From 46c8ba2c9fec77195091ddcf7ee0bb3d9a6e5f54 Mon Sep 17 00:00:00 2001
From: Johannes Altmanninger <aclopte@gmail.com>
Date: Wed, 7 Aug 2024 10:14:31 +0200
Subject: [PATCH] Replace select with a 64-bit-time_t wrapper

Part of #10634
---
 src/fd_monitor.rs      | 27 +++++++++++++--------------
 src/fd_readable_set.rs | 11 ++++++-----
 src/libc.c             | 30 ++++++++++++++++++++++++++++++
 src/libc.rs            | 28 +++++++++++++++++++++++++++-
 4 files changed, 76 insertions(+), 20 deletions(-)

diff --git a/src/fd_monitor.rs b/src/fd_monitor.rs
index d7f86e5c0..067c7d755 100644
--- a/src/fd_monitor.rs
+++ b/src/fd_monitor.rs
@@ -7,6 +7,7 @@ use crate::common::exit_without_destructors;
 use crate::fd_readable_set::FdReadableSet;
 use crate::fds::AutoCloseFd;
 use crate::flog::FLOG;
+use crate::libc::{select64, timeval64};
 use crate::threads::assert_is_background_thread;
 use crate::wutil::perror;
 use errno::errno;
@@ -142,26 +143,24 @@ impl FdEventSignaller {
     /// but guarantees that the next call to wait() will not block.
     /// Return true if readable, false if not readable, or not interrupted by a signal.
     pub fn poll(&self, wait: bool /* = false */) -> bool {
-        let mut timeout = libc::timeval {
+        let mut timeout = timeval64 {
             tv_sec: 0,
             tv_usec: 0,
         };
         let mut fds: libc::fd_set = unsafe { std::mem::zeroed() };
         unsafe { libc::FD_ZERO(&mut fds) };
         unsafe { libc::FD_SET(self.read_fd(), &mut fds) };
-        let res = unsafe {
-            libc::select(
-                self.read_fd() + 1,
-                &mut fds,
-                std::ptr::null_mut(),
-                std::ptr::null_mut(),
-                if wait {
-                    std::ptr::null_mut()
-                } else {
-                    &mut timeout
-                },
-            )
-        };
+        let res = select64(
+            self.read_fd() + 1,
+            &mut fds,
+            std::ptr::null_mut(),
+            std::ptr::null_mut(),
+            if wait {
+                std::ptr::null_mut()
+            } else {
+                &mut timeout
+            },
+        );
         res > 0
     }
 
diff --git a/src/fd_readable_set.rs b/src/fd_readable_set.rs
index 00f1a2308..c76c9d28f 100644
--- a/src/fd_readable_set.rs
+++ b/src/fd_readable_set.rs
@@ -68,9 +68,10 @@ impl FdReadableSet {
     /// destructively modifies the set. Returns the result of `select()` or `poll()`.
     pub fn check_readable(&mut self, timeout_usec: u64) -> c_int {
         let null = std::ptr::null_mut();
+        use crate::libc::{select64, timeval64};
         if timeout_usec == Self::kNoTimeout {
             unsafe {
-                return libc::select(
+                return select64(
                     self.nfds_,
                     &mut self.fdset_,
                     null,
@@ -79,12 +80,12 @@ impl FdReadableSet {
                 );
             }
         } else {
-            let mut tvs = libc::timeval {
-                tv_sec: (timeout_usec / kUsecPerSec) as libc::time_t,
-                tv_usec: (timeout_usec % kUsecPerSec) as libc::suseconds_t,
+            let mut tvs = timeval64 {
+                tv_sec: (timeout_usec / kUsecPerSec).try_into().unwrap(),
+                tv_usec: (timeout_usec % kUsecPerSec).try_into().unwrap(),
             };
             unsafe {
-                return libc::select(self.nfds_, &mut self.fdset_, null, null, &mut tvs);
+                return select64(self.nfds_, &mut self.fdset_, null, null, &mut tvs);
             }
         }
     }
diff --git a/src/libc.c b/src/libc.c
index ba584c70e..b0188d622 100644
--- a/src/libc.c
+++ b/src/libc.c
@@ -1,3 +1,4 @@
+#include <assert.h>
 #include <dirent.h>
 #include <fcntl.h>
 #include <locale.h>
@@ -7,6 +8,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/resource.h>
+#include <sys/select.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <time.h>
@@ -14,6 +16,12 @@
 
 #define UNUSED(x) (void)(x)
 
+#define assert_or_die(x)   \
+    do {                   \
+        assert((x));       \
+        if (!(x)) abort(); \
+    } while (false)
+
 size_t C_MB_CUR_MAX() { return MB_CUR_MAX; }
 
 uint64_t C_ST_LOCAL() {
@@ -219,3 +227,25 @@ bool C_localtime64_r(int64_t timep, struct tm* result) {
     time_t timep_ = timep;
     return localtime_r(&timep_, result);
 }
+
+struct timeval64 {
+    int64_t tv_sec;
+    int64_t tv_usec;
+};
+
+int C_select64(int nfds, fd_set* readfds, fd_set* writefds, fd_set* errorfds,
+               struct timeval64* timeout64) {
+    struct timeval timeout;
+    if (timeout64) {
+        timeout.tv_sec = timeout64->tv_sec;
+        timeout.tv_usec = timeout64->tv_usec;
+        assert_or_die(timeout.tv_sec == timeout64->tv_sec);
+        assert_or_die(timeout.tv_usec == timeout64->tv_usec);
+    }
+    int result = select(nfds, readfds, writefds, errorfds, timeout64 ? &timeout : NULL);
+    if (timeout64) {
+        timeout64->tv_sec = timeout.tv_sec;
+        timeout64->tv_usec = timeout.tv_usec;
+    }
+    return result;
+}
diff --git a/src/libc.rs b/src/libc.rs
index e960e4856..b8a33196d 100644
--- a/src/libc.rs
+++ b/src/libc.rs
@@ -1,6 +1,6 @@
 use std::{ffi::CStr, sync::atomic::AtomicPtr};
 
-use libc::{c_char, c_int};
+use libc::{c_char, c_int, fd_set};
 use once_cell::sync::Lazy;
 
 pub static _PATH_BSHELL: AtomicPtr<c_char> = AtomicPtr::new(std::ptr::null_mut());
@@ -123,3 +123,29 @@ pub(crate) fn localtime64_r(timep: i64) -> Option<libc::tm> {
 extern "C" {
     fn C_localtime64_r(timep: i64, result: *mut libc::tm) -> bool;
 }
+
+#[repr(C)]
+#[derive(Clone, Copy)]
+pub(crate) struct timeval64 {
+    pub tv_sec: i64,
+    pub tv_usec: i64,
+}
+
+pub(crate) fn select64(
+    nfds: c_int,
+    readfds: *mut fd_set,
+    writefds: *mut fd_set,
+    errorfds: *mut fd_set,
+    timeout: *mut timeval64,
+) -> c_int {
+    unsafe { C_select64(nfds, readfds, writefds, errorfds, timeout) }
+}
+extern "C" {
+    fn C_select64(
+        nfds: c_int,
+        readfds: *mut fd_set,
+        writefds: *mut fd_set,
+        errorfds: *mut fd_set,
+        timeout: *mut timeval64,
+    ) -> c_int;
+}