added cross-platform getpass implementation [#8228]

base/libgit2/utils.jl

@@ -15,10 +15,39 @@ isset(val::Integer, flag::Integer) = (val & flag == flag)
 reset(val::Integer, flag::Integer) = (val &= ~flag)
 toggle(val::Integer, flag::Integer) = (val |= flag)
 
+@windows_only function getpass(prompt::AbstractString)
+    print(prompt)
+    flush(STDOUT)
+    p = Array(UInt8, 128) # mimic Unix getpass in ignoring more than 128-char passwords
+                          # (also avoids any potential memory copies arising from push!)
+    try
+        plen = 0
+        while true
+            c = ccall(:_getch, UInt8, ())
+            if c == 0xff || c == UInt8('\n') || c == UInt8('\r')
+                break # EOF or return
+            elseif c == 0x00 || c == 0xe0
+                ccall(:_getch, UInt8, ()) # ignore function/arrow keys
+            elseif c == UInt8('\b') && plen > 0
+                plen -= 1 # delete last character on backspace
+            elseif !iscntrl(Char(c)) && plen < 128
+                p[plen += 1] = c
+            end
+        end
+        return bytestring(pointer(p), plen)
+    finally
+        fill!(p, 0) # don't leave password in memory
+    end
+
+    return ""
+end
+
+@unix_only getpass(prompt::AbstractString) = bytestring(pointer_to_string(ccall(:getpass, Cstring, (Cstring,), prompt), true))
+
 function prompt(msg::AbstractString; default::AbstractString="", password::Bool=false)
     msg = !isempty(default) ? msg*" [$default]:" : msg*":"
     uinput = if password
-        bytestring(ccall(:getpass, Cstring, (Cstring,), msg))
+        getpass(msg)
     else
         print(msg)
         chomp(readline(STDIN))