[libvirt] [PATCH 4/6] storage: Make virStorageFileReadHeader more universal
Peter Krempa
pkrempa at redhat.com
Fri Jun 23 13:33:16 UTC 2017
Allow specifying offset to read an arbitrary position in the file. This
warrants a rename to virStorageFileRead.
---
src/qemu/qemu_driver.c | 3 +--
src/storage/storage_backend.h | 9 +++++----
src/storage/storage_backend_fs.c | 20 +++++++++++++------
src/storage/storage_backend_gluster.c | 37 ++++++++++++++++++++++-------------
src/storage/storage_source.c | 30 +++++++++++++++-------------
src/storage/storage_source.h | 7 ++++---
6 files changed, 63 insertions(+), 43 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 052c7f0fc..4c4a6a036 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -11584,8 +11584,7 @@ qemuStorageLimitsRefresh(virQEMUDriverPtr driver,
goto cleanup;
}
} else {
- if ((len = virStorageFileReadHeader(src, VIR_STORAGE_MAX_HEADER,
- &buf)) < 0)
+ if ((len = virStorageFileRead(src, 0, VIR_STORAGE_MAX_HEADER, &buf)) < 0)
goto cleanup;
}
diff --git a/src/storage/storage_backend.h b/src/storage/storage_backend.h
index 21ac84552..193cf134d 100644
--- a/src/storage/storage_backend.h
+++ b/src/storage/storage_backend.h
@@ -154,9 +154,10 @@ typedef int
struct stat *st);
typedef ssize_t
-(*virStorageFileBackendReadHeader)(virStorageSourcePtr src,
- ssize_t max_len,
- char **buf);
+(*virStorageFileBackendRead)(virStorageSourcePtr src,
+ size_t offset,
+ size_t len,
+ char **buf);
typedef const char *
(*virStorageFileBackendGetUniqueIdentifier)(virStorageSourcePtr src);
@@ -186,7 +187,7 @@ struct _virStorageFileBackend {
* error on failure. */
virStorageFileBackendInit backendInit;
virStorageFileBackendDeinit backendDeinit;
- virStorageFileBackendReadHeader storageFileReadHeader;
+ virStorageFileBackendRead storageFileRead;
virStorageFileBackendGetUniqueIdentifier storageFileGetUniqueIdentifier;
/* The following group of callbacks is expected to set errno
diff --git a/src/storage/storage_backend_fs.c b/src/storage/storage_backend_fs.c
index bf1d7de43..847dbc9e0 100644
--- a/src/storage/storage_backend_fs.c
+++ b/src/storage/storage_backend_fs.c
@@ -779,9 +779,10 @@ virStorageFileBackendFileStat(virStorageSourcePtr src,
static ssize_t
-virStorageFileBackendFileReadHeader(virStorageSourcePtr src,
- ssize_t max_len,
- char **buf)
+virStorageFileBackendFileRead(virStorageSourcePtr src,
+ size_t offset,
+ size_t len,
+ char **buf)
{
int fd = -1;
ssize_t ret = -1;
@@ -793,7 +794,14 @@ virStorageFileBackendFileReadHeader(virStorageSourcePtr src,
return -1;
}
- if ((ret = virFileReadHeaderFD(fd, max_len, buf)) < 0) {
+ if (offset > 0) {
+ if (lseek(fd, offset, SEEK_SET) == (off_t) -1) {
+ virReportSystemError(errno, _("cannot seek into '%s'"), src->path);
+ goto cleanup;
+ }
+ }
+
+ if ((ret = virFileReadHeaderFD(fd, len, buf)) < 0) {
virReportSystemError(errno,
_("cannot read header '%s'"), src->path);
goto cleanup;
@@ -850,7 +858,7 @@ virStorageFileBackend virStorageFileBackendFile = {
.storageFileCreate = virStorageFileBackendFileCreate,
.storageFileUnlink = virStorageFileBackendFileUnlink,
.storageFileStat = virStorageFileBackendFileStat,
- .storageFileReadHeader = virStorageFileBackendFileReadHeader,
+ .storageFileRead = virStorageFileBackendFileRead,
.storageFileAccess = virStorageFileBackendFileAccess,
.storageFileChown = virStorageFileBackendFileChown,
@@ -865,7 +873,7 @@ virStorageFileBackend virStorageFileBackendBlock = {
.backendDeinit = virStorageFileBackendFileDeinit,
.storageFileStat = virStorageFileBackendFileStat,
- .storageFileReadHeader = virStorageFileBackendFileReadHeader,
+ .storageFileRead = virStorageFileBackendFileRead,
.storageFileAccess = virStorageFileBackendFileAccess,
