diff mbox series

[v7,05/12] libs: add libxenhypfs

Message ID 20200402154616.16927-6-jgross@suse.com (mailing list archive)
State Superseded
Headers show
Series Add hypervisor sysfs-like support | expand

Commit Message

Jürgen Groß April 2, 2020, 3:46 p.m. UTC
Add the new library libxenhypfs for access to the hypervisor filesystem.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Wei Liu <wl@xen.org>
---
V1:
- rename to libxenhypfs
- add xenhypfs_write()

V3:
- major rework due to new hypervisor interface
- add decompression capability

V4:
- add dependency to libz in pkgconfig file (Wei Liu)

V7:
- don't assume hypervisor's sizeof(bool) is same as in user land
---
 .gitignore                          |   2 +
 tools/Rules.mk                      |   6 +
 tools/libs/Makefile                 |   1 +
 tools/libs/hypfs/Makefile           |  16 ++
 tools/libs/hypfs/core.c             | 536 ++++++++++++++++++++++++++++++++++++
 tools/libs/hypfs/include/xenhypfs.h |  75 +++++
 tools/libs/hypfs/libxenhypfs.map    |  10 +
 tools/libs/hypfs/xenhypfs.pc.in     |  10 +
 8 files changed, 656 insertions(+)
 create mode 100644 tools/libs/hypfs/Makefile
 create mode 100644 tools/libs/hypfs/core.c
 create mode 100644 tools/libs/hypfs/include/xenhypfs.h
 create mode 100644 tools/libs/hypfs/libxenhypfs.map
 create mode 100644 tools/libs/hypfs/xenhypfs.pc.in

Comments

George Dunlap April 27, 2020, 2:53 p.m. UTC | #1
> On Apr 2, 2020, at 4:46 PM, Juergen Gross <JGross@suse.com> wrote:
> 
> Add the new library libxenhypfs for access to the hypervisor filesystem.
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>
> Acked-by: Wei Liu <wl@xen.org>

Just a few questions...

> +/* Returned buffer and dirent should be freed via free(). */
> +void *xenhypfs_read_raw(xenhypfs_handle *fshdl, const char *path,
> +                        struct xenhypfs_dirent **dirent);
> +
> +/* Returned buffer should be freed via free(). */
> +char *xenhypfs_read(xenhypfs_handle *fshdl, const char *path);

What’s the difference between these two?  And what’s the `dirent` argument to xenhypfs_read_raw() for?

 -George
Jürgen Groß May 7, 2020, 11:35 a.m. UTC | #2
On 27.04.20 16:53, George Dunlap wrote:
> 
> 
>> On Apr 2, 2020, at 4:46 PM, Juergen Gross <JGross@suse.com> wrote:
>>
>> Add the new library libxenhypfs for access to the hypervisor filesystem.
>>
>> Signed-off-by: Juergen Gross <jgross@suse.com>
>> Acked-by: Wei Liu <wl@xen.org>
> 
> Just a few questions...
> 
>> +/* Returned buffer and dirent should be freed via free(). */
>> +void *xenhypfs_read_raw(xenhypfs_handle *fshdl, const char *path,
>> +                        struct xenhypfs_dirent **dirent);
>> +
>> +/* Returned buffer should be freed via free(). */
>> +char *xenhypfs_read(xenhypfs_handle *fshdl, const char *path);
> 
> What’s the difference between these two?  And what’s the `dirent` argument to xenhypfs_read_raw() for?

xenhypfs_read() is returning the printable content (if possible),
e.g. "1" for an entry of type integer containing 0x00000001

xenhypfs_read_raw() returns the raw content (e.g. the binary
value 0x00000001 in above example) and the entry format data in
dirent (type, size and enconding of entry).


