/**
 * @file cpio.h
 * @brief CPIO newc archive parser.
 *
 * Parses CPIO archives in the SVR4/newc format (magic "070701").
 * Used to read files from the initial ramdisk loaded by GRUB.
 */

#ifndef CPIO_H
#define CPIO_H

#include <stdint.h>
#include <stddef.h>

/**
 * CPIO newc header (110 bytes).
 * All fields are 8-character hexadecimal ASCII strings.
 */
typedef struct cpio_newc_header {
    char magic[6];       /**< Must be "070701". */
    char ino[8];
    char mode[8];
    char uid[8];
    char gid[8];
    char nlink[8];
    char mtime[8];
    char filesize[8];
    char devmajor[8];
    char devminor[8];
    char rdevmajor[8];
    char rdevminor[8];
    char namesize[8];
    char check[8];
} cpio_newc_header_t;

/** Size of the CPIO newc header in bytes. */
#define CPIO_HEADER_SIZE 110

/** CPIO newc magic string. */
#define CPIO_MAGIC "070701"

/** Trailer entry name that marks end of archive. */
#define CPIO_TRAILER "TRAILER!!!"

/**
 * CPIO file entry (result of iteration or lookup).
 */
typedef struct cpio_entry {
    const char *name;    /**< Filename (pointer into archive). */
    uint32_t namesize;   /**< Length of filename including NUL. */
    const void *data;    /**< Pointer to file data within archive. */
    uint32_t datasize;   /**< Size of file data in bytes. */
    uint32_t mode;       /**< File mode/permissions. */
} cpio_entry_t;

/**
 * Initialize the CPIO parser with the archive location.
 *
 * @param archive_start Pointer to the start of the CPIO archive in memory.
 * @param archive_size  Size of the archive in bytes (0 if unknown).
 */
void cpio_init(const void *archive_start, uint32_t archive_size);

/**
 * Find a file in the CPIO archive by name.
 *
 * @param name    Filename to search for (without leading "./").
 * @param entry   Output: filled with file information if found.
 * @return 0 on success, -1 if not found.
 */
int cpio_find(const char *name, cpio_entry_t *entry);

/**
 * Iterate through all entries in the CPIO archive.
 *
 * Call with *offset = 0 to start. Returns 0 on success, -1 when no
 * more entries exist or the TRAILER is reached.
 *
 * @param offset  In/out: current position in the archive.
 * @param entry   Output: filled with the next entry's information.
 * @return 0 on success, -1 at end of archive.
 */
int cpio_next(uint32_t *offset, cpio_entry_t *entry);

/**
 * Get the number of files in the CPIO archive (excluding TRAILER).
 *
 * @return Number of files.
 */
uint32_t cpio_count(void);

#endif /* CPIO_H */