3d5fb4c267
Build system changes: - scripts/gen_initrd.sh packs all files from apps/ into a newc-format CPIO archive at build/isodir/boot/initrd.cpio. - CMakeLists.txt adds 'initrd' target as ISO dependency. GRUB loads the archive as a Multiboot2 module via 'module2 /boot/initrd.cpio'. - apps/README added as placeholder file for initial ramdisk content. Kernel changes: - kernel.c scans Multiboot2 tags for MULTIBOOT_TAG_TYPE_MODULE to find the initrd's physical address range, then passes it to cpio_init(). - cpio.c/h implements a parser for the SVR4/newc CPIO format: - cpio_init(): lists archive contents on startup - cpio_find(): look up a file by name (handles ./ prefix) - cpio_next(): iterate through all entries - cpio_count(): count files in archive - The initrd lives in identity-mapped physical memory, so no additional mapping is needed to access it. Verified in QEMU: GRUB loads the module at 0x0014A000, CPIO parser finds the README file (38 bytes). All existing functionality (Ring 3 processes, syscalls) continues to work.
93 lines
2.5 KiB
C
93 lines
2.5 KiB
C
/**
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* @file cpio.h
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* @brief CPIO newc archive parser.
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*
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* Parses CPIO archives in the SVR4/newc format (magic "070701").
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* Used to read files from the initial ramdisk loaded by GRUB.
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*/
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#ifndef CPIO_H
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#define CPIO_H
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#include <stdint.h>
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#include <stddef.h>
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/**
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* CPIO newc header (110 bytes).
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* All fields are 8-character hexadecimal ASCII strings.
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*/
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typedef struct cpio_newc_header {
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char magic[6]; /**< Must be "070701". */
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char ino[8];
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char mode[8];
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char uid[8];
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char gid[8];
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char nlink[8];
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char mtime[8];
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char filesize[8];
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char devmajor[8];
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char devminor[8];
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char rdevmajor[8];
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char rdevminor[8];
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char namesize[8];
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char check[8];
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} cpio_newc_header_t;
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/** Size of the CPIO newc header in bytes. */
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#define CPIO_HEADER_SIZE 110
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/** CPIO newc magic string. */
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#define CPIO_MAGIC "070701"
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/** Trailer entry name that marks end of archive. */
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#define CPIO_TRAILER "TRAILER!!!"
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/**
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* CPIO file entry (result of iteration or lookup).
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*/
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typedef struct cpio_entry {
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const char *name; /**< Filename (pointer into archive). */
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uint32_t namesize; /**< Length of filename including NUL. */
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const void *data; /**< Pointer to file data within archive. */
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uint32_t datasize; /**< Size of file data in bytes. */
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uint32_t mode; /**< File mode/permissions. */
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} cpio_entry_t;
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/**
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* Initialize the CPIO parser with the archive location.
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*
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* @param archive_start Pointer to the start of the CPIO archive in memory.
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* @param archive_size Size of the archive in bytes (0 if unknown).
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*/
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void cpio_init(const void *archive_start, uint32_t archive_size);
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/**
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* Find a file in the CPIO archive by name.
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*
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* @param name Filename to search for (without leading "./").
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* @param entry Output: filled with file information if found.
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* @return 0 on success, -1 if not found.
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*/
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int cpio_find(const char *name, cpio_entry_t *entry);
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/**
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* Iterate through all entries in the CPIO archive.
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*
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* Call with *offset = 0 to start. Returns 0 on success, -1 when no
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* more entries exist or the TRAILER is reached.
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*
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* @param offset In/out: current position in the archive.
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* @param entry Output: filled with the next entry's information.
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* @return 0 on success, -1 at end of archive.
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*/
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int cpio_next(uint32_t *offset, cpio_entry_t *entry);
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/**
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* Get the number of files in the CPIO archive (excluding TRAILER).
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*
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* @return Number of files.
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*/
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uint32_t cpio_count(void);
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#endif /* CPIO_H */
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