.pos = out->f.fat32.entry.file_size;
+        } else {
+            out->f.fat32.pos = 0;
+        }
         return 0;
     }
 

source/kernel/C/filesystems/vfs.c

@@ -273,11 +273,10 @@ static bool cursor_blink_task(uint32_t pid, uint64_t now_ticks, void* ctx, int*
     if (!next_toggle_tick)
         return false;
 
-    if (now_ticks < *next_toggle_tick)
-        return false;
-
-    ft_ctx->cursor_enabled = !ft_ctx->cursor_enabled;
-    *next_toggle_tick = now_ticks + 50;
+    while (now_ticks >= *next_toggle_tick) {
+        ft_ctx->cursor_enabled = !ft_ctx->cursor_enabled;
+        *next_toggle_tick += 50;
+    }
     return false;
 }
 

source/kernel/C/multitasking.c

@@ -18,7 +18,6 @@ volatile int pit_ticks = 0;
 void process_pit(InterruptFrame* frame) {
     (void)frame;
     pit_ticks++;
-    multitasking_on_pit_tick((uint64_t)pit_ticks);
     outb(0x20, 0x20);  // Notify the PIC that we've handled the interrupt
 }
 
@@ -34,6 +33,6 @@ void pit_sleep(uint32_t milliseconds) {
     uint32_t target_ticks = pit_ticks + (milliseconds / (1000 / pit_freq));
 
     while (pit_ticks < target_ticks) {
-        
+        asm volatile("hlt");
     }
 }

source/kernel/C/pit.c

@@ -15,7 +15,6 @@
 #include <graphics.h>
 #include <tty.h>
 #include <keyboard.h>
-#include <multitasking.h>
 
 int cmd_exec(int argc, char** argv)
 {
@@ -25,28 +24,30 @@ int cmd_exec(int argc, char** argv)
         return 1;
     }
 
-    user_task_spec_t spec;
-    memset(&spec, 0, sizeof(spec));
-
     const char* path = argv[1];
-    spec.path = path;
 
+    const char* user_argv[34];
     int user_argc = 0;
-    for (int i = 2; i < argc && user_argc < 31; ++i)
-        spec.argv[user_argc++] = argv[i];
 
-    spec.argc = user_argc;
-    spec.argv[user_argc] = NULL;
+    // argv[0] should be the program name (basename)
+    const char* basename = vfs_basename(path);
+    // user_argv[user_argc++] = basename;
+
+    // copy actual arguments AFTER the program path
+    for (int i = 2; i < argc && user_argc < 33; ++i)
+        user_argv[user_argc++] = argv[i];
+
+    user_argv[user_argc] = NULL;
 
     tty_flush_input();
     keyboard_flush_buffer();
 
-    uint32_t pid = multitasking_spawn_userland(path, &spec);
-    if (pid == 0) {
-        eprintf("exec: failed to create task");
+    if (userland_exec(path, user_argc, user_argv, NULL) != 0) {
+        keyboard_flush_buffer();
+        eprintf("exec: failed to load ELF");
         return -1;
     }
 
-    printf("exec: scheduled '%s' as pid %u", path, pid);
+    keyboard_flush_buffer();
     return 0;
 }

source/kernel/C/shell/commands/exec.c

@@ -3,17 +3,17 @@
 
 static const char* state_name(task_state_t state) {
     switch (state) {
-        case TASK_STATE_READY: return "READY";
-        case TASK_STATE_RUNNING: return "RUNNING";
-        case TASK_STATE_EXITED: return "EXITED";
-        default: return "UNKNOWN";
+        case TASK_STATE_READY:   return "ready";
+        case TASK_STATE_RUNNING: return "running";
+        case TASK_STATE_EXITED:  return "exited";
+        default: return "?";
     }
 }
 
 static const char* type_name(task_type_t type) {
     switch (type) {
-        case TASK_TYPE_KERNEL: return "KERNEL";
-        case TASK_TYPE_USERLAND: return "USER";
+        case TASK_TYPE_KERNEL:   return "kernel";
+        case TASK_TYPE_USERLAND: return "userland";
         default: return "?";
     }
 }
@@ -24,7 +24,7 @@ typedef struct {
 
 static bool print_task_row(const task_info_t* info, void* ctx_ptr) {
     list_ctx_t* ctx = (list_ctx_t*)ctx_ptr;
-    printf("%4u  %-6s %-8s exit=%d runtime_ticks=%u  %s",
+    printf("%2u  %8s %10s    exit=%02d runtime_ticks=%02u  %s",
            info->pid,
            type_name(info->type),
            state_name(info->state),
@@ -41,10 +41,10 @@ int cmd_tasks(int argc, char** argv) {
 
     list_ctx_t ctx = {0};
 
-    printf("PID   TYPE   STATE    DETAILS");
+    printf("PID     TYPE      STATE    DETAILS");
     multitasking_for_each_task(print_task_row, &ctx);
 
-    printf("total=%u active=%u",
+    printf("\ntotal=%02u active=%02u",
            multitasking_count_tasks(),
            multitasking_count_running());
 

source/kernel/C/shell/commands/tasks.c

@@ -113,8 +113,6 @@ void stream_init(void)
 
 int stream_set_file(stream_t s, vfs_file_t* file)
 {
-    fd_table_init();
-
     streams[s].file = file;
     streams[s].index = s;
 
