From 86fc8288aa24e6bb4e5fda03f9536c92b666170b Mon Sep 17 00:00:00 2001
From: Steve Kemp <steve@steve.org.uk>
Date: Sat, 4 Jul 2026 19:58:27 +0300
Subject: [PATCH] Implement `mkdir` and `rmdir`.

This closes #121, and adds a simple test-case too.
---
 PRIMITIVES.md                  |  4 ++++
 README.md                      |  2 +-
 compiler/template.tmpl         | 43 ++++++++++++++++++++++++++++++++++
 test/mkdir-rmdir.lisp          |  6 +++++
 test/mkdir-rmdir.test.expected |  2 ++
 5 files changed, 56 insertions(+), 1 deletion(-)
 create mode 100644 test/mkdir-rmdir.lisp
 create mode 100644 test/mkdir-rmdir.test.expected

diff --git a/PRIMITIVES.md b/PRIMITIVES.md
index 7e9e184..dc1b6a3 100644
--- a/PRIMITIVES.md
+++ b/PRIMITIVES.md
@@ -111,6 +111,8 @@ Note that functions have their names mangled a little bit ("-" is converted to "
   * `int`
     * Convert the given float, or character, to an integer.
     * Anything else becomes zero.
+  * `mkdir`
+    * Create the named directory.  **NOTE**: Mode is fixed at 0755, and parent directories must exist.
   * `newline`
     * Print a newline.
   * `not`
@@ -129,6 +131,8 @@ Note that functions have their names mangled a little bit ("-" is converted to "
     * Print the given string.
   * `random`
     * Return a random integer between zero and N.
+  * `rmdir`
+    * Remove the named directory.
   * `setnth`
     * Update the Nth item in the given list with the specified value.
     * The list is updated in-place.
diff --git a/README.md b/README.md
index 9625c47..03432ae 100644
--- a/README.md
+++ b/README.md
@@ -64,7 +64,7 @@ It should be noted that we prepend a standard library of functions to all user p
 * File I/O operations:
   * `fopen`, `fclose`, `fread`, and `fwrite`.
 * Filesystem primitive:
-  * `dir?`, `entries`, `exists?`, `file?`, `stat`, `unlink` and `which`.
+  * `dir?`, `entries`, `exists?`, `file?`, `mkdir`, `rmdir`, `stat`, `unlink` and `which`.
 * Comparison operations:
   * `=`, `<`, `<=`, `>=`, `>`, and `!` to invert a result.
 * Special forms
diff --git a/compiler/template.tmpl b/compiler/template.tmpl
index a5c32a9..7b0cf1b 100644
--- a/compiler/template.tmpl
+++ b/compiler/template.tmpl
@@ -37,6 +37,8 @@ SYS_close       equ 3
 SYS_stat        equ 4
 SYS_lseek       equ 8
 SYS_exit        equ 60
+SYS_mkdir       equ 83
+SYS_rmdir       equ 84
 SYS_unlink      equ 87
 SYS_getdents64  equ 217
 SYS_getrandom   equ 318
@@ -1423,6 +1425,27 @@ FUNC fn_int
     ret
 
 
+;; Make a directory, mode is fixed
+FUNC fn_mkdir
+    mov rbx, rdi
+    GET_TAG_BITS rbx
+    cmp rbx, TAG_ID_STRING
+    jne type_error
+
+    UNTAG_REG rdi
+    mov rax, SYS_mkdir
+    mov rsi, 0o755        ; mode in octal
+    syscall
+    test rax,rax
+    js .failure
+    TAG_INTEGER_REG rax
+    ret
+.failure:
+    xor rax,rax
+    TAG_NIL_REG rax
+    ret
+
+
 ;; A nil becomes 1, anything else becomes nil.
 FUNC fn_not
     mov rax, rdi
@@ -1535,6 +1558,26 @@ FUNC fn_random
 
 
 
+;; Remove a directory, mode is fixed
+FUNC fn_rmdir
+    mov rbx, rdi
+    GET_TAG_BITS rbx
+    cmp rbx, TAG_ID_STRING
+    jne type_error
+
+    UNTAG_REG rdi
+    mov rax, SYS_rmdir
+    syscall
+    test rax,rax
+    js .failure
+    TAG_INTEGER_REG rax
+    ret
+.failure:
+    xor rax,rax
+    TAG_NIL_REG rax
+    ret
+
+
 ;; Update the Nth list item, leaving everything else as-is.
 FUNC fn_setnth
     mov rbx,rdi                ; arg1: list
diff --git a/test/mkdir-rmdir.lisp b/test/mkdir-rmdir.lisp
new file mode 100644
index 0000000..fb0fc07
--- /dev/null
+++ b/test/mkdir-rmdir.lisp
@@ -0,0 +1,6 @@
+(defun main ()
+  (mkdir "foo")
+  (println "Does foo/ exist:" (dir? "foo"))
+  (rmdir "foo")
+  (println "Does foo/ exist:" (dir? "foo"))
+  )
diff --git a/test/mkdir-rmdir.test.expected b/test/mkdir-rmdir.test.expected
new file mode 100644
index 0000000..63e86f0
--- /dev/null
+++ b/test/mkdir-rmdir.test.expected
@@ -0,0 +1,2 @@
+Does foo/ exist:1
+Does foo/ exist:<nil>