Version v0.2.74 - Added silent decrypt mode for clean pipe operations

encrypted.txt

@@ -0,0 +1,11 @@
+
+
+-----BEGIN OTP MESSAGE-----
+Version: v0.2.72
+Pad-ChkSum: 97d9d82b5414a9439102f3811fb90ab1d6368a00d33229a18b306476f9d04f82
+Pad-Offset: 2873419
+
+iR6J7HHK1Oc6
+-----END OTP MESSAGE-----
+
+

otp.c

@@ -46,10 +46,26 @@ static const int base64_decode_table[256] = {
 // Global variable for current pads directory (can be local or OTP thumb drive)
 static char current_pads_dir[512] = DEFAULT_PADS_DIR;
 
+// Global variable for default pad path from preferences
+static char default_pad_path[1024] = "";
+
 // Function prototypes
 int main(int argc, char* argv[]);
 int interactive_mode(void);
 int command_line_mode(int argc, char* argv[]);
+int pipe_mode(int argc, char* argv[], const char* piped_text);
+
+// Stdin detection functions
+int has_stdin_data(void);
+char* read_stdin_text(void);
+
+// Preferences management functions
+int load_preferences(void);
+int save_preferences(void);
+char* get_preference(const char* key);
+int set_preference(const char* key, const char* value);
+char* get_default_pad_path(void);
+int set_default_pad_path(const char* pad_path);
 
 // OTP thumb drive detection function
 int detect_otp_thumb_drive(char* otp_drive_path, size_t path_size);
@@ -65,6 +81,7 @@ int generate_pad(uint64_t size_bytes, int show_progress);
 int generate_pad_with_entropy(uint64_t size_bytes, int show_progress, int use_keyboard_entropy);
 int encrypt_text(const char* pad_identifier, const char* input_text);
 int decrypt_text(const char* pad_identifier, const char* encrypted_message);
+int decrypt_text_silent(const char* pad_identifier, const char* encrypted_message);
 int encrypt_file(const char* pad_identifier, const char* input_file, const char* output_file, int ascii_armor);
 int decrypt_file(const char* input_file, const char* output_file);
 int decrypt_binary_file(FILE* input_fp, const char* output_file);
@@ -115,16 +132,35 @@ void get_directory_display(const char* file_path, char* result, size_t result_si
 void print_usage(const char* program_name);
 
 int main(int argc, char* argv[]) {
+    // Load preferences first
+    load_preferences();
+    
+    // Check for piped input first (before any output)
+    int is_pipe_mode = (argc == 1 && has_stdin_data());
+    
     // Check for OTP thumb drive on startup
     char otp_drive_path[512];
     if (detect_otp_thumb_drive(otp_drive_path, sizeof(otp_drive_path))) {
-        printf("Detected OTP thumb drive: %s\n", otp_drive_path);
-        printf("Using as default pads directory for this session.\n\n");
+        // Only show messages in interactive/command mode, not pipe mode
+        if (!is_pipe_mode) {
+            printf("Detected OTP thumb drive: %s\n", otp_drive_path);
+            printf("Using as default pads directory for this session.\n\n");
+        }
         strncpy(current_pads_dir, otp_drive_path, sizeof(current_pads_dir) - 1);
         current_pads_dir[sizeof(current_pads_dir) - 1] = '\0';
     }
     
-    if (argc == 1) {
+    if (is_pipe_mode) {
+        // No arguments but has piped data - enter pipe mode
+        char* piped_text = read_stdin_text();
+        if (piped_text) {
+            int result = pipe_mode(argc, argv, piped_text);
+            free(piped_text);
+            return result;
+        }
+        // If reading stdin failed, fall back to interactive mode
+        return interactive_mode();
+    } else if (argc == 1) {
         return interactive_mode();
     } else {
         return command_line_mode(argc, argv);
@@ -158,6 +194,7 @@ int interactive_mode(void) {
                 handle_pads_menu();
                 break;
             case 'X':
+            case 'Q':
                 printf("Goodbye!\n");
                 return 0;
             default:
@@ -202,6 +239,16 @@ int command_line_mode(int argc, char* argv[]) {
     }
     else if (strcmp(argv[1], "decrypt") == 0 || strcmp(argv[1], "-d") == 0) {
         if (argc == 2) {
+            // Check for piped input first
+            if (has_stdin_data()) {
+                // Piped decrypt mode - read stdin and decrypt silently
+                char* piped_message = read_stdin_text();
+                if (piped_message) {
+                    int result = decrypt_text_silent(NULL, piped_message);
+                    free(piped_message);
+                    return result;
+                }
+            }
             // Interactive mode - no arguments needed
             return decrypt_text(NULL, NULL);
         }
@@ -1127,10 +1174,39 @@ int generate_pad_with_entropy(uint64_t size_bytes, int display_progress, int use
     // Get final paths in pads directory
     get_pad_path(chksum_hex, pad_path, state_path);
     
