fix #6185: client/docs: explicitly mention archive name restrictions

Mention in the docs and the api parameter description the limitations
for archive name labels. They must contain alphanumerics, hyphens and
underscores only to match the regex pattern.

By setting this in the api parameter description, it will be included
in the man page for proxmox-backup-client.

Fixes: https://bugzilla.proxmox.com/show_bug.cgi?id=6185
Signed-off-by: Christian Ebner <c.ebner@proxmox.com>

docs/backup-client.rst

@@ -169,6 +169,7 @@ the client. The format is:
 
     <archive-name>.<type>:<source-path>
 
+The ``archive-name`` must contain alphanumerics, hyphens and underscores only.
 Common types are ``.pxar`` for file archives and ``.img`` for block
 device images. To create a backup of a block device, run the following command:
 

pbs-client/src/backup_specification.rs

@@ -7,10 +7,12 @@ const_regex! {
     BACKUPSPEC_REGEX = r"^([a-zA-Z0-9_-]+\.(pxar|img|conf|log)):(.+)$";
 }
 
-pub const BACKUP_SOURCE_SCHEMA: Schema =
-    StringSchema::new("Backup source specification ([<label>:<path>]).")
-        .format(&ApiStringFormat::Pattern(&BACKUPSPEC_REGEX))
-        .schema();
+pub const BACKUP_SOURCE_SCHEMA: Schema = StringSchema::new(
+    "Backup source specification ([<label>:<path>]), the specification \
+    'label' must contain alphanumerics, hyphens and underscores only.",
+)
+.format(&ApiStringFormat::Pattern(&BACKUPSPEC_REGEX))
+.schema();
 
 pub enum BackupSpecificationType {
     PXAR,

proxmox-backup-client/src/main.rs

@@ -628,7 +628,8 @@ fn spawn_catalog_upload(
        properties: {
            backupspec: {
                type: Array,
-               description: "List of backup source specifications ([<label.ext>:<path>] ...)",
+               description: "List of backup source specifications ([<label.ext>:<path>] ...), the \
+                    specifications 'label' must contain alphanumerics, hyphens and underscores only.",
                items: {
                    schema: BACKUP_SOURCE_SCHEMA,
                }