Juergen
diff mbox series

Patch

diff --git a/.gitignore b/.gitignore
index b2624df79a..e98c3f056d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -109,6 +109,8 @@  tools/libs/evtchn/headers.chk
 tools/libs/evtchn/xenevtchn.pc
 tools/libs/gnttab/headers.chk
 tools/libs/gnttab/xengnttab.pc
+tools/libs/hypfs/headers.chk
+tools/libs/hypfs/xenhypfs.pc
 tools/libs/call/headers.chk
 tools/libs/call/xencall.pc
 tools/libs/foreignmemory/headers.chk
diff --git a/tools/Rules.mk b/tools/Rules.mk
index 9bac15c8d1..711e9598cd 100644
--- a/tools/Rules.mk
+++ b/tools/Rules.mk
@@ -19,6 +19,7 @@  XEN_LIBXENGNTTAB   = $(XEN_ROOT)/tools/libs/gnttab
 XEN_LIBXENCALL     = $(XEN_ROOT)/tools/libs/call
 XEN_LIBXENFOREIGNMEMORY = $(XEN_ROOT)/tools/libs/foreignmemory
 XEN_LIBXENDEVICEMODEL = $(XEN_ROOT)/tools/libs/devicemodel
+XEN_LIBXENHYPFS    = $(XEN_ROOT)/tools/libs/hypfs
 XEN_LIBXC          = $(XEN_ROOT)/tools/libxc
 XEN_XENLIGHT       = $(XEN_ROOT)/tools/libxl
 # Currently libxlutil lives in the same directory as libxenlight
@@ -134,6 +135,11 @@  SHDEPS_libxendevicemodel = $(SHLIB_libxentoollog) $(SHLIB_libxentoolcore) $(SHLI
 LDLIBS_libxendevicemodel = $(SHDEPS_libxendevicemodel) $(XEN_LIBXENDEVICEMODEL)/libxendevicemodel$(libextension)
 SHLIB_libxendevicemodel  = $(SHDEPS_libxendevicemodel) -Wl,-rpath-link=$(XEN_LIBXENDEVICEMODEL)
 
+CFLAGS_libxenhypfs = -I$(XEN_LIBXENHYPFS)/include $(CFLAGS_xeninclude)
+SHDEPS_libxenhypfs = $(SHLIB_libxentoollog) $(SHLIB_libxentoolcore) $(SHLIB_xencall)
+LDLIBS_libxenhypfs = $(SHDEPS_libxenhypfs) $(XEN_LIBXENHYPFS)/libxenhypfs$(libextension)
+SHLIB_libxenhypfs  = $(SHDEPS_libxenhypfs) -Wl,-rpath-link=$(XEN_LIBXENHYPFS)
+
 # code which compiles against libxenctrl get __XEN_TOOLS__ and
 # therefore sees the unstable hypercall interfaces.
 CFLAGS_libxenctrl = -I$(XEN_LIBXC)/include $(CFLAGS_libxentoollog) $(CFLAGS_libxenforeignmemory) $(CFLAGS_libxendevicemodel) $(CFLAGS_xeninclude) -D__XEN_TOOLS__
diff --git a/tools/libs/Makefile b/tools/libs/Makefile
index 88901e7341..69cdfb5975 100644
--- a/tools/libs/Makefile
+++ b/tools/libs/Makefile
@@ -9,6 +9,7 @@  SUBDIRS-y += gnttab
 SUBDIRS-y += call
 SUBDIRS-y += foreignmemory
 SUBDIRS-y += devicemodel
+SUBDIRS-y += hypfs
 
