proc: fix could not read process comm name error

fix #531

proc/proc_linux.go

@@ -1,13 +1,15 @@
 package proc
 
 import (
+	"bytes"
 	"debug/gosym"
 	"errors"
 	"fmt"
 	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
+	"regexp"
 	"strconv"
 	"strings"
 	"sync"
@@ -350,12 +352,30 @@ func (dbp *Process) loadProcessInformation(wg *sync.WaitGroup) {
 	defer wg.Done()
 
 	comm, err := ioutil.ReadFile(fmt.Sprintf("/proc/%d/comm", dbp.Pid))
-	if err != nil {
-		fmt.Printf("Could not read process comm name: %v\n", err)
-		os.Exit(1)
+	if err == nil {
+		// removes newline character
+		comm = bytes.TrimSuffix(comm, []byte("\n"))
+	}
+
+	if comm == nil || len(comm) <= 0 {
+		stat, err := ioutil.ReadFile(fmt.Sprintf("/proc/%d/stat", dbp.Pid))
+		if err != nil {
+			fmt.Printf("Could not read proc stat: %v\n", err)
+			os.Exit(1)
+		}
+		expr := fmt.Sprintf("%d\\s*\\((.*)\\)", dbp.Pid)
+		rexp, err := regexp.Compile(expr)
+		if err != nil {
+			fmt.Printf("Regexp compile error: %v\n", err)
+			os.Exit(1)
+		}
+		match := rexp.FindSubmatch(stat)
+		if match == nil {
+			fmt.Printf("No match found using regexp '%s' in /proc/%d/stat\n", expr, dbp.Pid)
+			os.Exit(1)
+		}
+		comm = match[1]
 	}
-	// removes newline character
-	comm = comm[:len(comm)-1]
 	dbp.os.comm = strings.Replace(string(comm), "%", "%%", -1)
 }