client: xdg usage: place() vs find()

place() is used when creating a file, as it will create
intermediate directories, only use it when actually placing
a new file.

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

src/backup/key_derivation.rs

@@ -1,4 +1,4 @@
-use anyhow::{bail, format_err, Error};
+use anyhow::{bail, format_err, Context, Error};
 
 use serde::{Deserialize, Serialize};
 use chrono::{Local, TimeZone, DateTime};
@@ -146,8 +146,18 @@ pub fn encrypt_key_with_passphrase(
     })
 }
 
-pub fn load_and_decrypt_key(path: &std::path::Path, passphrase: &dyn Fn() -> Result<Vec<u8>, Error>) -> Result<([u8;32], DateTime<Local>), Error> {
+pub fn load_and_decrypt_key(
+    path: &std::path::Path,
+    passphrase: &dyn Fn() -> Result<Vec<u8>, Error>,
+) -> Result<([u8;32], DateTime<Local>), Error> {
+    do_load_and_decrypt_key(path, passphrase)
+        .with_context(|| format!("failed to load decryption key from {:?}", path))
+}
 
+fn do_load_and_decrypt_key(
+    path: &std::path::Path,
+    passphrase: &dyn Fn() -> Result<Vec<u8>, Error>,
+) -> Result<([u8;32], DateTime<Local>), Error> {
     let raw = file_get_contents(&path)?;
     let data = String::from_utf8(raw)?;
 

src/bin/proxmox-backup-client.rs

@@ -677,13 +677,13 @@ fn keyfile_parameters(param: &Value) -> Result<(Option<PathBuf>, CryptMode), Err
 
     Ok(match (keyfile, crypt_mode) {
         // no parameters:
-        (None, None) => (key::optional_default_key_path()?, CryptMode::Encrypt),
+        (None, None) => (key::find_default_encryption_key()?, CryptMode::Encrypt),
 
         // just --crypt-mode=none
         (None, Some(CryptMode::None)) => (None, CryptMode::None),
 
         // just --crypt-mode other than none
-        (None, Some(crypt_mode)) => match key::optional_default_key_path()? {
+        (None, Some(crypt_mode)) => match key::find_default_encryption_key()? {
             None => bail!("--crypt-mode without --keyfile and no default key file available"),
             Some(path) => (Some(path), crypt_mode),
         }

src/bin/proxmox_backup_client/key.rs

@@ -1,6 +1,6 @@
 use std::path::PathBuf;
 
-use anyhow::{bail, Error};
+use anyhow::{bail, format_err, Context, Error};
 use chrono::{Local, TimeZone};
 use serde::{Deserialize, Serialize};
 use xdg::BaseDirectories;
@@ -15,6 +15,8 @@ use proxmox_backup::backup::{
 };
 use proxmox_backup::tools;
 
+pub const DEFAULT_ENCRYPTION_KEY_FILE_NAME: &str = "encryption-key.json";
+
 pub fn master_pubkey_path() -> Result<PathBuf, Error> {
     let base = BaseDirectories::with_prefix("proxmox-backup")?;
 
@@ -24,13 +26,19 @@ pub fn master_pubkey_path() -> Result<PathBuf, Error> {
     Ok(path)
 }
 
-pub fn default_encryption_key_path() -> Result<PathBuf, Error> {
-    let base = BaseDirectories::with_prefix("proxmox-backup")?;
+pub fn find_default_encryption_key() -> Result<Option<PathBuf>, Error> {
+    BaseDirectories::with_prefix("proxmox-backup")
+        .map(|base| base.find_config_file(DEFAULT_ENCRYPTION_KEY_FILE_NAME))
+        .with_context(|| "error searching for default encryption key file")
+}
 
-    // usually $HOME/.config/proxmox-backup/encryption-key.json
-    let path = base.place_config_file("encryption-key.json")?;
-
-    Ok(path)
+pub fn place_default_encryption_key() -> Result<PathBuf, Error> {
+    BaseDirectories::with_prefix("proxmox-backup")
+        .map_err(Error::from)
+        .and_then(|base| {
+            base.place_config_file(DEFAULT_ENCRYPTION_KEY_FILE_NAME).map_err(Error::from)
+        })
+        .with_context(|| "failed to place default encryption key file in xdg home")
 }
 
 pub fn get_encryption_key_password() -> Result<Vec<u8>, Error> {
@@ -53,16 +61,6 @@ pub fn get_encryption_key_password() -> Result<Vec<u8>, Error> {
     bail!("no password input mechanism available");
 }
 
-/// Convenience helper to get the default key file path only if it exists.
-pub fn optional_default_key_path() -> Result<Option<PathBuf>, Error> {
-    let path = default_encryption_key_path()?;
-    Ok(if path.exists() {
-        Some(path)
-    } else {
-        None
-    })
-}
-
 #[api(
     default: "scrypt",
 )]
@@ -103,7 +101,7 @@ impl Default for Kdf {
 fn create(kdf: Option<Kdf>, path: Option<String>) -> Result<(), Error> {
     let path = match path {
         Some(path) => PathBuf::from(path),
-        None => default_encryption_key_path()?,
+        None => place_default_encryption_key()?,
     };
 
     let kdf = kdf.unwrap_or_default();
@@ -160,7 +158,8 @@ fn create(kdf: Option<Kdf>, path: Option<String>) -> Result<(), Error> {
 fn change_passphrase(kdf: Option<Kdf>, path: Option<String>) -> Result<(), Error> {
     let path = match path {
         Some(path) => PathBuf::from(path),
-        None => default_encryption_key_path()?,
+        None => find_default_encryption_key()?
+            .ok_or_else(|| format_err!("no encryption file provided and no default file found"))?,
     };
 
     let kdf = kdf.unwrap_or_default();