panic: runtime error: invalid memory address or nil pointer dereference

[rorycl]

Hi @phpdave11

I've found a PDF which causes a nil pointer dereference:

panic: runtime error: invalid memory address or nil pointer dereference

Perhaps it is because the PDF has form fields?

To reproduce:

package main
  
import (
    "fmt"
    "github.com/phpdave11/gofpdf"
    "github.com/phpdave11/gofpdf/contrib/gofpdi"
    "io"
    "io/ioutil"
    "net/http"
    "os"
    rpdf "rsc.io/pdf"
)

const PDF_WIDTH_IN_MM = 222.6264
const PDF_HEIGHT_IN_MM = 297.0000
const MM_TO_RMPOINTS = 2.83465

var Verbose bool = true

var url string = "http://www.campbell-lange.net/media/files/example_2020b.pdf"

func main() {

    resp, err := http.Get(url)
    if err != nil {
        panic(err)
    }
    defer resp.Body.Close()

    tmpFile, err := ioutil.TempFile(os.TempDir(), "pdfexample-")
    if err != nil {
        panic(err)
    }
    filer := tmpFile.Name()
    defer os.Remove(filer)

    _, err = io.Copy(tmpFile, resp.Body)
    if err != nil {
        panic(err)
    }
    // get pdf file information
    fi, err := rpdf.Open(filer)
    if err != nil {
        panic(err)
    }
    pageNum := fi.NumPage()
    if Verbose {
        fmt.Printf("Example PDF from %s\n", url)
        fmt.Printf("file: %s\n   pages: %3d\n", filer, pageNum)
    }

    // construct new gofpdf document
    pdf := gofpdf.NewCustom(&gofpdf.InitType{
        UnitStr: "pt",
        Size: gofpdf.SizeType{
            Wd: PDF_WIDTH_IN_MM * MM_TO_RMPOINTS,
            Ht: PDF_HEIGHT_IN_MM * MM_TO_RMPOINTS},
    })

    for p := 1; p <= pageNum; p++ {
        pdf.AddPage()

        bgpdf := gofpdi.ImportPage(pdf, filer, p, "/MediaBox")
        gofpdi.UseImportedTemplate(pdf, bgpdf, 0, 0, 210*MM_TO_RMPOINTS, 297

        if Verbose {
            fmt.Printf("   page : %3d processed\n", p)
        }
    }
}

By the way, pdftotext parses this ok so I assume the PDF is valid.

Cheers,
Rory