c - Golang的字符串和C Char *之间的转换为For Range时出现内存问题，退出状态3221226356

Question

更新:
我正在研究通过GCO实现C库的Golang代码。在C函数的参数之间有一个* Cchar对象。
我使用C.CString()函数将字符串转换为* char，但是当我需要使用for循环实现它时遇到了问题。
感谢@peterSON，我可以继续前进。现在，程序将运行更长的时间，直到失败。现在我得到结果，直到第三个周期(五个周期)为止。当开始第四个时，它再次指示“退出状态3221226356”

这是一段代码:

package main

//#include <stdio.h>
//#include <stdlib.h>
//#cgo CFLAGS: -I C:/Go-Project/src/Astrocal
//#cgo LDFLAGS: -L C:/Go-Project/src/Astrocal72 -lswedll64
//#include "swephexp.h"
import "C"

import (
    "fmt"
    "unsafe"
)

...

func (P DATA) FixStarUT() {

    C.swe_set_ephe_path(C.CString("C:/sweph/ephe")) // connect to library C. 
    var Cxx [6]C.double
    var serr string
    var Cserr *C.char = C.CString(serr)
    var FixStarCchar *C.char = C.CString("")

    var iFLAG = []uint32{33026, 35074, 266, 2314, 98562, 100610, 65802, 67851} // 33026, 35074, 266, 2314, 98562, 100610, 65802, 67851
    var fixStarSlice = []string{"aboras", "achernar", "adara", "ain", "vega"}

    fmt.Println("Memory Address of FixStarCchar before For Range ->", FixStarCchar)

    // For Range 1
    for i, valFixStar := range fixStarSlice {

        defer C.free(unsafe.Pointer(FixStarCchar))
        defer C.free(unsafe.Pointer(Cserr))

        FixStarCchar = C.CString(valFixStar)

        fmt.Println("\nExternal cycle:", i, "Star (valFixStar):", valFixStar)
        fmt.Println("Memory Add. of FixStarCchar ->", FixStarCchar)

        // For Range 2
        for i2, valSistem := range iFLAG {
            // C functions
            C.swe_set_topo(C.double(P.LONsite), C.double(P.LATsite), C.double(P.ALTsite))
            C.swe_fixstar_ut(FixStarCchar, C.double(P.JulianDay), C.int(valSistem), &Cxx[0], Cserr)

            // Exporting results to a slice
            var positionFixStar []float64
            positionFixStar = append(positionFixStar, float64(Cxx[0]), float64(Cxx[1]), float64(Cxx[2]), float64(Cxx[3]), float64(Cxx[4]), float64(Cxx[5]))

            fmt.Println("\tInternal cycle:", i2, "\tSistem:", valSistem, "\tPosition:", positionFixStar)
        }

    }
    C.swe_close() // disconnect library C
}

输出:

PS C:\Go-Project\src\Astrocal72> go run main.go
Memory Address of FixStarCchar before For Range -> 0x1019c80

External cycle: 0 Star (valFixStar): aboras
Memory Add. of FixStarCchar -> 0x1019ca0
        Internal cycle: 0       Sistem: 33026   Position: [331.7560238873596 -23.63731225621964 1 0 0 0]
        Internal cycle: 1       Sistem: 35074   Position: [343.5555314743071 -32.70632643606941 1 0 0 0]
        Internal cycle: 2       Sistem: 266     Position: [331.7521303243937 -23.639006118391627 1 0 0 0]
        Internal cycle: 3       Sistem: 2314    Position: [343.5525162650043 -32.709352136426915 1 0 0 0]
        Internal cycle: 4       Sistem: 98562   Position: [307.45659891000344 -23.63731225621964 1 0 0 0]
        Internal cycle: 5       Sistem: 100610  Position: [319.25465207507114 -32.705260202398776 1 0 0 0]
        Internal cycle: 6       Sistem: 65802   Position: [307.4527053470375 -23.63900611839163 1 0 0 0]
        Internal cycle: 7       Sistem: 67851   Position: [319.2516367429912 -32.7082857906988 0.9999999999999999 0 0 0]

External cycle: 1 Star (valFixStar): achernar
Memory Add. of FixStarCchar -> 0x101b3a0
        Internal cycle: 0       Sistem: 33026   Position: [344.86781077811537 -59.37245156484419 1 0 0 0]
        Internal cycle: 1       Sistem: 35074   Position: [24.13636287205359 -57.39092532881141 0.9999999999999999 0 0 0]
        Internal cycle: 2       Sistem: 266     Position: [344.86287075464315 -59.37668655703472 1 0 0 0]
        Internal cycle: 3       Sistem: 2314    Position: [24.138688732702057 -57.39568950801329 1 0 0 0]
        Internal cycle: 4       Sistem: 98562   Position: [320.56838580075924 -59.37245156484419 0.9999999999999998 0 0 0]
        Internal cycle: 5       Sistem: 100610  Position: [359.83323867384445 -57.39150066286222 1 0 0 0]
        Internal cycle: 6       Sistem: 65802   Position: [320.563445777287 -59.37668655703472 0.9999999999999999 0 0 0]
        Internal cycle: 7       Sistem: 67851   Position: [359.835563909282 -57.39626493585631 1 0 0 0]

