From 5c28a3eda7095808f13c28dabbdc0089f2d2df24 Mon Sep 17 00:00:00 2001
From: Dan Kortschak <dan@kortschak.io>
Date: Sun, 24 Apr 2022 17:46:57 +0930
Subject: [PATCH] Don't shell out to obtain process and system stats

---
 .../frontend/clientconfig/config_applemail.go | 14 +++---
 internal/frontend/theme/detect_darwin.go      |  5 +-
 internal/store/ulimit.go                      | 48 +++++++++----------
 3 files changed, 32 insertions(+), 35 deletions(-)

diff --git a/internal/frontend/clientconfig/config_applemail.go b/internal/frontend/clientconfig/config_applemail.go
index b50db72..f2e7c63 100644
--- a/internal/frontend/clientconfig/config_applemail.go
+++ b/internal/frontend/clientconfig/config_applemail.go
@@ -23,16 +23,16 @@ package clientconfig
 import (
 	"io/ioutil"
 	"os"
-	"os/exec"
 	"path/filepath"
 	"strconv"
 	"strings"
 	"time"
 
-	"github.com/ProtonMail/proton-bridge/v2/internal/bridge"
-	"github.com/ProtonMail/proton-bridge/v2/internal/config/useragent"
-	"github.com/ProtonMail/proton-bridge/v2/internal/frontend/types"
-	"github.com/ProtonMail/proton-bridge/v2/pkg/mobileconfig"
+	"github.com/ProtonMail/proton-bridge/internal/bridge"
+	"github.com/ProtonMail/proton-bridge/internal/config/useragent"
+	"github.com/ProtonMail/proton-bridge/internal/frontend/types"
+	"github.com/ProtonMail/proton-bridge/pkg/mobileconfig"
+	"golang.org/x/sys/execabs"
 )
 
 const (
@@ -56,10 +56,10 @@ func (c *appleMail) Configure(imapPort, smtpPort int, imapSSL, smtpSSL bool, use
 	}
 
 	if useragent.IsBigSurOrNewer() {
-		return exec.Command("open", bigSurPreferncesPane, confPath).Run() //nolint:gosec G204: open command is safe, mobileconfig is generated by us
+		return execabs.Command("open", bigSurPreferncesPane, confPath).Run() //nolint:gosec G204: open command is safe, mobileconfig is generated by us
 	}
 
-	return exec.Command("open", confPath).Run() //nolint:gosec G204: open command is safe, mobileconfig is generated by us
+	return execabs.Command("open", confPath).Run() //nolint:gosec G204: open command is safe, mobileconfig is generated by us
 }
 
 func prepareMobileConfig(imapPort, smtpPort int, imapSSL, smtpSSL bool, user types.User, address string) *mobileconfig.Config {
diff --git a/internal/frontend/theme/detect_darwin.go b/internal/frontend/theme/detect_darwin.go
index f9a8e84..b7da2e9 100644
--- a/internal/frontend/theme/detect_darwin.go
+++ b/internal/frontend/theme/detect_darwin.go
@@ -21,12 +21,13 @@
 package theme
 
 import (
-	"os/exec"
 	"strings"
+
+	"golang.org/x/sys/execabs"
 )
 
 func detectSystemTheme() Theme {
-	out, err := exec.Command("defaults", "read", "-g", "AppleInterfaceStyle").Output() //nolint:gosec
+	out, err := execabs.Command("defaults", "read", "-g", "AppleInterfaceStyle").Output() //nolint:gosec
 	if err == nil && strings.TrimSpace(string(out)) == "Dark" {
 		return Dark
 	}
diff --git a/internal/store/ulimit.go b/internal/store/ulimit.go
index 3765773..76c8527 100644
--- a/internal/store/ulimit.go
+++ b/internal/store/ulimit.go
@@ -18,47 +18,43 @@
 package store
 
 import (
-	"fmt"
 	"os"
-	"os/exec"
 	"runtime"
-	"strconv"
-	"strings"
+
+	"golang.org/x/sys/unix"
 )
 
-func uLimit() int {
+func isFdCloseToULimit() bool {
 	if runtime.GOOS != "darwin" && runtime.GOOS != "linux" {
-		return 0
+		return false
 	}
-	out, err := exec.Command("bash", "-c", "ulimit -n").Output()
-	if err != nil {
-		log.Print(err)
-		return 0
+
+	var fdPath string
+	switch runtime.GOOS {
+	case "darwin":
+		fdPath = "/dev/fd"
+	case "linux":
+		fdPath = "/proc/self/fd"
 	}
-	outStr := strings.Trim(string(out), " \n")
-	num, err := strconv.Atoi(outStr)
+	f, err := os.Open(fdPath)
 	if err != nil {
-		log.Print(err)
-		return 0
-	}
-	return num
-}
-
-func isFdCloseToULimit() bool {
-	if runtime.GOOS != "darwin" && runtime.GOOS != "linux" {
+		log.Warn("isFdCloseToULimit: ", err)
 		return false
 	}
-
-	pid := fmt.Sprint(os.Getpid())
-	out, err := exec.Command("lsof", "-p", pid).Output() //nolint:gosec
+	d, err := f.ReadDir(-1)
 	if err != nil {
 		log.Warn("isFdCloseToULimit: ", err)
 		return false
 	}
-	lines := strings.Split(string(out), "\n")
+	fd := len(d) - 1
+
+	var lim unix.Rlimit
+	err = unix.Getrlimit(unix.RLIMIT_NOFILE, &lim)
+	if err != nil {
+		log.Print(err)
+	}
+	ulimit := lim.Max
 
-	fd := len(lines) - 1
-	ulimit := uLimit()
 	log.Info("File descriptor check: num goroutines ", runtime.NumGoroutine(), " fd ", fd, " ulimit ", ulimit)
 	return fd >= int(0.95*float64(ulimit))
 }