diff options
| -rw-r--r-- | payloads/libpayload/include/cbfs_core.h | 26 | ||||
| -rw-r--r-- | payloads/libpayload/libcbfs/cbfs_core.c | 41 |
2 files changed, 66 insertions, 1 deletions
diff --git a/payloads/libpayload/include/cbfs_core.h b/payloads/libpayload/include/cbfs_core.h index a95cef7a3d..a2ee74459b 100644 --- a/payloads/libpayload/include/cbfs_core.h +++ b/payloads/libpayload/include/cbfs_core.h @@ -132,10 +132,34 @@ struct cbfs_file { char magic[8]; uint32_t len; uint32_t type; - uint32_t checksum; + uint32_t attributes_offset; uint32_t offset; + char filename[]; } __attribute__((packed)); +/* Depending on how the header was initialized, it may be backed with 0x00 or + * 0xff. Support both. */ +#define CBFS_FILE_ATTR_TAG_UNUSED 0 +#define CBFS_FILE_ATTR_TAG_UNUSED2 0xffffffff + +/* The common fields of extended cbfs file attributes. + Attributes are expected to start with tag/len, then append their + specific fields. */ +struct cbfs_file_attribute { + uint32_t tag; + /* len covers the whole structure, incl. tag and len */ + uint32_t len; + uint8_t data[0]; +} __attribute__((packed)); + +/* Given a cbfs_file, return the first file attribute, or NULL. */ +struct cbfs_file_attribute *cbfs_file_first_attr(struct cbfs_file *file); + +/* Given a cbfs_file and a cbfs_file_attribute, return the attribute that + * follows it, or NULL. */ +struct cbfs_file_attribute *cbfs_file_next_attr(struct cbfs_file *file, + struct cbfs_file_attribute *attr); + /*** Component sub-headers ***/ /* Following are component sub-headers for the "standard" diff --git a/payloads/libpayload/libcbfs/cbfs_core.c b/payloads/libpayload/libcbfs/cbfs_core.c index 7926d9d650..6a19b269c1 100644 --- a/payloads/libpayload/libcbfs/cbfs_core.c +++ b/payloads/libpayload/libcbfs/cbfs_core.c @@ -213,6 +213,47 @@ void *cbfs_get_file_content(struct cbfs_media *media, const char *name, return (void *)CBFS_SUBHEADER(file); } +struct cbfs_file_attribute *cbfs_file_first_attr(struct cbfs_file *file) +{ + /* attributes_offset should be 0 when there is no attribute, but all + * values that point into the cbfs_file header are invalid, too. */ + if (ntohl(file->attributes_offset) <= sizeof(*file)) + return NULL; + + /* There needs to be enough space for the file header and one + * attribute header for this to make sense. */ + if (ntohl(file->offset) <= + sizeof(*file) + sizeof(struct cbfs_file_attribute)) + return NULL; + + return (struct cbfs_file_attribute *) + (((uint8_t *)file) + ntohl(file->attributes_offset)); +} + +struct cbfs_file_attribute *cbfs_file_next_attr(struct cbfs_file *file, + struct cbfs_file_attribute *attr) +{ + /* ex falso sequitur quodlibet */ + if (attr == NULL) + return NULL; + + /* Is there enough space for another attribute? */ + if ((uint8_t *)attr + ntohl(attr->len) + + sizeof(struct cbfs_file_attribute) >= + (uint8_t *)file + ntohl(file->offset)) + return NULL; + + struct cbfs_file_attribute *next = (struct cbfs_file_attribute *) + (((uint8_t *)attr) + ntohl(attr->len)); + /* If any, "unused" attributes must come last. */ + if (ntohl(next->tag) == CBFS_FILE_ATTR_TAG_UNUSED) + return NULL; + if (ntohl(next->tag) == CBFS_FILE_ATTR_TAG_UNUSED2) + return NULL; + + return next; +} + int cbfs_decompress(int algo, void *src, void *dst, int len) { switch (algo) { |