+    // Try rename first (works for same filesystem)
     if (rename(temp_filename, pad_path) != 0) {
-        printf("Error: Cannot move pad file to pads directory\n");
+        // If rename fails, try copy and delete (works across filesystems)
+        FILE* temp_file = fopen(temp_filename, "rb");
+        FILE* dest_file = fopen(pad_path, "wb");
+        
+        if (!temp_file || !dest_file) {
+            printf("Error: Cannot copy pad file to pads directory\n");
+            if (temp_file) fclose(temp_file);
+            if (dest_file) fclose(dest_file);
+            unlink(temp_filename);
+            return 1;
+        }
+        
+        // Copy file in chunks
+        unsigned char copy_buffer[64 * 1024];
+        size_t bytes_read;
+        while ((bytes_read = fread(copy_buffer, 1, sizeof(copy_buffer), temp_file)) > 0) {
+            if (fwrite(copy_buffer, 1, bytes_read, dest_file) != bytes_read) {
+                printf("Error: Failed to copy pad file to pads directory\n");
+                fclose(temp_file);
+                fclose(dest_file);
+                unlink(temp_filename);
+                unlink(pad_path);
+                return 1;
+            }
+        }
+        
+        fclose(temp_file);
+        fclose(dest_file);
+        
+        // Remove temporary file after successful copy
         unlink(temp_filename);
-        return 1;
     }
     
     // Set pad file to read-only
@@ -1325,8 +1401,15 @@ int encrypt_text(const char* pad_identifier, const char* input_text) {
         printf("Warning: Failed to update state file\n");
     }
     
-    // Output in ASCII armor format
-    printf("\n\n-----BEGIN OTP MESSAGE-----\n");
+    // Output in ASCII armor format - clean format for piping, spaced format for interactive
+    int is_interactive = (input_text == NULL); // Interactive if no input_text provided
+    
+    if (is_interactive) {
+        printf("\n\n-----BEGIN OTP MESSAGE-----\n");
+    } else {
+        printf("-----BEGIN OTP MESSAGE-----\n");
+    }
+    
     printf("Version: %s\n", get_version());
     printf("Pad-ChkSum: %s\n", chksum_hex);
     printf("Pad-Offset: %lu\n", current_offset);
@@ -1338,7 +1421,11 @@ int encrypt_text(const char* pad_identifier, const char* input_text) {
         printf("%.64s\n", base64_cipher + i);
     }
     
-    printf("-----END OTP MESSAGE-----\n\n\n");
+    if (is_interactive) {
+        printf("-----END OTP MESSAGE-----\n\n\n");
+    } else {
+        printf("-----END OTP MESSAGE-----\n");
+    }
     
     // Cleanup
     free(pad_data);
@@ -1523,6 +1610,131 @@ int decrypt_text(const char* pad_identifier, const char* encrypted_message) {
     return 0;
 }
 
