[PATCH backup v4 1/4] fix #7054: client: remove trailing newlines from credentials

[Maximiliano Sandoval <m.sandoval@proxmox.com>]

Some tools, like systemd-ask-password can add a trailing new line to the file.
In order to improve usability we strip trailing newlines.

For repositories and fingerprints we simply strip trailing whitespaces. For
passwords, we refer to the password regex at proxmox-schema: `^[[:^cntrl:]]*$`,
we can only strip trailing control characters without potentially breaking
existing passwords. For the sake of avoiding to strip more than necessary we
only strip trailing newlines.

The encryption password is just a blob of bytes handled locally by the client,
we cannot remove trailing whitespace here without potential breakage. Creation
of such passwords (via proxmox_sys::tty::read_and_verify_password) only verifies
valid utf-8 and len >= 5 and thus the password might contain newlines.

Signed-off-by: Maximiliano Sandoval <m.sandoval@proxmox.com>
---
 pbs-client/src/tools/mod.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/pbs-client/src/tools/mod.rs b/pbs-client/src/tools/mod.rs
index 700436f8c..ca64b239e 100644
--- a/pbs-client/src/tools/mod.rs
+++ b/pbs-client/src/tools/mod.rs
@@ -189,6 +189,7 @@ fn get_secret_impl(env_variable: &str, credential_name: &str) -> Result<Option<S
 /// [credential]: https://systemd.io/CREDENTIALS/
 pub fn get_password() -> Result<Option<String>, Error> {
     get_secret_impl(ENV_VAR_PBS_PASSWORD, CRED_PBS_PASSWORD)
+        .map(|opt| opt.map(|s| s.trim_end_matches('\n').to_string()))
 }
 
 /// Gets an encryption password.
@@ -214,6 +215,7 @@ pub fn get_default_repository() -> Option<String> {
         .inspect_err(|err| {
             proxmox_log::error!("could not read default repository: {err:#}");
         })
+        .map(|opt| opt.map(|s| s.trim_end().to_string()))
         .unwrap_or_default()
 }
 
@@ -232,6 +234,7 @@ pub fn get_fingerprint() -> Option<String> {
         .inspect_err(|err| {
             proxmox_log::error!("could not read fingerprint: {err:#}");
         })
+        .map(|opt| opt.map(|s| s.trim_end().to_string()))
         .unwrap_or_default()
 }
 
-- 
2.47.3