[Libguestfs] [PATCH REPOST] Introduce a wrapper around xmlParseURI.
Richard W.M. Jones
rjones at redhat.com
Fri Nov 2 14:23:07 UTC 2018
We only use xmlParseURI to parse our own "homebrew" URIs, for example
the ones used by guestfish --add or virt-v2v. Unfortunately
xmlParseURI cannot handle URIs with spaces or other non-RFC-compliant
characters so simple commands like these fail:
$ guestfish -a 'ssh://example.com/virtual machine.img'
guestfish: --add: could not parse URI 'ssh://example.com/virtual machine.img'
$ guestfish -a 'ssh://example.com/バーチャルマシン.img'
guestfish: --add: could not parse URI 'ssh://example.com/バーチャルマシン.img'
This is a usability problem. However since these are not expected to
be generic RFC-compliant URIs we can perform the required
percent-escaping ourselves instead of demanding that the user does
this.
Note that the wrapper function should not be used on real URLs or
libvirt URLs.
---
common/mlxml/Makefile.am | 1 +
common/mlxml/xml-c.c | 45 +++++++--
common/mlxml/xml.ml | 1 +
common/mlxml/xml.mli | 4 +
common/options/uri.c | 5 +-
common/utils/Makefile.am | 2 +
common/utils/libxml2-utils.c | 178 ++++++++++++++++++++++++++++++++++
common/utils/libxml2-utils.h | 27 ++++++
docs/C_SOURCE_FILES | 2 +
v2v/input_vmx.ml | 8 +-
v2v/virt-v2v-input-vmware.pod | 5 +-
11 files changed, 260 insertions(+), 18 deletions(-)
diff --git a/common/mlxml/Makefile.am b/common/mlxml/Makefile.am
index 7f36b743a..95915f80c 100644
--- a/common/mlxml/Makefile.am
+++ b/common/mlxml/Makefile.am
@@ -53,6 +53,7 @@ libmlxml_a_CPPFLAGS = \
-I. \
-I$(top_builddir) \
-I$(top_srcdir)/gnulib/lib -I$(top_builddir)/gnulib/lib \
+ -I$(top_srcdir)/common/utils -I$(top_builddir)/common/utils \
-I$(shell $(OCAMLC) -where)
libmlxml_a_CFLAGS = \
$(WARN_CFLAGS) $(WERROR_CFLAGS) \
diff --git a/common/mlxml/xml-c.c b/common/mlxml/xml-c.c
index 3ebecb25e..6dcdb5ccb 100644
--- a/common/mlxml/xml-c.c
+++ b/common/mlxml/xml-c.c
@@ -27,17 +27,21 @@
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
+#include <errno.h>
#include <caml/alloc.h>
#include <caml/custom.h>
#include <caml/fail.h>
#include <caml/memory.h>
#include <caml/mlvalues.h>
+#include <caml/unixsupport.h>
#include <libxml/xpath.h>
#include <libxml/xpathInternals.h>
#include <libxml/uri.h>
+#include "libxml2-utils.h"
+
#pragma GCC diagnostic ignored "-Wmissing-prototypes"
/* xmlDocPtr type */
@@ -426,16 +430,11 @@ mllib_xml_doc_get_root_element (value docv)
}
}
-value
-mllib_xml_parse_uri (value strv)
+static value
+Val_uri (xmlURIPtr uri)
{
- CAMLparam1 (strv);
+ CAMLparam0 ();
CAMLlocal3 (rv, sv, ov);
- xmlURIPtr uri;
-
- uri = xmlParseURI (String_val (strv));
- if (uri == NULL)
- caml_invalid_argument ("parse_uri: unable to parse URI");
rv = caml_alloc_tuple (9);
@@ -514,7 +513,37 @@ mllib_xml_parse_uri (value strv)
else ov = Val_int (0);
Store_field (rv, 8, ov);
+ CAMLreturn (rv);
+}
+
+value