+int decrypt_text_silent(const char* pad_identifier, const char* encrypted_message) {
+    // For piped decrypt mode - silent operation with minimal output
+    (void)pad_identifier; // Suppress unused parameter warning
+    
+    char line[MAX_LINE_LENGTH];
+    char stored_chksum[MAX_HASH_LENGTH];
+    char current_chksum[MAX_HASH_LENGTH];
+    uint64_t pad_offset;
+    char base64_data[MAX_INPUT_SIZE * 2] = {0};
+    int in_data_section = 0;
+    
+    if (encrypted_message != NULL) {
+        // Parse provided encrypted message
+        char *message_copy = strdup(encrypted_message);
+        char *line_ptr = strtok(message_copy, "\n");
+        
+        int found_begin = 0;
+        while (line_ptr != NULL) {
+            if (strcmp(line_ptr, "-----BEGIN OTP MESSAGE-----") == 0) {
+                found_begin = 1;
+            }
+            else if (strcmp(line_ptr, "-----END OTP MESSAGE-----") == 0) {
+                break;
+            }
+            else if (found_begin) {
+                if (strncmp(line_ptr, "Pad-ChkSum: ", 12) == 0) {
+                    strncpy(stored_chksum, line_ptr + 12, 64);
+                    stored_chksum[64] = '\0';
+                }
+                else if (strncmp(line_ptr, "Pad-Offset: ", 12) == 0) {
+                    pad_offset = strtoull(line_ptr + 12, NULL, 10);
+                }
+                else if (strlen(line_ptr) == 0) {
+                    in_data_section = 1;
+                }
+                else if (in_data_section) {
+                    strncat(base64_data, line_ptr, sizeof(base64_data) - strlen(base64_data) - 1);
+                }
+            }
+            line_ptr = strtok(NULL, "\n");
+        }
+        free(message_copy);
+        
+        if (!found_begin) {
+            fprintf(stderr, "Error: Invalid message format - missing BEGIN header\n");
+            return 1;
+        }
+    } else {
+        fprintf(stderr, "Error: No encrypted message provided\n");
+        return 1;
+    }
+    
+    // Now we have the pad chksum from the message, construct filename
+    char pad_path[MAX_HASH_LENGTH + 20];
+    char state_path[MAX_HASH_LENGTH + 20];
+    get_pad_path(stored_chksum, pad_path, state_path);
+    
+    // Check if we have this pad
+    if (access(pad_path, R_OK) != 0) {
+        fprintf(stderr, "Error: Required pad not found: %s\n", stored_chksum);
+        return 1;
+    }
+    
+    // Verify pad integrity (silent check)
+    if (calculate_checksum(pad_path, current_chksum) != 0) {
+        fprintf(stderr, "Error: Cannot calculate current pad checksum\n");
+        return 1;
+    }
+    
+    if (strcmp(stored_chksum, current_chksum) != 0) {
+        fprintf(stderr, "Error: Pad integrity check failed!\n");
+        return 1;
+    }
+    
+    // Decode base64
+    int ciphertext_len;
+    unsigned char* ciphertext = custom_base64_decode(base64_data, &ciphertext_len);
+    if (!ciphertext) {
+        fprintf(stderr, "Error: Invalid base64 data\n");
+        return 1;
+    }
+    
+    // Read pad data at specified offset
+    FILE* pad_file = fopen(pad_path, "rb");
+    if (!pad_file) {
+        fprintf(stderr, "Error: Cannot open pad file %s\n", pad_path);
+        free(ciphertext);
+        return 1;
+    }
+    
+    if (fseek(pad_file, pad_offset, SEEK_SET) != 0) {
+        fprintf(stderr, "Error: Cannot seek to offset %lu in pad file\n", pad_offset);
+        free(ciphertext);
+        fclose(pad_file);
+        return 1;
+    }
+    
+    unsigned char* pad_data = malloc(ciphertext_len);
+    if (fread(pad_data, 1, ciphertext_len, pad_file) != (size_t)ciphertext_len) {
+        fprintf(stderr, "Error: Cannot read pad data\n");
+        free(ciphertext);
+        free(pad_data);
+        fclose(pad_file);
+        return 1;
+    }
+    fclose(pad_file);
+    
+    // XOR decrypt
+    char* plaintext = malloc(ciphertext_len + 1);
+    for (int i = 0; i < ciphertext_len; i++) {
+        plaintext[i] = ciphertext[i] ^ pad_data[i];
+    }
+    plaintext[ciphertext_len] = '\0';
+    
+    // Output only the decrypted text - no extra messages
+    printf("%s\n", plaintext);
+    
+    // Cleanup
+    free(ciphertext);
+    free(pad_data);
+    free(plaintext);
+    
+    return 0;
+}
+
 int encrypt_file(const char* pad_identifier, const char* input_file, const char* output_file, int ascii_armor) {
     char* pad_chksum = find_pad_by_prefix(pad_identifier);
     if (!pad_chksum) {
@@ -2293,6 +2505,212 @@ void get_pad_path(const char* chksum, char* pad_path, char* state_path) {
     snprintf(state_path, 1024, "%s/%s.state", current_pads_dir, chksum);
 }
 
