英文:
C and Go interoperability issue involving C.free()
问题
我有一个Go函数，它包装了lib_proc.h中的proc_name(pid,...)函数。
这是完整的C原型：
int proc_name(int pid, void * buffer, uint32_t buffersize) __OSX_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);
可以在这里找到它：/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.10.sdk/usr/include/libproc.h（至少在我的系统上）。
以下是Go代码：
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;
}
除非删除C.free(unsafe.Pointer(...))和import "unsafe"语句，否则此代码将无法编译。
DarwinProcess::NameOf(pid)方法只适用于Mac OS X，如果从代码中删除C.free(...)，它实际上可以工作。
在go build之后，我得到以下错误消息：
could not determine kind of name for C.free（这是整个编译器输出）。
对我来说，删除C.free(...)是不可接受的，我必须找到如何正确释放使用C.CString()分配的内存的方法。
我感到困惑，因为根据文档，一切都做得正确。我在这里和网络上都没有找到解决方案。
英文:
I've a Go function that wraps the proc_name(pid,...) function from lib_proc.h.
This is the complete C prototype:
<pre><code>
<!-- language: lang-c -->
int proc_name(int pid, void * buffer, uint32_t buffersize) __OSX_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_2_0);
</code></pre>
that 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).
It follows Go code:
<pre><code>
<!-- language: lang-go -->
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;
}
</code></pre>
This code won't compile unless the call to C.free(unsafe.Pointer(...)) and import "unsafe" clause are removed.
DarwinProcess::NameOf(pid) method is meant to work only on Mac OS X and it actually works if C.free(...) is removed from code.
In its actual form after go build I get the following error message:
could not determine kind of name for C.free (and nothing more, this is the whole compiler output).
Removing C.free(...) is not acceptable to me, I must find how to properly free the memory allocated with C.CString().
I'm puzzled since, according to documentation, everything is done properly. I have not been able to find a solution nor searching here nor on the web.
答案1
得分: 21
libproc.h没有包含stdlib.h，其中声明了free()函数。因此，编译器无法解析该名称。在我在cgo注释块的开头添加了#include <stdlib.h>之后，你的代码在我的系统上成功构建了。
英文:
libproc.h doesn't include stdlib.h, where free() is declared. As such, the compiler cannot resolve the name. After I added #include <stdlib.h> at the beginning of the cgo comment block your code built successfully on my system.
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