# Function Reference - Call Graph Analysis

> This documentation is automatically derived from [`Callgraph.svg`](Callgraph.svg) and provides a comprehensive overview of all functions in the zosstorage project, organized by module.

## Table of Contents

- [Main Entry Points](#main-entry-points)
- [CLI & Configuration](#cli--configuration)
- [Orchestration](#orchestration)
- [Device Discovery](#device-discovery)
- [Partition Management](#partition-management)
- [Filesystem Operations](#filesystem-operations)
- [Mount Operations](#mount-operations)
- [Idempotency & State](#idempotency--state)
- [Reporting](#reporting)
- [Utilities](#utilities)
- [Logging](#logging)
- [Type Definitions](#type-definitions)

---

## Main Entry Points

### [`src/main.rs`](../src/main.rs)

| Function | Purpose |
|----------|---------|
| `main()` | Application entry point; initializes the program and handles top-level errors |
| `real_main()` | Core application logic; orchestrates the main workflow after initialization |

---

## CLI & Configuration

### [`src/cli/args.rs`](../src/cli/args.rs)

**Structs:** `Cli`, `LogLevelArg` (enum)

| Function | Purpose |
|----------|---------|
| `from_args()` | Parses command-line arguments and returns a `Cli` configuration object |

### [`src/config/loader.rs`](../src/config/loader.rs)

| Function | Purpose |
|----------|---------|
| `load_and_merge()` | Loads configuration from multiple sources and merges them into a unified config |
| `validate()` | Validates the merged configuration for correctness and completeness |
| `to_value()` | Converts configuration structures to internal value representation |
| `merge_value()` | Recursively merges configuration values, handling conflicts appropriately |
| `cli_overlay_value()` | Overlays CLI-provided values onto existing configuration |
| `kernel_cmdline_topology()` | Extracts topology information from kernel command line parameters |
| `parse_topology_token()` | Parses individual topology tokens from kernel cmdline |
| `default_config()` | Generates default configuration values when no config file is present |

---

## Orchestration

### [`src/orchestrator/run.rs`](../src/orchestrator/run.rs)

**Structs:** `Context`

| Function | Purpose |
|----------|---------|
| `Context::new()` | Creates a new orchestration context with default settings |
| `Context::with_show()` | Builder method to enable show/dry-run mode |
| `Context::with_apply()` | Builder method to enable apply mode (actual execution) |
| `Context::with_report_path()` | Builder method to set the report output path |
| `Context::with_mount_existing()` | Builder method to configure mounting of existing filesystems |
| `Context::with_report_current()` | Builder method to enable reporting of current system state |
| `Context::with_topology_from_cli()` | Builder method to set topology from CLI arguments |
| `Context::with_topology_from_cmdline()` | Builder method to set topology from kernel cmdline |
| `run()` | Main orchestration function; coordinates all storage operations |
| `build_device_filter()` | Constructs device filter based on configuration and user input |
| `enforce_empty_disks()` | Validates that target disks are empty before proceeding |
| `role_str()` | Converts partition role enum to human-readable string |
| `build_summary_json()` | Builds a JSON summary of operations performed |

---

## Device Discovery

### [`src/device/discovery.rs`](../src/device/discovery.rs)

**Structs:** `Disk`, `DeviceFilter`, `SysProvider`  
**Traits:** `DeviceProvider`

| Function | Purpose |
|----------|---------|
| `DeviceFilter::matches()` | Checks if a device matches the configured filter criteria |
| `SysProvider::new()` | Creates a new sysfs-based device provider |
| `SysProvider::list_block_devices()` | Lists all block devices found via sysfs |
| `SysProvider::probe_properties()` | Probes detailed properties of a specific device |
| `discover()` | Entry point for device discovery using default provider |
| `discover_with_provider()` | Device discovery with custom provider (for testing/flexibility) |
| `is_ignored_name()` | Checks if device name should be ignored (loop, ram, etc.) |
| `sys_block_path()` | Constructs sysfs path for a given block device |
| `base_name()` | Extracts base device name from path |
| `is_removable_sysfs()` | Checks if device is removable via sysfs |
| `is_partition_sysfs()` | Checks if device is a partition via sysfs |
| `read_disk_size_bytes()` | Reads disk size in bytes from sysfs |
| `read_rotational()` | Determines if disk is rotational (HDD) or not (SSD) |
| `read_model_serial()` | Reads device model and serial number |
| `read_optional_string()` | Utility to safely read optional string values from sysfs |

---

## Partition Management

### [`src/partition/plan.rs`](../src/partition/plan.rs)

**Structs:** `PartitionSpec`, `DiskPlan`, `PartitionPlan`, `PartitionResult`  
**Enums:** `PartRole`

| Function | Purpose |
|----------|---------|
| `plan_partitions()` | Creates partition plans for all target disks based on topology |
| `apply_partitions()` | Executes partition plans using sgdisk tool |
| `type_code()` | Returns GPT partition type code for a given partition role |
| `part_dev_path()` | Constructs device path for a partition (e.g., /dev/sda1) |
| `sector_size_bytes()` | Reads logical sector size of disk |
| `parse_sgdisk_info()` | Parses output from sgdisk to extract partition information |

