On 04/07/2017 06:30 PM, John Ferlan wrote:
> Add bool 'zero_end' and logic that would allow a caller to wipe specific
> portions of a target device either from the beginning (the default) or
> from the end when zero_end is true.
>
> This will allow for this code to wipe out partition table information
> from a device.
>
> Signed-off-by: John Ferlan <jferlan@xxxxxxxxxx>
> ---
> src/storage/storage_util.c | 48 +++++++++++++++++++++++++++++++++-------------
> 1 file changed, 35 insertions(+), 13 deletions(-)
>
> diff --git a/src/storage/storage_util.c b/src/storage/storage_util.c
> index a2d89af..c1734e7 100644
> --- a/src/storage/storage_util.c
> +++ b/src/storage/storage_util.c
> @@ -2516,24 +2516,44 @@ static int
> storageBackendWipeLocal(const char *path,
> int fd,
> unsigned long long wipe_len,
> - size_t writebuf_length)
> + size_t writebuf_length,
> + bool zero_end)
> {
> int ret = -1, written = 0;
> unsigned long long remaining = 0;
> + off_t size;
> size_t write_size = 0;
> char *writebuf = NULL;
>
> - VIR_DEBUG("wiping start: 0 len: %llu", wipe_len);
> -
> if (VIR_ALLOC_N(writebuf, writebuf_length) < 0)
> goto cleanup;
>
> - if (lseek(fd, 0, SEEK_SET) < 0) {
> - virReportSystemError(errno,
> - _("Failed to seek to the start in volume "
> - "with path '%s'"),
> - path);
> - goto cleanup;
> + if (!zero_end) {
> + if (lseek(fd, 0, SEEK_SET) < 0) {
> + virReportSystemError(errno,
> + _("Failed to seek to the start in volume "
> + "with path '%s'"),
> + path);
> + goto cleanup;
> + }
> + VIR_DEBUG("wiping start: 0 len: %llu", wipe_len);
> + } else {
> + if ((size = lseek(fd, 0, SEEK_END)) == (off_t)-1) {
> + virReportSystemError(errno,
> + _("Failed to seek to the end in volume "
> + "with path '%s'"),
> + path);
> + goto cleanup;
> + }
> + size -= wipe_len;
> + if (lseek(fd, size, SEEK_SET) < 0) {
> + virReportSystemError(errno,
> + _("Failed to seek to %zd bytes in volume "
> + "with path '%s'"),
> + size, path);
Is off_t really ssize_t? I think we should typecast it.
> + goto cleanup;
> + }
Or, instead of these two seeks:
if ((size = lseek(fd, -wipe_len, SEEK_END)) < 0) {
virReportSystemError();
goto cleanup;
}
> + VIR_DEBUG("wiping start: %zd len: %llu", size, wipe_len);
This DEBUG is the same as in the other body for the if statement. While
it's just VIR_DEBUG I wouldn't care, but just consider the following
for a moment:
Move this VIR_DEBUG right after this if statement and initialize @size
to zero (and obviously drop the other VIR_DEBUG with hardcoded 0). That
way we know what the current position is and how long section is to be
wiped.
Or even better:
+ if (!zero_end) {
+ if ((size = lseek(fd, 0, SEEK_SET)) < 0) {
+ virReportSystemError(errno,
+ _("Failed to seek to the start in volume "
+ "with path '%s'"),
+ path);
+ goto cleanup;
+ }
+ } else {
+ if ((size = lseek(fd, -wipe_len, SEEK_END)) < 0) {
+ virReportSystemError(errno,
+ _("Failed to seek to %llu bytes to the end in volume "
+ "with path '%s'"),
+ wipe_len, path);
+ goto cleanup;
+ }
}
+ VIR_DEBUG("wiping start: %zd len: %llu", (ssize_t) size, wipe_len);
> }
>
> remaining = wipe_len;
> @@ -2573,7 +2593,8 @@ storageBackendWipeLocal(const char *path,
> static int
> storageBackendVolWipeLocalFile(const char *path,
> unsigned int algorithm,
> - unsigned long long allocation)
> + unsigned long long allocation,
> + bool zero_end)
> {
> int ret = -1, fd = -1;
> const char *alg_char = NULL;
> @@ -2648,7 +2669,8 @@ storageBackendVolWipeLocalFile(const char *path,
> if (S_ISREG(st.st_mode) && st.st_blocks < (st.st_size / DEV_BSIZE)) {
> ret = storageBackendVolZeroSparseFileLocal(path, st.st_size, fd);
> } else {
> - ret = storageBackendWipeLocal(path, fd, allocation, st.st_blksize);
> + ret = storageBackendWipeLocal(path, fd, allocation, st.st_blksize,
> + zero_end);
> }
> if (ret < 0)
> goto cleanup;
> @@ -2686,7 +2708,7 @@ storageBackendVolWipePloop(virStorageVolDefPtr vol,
> goto cleanup;
>
> if (storageBackendVolWipeLocalFile(target_path, algorithm,
> - vol->target.allocation) < 0)
> + vol->target.allocation, false) < 0)
> goto cleanup;
>
> if (virFileRemove(disk_desc, 0, 0) < 0) {
> @@ -2735,7 +2757,7 @@ virStorageBackendVolWipeLocal(virConnectPtr conn ATTRIBUTE_UNUSED,
> ret = storageBackendVolWipePloop(vol, algorithm);
> } else {
> ret = storageBackendVolWipeLocalFile(vol->target.path, algorithm,
> - vol->target.allocation);
> + vol->target.allocation, false);
> }
>
> return ret;
>
Michal
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