C and Go related to C.free ()

Question

I have a Go function that wraps the proc_name(pid,...) lib_proc.h from lib_proc.h .

This is a complete C prototype:

 int proc_name(int pid, void * buffer, uint32_t buffersize) __OSX_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0); 

which can be found here /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.10.sdk/usr/include/libproc.h (at least on my system).

This follows the Go code:

 package goproc /* #include "libproc.h" int call_proc_name(int pid, char *name, int name_size) { return proc_name(pid, name, name_size); } */ import "C" import "unsafe" import "strings" type DarwinProcess struct { Process } func (DarwinProcess) NameOf(pid int) string { name := C.CString(strings.Repeat("\x00", 1024)) defer C.free(unsafe.Pointer(name)) nameLen := C.call_proc_name(C.int(pid), name, C.int(1024)) var result string if (nameLen > 0) { result = C.GoString(name); } else { result = "" } return result; } 

This code will not compile unless a call to C.free(unsafe.Pointer(...)) and import "unsafe" is removed. DarwinProcess::NameOf(pid) method is only for Mac OS X , and it really works if C.free(...) removed from the code.

In its actual form, after go build , the following error message appears: could not determine kind of name for C.free (and nothing more, this is all the compiler output).

Removing C.free(...) unacceptable to me, I have to find how to properly free the memory allocated with C.CString() .

I am puzzled that, according to the documentation , everything is done correctly. I could not find a solution and did not search here or on the Internet.

Answer 1

libproc.h does not include stdlib.h where free() declared. Therefore, the compiler cannot resolve the name. After I added #include <stdlib.h> at the beginning of the cgo comment block, your code was successfully created on my system.