+mllib_xml_parse_uri (value strv)
+{
+ CAMLparam1 (strv);
+ CAMLlocal1 (rv);
+ xmlURIPtr uri;
+
+ uri = xmlParseURI (String_val (strv));
+ if (uri == NULL)
+ caml_invalid_argument ("parse_uri: unable to parse URI");
+
+ rv = Val_uri (uri);
xmlFreeURI (uri);
+ CAMLreturn (rv);
+}
+
+value
+mllib_xml_parse_nonstandard_uri (value strv)
+{
+ CAMLparam1 (strv);
+ CAMLlocal1 (rv);
+ xmlURIPtr uri;
+ uri = guestfs_int_parse_nonstandard_uri (String_val (strv));
+ if (uri == NULL)
+ unix_error (errno, (char *) "Xml.parse_uri", strv);
+
+ rv = Val_uri (uri);
+ xmlFreeURI (uri);
CAMLreturn (rv);
}
diff --git a/common/mlxml/xml.ml b/common/mlxml/xml.ml
index 5b5c09c00..faeea35ee 100644
--- a/common/mlxml/xml.ml
+++ b/common/mlxml/xml.ml
@@ -162,3 +162,4 @@ type uri = {
}
external parse_uri : string -> uri = "mllib_xml_parse_uri"
+external parse_nonstandard_uri : string -> uri = "mllib_xml_parse_nonstandard_uri"
diff --git a/common/mlxml/xml.mli b/common/mlxml/xml.mli
index f561bd673..73c2fdd4b 100644
--- a/common/mlxml/xml.mli
+++ b/common/mlxml/xml.mli
@@ -115,3 +115,7 @@ val parse_uri : string -> uri
Note this is different from the {!URI} module which is specialized
for parsing the [-a] parameter on the command line. This function
exposes the full [xmlParseURI] interface. *)
+
+val parse_nonstandard_uri : string -> uri
+(** Similar to {!parse_uri} but only for use with our non-standard
+ URIs. See [guestfs_int_parse_nonstandard_uri] in [common/utils]. *)
diff --git a/common/options/uri.c b/common/options/uri.c
index ac36bccb2..88a5f0560 100644
--- a/common/options/uri.c
+++ b/common/options/uri.c
@@ -38,6 +38,7 @@
#include "guestfs.h"
#include "guestfs-utils.h"
+#include "libxml2-utils.h"
#include "uri.h"
static int is_uri (const char *arg);
@@ -114,9 +115,9 @@ parse (const char *arg, char **path_ret, char **protocol_ret,
CLEANUP_FREE char *socket = NULL;
char *path;
- uri = xmlParseURI (arg);
+ uri = guestfs_int_parse_nonstandard_uri (arg);
if (!uri) {
- fprintf (stderr, _("%s: --add: could not parse URI ‘%s’\n"),
+ fprintf (stderr, _("%s: --add: could not parse URI ‘%s’: %m\n"),
getprogname (), arg);
return -1;
}
diff --git a/common/utils/Makefile.am b/common/utils/Makefile.am
index a0154d85f..4ff9efcbd 100644
--- a/common/utils/Makefile.am
+++ b/common/utils/Makefile.am
@@ -26,6 +26,8 @@ libutils_la_SOURCES = \
gnulib-cleanups.c \
guestfs-utils.h \
libxml2-cleanups.c \
+ libxml2-utils.c \
+ libxml2-utils.h \
libxml2-writer-macros.h \
utils.c
libutils_la_CPPFLAGS = \
diff --git a/common/utils/libxml2-utils.c b/common/utils/libxml2-utils.c
new file mode 100644
index 000000000..8a05aa5b1
--- /dev/null
+++ b/common/utils/libxml2-utils.c
@@ -0,0 +1,178 @@
+/* libguestfs
+ * Copyright (C) 2017 Red Hat Inc.
+ *
+ * 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; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * Utility functions using libxml2.
