fix: use /etc/os-release PRETTY_NAME for firmware version

Parse PRETTY_NAME from /etc/os-release (standard on mLinux and most Linux)
instead of /etc/mlinux-version which has ASCII art header.

Falls back to /etc/issue if os-release not available.

Author: reissjason

src-linux/sys_linux.c

@@ -484,36 +484,55 @@ str_t sys_version () {
 
 str_t sys_firmware () {
     // Try to read firmware version from system files
-    // Check /etc/mlinux-version first (mLinux specific)
+    // Prefer /etc/os-release PRETTY_NAME (standard, works on mLinux and most Linux)
     if( firmwareTxt == NULL ) {
-        FILE* f = fopen("/etc/mlinux-version", "r");
-        if( f == NULL )
-            f = fopen("/etc/issue", "r");
+        FILE* f = fopen("/etc/os-release", "r");
         if( f ) {
-            char buf[128];
-            if( fgets(buf, sizeof(buf), f) ) {
-                // Trim trailing whitespace and escape sequences (like \n \l in /etc/issue)
-                int n = strlen(buf);
-                while( n > 0 && strchr(" \t\r\n", buf[n-1]) ) --n;
-                buf[n] = 0;
-                // Remove escape sequences like \n, \l, etc. from /etc/issue
-                char* p = buf;
-                while( (p = strchr(p, '\\')) != NULL ) {
-                    if( p[1] ) {
-                        memmove(p, p+2, strlen(p+2)+1);
-                    } else {
-                        *p = 0;
-                        break;
-                    }
+            char buf[256];
+            while( fgets(buf, sizeof(buf), f) ) {
+                if( strncmp(buf, "PRETTY_NAME=", 12) == 0 ) {
+                    char* val = buf + 12;
+                    // Remove quotes if present
+                    if( *val == '"' ) val++;
+                    int n = strlen(val);
+                    while( n > 0 && strchr(" \t\r\n\"", val[n-1]) ) --n;
+                    val[n] = 0;
+                    firmwareTxt = rt_strdup(val);
+                    break;
                 }
-                // Trim again after removing escapes
-                n = strlen(buf);
-                while( n > 0 && strchr(" \t\r\n", buf[n-1]) ) --n;
-                buf[n] = 0;
-                firmwareTxt = rt_strdup(buf);
             }
             fclose(f);
         }
+        // Fallback to /etc/issue if os-release didn't work
+        if( firmwareTxt == NULL ) {
+            f = fopen("/etc/issue", "r");
+            if( f ) {
+                char buf[128];
+                if( fgets(buf, sizeof(buf), f) ) {
+                    // Trim trailing whitespace and escape sequences (like \n \l in /etc/issue)
+                    int n = strlen(buf);
+                    while( n > 0 && strchr(" \t\r\n", buf[n-1]) ) --n;
+                    buf[n] = 0;
+                    // Remove escape sequences like \n, \l, etc. from /etc/issue
+                    char* p = buf;
+                    while( (p = strchr(p, '\\')) != NULL ) {
+                        if( p[1] ) {
+                            memmove(p, p+2, strlen(p+2)+1);
+                        } else {
+                            *p = 0;
+                            break;
+                        }
+                    }
+                    // Trim again after removing escapes
+                    n = strlen(buf);
+                    while( n > 0 && strchr(" \t\r\n", buf[n-1]) ) --n;
+                    buf[n] = 0;
+                    if( n > 0 )
+                        firmwareTxt = rt_strdup(buf);
+                }
+                fclose(f);
+            }
+        }
     }
     return firmwareTxt;
 }