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storage: Make virStorageFileReadHeader more universal

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Allow specifying offset to read an arbitrary position in the file. This
warrants a rename to virStorageFileRead.
This commit is contained in:
Peter Krempa 2017-05-12 13:57:25 +02:00
parent 9506bd25a3
commit 204f373a91
6 changed files with 67 additions and 45 deletions
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3
src/qemu/qemu_driver.c
View File

@ -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;
}

9
src/storage/storage_backend.h
View File

@ -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

20
src/storage/storage_backend_fs.c
View File

@ -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,

40
src/storage/storage_backend_gluster.c
View File

@ -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;
@ -246,7 +246,7 @@ virStorageBackendGlusterRefreshVol(virStorageBackendGlusterStatePtr state,
glfs_fd_t *fd = NULL;
virStorageSourcePtr meta = NULL;
char *header = NULL;
ssize_t len = VIR_STORAGE_MAX_HEADER;
ssize_t len;
int backingFormat;
*volptr = NULL;
@ -292,7 +292,8 @@ virStorageBackendGlusterRefreshVol(virStorageBackendGlusterStatePtr state,
goto cleanup;
}
if ((len = virStorageBackendGlusterReadHeader(fd, name, len, &header)) < 0)
if ((len = virStorageBackendGlusterRead(fd, name, VIR_STORAGE_MAX_HEADER,
&header)) < 0)
goto cleanup;
if (!(meta = virStorageFileGetMetadataFromBuf(name, header, len,
@ -721,9 +722,10 @@ 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 +739,16 @@ 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 +861,7 @@ virStorageFileBackend virStorageFileBackendGluster = {
.storageFileCreate = virStorageFileBackendGlusterCreate,
.storageFileUnlink = virStorageFileBackendGlusterUnlink,
.storageFileStat = virStorageFileBackendGlusterStat,
.storageFileReadHeader = virStorageFileBackendGlusterReadHeader,
.storageFileRead = virStorageFileBackendGlusterRead,
.storageFileAccess = virStorageFileBackendGlusterAccess,
.storageFileChown = virStorageFileBackendGlusterChown,

33
src/storage/storage_source.c
View File

@ -64,7 +64,7 @@ virStorageFileSupportsBackingChainTraversal(virStorageSourcePtr src)
}
return backend->storageFileGetUniqueIdentifier &&
backend->storageFileReadHeader &&
backend->storageFileRead &&
backend->storageFileAccess;
}
@ -263,20 +263,22 @@ virStorageFileStat(virStorageSourcePtr src,
/**
* virStorageFileReadHeader: read the beginning bytes of a file into a buffer
* virStorageFileRead: read bytes from a file into a buffer
*
* @src: file structure pointing to the file
* @max_len: maximum number of bytes read from the storage file
* @buf: buffer to read the data into. buffer shall be freed by caller)
* @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
* function isn't supported by the backend.
* 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 +288,19 @@ 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 '%zd' bytes from storage '%p' starting at offset '%zu'",
ret, src, offset);
return ret;
}
@ -444,8 +447,8 @@ 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 +568,8 @@ 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)))

7
src/storage/storage_source.h
View File

@ -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);