+ *
+ * These functions these I<must not> call internal library functions
+ * such as C<safe_*>, C<error> or C<perrorf>, or any C<guestfs_int_*>.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <locale.h>
+#include <langinfo.h>
+#include <iconv.h>
+
+#include <libxml/uri.h>
+
+#include "c-ctype.h"
+
+/* NB: MUST NOT include "guestfs-internal.h". */
+#include "guestfs.h"
+#include "guestfs-utils.h"
+#include "libxml2-utils.h"
+
+static char *local_string_to_utf8 (/* const */ char *input);
+
+/**
+ * This is a wrapper around C<xmlParseURI>. That function cannot
+ * handle spaces and some non-ASCII characters found in URIs. This
+ * wrapper URI-encodes those before calling C<xmlParseURI> and returns
+ * the URI structure.
+ *
+ * This function should B<only> be called for the URIs that libguestfs
+ * has invented, for things like guestfish I<--add> and virt-v2v.
+ *
+ * For real URIs or libvirt URIs this may cause corruption in corner
+ * cases. (See L<https://news.ycombinator.com/item?id=11673058>
+ * describing some of the complexity involved in dealing with real
+ * URI).
+ *
+ * On error, returns C<NULL> and sets C<errno> appropriately.
+ *
+ * Caller must call C<xmlFreeURI> on the returned structure or use the
+ * C<CLEANUP_XMLFREEURI> cleanup macro.
+ */
+xmlURIPtr
+guestfs_int_parse_nonstandard_uri (const char *arg)
+{
+ CLEANUP_FREE char *uri = NULL;
+ CLEANUP_FREE char *escaped_uri = NULL;
+ static const char hexdigit[] = "0123456789abcdef";
+ size_t i, j, len;
+ xmlURIPtr ret;
+
+ /* Convert the string to UTF-8. */
+ uri = local_string_to_utf8 ((char *) arg);
+ if (uri == NULL)
+ return NULL;
+
+ /* Since we know the URI is in well-formed UTF-8 we can iterate over
+ * the bytes to do the escaping. The output of this will never be
+ * more than 3 times larger (each byte might be rewritten as ‘%XX’).
+ */
+ len = strlen (uri);
+ escaped_uri = malloc (3*len + 1);
+ if (escaped_uri == NULL)
+ return NULL;
+
+ for (i = j = 0; i < strlen (uri); ++i) {
+ /* See RFC 3986 appendix A. Note this leaves existing %-encoded
+ * escapes alone.
+ */
+ if (c_isalnum (uri[i]) ||
+ strchr ("%-._~:/?#[]@!$&'()*+,;=", uri[i]) != NULL)
+ escaped_uri[j++] = uri[i];
+ else {
+ escaped_uri[j++] = '%';
+ escaped_uri[j++] = hexdigit [(((unsigned char) uri[i]) >> 4) & 0xf];
+ escaped_uri[j++] = hexdigit [((unsigned char) uri[i]) & 0xf];
+ }
+ }
+ escaped_uri[j++] = '\0';
+
+ /* libxml2 xmlParseURI does not reliably set errno, so it's likely
+ * best to ignore whatever errno is returned and overwrite it with
+ * EINVAL.
+ */
+ ret = xmlParseURI (escaped_uri);
+ if (ret == NULL) {
+ errno = EINVAL;
+ return NULL;
+ }
+
+ return ret;
+}
+
+/* Would be const, but the interface to iconv is not const-correct on
+ * all platforms. The input string is not touched.
