resume flag overwrites output file

[minispooner]

httpx version:

v1.2.4

Current Behavior:

when passing -resume and -o OUTPUT_FILE flags, httpx clears and overwrites the OUTPUT_FILE contents

Expected Behavior:

when passing -resume and -o OUTPUT_FILE flags, httpx should NOT clear and overwrite the OUTPUT_FILE contents. instead, httpx should APPEND to the OUTPUT_FILE contents (but not write the application header display again, simply pick up where it left off).

Steps To Reproduce:

setup dummy hosts file

echo "example.com" > five_hosts.txt
echo "www.google.com" >> five_hosts.txt
echo "www.facebook.com" >> five_hosts.txt
echo "example2.com" >> five_hosts.txt
echo "www.twitter.com" >> five_hosts.txt

setup resume.cfg file to pretend like httpx has already run once

echo "resume_from=www.facebook.com" > resume.cfg
echo "index=3" >> resume.cfg # not sure if index is 0-based or 1-based...

setup a fake previous* run output file

echo "this text will no longer appear" > out.txt

run 2nd attempt of httpx

cat five_hosts.txt | httpx -o out.txt -resume
cat out.txt | grep "this text will no longer appear"

text not found using grep, showing that the -resume flag overwrites previous output data instead of appending to it. "resume" should intuitively append, not overwrite

I just ran these steps and validated the steps to reproduce work as described above.

screenshot below

[ibitebyt3s]

Took a look at this and got an unfinished idea because I ran out of time today.

1. Add extra if else block(s?) (nested?) that opens the file pointer with the os.O_APPEND flag near this if block where it's always creating a new empty file. Something like f, err = os.OpenFile(r.options.Output, os.O_APPEND) migth be part of the code.
   

   httpx/runner/runner.go

   Line 562 in f2cd5b8

   if r.options.Output != "" {

2. If appending to it, add a check to handle the case were the file doesn't exist. I thought that exiting the program might be the best way to do it instead of continuing execution.
3. Keep in mind what else I could have missed.

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I'll notify in this thread if I begin to work on it.
Found this blog post with code snippets, that was a useful refresher of golang file handling.