---

## Filesystem Operations

### [`src/fs/plan.rs`](../src/fs/plan.rs)

**Structs:** `FsSpec`, `FsPlan`, `FsResult`  
**Enums:** `FsKind`

| Function | Purpose |
|----------|---------|
| `plan_filesystems()` | Plans filesystem creation for all partitions |
| `make_filesystems()` | Creates filesystems according to plan (mkfs.* tools) |
| `capture_uuid()` | Captures UUID of newly created filesystem |
| `parse_blkid_export()` | Parses blkid export format to extract filesystem metadata |
| `probe_existing_filesystems()` | Detects existing filesystems on partitions |

---

## Mount Operations

### [`src/mount/ops.rs`](../src/mount/ops.rs)

**Structs:** `PlannedMount`, `PlannedSubvolMount`, `MountPlan`, `MountResult`

| Function | Purpose |
|----------|---------|
| `fstype_str()` | Converts FsKind enum to mount filesystem type string |
| `plan_mounts()` | Creates mount plans for all filesystems |
| `apply_mounts()` | Executes mount operations and creates mount points |
| `maybe_write_fstab()` | Conditionally writes /etc/fstab entries for persistent mounts |

---

## Idempotency & State

### [`src/idempotency/mod.rs`](../src/idempotency/mod.rs)

| Function | Purpose |
|----------|---------|
| `detect_existing_state()` | Detects existing partitions and filesystems to avoid destructive operations |
| `is_empty_disk()` | Checks if a disk has no partition table or filesystems |
| `parse_blkid_export()` | Parses blkid output to identify existing filesystems |
| `read_proc_partitions_names()` | Reads partition names from /proc/partitions |
| `base_name()` | Extracts base name from device path |
| `is_partition_of()` | Checks if one device is a partition of another |

---

## Reporting

### [`src/report/state.rs`](../src/report/state.rs)

**Structs:** `StateReport`

| Function | Purpose |
|----------|---------|
| `build_report()` | Builds comprehensive state report of operations performed |
| `write_report()` | Writes report to specified output path (JSON format) |

---

## Utilities

### [`src/util/mod.rs`](../src/util/mod.rs)

**Structs:** `CmdOutput`

| Function | Purpose |
|----------|---------|
| `which_tool()` | Locates external tool in PATH (sgdisk, mkfs.*, etc.) |
| `run_cmd()` | Executes shell command and returns exit status |
| `run_cmd_capture()` | Executes command and captures stdout/stderr |
| `udev_settle()` | Waits for udev to process device events |
| `is_efi_boot()` | Detects if system booted in EFI mode |

---

## Logging

### [`src/logging/mod.rs`](../src/logging/mod.rs)

**Structs:** `LogOptions`

| Function | Purpose |
|----------|---------|
| `LogOptions::from_cli()` | Creates logging configuration from CLI arguments |
| `level_from_str()` | Converts string to log level enum |
| `init_logging()` | Initializes logging subsystem with configured options |

---

## Type Definitions

### [`src/types.rs`](../src/types.rs)

**Core Configuration Structures:**

- `Config` - Top-level configuration structure
- `LoggingConfig` - Logging configuration
- `DeviceSelection` - Device selection criteria
- `Topology` - Storage topology definition (enum)
- `Partitioning` - Partition layout specification
- `BiosBootSpec`, `EspSpec`, `DataSpec`, `CacheSpec` - Partition type specifications
- `FsOptions`, `BtrfsOptions`, `BcachefsOptions`, `VfatOptions` - Filesystem options
- `MountScheme`, `MountSchemeKind` - Mount configuration
- `ReportOptions` - Report generation configuration

### [`src/errors.rs`](../src/errors.rs)

**Error Types:**

- `Error` - Main error enum for all error conditions
- `Result<T>` - Type alias for `std::result::Result<T, Error>`

---

## Call Graph Relationships

### Main Execution Flow

```
main() → real_main() → orchestrator::run()
    ↓
    ├─→ cli::from_args()
    ├─→ config::load_and_merge()
    ├─→ logging::init_logging()
    ├─→ device::discover()
    ├─→ partition::plan_partitions()
    ├─→ partition::apply_partitions()
    ├─→ fs::plan_filesystems()
    ├─→ fs::make_filesystems()
    ├─→ mount::plan_mounts()
    ├─→ mount::apply_mounts()
    └─→ report::build_report() / write_report()
```

### Key Dependencies

- **Orchestrator** (`run()`) calls: All major subsystems
- **Device Discovery** uses: Utilities for system probing
- **Partition/FS/Mount** operations use: Utilities for command execution
- **All operations** call: `util::run_cmd()` or `util::run_cmd_capture()`
- **Idempotency checks** called by: Orchestrator before destructive operations

---

## Function Count Summary

- **Main Entry**: 2 functions
- **CLI & Config**: 9 functions
- **Orchestration**: 13 functions  
- **Device Discovery**: 14 functions
- **Partition Management**: 6 functions
- **Filesystem Operations**: 5 functions
- **Mount Operations**: 4 functions
- **Idempotency**: 6 functions
- **Reporting**: 2 functions
- **Utilities**: 6 functions
- **Logging**: 3 functions

**Total: 70 documented functions** across 15 source files

---

## References

- Original call graph visualization: [`docs/Callgraph.svg`](Callgraph.svg)
- Architecture documentation: [`docs/ARCHITECTURE.md`](ARCHITECTURE.md)
- API documentation: [`docs/API.md`](API.md)