liblinux++

commit 6f3496ae521b5cb620b09de33f5c13030a02a417
parent a1233648a601a398356c9a3c3d9f63ed1a7a7e73
Author: Henry Wilson <henry@henryandlizzy.uk>
Date:   Thu,  8 Jan 2026 21:05:01 +0000

Warn all the things

Diffstat:
M
Tupfile
 | 
2
+-
M
linux.hpp
 | 
11
+++++------
M
ls.cpp
 | 
22
+++++++++++-----------
M
sleep.cpp
 | 
11
++++-------
M
syscalls.h
 | 
2
+-
M
tac.cpp
 | 
5
++---

6 files changed, 24 insertions(+), 29 deletions(-)
diff --git a/Tupfile b/Tupfile
@@ -1,4 +1,4 @@
-CXXFLAGS = -std=c++23 -Werror -g -fno-exceptions -fno-rtti -fno-asynchronous-unwind-tables -fno-builtin -fno-pic -fno-pie -fno-stack-protector -fdiagnostics-color=always
+CXXFLAGS = -std=c++23 -Wall -Werror -Wextra -Wpedantic -g -fno-exceptions -fno-rtti -fno-asynchronous-unwind-tables -fno-builtin -fno-pic -fno-pie -fno-stack-protector -fdiagnostics-color=always -nostdinc -nostdlibinc -nostdinc++
 LDFLAGS = --gc-sections
 
 : |> ./errno.sh > %o |> errno.hpp
diff --git a/linux.hpp b/linux.hpp
@@ -130,7 +130,7 @@ struct c_str
 		static_assert(arr[N-1] == '\0');
 	}
 private:
-	char const* str;
+	[[maybe_unused]] char const* str;
 };
 
 [[noreturn]]
@@ -155,14 +155,13 @@ extern syscall_result<file> openat(file fd, c_str name, int flags, int mode) noe
 
 extern syscall_result<void> close(file fd) noexcept;
 
-struct linux_dirent64 {
+struct [[gnu::packed]] linux_dirent64 {
 	ino64_t        d_ino;    /* 64-bit inode number */
 	off64_t        d_off;    /* Not an offset; see getdents() */
 	unsigned short d_reclen; /* Size of this dirent */
 	unsigned char  d_type;   /* File type */
-	char           d_name[]; /* Filename (null-terminated) */
 };
-extern syscall_result<size_t> getdents64(file dir, linux_dirent64 dirp[], size_t count) noexcept;
+extern syscall_result<size_t> getdents64(file dir, span<char> buffer) noexcept;
 
 extern syscall_result<void*> mmap(void* addr, size_t len, unsigned long prot, unsigned long flags, file fd, size_t off) noexcept;
 extern syscall_result<void> munmap(void* addr, size_t len) noexcept;
@@ -215,8 +214,8 @@ struct in_addr
 
 	operator addr_ref() const { return {.fat_ptr = {(char const*)this, sizeof(*this)}}; }
 private:
-	uint16_t family;
-	uint8_t data[14];
+	[[maybe_unused]] uint16_t family;
+	[[maybe_unused]] uint8_t data[14];
 };
 
 extern syscall_result<void> bind(file socket, addr_ref addr);
diff --git a/ls.cpp b/ls.cpp
@@ -14,26 +14,26 @@ int main()
 	auto dir = openat(AT_FDCWD, ".", O_RDONLY, 0);
 	assert(dir);
 
-	linux_dirent64 buf[4];
-	span<char const> ios[4];
+	alignas(linux_dirent64) char buf[256];
+	span<char const> ios[sizeof(buf)/sizeof(linux_dirent64)];
 	for (;;)
 	{
 		unsigned n_io = 0;
-		auto res = getdents64(*dir, buf, sizeof(buf));
-		ssize_t n = *res;
+		auto res = getdents64(*dir, buf);
+		size_t n = *res;
 
 		if (!n)
 			break;
 
-		char* const begin = reinterpret_cast<char*>(buf);
-
-		for (ssize_t i = 0; i + sizeof(linux_dirent64) < n;)
+		for (size_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};
+			auto e = reinterpret_cast<linux_dirent64*>(buf + i);
+			char* const name = buf + i + sizeof(linux_dirent64);
+			size_t len = strlen(name);
+			name[len++] = '\n';
+			ios[n_io++] = span<char const>{name, len};
 			i += e->d_reclen;
+			break;
 		}
 		*write(stdout, ios);
 	}
diff --git a/sleep.cpp b/sleep.cpp
@@ -2,14 +2,11 @@
 
 bool parse_digit(char c, uint64_t& out)
 {
-	switch (c)
-	{
-	case '0' ... '9':
-		out = c - '0';
-		return true;
-	default:
+	if (c < '0' or '9' < c)
 		return false;
-	}
+
+	out = c - '0';
+	return true;
 }
 
 bool parse_u64(char const* p, uint64_t& out)
diff --git a/syscalls.h b/syscalls.h
@@ -3,7 +3,7 @@ extern_alias _Z8unlinkat4file5c_str12unlink_flags
 SYS(unlinkat)
 
 extern getdents64
-extern_alias _Z10getdents644fileP14linux_dirent64m
+extern_alias _Z10getdents644file4spanIcE
 SYS(getdents64)
 
 extern read
diff --git a/tac.cpp b/tac.cpp
@@ -37,15 +37,14 @@ int main()
 
 	while (len == cap)
 	{
-		auto m = mmap(buf + cap, cap ?: 0x1000, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE, {}, 0);
+		auto m = mmap(buf + cap, cap ? cap : 0x1000, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE, {}, 0);
 		if (!m)
 			return 1;
-		cap += cap ?: 0x1000;
+		cap += cap ? cap : 0x1000;
 
 		len += rd(stdin, buf + len, buf + cap);
 	}
 
-reverse:
 	char const* end = buf + len;
 	char const* str = end;