@@ -182,7 +180,6 @@ void fd_table_init(void)
 
 bool fd_valid(int fd)
 {
-    fd_table_init();
     return fd >= 0 && fd < STREAM_MAX_FDS && fd_table[fd].used;
 }
 
@@ -199,8 +196,6 @@ vfs_file_t* fd_get_file(int fd)
 
 int fd_open(const char* path, int flags)
 {
-    fd_table_init();
-
     int fd = fd_alloc_slot();
     if (fd < 0)
         return -1;
@@ -224,8 +219,6 @@ int fd_open(const char* path, int flags)
 
 int fd_close(int fd)
 {
-    fd_table_init();
-
     if (!fd_valid(fd))
         return -1;
 
@@ -238,8 +231,6 @@ int fd_close(int fd)
 
 int fd_dup2(int oldfd, int newfd)
 {
-    fd_table_init();
-
     if (!fd_valid(oldfd) || newfd < 0 || newfd >= STREAM_MAX_FDS)
         return -1;
 
@@ -255,8 +246,6 @@ int fd_dup2(int oldfd, int newfd)
 
 int fd_dup(int oldfd)
 {
-    fd_table_init();
-
     if (!fd_valid(oldfd))
         return -1;
 

source/kernel/C/stream.c

@@ -508,8 +508,6 @@ static void fat32_short_name(const fat32_dir_entry_t* e, char* out, size_t out_s
 }
 
 static int sys_getdents64(uint64_t fd, char* buf, uint64_t buflen) {
-    fd_table_init();
-
     if (!buf || buflen < sizeof(linux_dirent64_t))
         return -LINUX_EINVAL;
     if (!fd_valid((int)fd))
@@ -676,7 +674,6 @@ static int sys_getdents64(uint64_t fd, char* buf, uint64_t buflen) {
 
 static int64 sys_open_common(int dirfd, const char* path, int flags, int mode) {
     (void)mode;
-    fd_table_init();
 
     if (path == NULL)
         return -LINUX_EINVAL;
@@ -696,8 +693,6 @@ static int64 sys_open_common(int dirfd, const char* path, int flags, int mode) {
 }
 
 static int64 sys_close(uint64_t fd) {
-    fd_table_init();
-
     if (!fd_valid((int)fd))
         return -LINUX_EBADF;
 
@@ -770,8 +765,6 @@ static int64 sys_statx(int dirfd, const char* path, int flags, unsigned int mask
 }
 
 static int64 sys_read(uint64_t fd, char* buf, uint64_t count) {
-    fd_table_init();
-
     if (buf == NULL || count == 0)
         return 0;
 
@@ -794,8 +787,6 @@ static int64 sys_read(uint64_t fd, char* buf, uint64_t count) {
 }
 
 static int64 sys_write(uint64_t fd, const char* buf, uint64_t count) {
-    fd_table_init();
-
     if (buf == NULL || count == 0)
         return 0;
 
@@ -874,7 +865,6 @@ static int64 sys_ioctl(uint64_t fd, uint64_t req, uint64_t arg) {
 }
 
 static int64 sys_fcntl(uint64_t fd, uint64_t cmd, uint64_t arg) {
-    fd_table_init();
     if (!fd_valid((int)fd))
         return -LINUX_EBADF;
 
@@ -912,8 +902,6 @@ static int64 sys_access_common(int dirfd, const char* path, int mode) {
 }
 
 static int64 sys_lseek(uint64_t fd, int64_t offset, uint64_t whence) {
-    fd_table_init();
-
     if (!fd_valid((int)fd))
         return -LINUX_EBADF;
 
@@ -945,8 +933,6 @@ static int64 sys_lseek(uint64_t fd, int64_t offset, uint64_t whence) {
 }
 
 static int64 sys_dup2(uint64_t oldfd, uint64_t newfd) {
-    fd_table_init();
-
     if (!fd_valid((int)oldfd))
         return -LINUX_EBADF;
 
@@ -958,8 +944,6 @@ static int64 sys_dup2(uint64_t oldfd, uint64_t newfd) {
 }
 
 static int64 sys_dup(uint64_t oldfd) {
-    fd_table_init();
-
     if (!fd_valid((int)oldfd))
         return -LINUX_EBADF;
 
@@ -1177,6 +1161,21 @@ static int64 sys_futex(uint32_t* uaddr, int op, uint32_t val,
     }
 }
 
+struct passwd {
+    char *pw_name;
+    int pw_uid;
+};
+
+struct passwd fake_root = {
+    .pw_name = "root",
+    .pw_uid = 0,
+};
+
+struct passwd* getpwuid(int uid) {
+    if (uid == 0)
+        return &fake_root;
+    return NULL;
+}
 
 // THIS IS FOR INTERRUPT 0X80
 void int80_handler(InterruptFrame* frame)
@@ -1304,6 +1303,9 @@ uint64_t syscall_dispatch (
         case LINUX_SYS_CHDIR:
             return sys_chdir((const char*)arg1);
 
+        case LINUX_SYS_FORK:
+            return 0;
+
         case LINUX_SYS_UNAME:
             return sys_uname((linux_utsname_t*)arg1);