liblinux++

commit 2abb614c632657f830b07459434c8e9bb231141c
parent 4926e536c96ec95b47c4457adc16a182842ce862
Author: Henry Wilson <henry@henryandlizzy.uk>
Date:   Tue, 23 Dec 2025 15:47:26 +0000

Convert ls to .cpp

Diffstat:
M
linux.hpp
 | 
9
+++++----
D
ls.c
 | 
42
------------------------------------------
A
ls.cpp
 | 
42
++++++++++++++++++++++++++++++++++++++++++
M
x86_64.s
 | 
3
++-

4 files changed, 49 insertions(+), 47 deletions(-)
diff --git a/linux.hpp b/linux.hpp
@@ -44,9 +44,7 @@ enum {
 template <typename T>
 struct span
 {
-	T* data;
-	size_t len;
-
+	span() = default;
 	inline span(T* p, size_t n)
 	: data{p}
 	, len{n}
@@ -56,6 +54,9 @@ struct span
 	inline span(T (&arr)[N])
 	: span{arr, N}
 	{}
+private:
+	T* data = nullptr;
+	size_t len = 0;
 };
 
 struct file
@@ -150,7 +151,7 @@ struct linux_dirent64 {
 	unsigned char  d_type;   /* File type */
 	char           d_name[]; /* Filename (null-terminated) */
 };
-extern syscall_result<ssize_t> getdents64(file dir, linux_dirent64 dirp[], size_t count);
+extern syscall_result<size_t> getdents64(file dir, linux_dirent64 dirp[], size_t count);
 
 extern syscall_result<void*> mmap(void* addr, unsigned long len, unsigned long prot, unsigned long flags, file fd, unsigned long off);
 
diff --git a/ls.c b/ls.c
@@ -1,42 +0,0 @@
-#include "linux.h"
-
-#define assert(x) if (!(x)) __builtin_trap()
-
-size_t strlen(char const* p)
-{
-	char const* const begin = p;
-	while (*p)
-		++p;
-
-	return p - begin;
-}
-
-int main()
-{
-	int fd = openat(AT_FDCWD, ".", O_RDONLY, 0);
-	assert(fd >= 0);
-
-	struct linux_dirent64 buf[4];
-	struct iovecc ios[4];
-	for (;;)
-	{
-		unsigned n_io = 0;
-		ssize_t n = getdents64(fd, buf, sizeof(buf));
-		assert (n >= 0);
-
-		if (!n)
-			break;
-
-		char* const begin = (void*)buf;
-
-		for (ssize_t i = 0; i + sizeof(struct linux_dirent64) < n;)
-		{
-			struct linux_dirent64* e = (void*)(begin + i);
-			size_t len = strlen(e->d_name);
-			e->d_name[len++] = '\n';
-			ios[n_io++] = (struct iovecc){e->d_name, len};
-			i += e->d_reclen;
-		}
-		writev(1, ios, n_io);
-	}
-}
diff --git a/ls.cpp b/ls.cpp
@@ -0,0 +1,42 @@
+#include "linux.hpp"
+
+#define assert(x) if (!(x)) __builtin_trap()
+
+size_t strlen(char const* p)
+{
+	char const* const begin = p;
+	while (*p)
+		++p;
+
+	return p - begin;
+}
+
+int main()
+{
+	auto dir = openat(AT_FDCWD, ".", O_RDONLY, 0);
+	assert(dir);
+
+	linux_dirent64 buf[4];
+	span<char const> ios[4];
+	for (;;)
+	{
+		unsigned n_io = 0;
+		auto res = getdents64(*dir, buf, sizeof(buf));
+		ssize_t n = *res;
+
+		if (!n)
+			break;
+
+		char* const begin = reinterpret_cast<char*>(buf);
+
+		for (ssize_t i = 0; i + sizeof(linux_dirent64) < n;)
+		{
+			auto e = reinterpret_cast<linux_dirent64*>(begin + i);
+			size_t len = strlen(e->d_name);
+			e->d_name[len++] = '\n';
+			ios[n_io++] = span<char const>{e->d_name, len};
+			i += e->d_reclen;
+		}
+		write(stdout, ios);
+	}
+}
diff --git a/x86_64.s b/x86_64.s
@@ -62,7 +62,7 @@ extern_alias _Z4mmapPvmmm4filem
 _syscall	9	syscall6
 
 extern writev
-extern_alias _Z5writei4spanIKS_IKcEE
+extern_alias _Z5write4file4spanIKS0_IKcEE
 _syscall	20	syscall3
 
 extern nanosleep
@@ -74,6 +74,7 @@ extern_alias _Z4exiti
 _syscall	60	syscall3
 
 extern getdents64
+extern_alias _Z10getdents644fileP14linux_dirent64y
 _syscall	217	syscall3
 
 extern openat