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
--
libvir-list mailing list
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https://www.redhat.com/mailman/listinfo/libvir-list
On 06/23/2017 09:33 AM, Peter Krempa wrote:
> 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/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;
> }
>
Should :
ssize_t len = VIR_STORAGE_MAX_HEADER;
change to size_t and a new variable "ssize_t read_len" be created and
used for the following and subsequent virStorageFileGetMetadataFromBuf
call? (although that also takes a size_t for the 3rd param).
> - 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
Probably should put the description below the args and restate since it
reading @len bytes of data starting at @offset
> *
> * @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);
"read %zd bytes from storage %p starting at offset %zu", ret, src, offset
With a few tweaks:
Reviewed-by: John Ferlan <jferlan@redhat.com>
John
[...]
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On Sat, Jul 01, 2017 at 10:43:09 -0400, John Ferlan wrote: > > > On 06/23/2017 09:33 AM, Peter Krempa wrote: > > 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/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 [...] > > @@ -292,7 +292,7 @@ virStorageBackendGlusterRefreshVol(virStorageBackendGlusterStatePtr state, > > goto cleanup; > > } > > > > Should : > > ssize_t len = VIR_STORAGE_MAX_HEADER; > > change to size_t and a new variable "ssize_t read_len" be created and > used for the following and subsequent virStorageFileGetMetadataFromBuf > call? (although that also takes a size_t for the 3rd param). I actually just used VIR_STORAGE_MAX_HEADER constant directly in the call of virStorageBackendGlusterRead. The original variable will thus be used only for the return value, which is signed. > > > - if ((len = virStorageBackendGlusterReadHeader(fd, name, len, &header)) < 0) > > + if ((len = virStorageBackendGlusterRead(fd, name, len, &header)) < 0) > > goto cleanup; > > > > if (!(meta = virStorageFileGetMetadataFromBuf(name, header, len, -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
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