fix: fix validate_username follow Linux username rules.

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- Maximum 32 characters
- Must start with a lowercase letter (a-z) or underscore (_)
- Emaining characters: lowercase letters (a-z), digits (0-9),
  underscores (_), or hyphens (-)

Author: eatradish

i18n/en-US/dkcli.ftl

@@ -42,6 +42,8 @@ swap-size = Size of the swapfile (GiB)
 hostname-illegal = The specified hostname contains invalid character(s): { $c }
 username-illegal = The specified username contains invalid character(s): { $c }
 username-illegal-starts-with-number = The specified UNIX user name cannot begin with a number.
+username-illegal-starts-with = The specified username starts with invalid character(s): { $c }
+username-illegal-too-long = The specified username is too long.
 hostname-illegal-starts-with = The specified hostname starts with invalid character(s): { $c }
 hostname-illegal-ends-with = The specified hostname ends with invalid character(s): { $c }
 hostname-illegal-too-loong = The specified hostname is too long.

i18n/zh-CN/dkcli.ftl

@@ -43,6 +43,8 @@ hostname-illegal = 指定的主机名中包含无效字符：{ $c }
 hostname-illegal-startswith = 指定的主机名以无效字符字符开头：{ $c }
 username-illegal = 指定的 UNIX 用户名中包含无效字符：{ $c }
 username-illegal-starts-with-number = 指定的 UNIX 用户名中开头不能是数字。
+username-illegal-starts-with = 指定的 UNIX 用户名以无效字符开头：{ $c }
+username-illegal-too-long = 指定的 UNIX 用户名过长。
 fullname-illegal = 指定的用户全名中包含无效字符：':'
 squashfs-empty = 系统发行元数据文件中未包含 `squashfs'，该元数据文件可能已损坏。
 confirm-password = 确认密码

src/main.rs

@@ -822,16 +822,33 @@ fn validate_hostname(input: &str) -> std::result::Result<Validation, Box<dyn Err
 }
 
 fn validate_username(input: &str) -> std::result::Result<Validation, Box<dyn Error + Send + Sync>> {
-    if input.starts_with(|x: char| x.is_ascii_digit()) {
+    if input.is_empty() {
+        return Ok(Validation::Invalid(fl!("username-illegal", c = "").into()));
+    }
+
+    // Maximum 32 characters
+    if input.chars().count() > 32 {
+        return Ok(Validation::Invalid(fl!("username-illegal-too-long").into()));
+    }
+
+    // Must start with a lowercase letter (a-z) or underscore (_)
+    let first = input.chars().next().unwrap();
+    if first.is_ascii_digit() {
         return Ok(Validation::Invalid(
             fl!("username-illegal-starts-with-number").into(),
         ));
     }
+    if !first.is_ascii_lowercase() && first != '_' {
+        return Ok(Validation::Invalid(
+            fl!("username-illegal-starts-with", c = first.to_string()).into(),
+        ));
+    }
 
-    for i in input.chars() {
-        if !i.is_ascii_lowercase() && !i.is_ascii_digit() {
+    // Emaining characters: lowercase letters (a-z), digits (0-9), underscores (_), or hyphens (-)
+    for c in input.chars().skip(1) {
+        if !c.is_ascii_lowercase() && !c.is_ascii_digit() && c != '_' && c != '-' {
             return Ok(Validation::Invalid(
-                fl!("username-illegal", c = i.to_string()).into(),
+                fl!("username-illegal", c = c.to_string()).into(),
             ));
         }
     }
@@ -1148,6 +1165,9 @@ fn test_hostname_validation() {
 fn test_username_validation() {
     assert_eq!(validate_username("foo").unwrap(), Validation::Valid);
     assert_eq!(validate_username("cth451").unwrap(), Validation::Valid);
+    assert_eq!(validate_username("foo_bar").unwrap(), Validation::Valid);
+    assert_eq!(validate_username("foo-bar").unwrap(), Validation::Valid);
+    assert_eq!(validate_username("_foo").unwrap(), Validation::Valid);
     assert!(matches!(
         validate_username("老白").unwrap(),
         Validation::Invalid(..)
@@ -1160,4 +1180,12 @@ fn test_username_validation() {
         validate_username("123bai").unwrap(),
         Validation::Invalid(..)
     ));
+    assert!(matches!(
+        validate_username("-foobar").unwrap(),
+        Validation::Invalid(..)
+    ));
+    assert!(matches!(
+        validate_username(&"a".repeat(33)).unwrap(),
+        Validation::Invalid(..)
+    ));
 }