From 94ee5cd6002bfaf0d9eb5f5e65216f3f2dd3cc96 Mon Sep 17 00:00:00 2001
From: Simon Krueger <skrueger@meta.com>
Date: Thu, 21 Nov 2024 11:33:48 -0800
Subject: [PATCH] Use folly::fileops qualified name

Summary:
This updates `open`, `close`, `read`, `write`, and `pipe` call sites to use
`folly::fileops` qualified name lookup.

This is the 2nd phase in a 3-phase change to remove folly's global definitions
of the posix functions that conflict with windows CRT.
The 1st phase created namespaces for folly's posix functions. The 2nd phase
updates callsites to use the qualified name of folly's  `open`, `close`,
`read`, `write`, and `pipe`  functions. The 3rd and final phase will remove
folly's globally defined posix functions and have windows CRT define them
again.

**What is the reason for this change?**
Folly's global definitions of posix functions on Windows causes `#include`
order issues if folly is not included first.

For example, when `gtest/gtest.h` is included before folly, gtest includes
`windows.h` and that declares `open`, `read`, and `chdir`, which creates
ambiguous references to folly's `open`, `read`, and `chdir`.

Another example is where posix functions go undeclared when
`folly/portability/windows.h` is included without other portability headers
(e.g., `folly/portability/unistd.h`). `folly/portability/windows.h` includes
`windows.h` in a way that only underscore versions of the posix functions are
available (e.g., `_open`, `_close`).

These issues create friction for windows development.

**Background: What is the purpose of `folly::portability::{fcntl,stdlib,sysstat,unistd}`?**
It is a portability layer to make posix functions available and behave
consistently across platforms. Some posix functions don't exist on windows
(e.g., `sysconf`). Some other posix functions, folly changes to adapt behavior
across platforms. For example, on windows folly defines `open`, `read`,
`write`, and `close` functions to work with sockets. Folly makes these
functions available in the global scope for convenience.

Reviewed By: Orvid

Differential Revision: D66192152

fbshipit-source-id: d585746baae0e174bfdc22e9e4565e323f5e08fe
---
 watchman/main.cpp | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/watchman/main.cpp b/watchman/main.cpp
index 501cf8e2db10..fc9f496dca8d 100644
--- a/watchman/main.cpp
+++ b/watchman/main.cpp
@@ -13,6 +13,7 @@
 #include <folly/String.h>
 #include <folly/init/Init.h>
 #include <folly/net/NetworkSocket.h>
+#include <folly/portability/Fcntl.h>
 #include <folly/system/Shell.h>
 
 #include <stdio.h>
@@ -138,14 +139,15 @@ std::optional<std::string> detect_starting_command(pid_t ppid) {
 #endif
 
   // redirect std{in,out,err}
-  int fd = ::open("/dev/null", O_RDONLY);
+  int fd = folly::fileops::open("/dev/null", O_RDONLY);
   if (fd != -1) {
     ignore_result(::dup2(fd, STDIN_FILENO));
     folly::fileops::close(fd);
   }
 
   if (logging::log_name != "-") {
-    fd = open(logging::log_name.c_str(), O_WRONLY | O_APPEND | O_CREAT, 0600);
+    fd = folly::fileops::open(
+        logging::log_name.c_str(), O_WRONLY | O_APPEND | O_CREAT, 0600);
     if (fd != -1) {
       ignore_result(::dup2(fd, STDOUT_FILENO));
       ignore_result(::dup2(fd, STDERR_FILENO));