From c134dbfeaa1f24c892919b483c3fc00a05822efb Mon Sep 17 00:00:00 2001 From: Oliver O'Halloran Date: Fri, 13 Jan 2017 17:56:17 +1100 Subject: [PATCH] vpd: add vpd_valid() to check keyword VPD blobs Adds a function to check whether a blob is a valid IBM ASCII keyword VPD blob. This allows us to recognise when we do and do not have a VPD blob and act accordingly. Signed-off-by: Oliver O'Halloran [stewart@linux.vnet.ibm.com: check if initial 0x84 exists. Spotted by Vasant] Signed-off-by: Stewart Smith --- core/vpd.c | 29 +++++++++++++++++++++++++++++ include/vpd.h | 2 ++ 2 files changed, 31 insertions(+) diff --git a/core/vpd.c b/core/vpd.c index 505b3d639ef4..d6591981c7aa 100644 --- a/core/vpd.c +++ b/core/vpd.c @@ -46,6 +46,35 @@ const void *vpd_find_keyword(const void *rec, size_t rec_sz, return NULL; } +/* vpd_valid - does some basic sanity checks to ensure a VPD blob is + * actually a VPD blob + */ +bool vpd_valid(const void *vvpd, size_t vpd_size) +{ + const uint8_t *vpd = vvpd; + int size, i = 0; + + /* find the record start byte */ + while (i < vpd_size) + if (vpd[i++] == 0x84) + break; + + if (i >= vpd_size) + return false; + + /* next two bytes are the record length, little endian */ + size = 2; + size += vpd[i]; + size += vpd[i + 1] << 8; + + i += size; /* skip to the end marker */ + + if (i >= vpd_size || vpd[i] != 0x78) + return false; + + return true; +} + /* Locate a record in a VPD blob * * Note: This works with VPD LIDs. It will scan until it finds diff --git a/include/vpd.h b/include/vpd.h index bc60d81f782e..02bbde25e7a7 100644 --- a/include/vpd.h +++ b/include/vpd.h @@ -34,6 +34,8 @@ const void *vpd_find(const void *vpd, size_t vpd_size, const char *record, const char *keyword, uint8_t *sz); +bool vpd_valid(const void *vvpd, size_t vpd_size); + /* Add model property to dt_root */ void add_dtb_model(void);