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@redhat.com> --- 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