[libc-commits] [libc] Implement inet_pton (PR #224644)

[Pavel Labath via libc-commits]

================
@@ -0,0 +1,72 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file contains the implementation for inet_pton
+///
+//===----------------------------------------------------------------------===//
+
+#include "inet_pton.h"
+
+#include "hdr/errno_macros.h"
+#include "hdr/stdint_proxy.h"
+#include "hdr/sys_socket_macros.h"
+#include "hdr/types/struct_in6_addr.h"
+#include "hdr/types/struct_in_addr.h"
+#include "src/__support/CPP/string_view.h"
+#include "src/__support/common.h"
+#include "src/__support/libc_errno.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/macros/null_check.h"
+#include "src/__support/str_to_integer.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(int, inet_pton,
+                   (int af, const char *__restrict src, void *__restrict dst)) {
+  LIBC_CRASH_ON_NULLPTR(src);
+  LIBC_CRASH_ON_NULLPTR(dst);
+  if (af == AF_INET6) {
+    return 0;
+  } else if (af != AF_INET) {
+    libc_errno = EAFNOSUPPORT;
+    return -1;
+  }
+  uint8_t bytes[4];
+  size_t start = 0;
+  cpp::string_view str(src);
+  size_t i{0};
+  for (; i < 4; ++i) {
+    size_t end = str.find_first_of('.', start);
+    if (i < 3 && start == cpp::string_view::npos)
+      return 0; // Missing dot
+    if (i == 3 && end != cpp::string_view::npos)
+      return 0; // Extra dot
+    cpp::string_view part =
+        (i == 3) ? str.substr(start) : str.substr(start, end - start);
+    if (part.empty())
+      return 0; // empty part e.g. 192..1.1
+    if (part.size() > 1 && part[0] == '0')
+      return 0;
+    // Ensure all characters are valid ascii
+    for (char c : part) {
+      if (c < '0' || c > '9')
+        return 0;
+    }
+    auto result = internal::strtointeger<uint32_t>(part.data(), 10);
+    if (result.has_error() || result.value > 255 || result.value < 0)
----------------
labath wrote:

*u*int32_t can never be less than zero. Also, could we drop the `>255` part if we make this a uint8_t ?

https://github.com/llvm/llvm-project/pull/224644