Golang Context.Open方法代码示例

func (s *USB) Build(c *build.Context) error {
	f, err := c.Open(s.Conf)
	if err != nil {
		return err
	}
	buf, err := ioutil.ReadAll(f)
	if err != nil {
		log.Fatal(err)
	}

	var sysconf SysConf
	err = json.Unmarshal(buf, &sysconf)
	if err != nil {
		return err
	}
	fileOut := fmt.Sprintf("%s.c", s.Name)
	out, err := c.Create(fileOut)
	if err != nil {
		return err
	}
	tmpl, err := template.New("usbdb.c").Parse(jtab)
	err = tmpl.Execute(out, sysconf.Embeds)
	if err != nil {
		return err
	}
	return nil
}

func (dtc *DataToC) Build(c *build.Context) error {

	inFile, err := c.Open(dtc.Bin)
	if err != nil {
		return err
	}

	in, err := ioutil.ReadAll(inFile)
	if err != nil {
		return err
	}

	total := len(in)
	out, err := c.Create(fmt.Sprintf("%s.c", dtc.Name))

	if err != nil {
		return err
	}

	fmt.Fprintf(out, "unsigned char %vcode[] = {\n", dtc.Prefix)
	for len(in) > 0 {
		for j := 0; j < 16 && len(in) > 0; j++ {
			fmt.Fprintf(out, "0x%02x, ", in[0])
			in = in[1:]
		}
		fmt.Fprintf(out, "\n")

	}

	fmt.Fprintf(out, "0,\n};\nint %vlen = %v;\n", dtc.Prefix, total)
	return nil
}

// data2c takes the file at path and creates a C byte array containing it.
func data2c(name string, path string, c *build.Context) (string, error) {
	var out []byte
	var in []byte
	var file *os.File
	var err error
	if file, err = c.Open(path); err != nil {
		return "", fmt.Errorf("open :%s", err.Error())

	}

	if in, err = ioutil.ReadAll(file); err != nil {
		return "", nil
	}

	file.Close()

	total := len(in)

	out = []byte(fmt.Sprintf("static unsigned char ramfs_%s_code[] = {\n", name))
	for len(in) > 0 {
		for j := 0; j < 16 && len(in) > 0; j++ {
			out = append(out, []byte(fmt.Sprintf("0x%02x, ", in[0]))...)
			in = in[1:]
		}
		out = append(out, '\n')
	}

	out = append(out, []byte(fmt.Sprintf("0,\n};\nint ramfs_%s_len = %v;\n", name, total))...)

	return string(out), nil
}

func (etc *ElfToC) Build(c *build.Context) error {
	fileName := ""

	if xf, err := c.Open(etc.Elf); err != nil {
		return fmt.Errorf("open :%s", err.Error())
	} else {
		fileName = xf.Name()
		xf.Close()
	}

	f, err := elf.Open(fileName)
	if err != nil {
		return err
	}
	var dataend, codeend, end uint64
	var datastart, codestart, start uint64
	datastart, codestart, start = math.MaxUint64, math.MaxUint64, math.MaxUint64
	mem := []byte{}
	for _, v := range f.Progs {
		if v.Type != elf.PT_LOAD {
			continue
		}
		c.Printf("processing %v\n", v)
		// MUST alignt to 2M page boundary.
		// then MUST allocate a []byte that
		// is the right size. And MUST
		// see if by some off chance it
		// joins to a pre-existing segment.
		// It's easier than it seems. We produce ONE text
		// array and ONE data array. So it's a matter of creating
		// a virtual memory space with an assumed starting point of
		// 0x200000, and filling it. We just grow that as needed.

		curstart := v.Vaddr & ^uint64(0xfff) // 0x1fffff)
		curend := v.Vaddr + v.Memsz
		c.Printf("s %x e %x\n", curstart, curend)
		if curend > end {
			nmem := make([]byte, curend)
			copy(nmem, mem)
			mem = nmem
		}
		if curstart < start {
			start = curstart
		}

		if v.Flags&elf.PF_X == elf.PF_X {
			if curstart < codestart {
				codestart = curstart
			}
			if curend > codeend {
				codeend = curend
			}
			c.Printf("code s %v e %v\n", codestart, codeend)
		} else {
			if curstart < datastart {
				datastart = curstart
			}
			if curend > dataend {
				dataend = curend
			}
			c.Printf("data s %v e %v\n", datastart, dataend)
		}
		for i := uint64(0); i < v.Filesz; i++ {
			if amt, err := v.ReadAt(mem[v.Vaddr+i:], int64(i)); err != nil && err != io.EOF {
				err := fmt.Errorf("%v: %v\n", amt, err)
				c.Println(err)
				return err
			} else if amt == 0 {
				if i < v.Filesz {
					err := fmt.Errorf("%v: Short read: %v of %v\n", v, i, v.Filesz)
					c.Println(err)
					return err
				}
				break
			} else {
				i = i + uint64(amt)
				c.Printf("i now %d\n", i)
			}
		}
		c.Printf("Processed %v\n", v)
	}
	c.Printf("gencode\n")
	// Gen code to stdout. For each file, create an array, a start, and an end variable.
	outfile, err := c.Create(fmt.Sprintf("%s.h", etc.Name))
	if err != nil {
		return err
	}

	_, file := path.Split(etc.Elf)

	gencode(outfile, file, "code", mem, codestart, codeend)
	gencode(outfile, file, "data", mem, datastart, dataend)

	return nil
}