Setting Broadcaster specific price segfault

[stronk-dev]

It works well in general, but when specifying 3 or more B's using CMD flags the program segfaults. This is caused due to an error being thrown in the ReadFromFile function, where os.Stat(s) returns an error which was not being covered by os.IsNotExist(err). After that info.IsDir() is called but info is undefined at that point

go-livepeer/cmd/livepeer/starter/starter.go

Line 1413 in 8bd65fb

prices, _ := common.ReadFromFile(broadcasterPrices)

go-livepeer/common/readfromfile.go

Lines 12 to 19 in 8bd65fb

	func ReadFromFile(s string) (string, error) {
	info, err := os.Stat(s)
	if os.IsNotExist(err) {
	// If the supplied string is not a path to a file,
	// assume it is the pass and return it
	return s, nil
	}
	if info.IsDir() {

Entire segfault:

I0701 09:42:34.148159       1 db.go:458] Closing DB
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x1a087b2]
goroutine 26 [running]:
github.com/livepeer/go-livepeer/common.ReadFromFile({0x7ffc84ab8acc, 0x131})
	/common/readfromfile.go:19 +0x72
github.com/livepeer/go-livepeer/cmd/livepeer/starter.getBroadcasterPrices({0x7ffc84ab8acc, 0x131})
	/cmd/livepeer/starter/starter.go:1444 +0x49
github.com/livepeer/go-livepeer/cmd/livepeer/starter.StartLivepeer({_, _}, {0xc00052e2f0, 0xc00052e300, 0xc00052e310, 0xc00052e320, 0xc00052e330, 0xc00052e340, 0xc00052e350, 0xc00052e410, ...})
	/cmd/livepeer/starter/starter.go:766 +0x3fb3
main.main.func1()
	/cmd/livepeer/livepeer.go:97 +0x58
created by main.main
	/cmd/livepeer/livepeer.go:96 +0xca5

Proposed solution is to return the string as-is if the ReadFromFile errors

Edit: this issue probably only occurs when using CMD flags to

[ad-astra-video]

Just curious, what is the input string length max? Also, the max length is the file path?

[stronk-dev]

Just curious, what is the input string length max?

Not sure, somewhere between specifying 2 and 3 broadcaster prices :p
OS.Stat returns an error after some point where the input string is too long to be a file path/directory. A nice edge case which wasn't being checked for or covered by unit tests

Edit: basically what happened is os.Stat(s) returns an error which was not being covered by os.IsNotExist(err). After that info.IsDir() is called but info is undefined at that point