stage0 修复部分问题

stage0/spl_syscall.c

@@ -168,63 +168,70 @@ SYSCALL_2(vm_strcmp, const char *, const char *, strcmp(a1, a2))
 SYSCALL_3(vm_memcpy, void *, const void *, size_t, (memcpy(a1, a2, a3), (uintptr_t)a1))
 
 static spl_vm_val_t vm_printf(int nargs, spl_vm_val_t *args) {
-    (void)args;
-    if (nargs <= 0) {
+    if (nargs <= 0)
         return 0;
+
+    /* args[0] 是 SPL 的 []u8 format 参数。VM 里 slice 作为参数传递时，
+       栈上压的是"指向 slice 结构体的指针"，结构为 {ptr:*u8, len:u64} */
+    const spl_vm_val_t *fmt_slice = (const spl_vm_val_t *)args[0];
+    const char *fmt = (const char *)fmt_slice[0];
+    usize fmt_len = (usize)fmt_slice[1];
+
+    if (nargs <= 1) {
+        fwrite(fmt, 1, fmt_len, stdout);
+        return (spl_vm_val_t)nargs;
     }
-    const char *fmt = (const char *)args[0];
-    usize fmt_len = strlen(fmt);
+
     typedef VEC(char) string_builder_t;
     string_builder_t buffer;
     vec_init(buffer);
-    if (nargs <= 1) {
-        printf("%s", fmt);
-        return nargs;
-    }
-    int arg_idx = 0;
+
+    int arg_idx = 1; /* 0 是 format */
     char tmp_buf[32];
-    memset(tmp_buf, 0, sizeof(tmp_buf));
+
     for (usize i = 0; i < fmt_len; ++i) {
         if (fmt[i] != '%') {
             vec_push(buffer, fmt[i]);
             continue;
         }
-        arg_idx += 1;
-        if (++i >= fmt_len) {
-            continue;
-        }
-        switch (fmt[i]) {
-        case '.': {
-            Assert(i + 2 < fmt_len && arg_idx + 1 <= nargs && fmt[i + 1] == '*' &&
-                   fmt[i + 2] == 's');
-            for (usize j = 0; j < args[arg_idx]; ++j) {
-                vec_push(buffer, ((const char *)args[arg_idx + 1])[j]);
-            }
-            arg_idx += 1; /* %.*s 消耗 2 个实参（len, data），遇 % 已 +1，这里补 1 */
-            i += 2;
-        } break;
-        case 'd':
-            snprintf(tmp_buf, sizeof(tmp_buf), "%zd", args[arg_idx]);
-            for (usize j = 0; j < strlen(tmp_buf); ++j) {
-                vec_push(buffer, tmp_buf[j]);
-            }
+        if (++i >= fmt_len)
             break;
+        if (arg_idx >= nargs)
+            break;
+
+        switch (fmt[i]) {
+        case 'd': {
+            memset(tmp_buf, 0, sizeof(tmp_buf));
+            snprintf(tmp_buf, sizeof(tmp_buf), "%zd", (isize)args[arg_idx]);
+            for (usize j = 0; tmp_buf[j] != '\0'; ++j)
+                vec_push(buffer, tmp_buf[j]);
+            arg_idx++;
+            break;
+        }
         case 'c':
             vec_push(buffer, (char)args[arg_idx]);
+            arg_idx++;
             break;
-        case 's':
-            for (usize j = 0; j < strlen((const char *)args[arg_idx]); ++j) {
-                vec_push(buffer, ((const char *)args[arg_idx])[j]);
-            }
+        case 's': {
+            const spl_vm_val_t *s = (const spl_vm_val_t *)args[arg_idx];
+            const char *p = (const char *)s[0];
+            usize l = (usize)s[1];
+            for (usize j = 0; j < l; ++j)
+                vec_push(buffer, p[j]);
+            arg_idx++;
             break;
+        }
         default:
-            continue;
+            vec_push(buffer, '%');
+            vec_push(buffer, fmt[i]);
+            break;
         }
     }
-    vec_push(buffer, '\0');
-    printf("%s", buffer.data);
+
+    if (vec_size(buffer) > 0)
+        fwrite(buffer.data, 1, vec_size(buffer), stdout);
     vec_free(buffer);
-    return nargs;
+    return (spl_vm_val_t)nargs;
 }
 
 /* =================================================================