liblinux++

commit dc63fe778af6488f6b12a78b6b41a4beaaa07663
parent 44c8140fe7d217d01ad78509175d90d3248610c0
Author: Henry Wilson <henry@henryandlizzy.uk>
Date:   Tue, 23 Dec 2025 15:12:42 +0000

convert cat to .cpp

Diffstat:
M
linux.hpp
 | 
9
+++++++++
D
tac.c
 | 
58
----------------------------------------------------------
A
tac.cpp
 | 
59
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
M
x86_64.s
 | 
1
+

4 files changed, 69 insertions(+), 58 deletions(-)
diff --git a/linux.hpp b/linux.hpp
@@ -60,6 +60,7 @@ struct span
 
 struct file
 {
+	file() = default;
 	explicit file(int n) : num{n} {}
 	int num = -1;
 	inline operator bool() const { return num >= 0; }
@@ -122,10 +123,18 @@ extern void exit(int error_code);
 
 extern syscall_result<size_t> read(file fd, char data[], size_t count);
 extern syscall_result<size_t> read(file fd, span<char> data);
+inline syscall_result<size_t> read(file fd, char* begin, char* end)
+{
+	return read(fd, begin, end - begin);
+}
 
 extern syscall_result<size_t> write(file fd, char const data[], size_t count);
 extern syscall_result<size_t> write(file fd, span<char const> data);
 extern syscall_result<size_t> write(file fd, span<span<char const> const> data);
+inline syscall_result<size_t> write(file fd, char const* begin, char const* end)
+{
+	return write(fd, begin, end - begin);
+}
 
 extern syscall_result<file> openat(file fd, c_str name, int flags, int mode);
 
diff --git a/tac.c b/tac.c
@@ -1,58 +0,0 @@
-#include "linux.h"
-
-extern char mappable[];
-
-static int rd(int const fd, char* const start, char const* const end)
-{
-	char* pos = start;
-	while (pos != end)
-	{
-		int n = read(fd, pos, end - pos);
-		if (get_errno(n))
-			exit(2);
-		if (n == 0)
-			break;
-		pos += n;
-	}
-	return pos - start;
-}
-
-static void wr(int const fd, char const* start, char const* const end)
-{
-	while (start != end)
-	{
-		int n = write(fd, start, end - start);
-		if (get_errno(n))
-			exit(3);
-		start += n;
-	}
-}
-
-int main()
-{
-	char* buf = mappable;
-	size_t cap = 0;
-	size_t len = 0;
-
-	while (len == cap)
-	{
-		intptr_t m = mmap(buf + cap, cap ?: 0x1000, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
-		if (get_errno(m))
-			return 1;
-		cap += cap ?: 0x1000;
-
-		len += rd(0, buf + len, buf + cap);
-	}
-
-reverse:
-	char const* end = buf + len;
-	char const* str = end;
-
-	while (--str > buf)
-	{
-		while (str > buf && str[-1] != '\n')
-			--str;
-		wr(1, str, end);
-		end = str;
-	}
-}
diff --git a/tac.cpp b/tac.cpp
@@ -0,0 +1,59 @@
+#include "linux.hpp"
+
+extern char mappable[];
+
+static int rd(file const fd, char* const start, char* const end)
+{
+	char* pos = start;
+	while (pos != end)
+	{
+		auto res = read(fd, pos, end);
+		if (!res)
+			exit(2);
+		auto n = *res;
+		if (n == 0)
+			break;
+		pos += n;
+	}
+	return pos - start;
+}
+
+static void wr(file const fd, char const* start, char const* const end)
+{
+	while (start != end)
+	{
+		auto n = write(fd, start, end);
+		if (!n)
+			exit(3);
+		start += *n;
+	}
+}
+
+int main()
+{
+	char* buf = mappable;
+	size_t cap = 0;
+	size_t len = 0;
+
+	while (len == cap)
+	{
+		auto m = mmap(buf + cap, cap ?: 0x1000, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE, {}, 0);
+		if (!m)
+			return 1;
+		cap += cap ?: 0x1000;
+
+		len += rd(stdin, buf + len, buf + cap);
+	}
+
+reverse:
+	char const* end = buf + len;
+	char const* str = end;
+
+	while (--str > buf)
+	{
+		while (str > buf && str[-1] != '\n')
+			--str;
+		wr(stdout, str, end);
+		end = str;
+	}
+}
diff --git a/x86_64.s b/x86_64.s
@@ -58,6 +58,7 @@ extern_alias _Z5close4file
 _syscall	3	syscall3
 
 extern mmap
+extern_alias _Z4mmapPvmmm4filem
 _syscall	9	syscall6
 
 extern writev