1 files changed, 59 insertions, 0 deletions

diff --git a/examples/password_input.lua b/examples/password_input.lua
new file mode 100644
index 0000000..2994062
--- /dev/null
+++ b/examples/password_input.lua
@@ -0,0 +1,59 @@
+local sys = require "system"
+
+print [[
+
+This example shows how to disable the "echo" of characters read to the console,
+useful for reading secrets from the user.
+
+]]
+
+--- Function to read from stdin without echoing the input (for secrets etc).
+-- It will (in a platform agnostic way) disable echo on the terminal, read the
+-- input, and then re-enable echo.
+-- @param ... Arguments to pass to `io.stdin:read()`
+-- @return the results of `io.stdin:read(...)`
+local function read_secret(...)
+  local w_oldflags, p_oldflags
+
+  if sys.isatty(io.stdin) then
+    -- backup settings, configure echo flags
+    w_oldflags = sys.getconsoleflags(io.stdin)
+    p_oldflags = sys.tcgetattr(io.stdin)
+    -- set echo off to not show password on screen
+    assert(sys.setconsoleflags(io.stdin, w_oldflags - sys.CIF_ECHO_INPUT))
+    assert(sys.tcsetattr(io.stdin, sys.TCSANOW, { lflag = p_oldflags.lflag - sys.L_ECHO }))
+  end
+
+  local secret, err = io.stdin:read(...)
+
+  -- restore settings
+  if sys.isatty(io.stdin) then
+    io.stdout:write("\n")  -- Add newline after reading the password
+    sys.setconsoleflags(io.stdin, w_oldflags)
+    sys.tcsetattr(io.stdin, sys.TCSANOW, p_oldflags)
+  end
+
+  return secret, err
+end
+
+
+
+-- Get username
+io.write("Username: ")
+local username = io.stdin:read("*l")
+
+-- Get the secret
+io.write("Password: ")
+local password = read_secret("*l")
+
+-- Get domainname
+io.write("Domain  : ")
+local domain = io.stdin:read("*l")
+
+
+-- Print the results
+print("")
+print("Here's what we got:")
+print("  username: " .. username)
+print("  password: " .. password)
+print("  domain  : " .. domain)