"Executable names truncated #15" fix for darwin

process_darwin.go

@@ -2,9 +2,16 @@
 
 package ps
 
+// #include <libproc.h>
+// #include <stdlib.h>
+// #include <errno.h>
+import "C"
+
 import (
 	"bytes"
 	"encoding/binary"
+	"fmt"
+	"path/filepath"
 	"syscall"
 	"unsafe"
 )
@@ -27,6 +34,34 @@ func (p *DarwinProcess) Executable() string {
 	return p.binary
 }
 
+// bufSize references the constant that the implementation
+// of proc_pidpath uses under the hood to make sure that
+// no overflows happen.
+//
+// See https://opensource.apple.com/source/xnu/xnu-2782.40.9/libsyscall/wrappers/libproc/libproc.c
+const bufSize = C.PROC_PIDPATHINFO_MAXSIZE
+
+func getExePathFromPid(pid int) (path string, err error) {
+	// Allocate in the C heap a string (char* terminated
+	// with `/0`) of size `bufSize` and then make sure
+	// that we free that memory that gets allocated
+	// in C (see the `defer` below).
+	buf := C.CString(string(make([]byte, bufSize)))
+	defer C.free(unsafe.Pointer(buf))
+
+	// Call the C function `proc_pidpath` from the included
+	// header file (libproc.h).
+	ret, err := C.proc_pidpath(C.int(pid), unsafe.Pointer(buf), bufSize)
+	if ret <= 0 {
+		err = fmt.Errorf("failed to retrieve pid path: %v", err)
+		return
+	}
+
+	// Convert the C string back to a Go string.
+	path = C.GoString(buf)
+	return
+}
+
 func findProcess(pid int) (Process, error) {
 	ps, err := processes()
 	if err != nil {
@@ -63,10 +98,20 @@ func processes() ([]Process, error) {
 
 	darwinProcs := make([]Process, len(procs))
 	for i, p := range procs {
+		comm, err := getExePathFromPid(int(p.Pid))
+
+		if err != nil {
+			// Falls back to the kinfo_proc->kp_proc.p_comm if no string for the pid was found
+			comm = darwinCstring(p.Comm)
+		} else {
+			// returns the last element of the process execution path
+			comm = filepath.Base(comm)
+		}
+
 		darwinProcs[i] = &DarwinProcess{
 			pid:    int(p.Pid),
 			ppid:   int(p.PPid),
-			binary: darwinCstring(p.Comm),
+			binary: comm,
 		}
 	}