pcsc-sys: add nicer error message when pcsclite is not found on Linux

Fix #51

Author: bluetech

pcsc-sys/build.rs

@@ -1,5 +1,28 @@
 use std::env;
 
+fn print_pcsclite_error_message(target_os: &str) {
+    if target_os == "linux" {
+        eprintln!(
+            "If you are using Debian (or a derivative), try:
+
+    $ sudo apt install pkgconf libpcsclite-dev
+"
+        );
+        eprintln!(
+            "If you are using Arch (or a derivative), try:
+
+    $ sudo pacman -S pkgconf pcsclite
+"
+        );
+        eprintln!(
+            "If you are using Fedora (or a derivative), try:
+
+    $ sudo dnf install pkgconf pcsc-lite-devel
+"
+        );
+    }
+}
+
 fn main() {
     let target_os = env::var("CARGO_CFG_TARGET_OS")
         .expect(r#"The CARGO_CFG_TARGET_OS environment is not set in the build script."#);
@@ -25,17 +48,16 @@ fn main() {
                     env::var("PCSC_LIB_NAME").unwrap_or_else(|_| "pcsclite".to_string())
                 );
             } else {
-                pkg_config::Config::new()
-                    .atleast_version("1")
-                    .probe("libpcsclite")
-                    .unwrap_or_else(|_| {
-                        panic!(
-                            r#"Could not find a PCSC library.
-For the target OS `{}`, I tried to use pkg-config to find libpcsclite.
-Do you have pkg-config and libpcsclite configured for this target?"#,
-                            target_os
-                        )
-                    });
+                if let Err(err) = pkg_config::Config::new().atleast_version("1").probe("libpcsclite") {
+                    eprintln!("Could not find a PCSC library.");
+                    eprintln!(
+                        "For the target OS `{}`, I tried to use pkg-config to find libpcsclite.",
+                        target_os
+                    );
+                    eprintln!("The error given is: {}", err);
+                    print_pcsclite_error_message(&target_os);
+                    std::process::exit(1);
+                }
             }
         }
     };