+// Stdin detection functions implementation
+int has_stdin_data(void) {
+    // Check if stdin is a pipe/redirect (not a terminal)
+    if (!isatty(STDIN_FILENO)) {
+        return 1;
+    }
+    return 0;
+}
+
+char* read_stdin_text(void) {
+    size_t capacity = 4096;
+    size_t length = 0;
+    char* buffer = malloc(capacity);
+    
+    if (!buffer) {
+        return NULL;
+    }
+    
+    char chunk[1024];
+    while (fgets(chunk, sizeof(chunk), stdin)) {
+        size_t chunk_len = strlen(chunk);
+        
+        // Ensure we have enough capacity
+        while (length + chunk_len >= capacity) {
+            capacity *= 2;
+            char* new_buffer = realloc(buffer, capacity);
+            if (!new_buffer) {
+                free(buffer);
+                return NULL;
+            }
+            buffer = new_buffer;
+        }
+        
+        strcpy(buffer + length, chunk);
+        length += chunk_len;
+    }
+    
+    // Remove trailing newline if present
+    if (length > 0 && buffer[length - 1] == '\n') {
+        buffer[length - 1] = '\0';
+        length--;
+    }
+    
+    // If empty, free and return NULL
+    if (length == 0) {
+        free(buffer);
+        return NULL;
+    }
+    
+    return buffer;
+}
+
+int pipe_mode(int argc, char* argv[], const char* piped_text) {
+    (void)argc; // Suppress unused parameter warning
+    (void)argv; // Suppress unused parameter warning
+    
+    // Check if we have a default pad configured
+    char* default_pad = get_default_pad_path();
+    if (default_pad) {
+        // Verify the default pad exists and extract checksum
+        if (access(default_pad, R_OK) == 0) {
+            // Extract checksum from pad filename
+            char* filename = strrchr(default_pad, '/');
+            if (!filename) filename = default_pad;
+            else filename++; // Skip the '/'
+            
+            // Extract checksum (remove .pad extension)
+            if (strlen(filename) >= 68 && strstr(filename, ".pad")) {
+                char pad_checksum[65];
+                strncpy(pad_checksum, filename, 64);
+                pad_checksum[64] = '\0';
+                
+                free(default_pad);
+                
+                // Encrypt using the default pad (silent mode)
+                return encrypt_text(pad_checksum, piped_text);
+            }
+        }
+        
+        fprintf(stderr, "Error: Default pad not found or invalid: %s\n", default_pad);
+        free(default_pad);
+        return 1;
+    }
+    
+    fprintf(stderr, "Error: No default pad configured for pipe mode\n");
+    fprintf(stderr, "Configure a default pad in ~/.otp/otp.conf\n");
+    return 1;
+}
+
+// Preferences management functions implementation
+int load_preferences(void) {
+    char* home_dir = getenv("HOME");
+    if (!home_dir) {
+        return 1; // No home directory
+    }
+    
+    char preferences_dir[1024];
+    char preferences_file[1024];
+    snprintf(preferences_dir, sizeof(preferences_dir), "%s/.otp", home_dir);
+    snprintf(preferences_file, sizeof(preferences_file), "%s/otp.conf", preferences_dir);
+    
+    FILE* file = fopen(preferences_file, "r");
+    if (!file) {
+        return 0; // No preferences file, use defaults
+    }
+    
+    char line[1024];
+    while (fgets(line, sizeof(line), file)) {
+        // Remove newline
+        line[strcspn(line, "\n")] = 0;
+        
+        // Skip empty lines and comments
+        if (strlen(line) == 0 || line[0] == '#') {
+            continue;
+        }
+        
+        // Parse key=value pairs
+        char* equals = strchr(line, '=');
+        if (equals) {
+            *equals = '\0';
+            char* key = line;
+            char* value = equals + 1;
+            
+            // Trim whitespace
+            while (*key == ' ' || *key == '\t') key++;
+            while (*value == ' ' || *value == '\t') value++;
+            
+            if (strcmp(key, "default_pad") == 0) {
+                strncpy(default_pad_path, value, sizeof(default_pad_path) - 1);
+                default_pad_path[sizeof(default_pad_path) - 1] = '\0';
+            }
+        }
+    }
+    
+    fclose(file);
+    return 0;
+}
+
+int save_preferences(void) {
+    char* home_dir = getenv("HOME");
+    if (!home_dir) {
+        return 1;
+    }
+    
+    char preferences_dir[1024];
+    char preferences_file[1024];
+    snprintf(preferences_dir, sizeof(preferences_dir), "%s/.otp", home_dir);
+    snprintf(preferences_file, sizeof(preferences_file), "%s/otp.conf", preferences_dir);
+    
+    // Create .otp directory if it doesn't exist
+    struct stat st = {0};
+    if (stat(preferences_dir, &st) == -1) {
+        if (mkdir(preferences_dir, 0755) != 0) {
+            return 1;
+        }
+    }
+    
+    FILE* file = fopen(preferences_file, "w");
+    if (!file) {
+        return 1;
+    }
+    
+    fprintf(file, "# OTP Preferences File\n");
+    fprintf(file, "# This file is automatically generated and updated by the OTP program\n\n");
+    
+    if (strlen(default_pad_path) > 0) {
+        fprintf(file, "default_pad=%s\n", default_pad_path);
+    }
+    
+    fclose(file);
+    return 0;
+}
+
+char* get_preference(const char* key) {
+    if (strcmp(key, "default_pad") == 0) {
+        if (strlen(default_pad_path) > 0) {
+            return strdup(default_pad_path);
+        }
+    }
+    return NULL;
+}
+
+int set_preference(const char* key, const char* value) {
+    if (strcmp(key, "default_pad") == 0) {
+        if (value) {
+            strncpy(default_pad_path, value, sizeof(default_pad_path) - 1);
+            default_pad_path[sizeof(default_pad_path) - 1] = '\0';
+        } else {
+            default_pad_path[0] = '\0';
+        }
+        return save_preferences();
+    }
+    return 1;
+}
+
+char* get_default_pad_path(void) {
+    if (strlen(default_pad_path) > 0) {
+        return strdup(default_pad_path);
+    }
+    return NULL;
+}
+
+int set_default_pad_path(const char* pad_path) {
+    return set_preference("default_pad", pad_path);
+}
+
 // OTP thumb drive detection function implementation
 int detect_otp_thumb_drive(char* otp_drive_path, size_t path_size) {
     const char* mount_dirs[] = {"/media", "/run/media", "/mnt", NULL};
@@ -2305,14 +2723,39 @@ int detect_otp_thumb_drive(char* otp_drive_path, size_t path_size) {
         while ((mount_entry = readdir(mount_dir)) != NULL) {
             if (mount_entry->d_name[0] == '.') continue;
             