 ifeq ($(CONFIG_RUMP),y)
 SUBDIRS-y := toolcore
diff --git a/tools/libs/hypfs/Makefile b/tools/libs/hypfs/Makefile
new file mode 100644
index 0000000000..06dd449929
--- /dev/null
+++ b/tools/libs/hypfs/Makefile
@@ -0,0 +1,16 @@ 
+XEN_ROOT = $(CURDIR)/../../..
+include $(XEN_ROOT)/tools/Rules.mk
+
+MAJOR    = 1
+MINOR    = 0
+LIBNAME  := hypfs
+USELIBS  := toollog toolcore call
+
+APPEND_LDFLAGS += -lz
+
+SRCS-y                 += core.c
+
+include ../libs.mk
+
+$(PKG_CONFIG_LOCAL): PKG_CONFIG_INCDIR = $(XEN_LIBXENHYPFS)/include
+$(PKG_CONFIG_LOCAL): PKG_CONFIG_CFLAGS_LOCAL = $(CFLAGS_xeninclude)
diff --git a/tools/libs/hypfs/core.c b/tools/libs/hypfs/core.c
new file mode 100644
index 0000000000..befdc66e96
--- /dev/null
+++ b/tools/libs/hypfs/core.c
@@ -0,0 +1,536 @@ 
+/*
+ * Copyright (c) 2019 SUSE Software Solutions Germany GmbH
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#define __XEN_TOOLS__ 1
+
+#define _GNU_SOURCE
+
+#include <errno.h>
+#include <inttypes.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <zlib.h>
+
+#include <xentoollog.h>
+#include <xenhypfs.h>
+#include <xencall.h>
+#include <xentoolcore_internal.h>
+
+#include <xen/xen.h>
+#include <xen/hypfs.h>
+
+#define BUF_SIZE 4096
+
+struct xenhypfs_handle {
+    xentoollog_logger *logger, *logger_tofree;
+    unsigned int flags;
+    xencall_handle *xcall;
+};
+
+xenhypfs_handle *xenhypfs_open(xentoollog_logger *logger,
+                               unsigned open_flags)
+{
+    xenhypfs_handle *fshdl = calloc(1, sizeof(*fshdl));
+
+    if (!fshdl)
+        return NULL;
+
+    fshdl->flags = open_flags;
+    fshdl->logger = logger;
+    fshdl->logger_tofree = NULL;
+
+    if (!fshdl->logger) {
+        fshdl->logger = fshdl->logger_tofree =
+            (xentoollog_logger*)
+            xtl_createlogger_stdiostream(stderr, XTL_PROGRESS, 0);
+        if (!fshdl->logger)
+            goto err;
+    }
+
+    fshdl->xcall = xencall_open(fshdl->logger, 0);
+    if (!fshdl->xcall)
+        goto err;
+
+    /* No need to remember supported version, we only support V1. */
+    if (xencall1(fshdl->xcall, __HYPERVISOR_hypfs_op,
+                 XEN_HYPFS_OP_get_version) < 0)
+        goto err;
+
+    return fshdl;
+
+err:
+    xtl_logger_destroy(fshdl->logger_tofree);
+    xencall_close(fshdl->xcall);
+    free(fshdl);
+    return NULL;
+}
+
+int xenhypfs_close(xenhypfs_handle *fshdl)
+{
+    if (!fshdl)
+        return 0;
+
+    xencall_close(fshdl->xcall);
+    xtl_logger_destroy(fshdl->logger_tofree);
+    free(fshdl);
+    return 0;
+}
+
+static int xenhypfs_get_pathbuf(xenhypfs_handle *fshdl, const char *path,
+                                char **path_buf)
+{
+    int ret = -1;
+    int path_sz;
+
+    if (!fshdl) {
+        errno = EBADF;
+        goto out;
+    }
+
+    path_sz = strlen(path) + 1;
+    if (path_sz > XEN_HYPFS_MAX_PATHLEN)
+    {
+        errno = ENAMETOOLONG;
+        goto out;
+    }
+
+    *path_buf = xencall_alloc_buffer(fshdl->xcall, path_sz);
+    if (!*path_buf) {
+        errno = ENOMEM;
+        goto out;
+    }
+    strcpy(*path_buf, path);
+
+    ret = path_sz;
+
+ out:
+    return ret;
+}
+
+static void *xenhypfs_inflate(void *in_data, size_t *sz)
+{
+    unsigned char *workbuf;
+    void *content = NULL;
+    unsigned int out_sz;
+    z_stream z = { .opaque = NULL };
+    int ret;
+
+    workbuf = malloc(BUF_SIZE);