.storageFileChown = virStorageFileBackendFileChown,
diff --git a/src/storage/storage_backend_gluster.c b/src/storage/storage_backend_gluster.c
index 93dce4042..8ea7e603c 100644
--- a/src/storage/storage_backend_gluster.c
+++ b/src/storage/storage_backend_gluster.c
@@ -151,20 +151,20 @@ virStorageBackendGlusterOpen(virStoragePoolObjPtr pool)
static ssize_t
-virStorageBackendGlusterReadHeader(glfs_fd_t *fd,
- const char *name,
- ssize_t maxlen,
- char **buf)
+virStorageBackendGlusterRead(glfs_fd_t *fd,
+ const char *name,
+ size_t len,
+ char **buf)
{
char *s;
size_t nread = 0;
- if (VIR_ALLOC_N(*buf, maxlen) < 0)
+ if (VIR_ALLOC_N(*buf, len) < 0)
return -1;
s = *buf;
- while (maxlen) {
- ssize_t r = glfs_read(fd, s, maxlen, 0);
+ while (len) {
+ ssize_t r = glfs_read(fd, s, len, 0);
if (r < 0 && errno == EINTR)
continue;
if (r < 0) {
@@ -175,7 +175,7 @@ virStorageBackendGlusterReadHeader(glfs_fd_t *fd,
if (r == 0)
return nread;
s += r;
- maxlen -= r;
+ len -= r;
nread += r;
}
return nread;
@@ -292,7 +292,7 @@ virStorageBackendGlusterRefreshVol(virStorageBackendGlusterStatePtr state,
goto cleanup;
}
- if ((len = virStorageBackendGlusterReadHeader(fd, name, len, &header)) < 0)
+ if ((len = virStorageBackendGlusterRead(fd, name, len, &header)) < 0)
goto cleanup;
if (!(meta = virStorageFileGetMetadataFromBuf(name, header, len,
@@ -721,9 +721,10 @@ virStorageFileBackendGlusterStat(virStorageSourcePtr src,
static ssize_t
-virStorageFileBackendGlusterReadHeader(virStorageSourcePtr src,
- ssize_t max_len,
- char **buf)
+virStorageFileBackendGlusterRead(virStorageSourcePtr src,
+ size_t offset,
+ size_t len,
+ char **buf)
{
virStorageFileBackendGlusterPrivPtr priv = src->drv->priv;
glfs_fd_t *fd = NULL;
@@ -737,8 +738,16 @@ virStorageFileBackendGlusterReadHeader(virStorageSourcePtr src,
return -1;
}
- ret = virStorageBackendGlusterReadHeader(fd, src->path, max_len, buf);
+ if (offset > 0) {
+ if (glfs_lseek(fd, offset, SEEK_SET) == (off_t) -1) {
+ virReportSystemError(errno, _("cannot seek into '%s'"), src->path);
+ goto cleanup;
+ }
+ }
+
+ ret = virStorageBackendGlusterRead(fd, src->path, len, buf);
+ cleanup:
if (fd)
glfs_close(fd);
@@ -851,7 +860,7 @@ virStorageFileBackend virStorageFileBackendGluster = {
.storageFileCreate = virStorageFileBackendGlusterCreate,
.storageFileUnlink = virStorageFileBackendGlusterUnlink,
.storageFileStat = virStorageFileBackendGlusterStat,
- .storageFileReadHeader = virStorageFileBackendGlusterReadHeader,
+ .storageFileRead = virStorageFileBackendGlusterRead,
.storageFileAccess = virStorageFileBackendGlusterAccess,
.storageFileChown = virStorageFileBackendGlusterChown,
diff --git a/src/storage/storage_source.c b/src/storage/storage_source.c
index c91d629c8..130c2d2f3 100644
--- a/src/storage/storage_source.c
+++ b/src/storage/storage_source.c
@@ -64,7 +64,7 @@ virStorageFileSupportsBackingChainTraversal(virStorageSourcePtr src)
}
return backend->storageFileGetUniqueIdentifier &&
- backend->storageFileReadHeader &&
+ backend->storageFileRead &&
backend->storageFileAccess;
}
@@ -263,10 +263,11 @@ virStorageFileStat(virStorageSourcePtr src,
/**
- * virStorageFileReadHeader: read the beginning bytes of a file into a buffer
+ * virStorageFileRead: read the beginning bytes of a file into a buffer
*
* @src: file structure pointing to the file
- * @max_len: maximum number of bytes read from the storage file
+ * @offset: number of bytes to skip in the storage file
+ * @len: maximum number of bytes read from the storage file
* @buf: buffer to read the data into. buffer shall be freed by caller)
*
* Returns the count of bytes read on success and -1 on failure, -2 if the
@@ -274,9 +275,10 @@ virStorageFileStat(virStorageSourcePtr src,
* Libvirt error is reported on failure.