-            // Check if drive name starts with "OTP"
-            if (strncmp(mount_entry->d_name, "OTP", 3) != 0) continue;
-            
             char mount_path[512];
             snprintf(mount_path, sizeof(mount_path), "%s/%s", mount_dirs[mount_idx], mount_entry->d_name);
             
-            // For /run/media, we need to go one level deeper (skip username)
-            if (strcmp(mount_dirs[mount_idx], "/run/media") == 0) {
+            // For /media, we need to go one level deeper (user directories)
+            if (strcmp(mount_dirs[mount_idx], "/media") == 0) {
+                // This is /media/[username] - look inside for drives
+                DIR* user_dir = opendir(mount_path);
+                if (!user_dir) continue;
+                
+                struct dirent* user_entry;
+                while ((user_entry = readdir(user_dir)) != NULL) {
+                    if (user_entry->d_name[0] == '.') continue;
+                    
+                    // Check if drive name starts with "OTP"
+                    if (strncmp(user_entry->d_name, "OTP", 3) != 0) continue;
+                    
+                    char user_mount_path[512];
+                    snprintf(user_mount_path, sizeof(user_mount_path), "%s/%s", mount_path, user_entry->d_name);
+                    
+                    // Check if this is a readable directory
+                    DIR* drive_dir = opendir(user_mount_path);
+                    if (drive_dir) {
+                        closedir(drive_dir);
+                        strncpy(otp_drive_path, user_mount_path, path_size - 1);
+                        otp_drive_path[path_size - 1] = '\0';
+                        closedir(user_dir);
+                        closedir(mount_dir);
+                        return 1; // Found OTP drive
+                    }
+                }
+                closedir(user_dir);
+            } else if (strcmp(mount_dirs[mount_idx], "/run/media") == 0) {
+                // For /run/media, we need to go one level deeper (skip username)
                 DIR* user_dir = opendir(mount_path);
                 if (!user_dir) continue;
                 
