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Diffstat (limited to 'src/img4.c')
| -rw-r--r-- | src/img4.c | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/src/img4.c b/src/img4.c new file mode 100644 index 0000000..e18b419 --- /dev/null +++ b/src/img4.c @@ -0,0 +1,140 @@ +/* + * img4.c + * Functions for handling the new IMG4 format + * + * Copyright (c) 2013 Nikias Bassen. All Rights Reserved. + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#include <stdlib.h> +#include <string.h> + +#include "img4.h" + +#define ASN1_CONSTRUCTED 0x20 +#define ASN1_SEQUENCE 0x10 +#define ASN1_CONTEXT_SPECIFIC 0x80 +#define ASN1_IA5_STRING 0x16 + +#define IMG4_MAGIC "IMG4" +#define IMG4_MAGIC_SIZE 4 + +static unsigned char* asn1_create_element_header(unsigned char type, unsigned int size, unsigned char** data, unsigned int *data_size) +{ + unsigned char buf[5]; + unsigned int off = 0; + + if (!type || size == 0 || !data || !data_size) { + return NULL; + } + + buf[off++] = type; + + // first, calculate the size + if (size >= 0x1000000) { + // 1+4 bytes length + buf[off++] = 0x84; + buf[off++] = (size >> 24) & 0xFF; + buf[off++] = (size >> 16) & 0xFF; + buf[off++] = (size >> 8) & 0xFF; + buf[off++] = size & 0xFF; + } else if (size >= 0x10000) { + // 1+3 bytes length + buf[off++] = 0x83; + buf[off++] = (size >> 16) & 0xFF; + buf[off++] = (size >> 8) & 0xFF; + buf[off++] = size & 0xFF; + } else if (size >= 0x100) { + // 1+2 bytes length + buf[off++] = 0x82; + buf[off++] = (size >> 8) & 0xFF; + buf[off++] = (size & 0xFF); + } else if (size >= 0x80) { + // 1+1 byte length + buf[off++] = 0x81; + buf[off++] = (size & 0xFF); + } else { + // 1 byte length + buf[off++] = size & 0xFF; + } + + *data = malloc(off); + memcpy(*data, buf, off); + *data_size = off; + + return *data; +} + +int img4_stitch_component(const char* component_name, const unsigned char* component_data, unsigned int component_size, const unsigned char* blob, unsigned int blob_size, unsigned char** img4_data, unsigned int *img4_size) +{ + unsigned char* magic_header = NULL; + unsigned int magic_header_size = 0; + unsigned char* blob_header = NULL; + unsigned int blob_header_size = 0; + unsigned char* img4header = NULL; + unsigned int img4header_size = 0; + unsigned int content_size; + unsigned char* outbuf; + unsigned char* p; + + if (!component_name || !component_data || component_size == 0 || !blob || blob_size == 0 || !img4_data || !img4_size) { + return -1; + } + + /* first we need check if we have to change the tag for the given component */ + // FIXME: write proper ASN1 handling code for this + if (strcmp(component_name, "RestoreKernelCache") == 0) { + memcpy((char*)component_data+0xD, "rkrn", 4); + } else if (strcmp(component_name, "RestoreDeviceTree") == 0) { + memcpy((char*)component_data+0xD, "rdtr", 4); + } + + // create element header for the "IMG4" magic + asn1_create_element_header(ASN1_IA5_STRING, IMG4_MAGIC_SIZE, &magic_header, &magic_header_size); + // create element header for the blob (ApImg4Ticket) + asn1_create_element_header(ASN1_CONTEXT_SPECIFIC|ASN1_CONSTRUCTED, blob_size, &blob_header, &blob_header_size); + + // calculate the size for the final IMG4 file (asn1 sequence) + content_size = magic_header_size + IMG4_MAGIC_SIZE + component_size + blob_header_size + blob_size; + + // create element header for the final IMG4 asn1 blob + asn1_create_element_header(ASN1_SEQUENCE|ASN1_CONSTRUCTED, content_size, &img4header, &img4header_size); + + outbuf = (unsigned char*)malloc(img4header_size + content_size); + if (!outbuf) { + return -1; + } + p = outbuf; + + // now put everything together + memcpy(p, img4header, img4header_size); + p += img4header_size; + memcpy(p, magic_header, magic_header_size); + p += magic_header_size; + memcpy(p, IMG4_MAGIC, IMG4_MAGIC_SIZE); + p += IMG4_MAGIC_SIZE; + memcpy(p, component_data, component_size); + p += component_size; + memcpy(p, blob_header, blob_header_size); + p += blob_header_size; + memcpy(p, blob, blob_size); + p += blob_size; + + *img4_data = outbuf; + *img4_size = (p - outbuf); + + return 0; +} |