I forgot what this changes, read the diff

src/assembly/syscalls.asm

@@ -7,6 +7,7 @@
     global sys_read
     global sys_wait4
     global sys_exit
+    global sys_getcwd
     global environ
 
     extern main
@@ -17,49 +18,53 @@ environ:   dq 0
     section .text
 
     sys_open:
-    mov     rax, 2       ; __NR_open
+        mov rax, 2
         syscall
         ret
 
     sys_close:
-    mov     rax, 3       ; __NR_close
+        mov rax, 3
         syscall
         ret
 
     sys_getdents64:
-    mov     rax, 217     ; __NR_getdents64
+        mov rax, 217
         syscall
         ret
 
     sys_stat:
-    mov     rax, 4       ; __NR_stat (legacy)
+        mov rax, 4
         syscall
         ret
 
     sys_read:
-    mov     rax, 0       ; __NR_read
+        mov rax, 0
         syscall
         ret
 
     sys_write:
-    mov     rax, 1       ; __NR_write
+        mov rax, 1
         syscall
         ret
 
     sys_wait4:
-    mov     rax, 61      ; __NR_wait4
+        mov rax, 61
         syscall
         ret
 
     sys_exit:
-    mov     rax, 60      ; __NR_exit
+        mov rax, 60
+        syscall
+        ret
+
+    sys_getcwd:
+        mov rax, 79
         syscall
         ret
 
     _start:
-    ; SysV ABI: rdi=argc, rsi=argv, rdx=envp
         mov [rel environ], rdx
         call main
-    mov     rdi, rax     ; exit code = return value of main
-    mov     rax, 60      ; __NR_exit
+        mov rdi, rax
+        mov rax, 60
         syscall

src/headers/nstdo.h

@@ -1,5 +1,5 @@
-#ifndef MINI_STDIO_H
-#define MINI_STDIO_H
+#ifndef nstdo_h
+#define nstdo_h
 
 #ifdef __cplusplus
 extern "C" {
@@ -12,7 +12,6 @@ typedef long          off_t;
 extern char **environ;
 char *getenv(const char *name);
 
-/* minimal open flags */
 #define O_RDONLY   0
 #define O_WRONLY   1
 #define O_RDWR     2
@@ -21,20 +20,17 @@ char *getenv(const char *name);
 #define O_APPEND   1024
 #define O_CLOEXEC  02000000
 
-/* minimal stdarg */
 typedef __builtin_va_list va_list;
 #define va_start(ap,last) __builtin_va_start(ap,last)
 #define va_arg(ap,type)   __builtin_va_arg(ap,type)
 #define va_end(ap)         __builtin_va_end(ap)
 
-/* syscall numbers */
 #define SYS_READ    0
 #define SYS_WRITE   1
 #define SYS_OPEN    2
 #define SYS_CLOSE   3
 #define SYS_LSEEK   8
 
-/* raw syscall wrapper */
 static inline long _syscall3(long nr, long a1, long a2, long a3) {
     long ret;
     asm volatile(
@@ -99,4 +95,4 @@ struct stat_t {
 }
 #endif
 
-#endif /* MINI_STDIO_H */
+#endif

src/main.c

@@ -7,6 +7,7 @@ extern long sys_stat(const char *pathname, struct stat_t *statbuf);
 extern long sys_write(int fd, const void *buf, size_t count);
 extern long sys_read(int fd, void *buf, size_t count);
 extern void sys_exit(int status);
+extern void sys_getcwd(char *buf, size_t size);
 
 static int streq(const char *a, const char *b) {
     while (*a && *b) {
@@ -133,6 +134,18 @@ static void lsCommand(const char *path, int longFlag) {
     sys_close(fd);
 }
 
+static void getcwdCommand() {
+    char buf[1024];
+    sys_getcwd(buf, sizeof(buf));
+    long len = str_len(buf);
+    if (len > 0 && buf[len - 1] != '/') {
+        buf[len++] = '/';
+    }
+    buf[len] = '\0';
+    buf[len++] = '\n';
+    sys_write(1, buf, len);
+}
+
 int main(int argc, char *argv[], char *envp[]) {
     (void)argc; (void)argv; (void)envp;
     char buf[512];
@@ -184,6 +197,8 @@ int main(int argc, char *argv[], char *envp[]) {
             int longFlag = (opt && streq(opt, "-l")) ? 1 : 0;
             const char *path = arg ? arg : ".";
             lsCommand(path, longFlag);
+        } else if (streq(cmd, "cwd")) {
+            getcwdCommand();
         }
     }