@@ -2339,14 +2782,17 @@ int detect_otp_thumb_drive(char* otp_drive_path, size_t path_size) {
                 }
                 closedir(user_dir);
             } else {
-                // Direct mount point (like /media/OTP_DRIVE or /mnt/OTP_DRIVE)
-                DIR* drive_dir = opendir(mount_path);
-                if (drive_dir) {
-                    closedir(drive_dir);
-                    strncpy(otp_drive_path, mount_path, path_size - 1);
-                    otp_drive_path[path_size - 1] = '\0';
-                    closedir(mount_dir);
-                    return 1; // Found OTP drive
+                // Direct mount point (like /mnt/OTP_DRIVE)
+                // Check if drive name starts with "OTP"
+                if (strncmp(mount_entry->d_name, "OTP", 3) == 0) {
+                    DIR* drive_dir = opendir(mount_path);
+                    if (drive_dir) {
+                        closedir(drive_dir);
+                        strncpy(otp_drive_path, mount_path, path_size - 1);
+                        otp_drive_path[path_size - 1] = '\0';
+                        closedir(mount_dir);
+                        return 1; // Found OTP drive
+                    }
                 }
             }
         }
@@ -2988,10 +3434,15 @@ int handle_pads_menu(void) {
         
         char input[10];
         if (fgets(input, sizeof(input), stdin)) {
-            char choice = toupper(input[0]);
-            if (choice == 'G') {
-                return handle_generate_menu();
+        char choice = toupper(input[0]);
+        if (choice == 'G') {
+            int result = handle_generate_menu();
+            if (result == 0) {
+                // After successful pad generation, return to pads menu
+                return handle_pads_menu();
             }
+            return result;
+        }
         }
         return 0;
     }
@@ -3060,7 +3511,12 @@ int handle_pads_menu(void) {
     
     // Handle actions first
     if (toupper(input[0]) == 'G') {
-        return handle_generate_menu();
+        int result = handle_generate_menu();
+        if (result == 0) {
+            // After successful pad generation, return to pads menu
+            return handle_pads_menu();
+        }
+        return result;
     } else if (toupper(input[0]) == 'B') {
         return 0; // Back to main menu
     }
@@ -3147,8 +3603,15 @@ void get_directory_display(const char* file_path, char* result, size_t result_si
             if (path_after_media) {
                 path_after_media++; // Skip the slash
                 
+                // For /media/user/LABEL pattern, skip the username to get to the drive label
+                if (strstr(media_start, "/media/")) {
+                    char* next_slash = strchr(path_after_media, '/');
+                    if (next_slash) {
+                        path_after_media = next_slash + 1;
+                    }
+                }
                 // For /run/media/user/LABEL pattern, skip the username
-                if (strstr(media_start, "/run/media/")) {
+                else if (strstr(media_start, "/run/media/")) {
                     char* next_slash = strchr(path_after_media, '/');
                     if (next_slash) {
                         path_after_media = next_slash + 1;
@@ -3157,15 +3620,23 @@ void get_directory_display(const char* file_path, char* result, size_t result_si
                 
                 // Extract just the USB label (up to next slash or end)
                 char* label_end = strchr(path_after_media, '/');
+                char usb_label[32];
                 if (label_end) {
                     size_t label_len = label_end - path_after_media;
-                    if (label_len > 11) label_len = 11; // Max 11 chars for display
-                    strncpy(result, path_after_media, label_len);
-                    result[label_len] = '\0';
+                    if (label_len > sizeof(usb_label) - 1) label_len = sizeof(usb_label) - 1;
+                    strncpy(usb_label, path_after_media, label_len);
+                    usb_label[label_len] = '\0';
                 } else {
                     // USB label is the last part
-                    strncpy(result, path_after_media, result_size - 1);
-                    result[result_size - 1] = '\0';
+                    strncpy(usb_label, path_after_media, sizeof(usb_label) - 1);
+                    usb_label[sizeof(usb_label) - 1] = '\0';
+                }
+                
+                // Format with USB: prefix, limiting total length to fit in result
+                snprintf(result, result_size, "USB:%s", usb_label);
+                // Truncate if too long
+                if (strlen(result) > 11) {
+                    result[11] = '\0';
                 }
                 return;
             }