4 files changed, 139 insertions, 0 deletions
diff --git a/programs/libc/unistd/CMakeLists.txt b/programs/libc/unistd/CMakeLists.txt
new file mode 100644
index 0000000..e3481bc
--- /dev/null
+++ b/programs/libc/unistd/CMakeLists.txt
@@ -0,0 +1,21 @@
+# wnix, a Unix-like operating system for WebAssembly applications.
+# Copyright (C) 2025  Xavier Del Campo Romero
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+target_sources(c PRIVATE
+    close.c
+    sbrk.c
+    write.c
+)
diff --git a/programs/libc/unistd/close.c b/programs/libc/unistd/close.c
new file mode 100644
index 0000000..94ca6fc
--- /dev/null
+++ b/programs/libc/unistd/close.c
@@ -0,0 +1,30 @@
+/*
+ * wnix, a Unix-like operating system for WebAssembly applications.
+ * Copyright (C) 2025  Xavier Del Campo Romero
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <unistd.h>
+#include <errno.h>
+
+int close(const int fd)
+{
+    int __wnix_close(int, int *) __attribute__((
+        __import_module__("wnix"),
+        __import_name__("close")
+    ));
+
+    return __wnix_close(fd, &errno);
+}
diff --git a/programs/libc/unistd/sbrk.c b/programs/libc/unistd/sbrk.c
new file mode 100644
index 0000000..7e32118
--- /dev/null
+++ b/programs/libc/unistd/sbrk.c
@@ -0,0 +1,56 @@
+/*
+ * wnix, a Unix-like operating system for WebAssembly applications.
+ * Copyright (C) 2025  Xavier Del Campo Romero
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <errno.h>
+#include <unistd.h>
+#include <stddef.h>
+#include <stdint.h>
+
+void *sbrk(const intptr_t increment)
+{
+    const unsigned pagesize = 64 << 10;
+    extern char __heap_base[];
+    static char *cur = __heap_base, *end;
+
+    if (increment < 0)
+    {
+        errno = EINVAL;
+        return NULL;
+    }
+    else if (!end)
+        end = cur + __builtin_wasm_memory_size(0) * pagesize;
+
+    if (increment >= (intptr_t)end || cur >= end - increment)
+    {
+        const unsigned long pages = (uintptr_t)increment / pagesize,
+            new_end = __builtin_wasm_memory_grow(0, pages);
+
+        if (!new_end)
+        {
+            errno = ENOMEM;
+            return NULL;
+        }
+
+        end = (void *)new_end;
+    }
+
+    void *ret = cur;
+
+    cur += increment;
+    return ret;
+}
diff --git a/programs/libc/unistd/write.c b/programs/libc/unistd/write.c
new file mode 100644
index 0000000..9151e61
--- /dev/null
+++ b/programs/libc/unistd/write.c
@@ -0,0 +1,32 @@
+/*
+ * wnix, a Unix-like operating system for WebAssembly applications.
+ * Copyright (C) 2025  Xavier Del Campo Romero
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <unistd.h>
+#include <sys/types.h>
+#include <errno.h>
+#include <stddef.h>
+
+ssize_t write(const int fd, const void *const p, const size_t sz)
+{
+    int __wnix_write(int, const void *, size_t, int *) __attribute__((
+        __import_module__("wnix"),
+        __import_name__("write")
+    ));
+
+    return __wnix_write(fd, p, sz, &errno);
+}