1 files changed, 101 insertions, 0 deletions
diff --git a/sop/src/errors.rs b/sop/src/errors.rs
new file mode 100644
index 00000000..0eae86b7
--- /dev/null
+++ b/sop/src/errors.rs
@@ -0,0 +1,101 @@
+/// Errors defined by the Stateless OpenPGP Protocol.
+#[derive(thiserror::Error, Debug, Clone)]
+pub enum Error {
+    /// No acceptable signatures found ("sop verify").
+    #[error("No acceptable signatures found")]
+    NoSignature,
+
+    /// Asymmetric algorithm unsupported ("sop encrypt").
+    #[error("Asymmetric algorithm unsupported")]
+    UnsupportedAsymmetricAlgo,
+
+    /// Certificate not encryption-capable (e.g., expired, revoked,
+    /// unacceptable usage flags) ("sop encrypt").
+    #[error("Certificate not encryption-capable")]
+    CertCannotEncrypt,
+
+    /// Missing required argument.
+    #[error("Missing required argument")]
+    MissingArg,
+
+    /// Incomplete verification instructions ("sop decrypt").
+    #[error("Incomplete verification instructions")]
+    IncompleteVerification,
+
+    /// Unable to decrypt ("sop decrypt").
+    #[error("Unable to decrypt")]
+    CannotDecrypt,
+
+    /// Non-"UTF-8" or otherwise unreliable password ("sop encrypt").
+    #[error("Non-UTF-8 or otherwise unreliable password")]
+    PasswordNotHumanReadable,
+
+    /// Unsupported option.
+    #[error("Unsupported option")]
+    UnsupportedOption,
+
+    /// Invalid data type (no secret key where "KEY" expected, etc).
+    #[error("Invalid data type")]
+    BadData,
+
+    /// Non-text input where text expected.
+    #[error("Non-text input where text expected")]
+    ExpectedText,
+
+    /// Output file already exists.
+    #[error("Output file already exists")]
+    OutputExists,
+
+    /// Input file does not exist.
+    #[error("Input file does not exist")]
+    MissingInput,
+
+    /// A "KEY" input is protected (locked) with a password, and "sop" cannot
+    /// unlock it.
+    #[error("A KEY input is protected with a password")]
+    KeyIsProtected,
+
+    /// Unsupported subcommand.
+    #[error("Unsupported subcommand")]
+    UnsupportedSubcommand,
+
+    /// An indirect parameter is a special designator (it starts with "@") but
+    /// "sop" does not know how to handle the prefix.
+    #[error("An indirect parameter is a special designator with unknown prefix")]
+    UnsupportedSpecialPrefix,
+
+    /// A indirect input parameter is a special designator (it starts with
+    /// "@"), and a filename matching the designator is actually present.
+    #[error("A indirect input parameter is a special designator matches file")]
+    AmbiguousInput,
+}
+
+impl From<Error> for i32 {
+    fn from(e: Error) -> Self {
+        use Error::*;
+        match e {
+            NoSignature => 3,
+            UnsupportedAsymmetricAlgo => 13,
+            CertCannotEncrypt => 17,
+            MissingArg => 19,
+            IncompleteVerification => 23,
+            CannotDecrypt => 29,
+            PasswordNotHumanReadable => 31,
+            UnsupportedOption => 37,
+            BadData => 41,
+            ExpectedText => 53,
+            OutputExists => 59,
+            MissingInput => 61,
+            KeyIsProtected => 67,
+            UnsupportedSubcommand => 69,
+            UnsupportedSpecialPrefix => 71,
+            AmbiguousInput => 73,
+        }
+    }
+}
+
+/// Prints the error and causes, if any.
+pub fn print_error_chain(err: &anyhow::Error) {
+    eprintln!("           {}", err);
+    err.chain().skip(1).for_each(|cause| eprintln!("  because: {}", cause));
+}