time-cond doesn't work for files with date before 1970-01-01

[piru]

I did this

touch -d '1969-12-31T00:00:00Z' reallyold.txt
curl --time-cond reallyold.txt -I https://curl.se

I expected the following

The date before 1970-01-01 being considered valid.

curl/libcurl version

curl 8.2.1

operating system

macOS 13.5.1 (22G90)

[piru]

Root cause is here:

curl/src/tool_getparam.c

Line 2652 in cb5e181

if(filetime >= 0) {

getfiletime should probably be changed to return success/failure indicator and store the time to curl_off_t * on success.