+    if (!workbuf)
+        return NULL;
+
+    z.next_in = in_data;
+    z.avail_in = *sz;
+    ret = inflateInit2(&z, MAX_WBITS + 32); /* 32 == gzip */
+
+    for (*sz = 0; ret == Z_OK; *sz += out_sz) {
+        z.next_out = workbuf;
+        z.avail_out = BUF_SIZE;
+        ret = inflate(&z, Z_SYNC_FLUSH);
+        if (ret != Z_OK && ret != Z_STREAM_END)
+            break;
+
+        out_sz = z.next_out - workbuf;
+        content = realloc(content, *sz + out_sz);
+        if (!content) {
+            ret = Z_MEM_ERROR;
+            break;
+        }
+        memcpy(content + *sz, workbuf, out_sz);
+    }
+
+    inflateEnd(&z);
+    if (ret != Z_STREAM_END) {
+        free(content);
+        content = NULL;
+        errno = EIO;
+    }
+    free(workbuf);
+    return content;
+}
+
+static void xenhypfs_set_attrs(struct xen_hypfs_direntry *entry,
+                               struct xenhypfs_dirent *dirent)
+{
+    dirent->size = entry->content_len;
+
+    switch(entry->type) {
+    case XEN_HYPFS_TYPE_DIR:
+        dirent->type = xenhypfs_type_dir;
+        break;
+    case XEN_HYPFS_TYPE_BLOB:
+        dirent->type = xenhypfs_type_blob;
+        break;
+    case XEN_HYPFS_TYPE_STRING:
+        dirent->type = xenhypfs_type_string;
+        break;
+    case XEN_HYPFS_TYPE_UINT:
+        dirent->type = xenhypfs_type_uint;
+        break;
+    case XEN_HYPFS_TYPE_INT:
+        dirent->type = xenhypfs_type_int;
+        break;
+    case XEN_HYPFS_TYPE_BOOL:
+        dirent->type = xenhypfs_type_bool;
+        break;
+    default:
+        dirent->type = xenhypfs_type_blob;
+    }
+
+    switch (entry->encoding) {
+    case XEN_HYPFS_ENC_PLAIN:
+        dirent->encoding = xenhypfs_enc_plain;
+        break;
+    case XEN_HYPFS_ENC_GZIP:
+        dirent->encoding = xenhypfs_enc_gzip;
+        break;
+    default:
+        dirent->encoding = xenhypfs_enc_plain;
+        dirent->type = xenhypfs_type_blob;
+    }
+
+    dirent->is_writable = entry->max_write_len;
+}
+
+void *xenhypfs_read_raw(xenhypfs_handle *fshdl, const char *path,
+                        struct xenhypfs_dirent **dirent)
+{
+    void *retbuf = NULL, *content = NULL;
+    char *path_buf = NULL;
+    const char *name;
+    struct xen_hypfs_direntry *entry;
+    int ret;
+    int sz, path_sz;
+
+    *dirent = NULL;
+    ret = xenhypfs_get_pathbuf(fshdl, path, &path_buf);
+    if (ret < 0)
+        goto out;
+
+    path_sz = ret;
+
+    for (sz = BUF_SIZE;; sz = sizeof(*entry) + entry->content_len) {
+        if (retbuf)
+            xencall_free_buffer(fshdl->xcall, retbuf);
+
+        retbuf = xencall_alloc_buffer(fshdl->xcall, sz);
+        if (!retbuf) {
+            errno = ENOMEM;
+            goto out;
+        }
+        entry = retbuf;
+
+        ret = xencall5(fshdl->xcall, __HYPERVISOR_hypfs_op, XEN_HYPFS_OP_read,
+                       (unsigned long)path_buf, path_sz,
+                       (unsigned long)retbuf, sz);
+        if (!ret)
+            break;
+
+        if (ret != ENOBUFS) {
+            errno = -ret;
+            goto out;
+        }
+    }
+
+    content = malloc(entry->content_len);
+    if (!content)
+        goto out;
+    memcpy(content, entry + 1, entry->content_len);
+
+    name = strrchr(path, '/');
+    if (!name)
+        name = path;
+    else {
+        name++;
+        if (!*name)
+            name--;
+    }
