On 19.10.23 11:46, 'Michael Adler' via EFI Boot Guard wrote:
> Resolves a regression from commit b23816ab9626 where efibootguard would
> skip config file probing for an entire device upon encountering a
> partition with an indeterminable FAT bit size.
>
> Additionally, simplified the implementation and added documentation for
> clarity.
>
> Fixes: b23816ab9626 ("fix: correctly calculate FAT bit size based on cluster
> count")
> Reported-by: Felix Moessbauer <felix.moessba...@siemens.com>
> Signed-off-by: Michael Adler <michael.ad...@siemens.com>
> ---
> tools/ebgpart.c | 69 ++++++++++++++++++++++++++++---------------------
> 1 file changed, 39 insertions(+), 30 deletions(-)
>
> diff --git a/tools/ebgpart.c b/tools/ebgpart.c
> index fc754df..9a9e179 100644
> --- a/tools/ebgpart.c
> +++ b/tools/ebgpart.c
> @@ -44,7 +44,7 @@ static void add_block_dev(PedDevice *dev)
> d->next = dev;
> }
>
> -static char *GUID_to_str(uint8_t *g)
> +static char *GUID_to_str(const uint8_t *g)
> {
> (void)snprintf(buffer, 37,
> "%02X%02X%02X%02X-%02X%02X-%02X%02X-%02X%02X-"
> @@ -73,26 +73,35 @@ static char *type_to_name(char t)
> return "not supported";
> }
>
> -static bool check_GPT_FAT_entry(int fd, struct EFIpartitionentry *e,
> - PedFileSystemType *pfst, uint32_t i)
> +/**
> + * @brief Determines the FAT bit size of a disk or partition.
> + *
> + * @param fd File descriptor to inspect.
> + * @param e A pointer to the EFI partition entry.
> + * @param fat_size A pointer where the detected FAT bit size will be stored.
> + *
> + * @return 0 if the FAT bit size is successfully determined and stored in
> + * `fat_size`; otherwise, returns a non-zero error code.
Why not returning fat_size directly?
>0: FAT partition of detected size
=0: non-FAT partition
<0: disk access error
Jan
> + */
> +static int check_GPT_FAT_entry(int fd, const struct EFIpartitionentry *e,
> + int *fat_size)
> {
> char *guid_str = GUID_to_str(e->type_GUID);
> if (strcmp(GPT_PARTITION_GUID_FAT_NTFS, guid_str) != 0 &&
> strcmp(GPT_PARTITION_GUID_ESP, guid_str) != 0) {
> - if (asprintf(&pfst->name, "%s", "not supported") == -1) {
> - goto error_asprintf;
> - }
> VERBOSE(stderr, "GPT entry has unsupported GUID: %s\n",
> guid_str);
> - return true;
> + *fat_size = 0;
> + return 0;
> }
> - VERBOSE(stdout, "GPT Partition #%u is FAT/NTFS.\n", i);
> + VERBOSE(stdout, "GPT Partition has a FAT/NTFS GUID\n");
> +
> /* Save current file offset */
> off64_t curr = lseek64(fd, 0, SEEK_CUR);
> if (curr == -1) {
> VERBOSE(stderr, "Error getting current seek position: %s\n",
> strerror(errno));
> - return false;
> + return -1;
> }
>
> /* seek to partition start */
> @@ -100,7 +109,7 @@ static bool check_GPT_FAT_entry(int fd, struct
> EFIpartitionentry *e,
> if (lseek64(fd, offset_start, SEEK_SET) == -1) {
> VERBOSE(stderr, "Error seeking to partition start: %s\n",
> strerror(errno));
> - return false;
> + return -1;
> }
>
> /* read FAT header */
> @@ -108,32 +117,17 @@ static bool check_GPT_FAT_entry(int fd, struct
> EFIpartitionentry *e,
> if (read(fd, &header, sizeof(header)) != sizeof(header)) {
> VERBOSE(stderr, "Error reading FAT header: %s\n",
> strerror(errno));
> - return false;
> + return -1;
> }
>
> /* restore pos */
> if (lseek64(fd, curr, SEEK_SET) == -1) {
> VERBOSE(stderr, "Error restoring seek position (%s)",
> strerror(errno));
> - return false;
> - }
> -
> - int fat_bits = determine_FAT_bits(&header);
> - if (fat_bits <= 0) {
> - /* not a FAT header */
> - return false;
> - }
> - if (asprintf(&pfst->name, "fat%d", fat_bits) == -1) {
> - VERBOSE(stderr,
> - "Error in asprintf - possibly out of memory.\n");
> - return false;
> + return -1;
> }
> - VERBOSE(stdout, "GPT Partition #%u is %s.\n", i, pfst->name);
> - return true;
> -
> -error_asprintf:
> - VERBOSE(stderr, "Error in asprintf - possibly out of memory.\n");
> - return false;
> + *fat_size = determine_FAT_bits(&header);
> + return 0;
> }
>
> static void read_GPT_entries(int fd, uint64_t table_LBA, uint32_t num,
> @@ -178,13 +172,28 @@ static void read_GPT_entries(int fd, uint64_t
> table_LBA, uint32_t num,
> tmpp->num = i + 1;
> tmpp->fs_type = pfst;
>
> - if (!check_GPT_FAT_entry(fd, &e, pfst, i)) {
> + int fat_size = 0;
> + if (check_GPT_FAT_entry(fd, &e, &fat_size)) {
> + VERBOSE(stderr,
> + "%u: error, skipping partitions on device\n",
> + i);
> free(pfst->name);
> free(pfst);
> free(tmpp);
> dev->part_list = NULL;
> continue;
> }
> + if (fat_size > 0) {
> + VERBOSE(stdout, "GPT Partition #%u is fat%d.\n", i,
> + fat_size);
> + if (asprintf(&pfst->name, "fat%d", fat_size) == -1) {
> + VERBOSE(stderr, "Error in asprintf - possibly "
> + "out of memory.\n");
> + return;
> + }
> + } else {
> + VERBOSE(stderr, "%u: not a FAT partition\n", i);
> + }
>
> *list_end = tmpp;
> list_end = &((*list_end)->next);
--
Siemens AG, Technology
Linux Expert Center
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