*/
ssize_t
-virStorageFileReadHeader(virStorageSourcePtr src,
- ssize_t max_len,
- char **buf)
+virStorageFileRead(virStorageSourcePtr src,
+ size_t offset,
+ size_t len,
+ char **buf)
{
ssize_t ret;
@@ -286,18 +288,18 @@ virStorageFileReadHeader(virStorageSourcePtr src,
return -1;
}
- if (!src->drv->backend->storageFileReadHeader) {
+ if (!src->drv->backend->storageFileRead) {
virReportError(VIR_ERR_INTERNAL_ERROR,
- _("storage file header reading is not supported for "
+ _("storage file reading is not supported for "
"storage type %s (protocol: %s)"),
virStorageTypeToString(src->type),
virStorageNetProtocolTypeToString(src->protocol));
return -2;
}
- ret = src->drv->backend->storageFileReadHeader(src, max_len, buf);
+ ret = src->drv->backend->storageFileRead(src, offset, len, buf);
- VIR_DEBUG("read of storage header %p: ret=%zd", src, ret);
+ VIR_DEBUG("read of storage %p: ret=%zd", src, ret);
return ret;
}
@@ -444,8 +446,8 @@ virStorageFileGetMetadataRecurse(virStorageSourcePtr src,
if (virHashAddEntry(cycle, uniqueName, (void *)1) < 0)
goto cleanup;
- if ((headerLen = virStorageFileReadHeader(src, VIR_STORAGE_MAX_HEADER,
- &buf)) < 0)
+ if ((headerLen = virStorageFileRead(src, 0, VIR_STORAGE_MAX_HEADER,
+ &buf)) < 0)
goto cleanup;
if (virStorageFileGetMetadataInternal(src, buf, headerLen,
@@ -565,8 +567,8 @@ virStorageFileGetBackingStoreStr(virStorageSourcePtr src)
if (virStorageFileAccess(src, F_OK) < 0)
return NULL;
- if ((headerLen = virStorageFileReadHeader(src, VIR_STORAGE_MAX_HEADER,
- &buf)) < 0)
+ if ((headerLen = virStorageFileRead(src, 0, VIR_STORAGE_MAX_HEADER,
+ &buf)) < 0)
return NULL;
if (!(tmp = virStorageSourceCopy(src, false)))
diff --git a/src/storage/storage_source.h b/src/storage/storage_source.h
index 6b3362244..6462baf6a 100644
--- a/src/storage/storage_source.h
+++ b/src/storage/storage_source.h
@@ -32,9 +32,10 @@ int virStorageFileCreate(virStorageSourcePtr src);
int virStorageFileUnlink(virStorageSourcePtr src);
int virStorageFileStat(virStorageSourcePtr src,
struct stat *stat);
-ssize_t virStorageFileReadHeader(virStorageSourcePtr src,
- ssize_t max_len,
- char **buf);
+ssize_t virStorageFileRead(virStorageSourcePtr src,
+ size_t offset,
+ size_t len,
+ char **buf);
const char *virStorageFileGetUniqueIdentifier(virStorageSourcePtr src);
int virStorageFileAccess(virStorageSourcePtr src, int mode);
int virStorageFileChown(const virStorageSource *src, uid_t uid, gid_t gid);
--
2.12.2
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