+    *dirent = calloc(1, sizeof(struct xenhypfs_dirent) + strlen(name) + 1);
+    if (!*dirent) {
+        free(content);
+        content = NULL;
+        errno = ENOMEM;
+        goto out;
+    }
+    (*dirent)->name = (char *)(*dirent + 1);
+    strcpy((*dirent)->name, name);
+    xenhypfs_set_attrs(entry, *dirent);
+
+ out:
+    ret = errno;
+    xencall_free_buffer(fshdl->xcall, path_buf);
+    xencall_free_buffer(fshdl->xcall, retbuf);
+    errno = ret;
+
+    return content;
+}
+
+char *xenhypfs_read(xenhypfs_handle *fshdl, const char *path)
+{
+    char *buf, *ret_buf = NULL;
+    struct xenhypfs_dirent *dirent;
+    int ret;
+
+    buf = xenhypfs_read_raw(fshdl, path, &dirent);
+    if (!buf)
+        goto out;
+
+    switch (dirent->encoding) {
+    case xenhypfs_enc_plain:
+        break;
+    case xenhypfs_enc_gzip:
+        ret_buf = xenhypfs_inflate(buf, &dirent->size);
+        if (!ret_buf)
+            goto out;
+        free(buf);
+        buf = ret_buf;
+        ret_buf = NULL;
+        break;
+    }
+
+    switch (dirent->type) {
+    case xenhypfs_type_dir:
+        errno = EISDIR;
+        break;
+    case xenhypfs_type_blob:
+        errno = EDOM;
+        break;
+    case xenhypfs_type_string:
+        ret_buf = buf;
+        buf = NULL;
+        break;
+    case xenhypfs_type_uint:
+    case xenhypfs_type_bool:
+        switch (dirent->size) {
+        case 1:
+            ret = asprintf(&ret_buf, "%"PRIu8, *(uint8_t *)buf);
+            break;
+        case 2:
+            ret = asprintf(&ret_buf, "%"PRIu16, *(uint16_t *)buf);
+            break;
+        case 4:
+            ret = asprintf(&ret_buf, "%"PRIu32, *(uint32_t *)buf);
+            break;
+        case 8:
+            ret = asprintf(&ret_buf, "%"PRIu64, *(uint64_t *)buf);
+            break;
+        default:
+            ret = -1;
+            errno = EDOM;
+        }
+        if (ret < 0)
+            ret_buf = NULL;
+        break;
+    case xenhypfs_type_int:
+        switch (dirent->size) {
+        case 1:
+            ret = asprintf(&ret_buf, "%"PRId8, *(int8_t *)buf);
+            break;
+        case 2:
+            ret = asprintf(&ret_buf, "%"PRId16, *(int16_t *)buf);
+            break;
+        case 4:
+            ret = asprintf(&ret_buf, "%"PRId32, *(int32_t *)buf);
+            break;
+        case 8:
+            ret = asprintf(&ret_buf, "%"PRId64, *(int64_t *)buf);
+            break;
+        default:
+            ret = -1;
+            errno = EDOM;
+        }
+        if (ret < 0)
+            ret_buf = NULL;
+        break;
+    }
+
+ out:
+    ret = errno;
+    free(buf);
+    free(dirent);
+    errno = ret;
+
+    return ret_buf;
+}
+
+struct xenhypfs_dirent *xenhypfs_readdir(xenhypfs_handle *fshdl,
+                                         const char *path,
+                                         unsigned int *num_entries)
+{
+    void *buf, *curr;
+    int ret;
+    char *names;
+    struct xenhypfs_dirent *ret_buf = NULL, *dirent;
+    unsigned int n = 0, name_sz = 0;
+    struct xen_hypfs_dirlistentry *entry;
+
+    buf = xenhypfs_read_raw(fshdl, path, &dirent);
+    if (!buf)
+        goto out;
+
+    if (dirent->type != xenhypfs_type_dir ||
+        dirent->encoding != xenhypfs_enc_plain) {
+        errno = ENOTDIR;
+        goto out;
+    }
+
+    if (dirent->size) {
+        curr = buf;
+        for (n = 1;; n++) {
