diff options
Diffstat (limited to 'src/initrd.c')
| -rw-r--r-- | src/initrd.c | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/src/initrd.c b/src/initrd.c new file mode 100644 index 0000000..caff8b3 --- /dev/null +++ b/src/initrd.c @@ -0,0 +1,167 @@ +/* SPDX-License-Identifier: copyleft-next-0.3.1 */ +/* Copyright 2021 - 2022, Kim Kuparinen < kimi.h.kuparinen@gmail.com > */ + +/** + * @file initrd.c + * Handle initrd, implement cpio with newc format. + */ + +#include <kmi/initrd.h> +#include <kmi/vmem.h> +#include <kmi/string.h> +#include <kmi/utils.h> +#include <kmi/attrs.h> +#include <kmi/debug.h> +#include <libfdt.h> + +/** GNU cpio, POSIX 'newc' format header. */ +struct __packed cpio_header { + /** Magic bytes. */ + char c_magic[6]; + + /** File inode. */ + char c_ino[8]; + + /** File type and permissions. */ + char c_mode[8]; + + /** User ID. */ + char c_uid[8]; + + /** Group ID. */ + char c_gid[8]; + + /** Number of links to this file. */ + char c_nlink[8]; + + /** Modification time. */ + char c_mtime[8]; + + /** Size of file. */ + char c_filesize[8]; + + /** Device major. */ + char c_devmajor[8]; + + /** Device minor. */ + char c_devminor[8]; + + /** Block device major. */ + char c_rdevmajor[8]; + + /** Block device minor. */ + char c_rdevminor[8]; + + /** Length of filename. */ + char c_namesize[8]; + + /** CRC check. */ + char c_check[8]; +}; + +/** + * Get next file in archive. + * Does not check for out of bounds. + * + * @param cp Pointer to current file header. + * @return Pointer to next file header. + */ +static struct cpio_header *__next_entry(struct cpio_header *cp) +{ + size_t blen = align_up( + sizeof(struct cpio_header) + convnum(cp->c_namesize, 8, 16), 4); + size_t tlen = align_up(convnum(cp->c_filesize, 8, 16), 4); + + return (struct cpio_header *)(((char *)cp) + blen + tlen); +} + +/** + * Get file with name in archive. + * + * @param c Pointer to initrd. + * @param fname Filename to look for. + * @param fname_len Length of filename. + * @return Pointer to corresponding file header if found, \c NULL otherwise. + */ +static struct cpio_header *__find_file(const char *c, const char *fname, + size_t fname_len) +{ + struct cpio_header *cp = (struct cpio_header *)c; + for (; cp; cp = __next_entry(cp)) { + size_t namelen = convnum(cp->c_namesize, 8, 16); + if (namelen == 0) + return NULL; + + if (namelen < fname_len) + continue; + + char *name = (char *)(cp + 1); + if (fname[0] != '/') + name += namelen - (fname_len + 1); /* match ending */ + + if (strncmp(name, fname, fname_len) == 0) + return cp; + } + + return NULL; +} + +/** Name of \c init program. */ +static char init_n[] = "init"; + +/** Length of \c init name. */ +static size_t init_nlen = ARRAY_SIZE(init_n) - 1; /* ignore trailing NULL */ + +pm_t get_initrdtop(const void *fdt) +{ + int chosen_offset = fdt_path_offset(fdt, "/chosen"); + struct cell_info ci = get_cellinfo(fdt, chosen_offset); + + void *initrd_end_ptr = (void *)fdt_getprop(fdt, chosen_offset, + "linux,initrd-end", NULL); + + /* fdt is only aware of physical memory pointers */ + return (pm_t)__va(fdt_load_int_ptr(ci.addr_cells, initrd_end_ptr)); +} + +pm_t get_initrdbase(const void *fdt) +{ + const int chosen_offset = fdt_path_offset(fdt, "/chosen"); + const struct cell_info ci = get_cellinfo(fdt, chosen_offset); + + void *initrd_base_ptr = (void *)fdt_getprop(fdt, chosen_offset, + "linux,initrd-start", NULL); + + return (pm_t)__va(fdt_load_int_ptr(ci.addr_cells, initrd_base_ptr)); +} + + +size_t get_init_size(const void *fdt) +{ + char *c = (char *)get_initrdbase(fdt); + struct cpio_header *cp = __find_file(c, init_n, init_nlen); + return convnum(cp->c_filesize, 8, 16); +} + +vm_t get_init_base(const void *fdt) +{ + char *c = (char *)get_initrdbase(fdt); + struct cpio_header *cp = __find_file(c, init_n, init_nlen); + size_t name_len = convnum(cp->c_namesize, 8, 16); + return ((vm_t)cp) + align_up(sizeof(struct cpio_header) + name_len, 4); +} + +stat_t move_init(const void *fdt, void *target) +{ + const char *c = (const char *)get_initrdbase(fdt); + + const struct cpio_header *cp = __find_file(c, init_n, init_nlen); + size_t name_len = convnum(cp->c_namesize, 8, 16); + size_t file_len = convnum(cp->c_filesize, 8, 16); + + char *fp = (char *)cp; + fp += align_up(sizeof(struct cpio_header) + name_len, 4); + + memmove(target, fp, file_len); + return OK; +} |