“Syscall()”在go包“Syscall”中意味着什么?

During the research of my another question Go package syscall conn.Read() is non-blocking and cause high CPU usage, I read source code in syscall package.

在研究我的另一个问题Go包syscall conn.Read()时，我阅读了syscall包中的源代码，它是非阻塞的，并导致高CPU使用率。

Since I found my last issue on OS X 10.8.3, here is the source code related:

由于我找到了上一期关于OS X 10.8.3的文章，下面是与之相关的源代码:

http://golang.org/src/pkg/syscall/zsyscall_darwin_amd64.go?h=Read#L898

http://golang.org/src/pkg/syscall/zsyscall_darwin_amd64.go?h=Read L898

I have no idea what Syscall(SYS_READ, uintptr(fd), uintptr(_p0), uintptr(len(p))) means, actually I don't understand stuffs like unsafe.Pointer & Syscall(). How they works?

我不知道Syscall(SYS_READ, uintptr(fd)， uintptr(_p0)， uintptr(len(p)))是什么意思，实际上我不理解一些不安全的东西。指针和系统调用()。他们是如何运作的吗?

Besides, can anyone explain the comment // THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT, how and why these things work with specific platform by different implementations? And how syscall package generate these interfaces?

另外，谁能解释一下注释//这个文件是由顶部的命令生成的吗?不编辑，如何以及为什么这些东西与特定的平台有不同的实现?以及syscall包如何生成这些接口?

If someone can explain a specific function like Read() related with syscall could be help me understand it better, thanks.

如果有人能解释一个与syscall相关的特定函数Read()，可以帮助我更好地理解它，谢谢。

1 个解决方案

#1

The Go Darwin syscall package func Read(fd int, p \[\]byte) (n int, err error) function is making a read (SYS_READ) system call:

Go Darwin syscall package func Read(fd int, p \[\]byte) (n int, err error)函数正在创建一个Read(SYS_READ)系统调用:

read Mac OS X Developer Tools Manual Page

阅读Mac OS X开发者工具手册页

ssize_t read(int fildes, void *buf, size_t nbyte);

读取(int fildes, void *buf, size_t nbyte);

Read() attempts to read nbyte bytes of data from the object referenced by the descriptor fildes into the buffer pointed to by buf.

Read()尝试从描述符fildes引用的对象中读取nbyte字节的数据到由buf指向的缓冲区中。

The Go Darwin syscall package Syscall function is:

Go Darwin syscall包syscall函数是:

// func Syscall(trap int64, a1, a2, a3 int64) (r1, r2, err int64);
// Trap # in AX, args in DI SI DX, return in AX DX

TEXT    ·Syscall(SB),7,$0
    CALL    runtime·entersyscall(SB)
    MOVQ    16(SP), DI
    MOVQ    24(SP), SI
    MOVQ    32(SP), DX
    MOVQ    $0, R10
    MOVQ    $0, R8
    MOVQ    $0, R9
    MOVQ    8(SP), AX   // syscall entry
    ADDQ    $0x2000000, AX
    SYSCALL
    JCC ok
    MOVQ    $-1, 40(SP) // r1
    MOVQ    $0, 48(SP)  // r2
    MOVQ    AX, 56(SP)  // errno
    CALL    runtime·exitsyscall(SB)
    RET
ok:
    MOVQ    AX, 40(SP)  // r1
    MOVQ    DX, 48(SP)  // r2
    MOVQ    $0, 56(SP)  // errno
    CALL    runtime·exitsyscall(SB)
    RET

#1