+            entry = curr;
+            name_sz += strlen(entry->name) + 1;
+            if (!entry->off_next)
+                break;
+
+            curr += entry->off_next;
+        }
+    }
+
+    ret_buf = malloc(n * sizeof(*ret_buf) + name_sz);
+    if (!ret_buf)
+        goto out;
+
+    *num_entries = n;
+    names = (char *)(ret_buf + n);
+    curr = buf;
+    for (n = 0; n < *num_entries; n++) {
+        entry = curr;
+        xenhypfs_set_attrs(&entry->e, ret_buf + n);
+        ret_buf[n].name = names;
+        strcpy(names, entry->name);
+        names += strlen(entry->name) + 1;
+        curr += entry->off_next;
+    }
+
+ out:
+    ret = errno;
+    free(buf);
+    free(dirent);
+    errno = ret;
+
+    return ret_buf;
+}
+
+int xenhypfs_write(xenhypfs_handle *fshdl, const char *path, const char *val)
+{
+    void *buf = NULL;
+    char *path_buf = NULL, *val_end;
+    int ret, saved_errno;
+    int sz, path_sz;
+    struct xen_hypfs_direntry *entry;
+    uint64_t mask;
+
+    ret = xenhypfs_get_pathbuf(fshdl, path, &path_buf);
+    if (ret < 0)
+        goto out;
+
+    path_sz = ret;
+    ret = -1;
+
+    sz = BUF_SIZE;
+    buf = xencall_alloc_buffer(fshdl->xcall, sz);
+    if (!buf) {
+        errno = ENOMEM;
+        goto out;
+    }
+
+    ret = xencall5(fshdl->xcall, __HYPERVISOR_hypfs_op, XEN_HYPFS_OP_read,
+                   (unsigned long)path_buf, path_sz,
+                   (unsigned long)buf, sizeof(*entry));
+    if (ret && errno != ENOBUFS)
+        goto out;
+    ret = -1;
+    entry = buf;
+    if (!entry->max_write_len) {
+        errno = EACCES;
+        goto out;
+    }
+    if (entry->encoding != XEN_HYPFS_ENC_PLAIN) {
+        /* Writing compressed data currently not supported. */
+        errno = EDOM;
+        goto out;
+    }
+
+    switch (entry->type) {
+    case XEN_HYPFS_TYPE_STRING:
+        if (sz < strlen(val) + 1) {
+            sz = strlen(val) + 1;
+            xencall_free_buffer(fshdl->xcall, buf);
+            buf = xencall_alloc_buffer(fshdl->xcall, sz);
+            if (!buf) {
+                errno = ENOMEM;
+                goto out;
+            }
+        }
+        sz = strlen(val) + 1;
+        strcpy(buf, val);
+        break;
+    case XEN_HYPFS_TYPE_UINT:
+        sz = entry->content_len;
+        errno = 0;
+        *(unsigned long long *)buf = strtoull(val, &val_end, 0);
+        if (errno || !*val || *val_end)
+            goto out;
+        mask = ~0ULL << (8 * sz);
+        if ((*(uint64_t *)buf & mask) && ((*(uint64_t *)buf & mask) != mask)) {
+            errno = ERANGE;
+            goto out;
+        }
+        break;
+    case XEN_HYPFS_TYPE_INT:
+        sz = entry->content_len;
+        errno = 0;
+        *(unsigned long long *)buf = strtoll(val, &val_end, 0);
+        if (errno || !*val || *val_end)
+            goto out;
+        mask = (sz == 8) ? 0 : ~0ULL << (8 * sz);
+        if ((*(uint64_t *)buf & mask) && ((*(uint64_t *)buf & mask) != mask)) {
+            errno = ERANGE;
+            goto out;
+        }
+        break;
+    case XEN_HYPFS_TYPE_BOOL:
+        sz = entry->content_len;
+        *(unsigned long long *)buf = 0;
+        if (!strcmp(val, "1") || !strcmp(val, "on") || !strcmp(val, "yes") ||
+            !strcmp(val, "true") || !strcmp(val, "enable"))
+            *(unsigned long long *)buf = 1;
+        else if (strcmp(val, "0") && strcmp(val, "no") && strcmp(val, "off") &&