External cycle: 2 Star (valFixStar): adara
Memory Add. of FixStarCchar -> 0x101ae40
        Internal cycle: 0       Sistem: 33026   Position: [110.31533627711894 -51.36455324165249 1 0 0 0]
        Internal cycle: 1       Sistem: 35074   Position: [104.3395190395512 -28.925572447433648 1 0 0 0]
        Internal cycle: 2       Sistem: 266     Position: [110.32409258962711 -51.363920733883326 0.9999999999999999 0 0 0]
        Internal cycle: 3       Sistem: 2314    Position: [104.34580120684954 -28.92581091916995 0.9999999999999999 0 0 0]
        Internal cycle: 4       Sistem: 98562   Position: [86.01591129976276 -51.36455324165249 0.9999999999999998 0 0 0]
        Internal cycle: 5       Sistem: 100610  Position: [80.0401030111902 -28.927947460228687 0.9999999999999999 0 0 0]
        Internal cycle: 6       Sistem: 65802   Position: [86.02466761227095 -51.363920733883326 1 0 0 0]
        Internal cycle: 7       Sistem: 67851   Position: [80.04638532334661 -28.92818591289178 1 0 0 0]

External cycle: 3 Star (valFixStar): ain
Memory Add. of FixStarCchar -> 0x101ad70
exit status 3221226356

无论如何，希望您能帮助我解决这个问题。

Answer 1

I thought that by freeing memory with C.Free (unsafe.Pointer ()) it would work, but it fails. It returns "could not determine kind of name for C.Free".

C.Free与 C.free不同。

例如，从文档中:

package main

// #include <stdio.h>
// #include <stdlib.h>
//
// static void myprint(char* s) {
//   printf("%s\n", s);
// }
import "C"
import "unsafe"

func main() {
    cs := C.CString("Hello from stdio")
    C.myprint(cs)
    C.free(unsafe.Pointer(cs))
}

输出:

Hello from stdio

Command cgo

Comment: I changed the code. Now it works a little better. Before, it failed the first cycle. Now in the third. I need it to reach 500 cycles – Jumanyi

exit status 3221226356消息可能表示内存损坏。除其他外，您对 C.swe_fixstar_ut的调用看起来可疑。

如果您在Go函数中隐藏cgo C API实现，则它会更健壮和更易读。例如，一些未编写的，未经测试的代码:

package main

/*
#cgo CFLAGS: -I C:/Users/peter/astro
#cgo LDFLAGS: -L C:/Users/peter/astro -lswedll64
#include "swephexp.h"
*/
import "C"

import (
    "errors"
    "strconv"
)

type SweErr struct {
    Code int32
    Err  error
}

func (e SweErr) Error() string {
    return strconv.Itoa(int(e.Code)) + ": " + e.Err.Error()
}

func SweFixstarUt(star string, tjd float64, iflag int32) (name string, xx []float64, rc int32, err error) {

    // Programming interface to the Swiss Ephemeris
    // https://www.astro.com/swisseph/swephprg.htm
    // 3.5. Error handling and return values
    // 5. Fixed stars functions
    // 5.2. swe_fixstar2_ut(), swe_fixstar2(), swe_fixstar_ut(), swe_fixstar()

    var swe struct {
        rc     C.int32
        star   [C.AS_MAXCH + 1]C.char
        tjd_ut C.double
        iflag  C.int32
        xx     [6]C.double
        serr   [C.AS_MAXCH + 1]C.char
    }

    if len(star) > len(swe.star)-1 {
        star = star[:len(swe.star)-1]
    }
    for i := 0; i < len(star); i++ {
        swe.star[i] = C.char(star[i])
    }
    swe.star[len(star)] = 0
    swe.tjd_ut = C.double(tjd)
    swe.iflag = C.int32(iflag)

    swe.rc = C.swe_fixstar_ut(
        &swe.star[0], swe.tjd_ut, swe.iflag, &swe.xx[0], &swe.serr[0],
    )
    swe.star[len(swe.star)-1] = 0
    swe.serr[len(swe.serr)-1] = 0

    if swe.rc < 0 {
        err := SweErr{
            Code: int32(swe.rc),
            Err:  errors.New(C.GoString(&swe.serr[0])),
        }
        return "", nil, 0, err
    }

    name = C.GoString(&swe.star[0])
    xx = make([]float64, len(swe.xx))
    for i := range xx {
        xx[i] = float64(swe.xx[i])
    }
    rc = int32(swe.rc)
    return name, xx, rc, nil
}

func main() {}

引用:

Programming interface to the Swiss Ephemeris

The C Programming Language, 2nd Edition

The Go Programming Language