devtools/src/jehanne/cmd/elf2c/elf2c.go

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2015-12-22 11:10:07 +01:00
package main
import (
"bufio"
"debug/elf"
"flag"
"fmt"
"io"
"math"
"os"
"path"
)
var dry = flag.Bool("dryrun", true, "don't really do it")
func gencode(w io.Writer, n, t string, m []byte, start, end uint64) {
fmt.Fprintf(os.Stderr, "Write %v %v start %v end %v\n", n, t, start, end)
fmt.Fprintf(w, "int %v_%v_start = %v;\n", n, t, start)
fmt.Fprintf(w, "int %v_%v_end = %v;\n", n, t, end)
fmt.Fprintf(w, "int %v_%v_len = %v;\n", n, t, end-start)
fmt.Fprintf(w, "uint8_t %v_%v_out[] = {\n", n, t)
for i := uint64(start); i < end; i += 16 {
for j := uint64(0); i+j < end && j < 16; j++ {
fmt.Fprintf(w, "0x%02x, ", m[j+i])
}
fmt.Fprintf(w, "\n")
}
fmt.Fprintf(w, "};\n")
}
func main() {
flag.Parse()
a := flag.Args()
for _, n := range a {
f, err := elf.Open(n)
if err != nil {
fmt.Printf("%v %v\n", n, err)
continue
}
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
}
fmt.Fprintf(os.Stderr, "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
fmt.Fprintf(os.Stderr, "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
}
fmt.Fprintf(os.Stderr, "code s %v e %v\n", codestart, codeend)
} else {
if curstart < datastart {
datastart = curstart
}
if curend > dataend {
dataend = curend
}
fmt.Fprintf(os.Stderr, "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 {
fmt.Fprintf(os.Stderr, "%v: %v\n", amt, err)
os.Exit(1)
} else if amt == 0 {
if i < v.Filesz {
fmt.Fprintf(os.Stderr, "%v: Short read: %v of %v\n", v, i, v.Filesz)
os.Exit(1)
}
break
} else {
i = i + uint64(amt)
fmt.Fprintf(os.Stderr, "i now %v\n", i)
}
}
fmt.Fprintf(os.Stderr, "Processed %v\n", v)
}
fmt.Fprintf(os.Stderr, "gencode\n")
// Gen code to stdout. For each file, create an array, a start, and an end variable.
w := bufio.NewWriter(os.Stdout)
_, file := path.Split(n)
gencode(w, file, "code", mem, codestart, codeend)
gencode(w, file, "data", mem, datastart, dataend)
w.Flush()
}
}