[PATCH backup 1/2] fix #7054: client: remove trailing newlines from credentials

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

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.

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.

In order to prevent an allocation for credentials that do not need to be
stripped we perform a preemptive check with str::ends_with before
allocating.

Signed-off-by: Maximiliano Sandoval <m.sandoval@proxmox.com>
---
 pbs-client/src/tools/mod.rs | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/pbs-client/src/tools/mod.rs b/pbs-client/src/tools/mod.rs
index 7a496d14c..8dc7c2cd5 100644
--- a/pbs-client/src/tools/mod.rs
+++ b/pbs-client/src/tools/mod.rs
@@ -169,6 +169,17 @@ fn get_secret_impl(env_variable: &str, credential_name: &str) -> Result<Option<S
         Ok(Some(password))
     } else if let Some(password) = get_credential(credential_name)? {
         String::from_utf8(password)
+            .map(|s| {
+                if matches!(credential_name, CRED_PBS_REPOSITORY | CRED_PBS_FINGERPRINT)
+                    && s.ends_with(char::is_whitespace)
+                {
+                    s.trim_end().to_string()
+                } else if credential_name == CRED_PBS_PASSWORD && s.ends_with(char::is_control) {
+                    s.trim_end_matches(char::is_control).to_string()
+                } else {
+                    s
+                }
+            })
             .map(Option::Some)
             .map_err(|_err| format_err!("credential {credential_name} is not utf8 encoded"))
     } else {
-- 
2.47.3