+ */
+static char *
+local_string_to_utf8 (/* const */ char *input)
+{
+ iconv_t ic;
+ size_t len, inlen, outlen, outalloc, r, prev;
+ int err;
+ char *out, *inp, *outp;
+
+ /* Convert from input locale to UTF-8. */
+ ic = iconv_open ("UTF-8", nl_langinfo (CODESET));
+ if (ic == (iconv_t) -1)
+ return NULL;
+
+ len = strlen (input);
+ outalloc = len; /* Initial guess. */
+
+ again:
+ inlen = len;
+ outlen = outalloc;
+ out = malloc (outlen + 1);
+ if (out == NULL) {
+ err = errno;
+ iconv_close (ic);
+ errno = err;
+ return NULL;
+ }
+ inp = input;
+ outp = out;
+
+ r = iconv (ic, (ICONV_CONST char **) &inp, &inlen, &outp, &outlen);
+ if (r == (size_t) -1) {
+ if (errno == E2BIG) {
+ err = errno;
+ prev = outalloc;
+ /* Try again with a larger output buffer. */
+ free (out);
+ outalloc *= 2;
+ if (outalloc < prev) {
+ iconv_close (ic);
+ errno = err;
+ return NULL;
+ }
+ goto again;
+ }
+ else {
+ /* Else some other conversion failure, eg. EILSEQ, EINVAL. */
+ err = errno;
+ iconv_close (ic);
+ free (out);
+ errno = err;
+ return NULL;
+ }
+ }
+
+ *outp = '\0';
+ iconv_close (ic);
+
+ return out;
+}
diff --git a/common/utils/libxml2-utils.h b/common/utils/libxml2-utils.h
new file mode 100644
index 000000000..d9916ea58
--- /dev/null
+++ b/common/utils/libxml2-utils.h
@@ -0,0 +1,27 @@
+/* libguestfs
+ * Copyright (C) 2017 Red Hat Inc.
+ *
+ * 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; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef GUESTFS_LIBXML2_UTILS_H_
+#define GUESTFS_LIBXML2_UTILS_H_
+
+#include <libxml/uri.h>
+
+/* libxml2-utils.c */
+extern xmlURIPtr guestfs_int_parse_nonstandard_uri (const char *uri);
+
+#endif /* GUESTFS_LIBXML2_UTILS_H_ */
diff --git a/docs/C_SOURCE_FILES b/docs/C_SOURCE_FILES
index 7f1c60b30..853484e0f 100644
--- a/docs/C_SOURCE_FILES
+++ b/docs/C_SOURCE_FILES
@@ -62,6 +62,8 @@ common/utils/cleanups.h
common/utils/gnulib-cleanups.c
common/utils/guestfs-utils.h
common/utils/libxml2-cleanups.c
+common/utils/libxml2-utils.c
+common/utils/libxml2-utils.h
common/utils/libxml2-writer-macros.h
common/utils/utils.c
common/visit/visit.c
diff --git a/v2v/input_vmx.ml b/v2v/input_vmx.ml
index b169b2537..30649b33b 100644
--- a/v2v/input_vmx.ml
+++ b/v2v/input_vmx.ml
@@ -38,11 +38,11 @@ type vmx_source =
let vmx_source_of_arg input_transport arg =
match input_transport, arg with
| None, arg -> File arg
- | Some `SSH, arg ->
+ | Some `SSH, uri ->
let uri =
- try Xml.parse_uri arg
- with Invalid_argument _ ->
- error (f_"remote vmx ‘%s’ could not be parsed as a URI") arg in
+ try Xml.parse_nonstandard_uri uri
+ with exn ->
+ error (f_"could not parse URI: %s") (Printexc.to_string exn) in
if uri.Xml.uri_scheme <> None && uri.Xml.uri_scheme <> Some "ssh" then
error (f_"vmx URI start with ‘ssh://...’");
if uri.Xml.uri_server = None then
diff --git a/v2v/virt-v2v-input-vmware.pod b/v2v/virt-v2v-input-vmware.pod
index 636652e50..f73e1fb55 100644
--- a/v2v/virt-v2v-input-vmware.pod
+++ b/v2v/virt-v2v-input-vmware.pod
@@ -152,10 +152,7 @@ authorized_keys.
When using the SSH input transport you must specify a remote
C<ssh://...> URI pointing to the VMX file. A typical URI looks like:
- ssh://root@esxi.example.com/vmfs/volumes/datastore1/my%20guest/my%20guest.vmx
-
-Any space must be escaped with C<%20> and other non-ASCII characters
-may also need to be URI-escaped.
+ ssh://root@esxi.example.com/vmfs/volumes/datastore1/my guest/my guest.vmx
The username is not required if it is the same as your local username.
--
2.19.0.rc0
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