+                 strcmp(val, "false") && strcmp(val, "disable")) {
+            errno = EDOM;
+            goto out;
+        }
+        break;
+    default:
+        /* No support for other types (yet). */
+        errno = EDOM;
+        goto out;
+    }
+
+    ret = xencall5(fshdl->xcall, __HYPERVISOR_hypfs_op,
+                   XEN_HYPFS_OP_write_contents,
+                   (unsigned long)path_buf, path_sz,
+                   (unsigned long)buf, sz);
+
+ out:
+    saved_errno = errno;
+    xencall_free_buffer(fshdl->xcall, path_buf);
+    xencall_free_buffer(fshdl->xcall, buf);
+    errno = saved_errno;
+    return ret;
+}
diff --git a/tools/libs/hypfs/include/xenhypfs.h b/tools/libs/hypfs/include/xenhypfs.h
new file mode 100644
index 0000000000..29c69712ce
--- /dev/null
+++ b/tools/libs/hypfs/include/xenhypfs.h
@@ -0,0 +1,75 @@ 
+/*
+ * Copyright (c) 2019 SUSE Software Solutions Germany GmbH
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef XENHYPFS_H
+#define XENHYPFS_H
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <sys/types.h>
+
+/* Callers who don't care don't need to #include <xentoollog.h> */
+struct xentoollog_logger;
+
+typedef struct xenhypfs_handle xenhypfs_handle;
+
+struct xenhypfs_dirent {
+    char *name;
+    size_t size;
+    enum {
+        xenhypfs_type_dir,
+        xenhypfs_type_blob,
+        xenhypfs_type_string,
+        xenhypfs_type_uint,
+        xenhypfs_type_int,
+        xenhypfs_type_bool
+    } type;
+    enum {
+        xenhypfs_enc_plain,
+        xenhypfs_enc_gzip
+    } encoding;
+    bool is_writable;
+};
+
+xenhypfs_handle *xenhypfs_open(struct xentoollog_logger *logger,
+                               unsigned int open_flags);
+int xenhypfs_close(xenhypfs_handle *fshdl);
+
+/* Returned buffer and dirent should be freed via free(). */
+void *xenhypfs_read_raw(xenhypfs_handle *fshdl, const char *path,
+                        struct xenhypfs_dirent **dirent);
+
+/* Returned buffer should be freed via free(). */
+char *xenhypfs_read(xenhypfs_handle *fshdl, const char *path);
+
+/* Returned buffer should be freed via free(). */
+struct xenhypfs_dirent *xenhypfs_readdir(xenhypfs_handle *fshdl,
+                                         const char *path,
+                                         unsigned int *num_entries);
+
+int xenhypfs_write(xenhypfs_handle *fshdl, const char *path, const char *val);
+
+#endif /* XENHYPFS_H */
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/tools/libs/hypfs/libxenhypfs.map b/tools/libs/hypfs/libxenhypfs.map
new file mode 100644
index 0000000000..47f1edda3e
--- /dev/null
+++ b/tools/libs/hypfs/libxenhypfs.map
@@ -0,0 +1,10 @@ 
+VERS_1.0 {
+	global:
+		xenhypfs_open;
+		xenhypfs_close;
+		xenhypfs_read_raw;
+		xenhypfs_read;
+		xenhypfs_readdir;
+		xenhypfs_write;
+	local: *; /* Do not expose anything by default */
+};
diff --git a/tools/libs/hypfs/xenhypfs.pc.in b/tools/libs/hypfs/xenhypfs.pc.in
new file mode 100644
index 0000000000..92a262c7a2
--- /dev/null
+++ b/tools/libs/hypfs/xenhypfs.pc.in
@@ -0,0 +1,10 @@ 
+prefix=@@prefix@@
+includedir=@@incdir@@
+libdir=@@libdir@@
+
+Name: Xenhypfs
+Description: The Xenhypfs library for Xen hypervisor
+Version: @@version@@
+Cflags: -I${includedir} @@cflagslocal@@
+Libs: @@libsflag@@${libdir} -lxenhypfs
+Requires.private: xentoolcore,xentoollog,xencall,z