mirror of
https://github.com/Atmosphere-NX/Atmosphere.git
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98 lines
2.5 KiB
C
98 lines
2.5 KiB
C
#include <string.h>
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#include <errno.h>
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#include "gpt.h"
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int gpt_get_header(efi_header_t *out, FILE *disk, size_t sector_size) {
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union {
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uint8_t sector[512];
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efi_header_t hdr;
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} d;
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if (disk == NULL || out == NULL) {
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errno = EINVAL;
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return -1;
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}
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/* Read and check the protective MBR. */
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if (fread(d.sector, 512, 1, disk) == 0) {
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return -1;
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}
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if (fseek(disk, sector_size - 512, SEEK_CUR) != 0) {
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return -1;
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}
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if (d.sector[0x1FE] != 0x55 || d.sector[0x1FF] != 0xAA) {
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errno = EILSEQ;
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return -1;
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}
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/* We only allow for the GPT header to be at sector 1 (like nx-bootloader). */
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if (fread(d.sector, 512, 1, disk) == 0) {
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return -1;
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}
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if (fseek(disk, sector_size - 512, SEEK_CUR) != 0) {
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return -1;
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}
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/* Check for "EFI PART". */
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if (memcmp(d.hdr.magic, "EFI PART", 8) != 0) {
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errno = EILSEQ;
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return -1;
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}
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/* Check whether we're really at sector 1, etc. (we won't check backup_lba). */
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if (d.hdr.header_lba != 1 || d.hdr.entries_first_lba < 2 || d.hdr.partitions_last_lba < d.hdr.partitions_first_lba) {
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errno = EILSEQ;
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return -1;
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}
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if (d.hdr.header_size < sizeof(efi_header_t) || d.hdr.entry_size < sizeof(efi_entry_t)) {
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errno = EILSEQ;
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return -1;
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}
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/* Some more checks: */
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if(d.hdr.header_size > sector_size || d.hdr.revision != 0x10000) {
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errno = ENOTSUP;
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return -1;
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}
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memcpy(out, &d.hdr, sizeof(efi_header_t));
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return 0;
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}
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int gpt_iterate_through_entries(FILE *disk, size_t sector_size, gpt_entry_iterator_t callback, void *param) {
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efi_header_t hdr;
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efi_entry_t entry;
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size_t offset = 2 * 512; /* Sector #2. */
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size_t delta;
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/* Get the header. */
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if (gpt_get_header(&hdr, disk, sector_size) == -1) {
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return -1;
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}
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/* Seek to the entry table. */
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if (fseek(disk, sector_size * hdr.entries_first_lba - offset, SEEK_CUR) != 0) {
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return -1;
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}
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offset = sector_size * hdr.entries_first_lba;
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delta = hdr.entry_size - sizeof(efi_entry_t);
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/* Iterate through the entries. */
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for (uint32_t i = 0; i < hdr.entry_count; i++) {
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if (fread(&entry, sizeof(efi_entry_t), 1, disk) == 0) {
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return -1;
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}
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if (callback(&entry, param, offset, disk) != 0) {
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return -1;
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}
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if (delta != 0 && fseek(disk, delta, SEEK_CUR) != 0) {
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return -1;
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}
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offset += hdr.entry_size;
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}
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return 0;
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}
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