[bug#47898] [PATCH] [core-updates] Add option --xpath0 to xmllint from libxml2

[bug#47898] [PATCH] [core-updates] Add option --xpath0 to xmllint from libxml2

[david larsson]

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Hi!
This patch adds the option to separate xpath results from xmllint by a 
null delimiter when using the --xpath0 option-flag. It is something 
that's been asked for for a long time by users on stackoverflow and 
merge-attempts have been made to upstream without success.

Examples:
   - https://gitlab.gnome.org/GNOME/libxml2/-/issues/227
   - https://gitlab.gnome.org/GNOME/libxml2/-/merge_requests/8

Best regards,
David

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From 714a6a26da55f7e06c94d3d2bb2965b9d2f832da Mon Sep 17 00:00:00 2001
From: David Larsson <david.larsson@selfhosted.xyz>
Date: Mon, 19 Apr 2021 20:39:23 +0200
Subject: [PATCH] gnu: libxml2: Add patch for xpath0 option to xmllint.

* gnu/packages/patches/libxml2-Add-option-xpath0.patch: New file...
* gnu/packages/xml.scm (libxml2) [source]: ...add it.
---
 .../patches/libxml2-Add-option-xpath0.patch   | 139 ++++++++++++++++++
 gnu/packages/xml.scm                          |   3 +-
 2 files changed, 141 insertions(+), 1 deletion(-)
 create mode 100644 gnu/packages/patches/libxml2-Add-option-xpath0.patch

diff --git a/gnu/packages/patches/libxml2-Add-option-xpath0.patch b/gnu/packages/patches/libxml2-Add-option-xpath0.patch
new file mode 100644
index 0000000000..3337374a8c
--- /dev/null
+++ b/gnu/packages/patches/libxml2-Add-option-xpath0.patch
@@ -0,0 +1,139 @@
+From e1df743329bdfd94fbfdea18303c5c6c6fe13403 Mon Sep 17 00:00:00 2001
+From: methuselah-0 <david.larsson@selfhosted.xyz>
+Date: Thu, 1 Apr 2021 08:33:56 +0200
+Subject: [PATCH] Add option --xpath0
+
+---
+ doc/xmllint.xml | 16 ++++++++++++++++
+ xmllint.c       | 32 +++++++++++++++++++++++---------
+ 2 files changed, 39 insertions(+), 9 deletions(-)
+
+diff --git a/doc/xmllint.xml b/doc/xmllint.xml
+index 1008179b..fcdc237e 100644
+--- a/doc/xmllint.xml
++++ b/doc/xmllint.xml
+@@ -70,6 +70,7 @@
+ 			<arg choice="plain"><option>--debug</option></arg>
+ 			<arg choice="plain"><option>--shell</option></arg>
+ 			<arg choice="plain"><option>--xpath "<replaceable class="option">XPath_expression</replaceable>"</option></arg>
++			<arg choice="plain"><option>--xpath0 "<replaceable class="option">XPath_expression</replaceable>"</option></arg>
+ 			<arg choice="plain"><option>--debugent</option></arg>
+ 			<arg choice="plain"><option>--copy</option></arg>
+ 			<arg choice="plain"><option>--recover</option></arg>
+@@ -537,6 +538,21 @@
+ 			node set is serialized in full in the output. In case
+ 			of an empty node set the "XPath set is empty" result
+ 			will be shown and an error exit code will be returned.
++			Results are separated by the newline character.
++		</para>
++	</listitem>
++		</varlistentry>
++
++		<varlistentry>
++	<term><option>--xpath0 "<replaceable class="option">XPath_expression</replaceable>"</option></term>
++	<listitem>
++		<para>
++			Run an XPath expression given as argument and print the
++			result. In case of a nodeset result, each node in the
++			node set is serialized in full in the output. In case
++			of an empty node set the "XPath set is empty" result
++			will be shown and an error exit code will be returned.
++			Results are separated by the null character.
+ 		</para>
+ 	</listitem>
+ 		</varlistentry>
+diff --git a/xmllint.c b/xmllint.c
+index 6ca1bf54..a60e1f4f 100644
+--- a/xmllint.c
++++ b/xmllint.c
+@@ -194,6 +194,7 @@ static int sax1 = 0;
+ #endif /* LIBXML_SAX1_ENABLED */
+ #ifdef LIBXML_XPATH_ENABLED
+ static const char *xpathquery = NULL;
++static const char *xpathsep = "\n";
+ #endif
+ static int options = XML_PARSE_COMPACT | XML_PARSE_BIG_LINES;
+ static int sax = 0;
+@@ -2095,7 +2096,7 @@ static void doXPathDump(xmlXPathObjectPtr cur) {
+             for (i = 0;i < cur->nodesetval->nodeNr;i++) {
+                 node = cur->nodesetval->nodeTab[i];
+                 xmlNodeDumpOutput(buf, NULL, node, 0, 0, NULL);
+-                xmlOutputBufferWrite(buf, 1, "\n");
++		xmlOutputBufferWrite(buf, 1, xpathsep);
+             }
+             xmlOutputBufferClose(buf);
+ #else
+@@ -2104,27 +2105,27 @@ static void doXPathDump(xmlXPathObjectPtr cur) {
+ 	    break;
+         }
+         case XPATH_BOOLEAN:
+-	    if (cur->boolval) printf("true\n");
+-	    else printf("false\n");
++	    if (cur->boolval) printf("true%s", xpathsep);
++	    else printf("false%s", xpathsep);
+ 	    break;
+         case XPATH_NUMBER:
+ 	    switch (xmlXPathIsInf(cur->floatval)) {
+ 	    case 1:
+-		printf("Infinity\n");
++	        printf("Infinity%s", xpathsep);
+ 		break;
+ 	    case -1:
+-		printf("-Infinity\n");
++	        printf("-Infinity%s", xpathsep);
+ 		break;
+ 	    default:
+ 		if (xmlXPathIsNaN(cur->floatval)) {
+-		    printf("NaN\n");
++		    printf("NaN%s", xpathsep);
+ 		} else {
+-		    printf("%0g\n", cur->floatval);
++		    printf("%0g%s", cur->floatval, xpathsep);
+ 		}
+ 	    }
+ 	    break;
+         case XPATH_STRING:
+-	    printf("%s\n", (const char *) cur->stringval);
++	    printf("%s%s", (const char *) cur->stringval, xpathsep);
+ 	    break;
+         case XPATH_UNDEFINED:
+ 	    fprintf(stderr, "XPath Object is uninitialized\n");
+@@ -3098,7 +3099,8 @@ static void usage(FILE *f, const char *name) {
+     fprintf(f, "\t--sax: do not build a tree but work just at the SAX level\n");
+     fprintf(f, "\t--oldxml10: use XML-1.0 parsing rules before the 5th edition\n");
+ #ifdef LIBXML_XPATH_ENABLED
+-    fprintf(f, "\t--xpath expr: evaluate the XPath expression, imply --noout\n");
++    fprintf(f, "\t--xpath expr: evaluate the XPath expression, results are separated by \\n, imply --noout\n");
++    fprintf(f, "\t--xpath0 expr: evaluate the XPath expression, results are separated by \\0, imply --noout\n");
+ #endif
+ 
+     fprintf(f, "\nLibxml project home page: http://xmlsoft.org/\n");
+@@ -3480,6 +3482,13 @@ main(int argc, char **argv) {
+ 	    i++;
+ 	    noout++;
+ 	    xpathquery = argv[i];
++	    xpathsep = "\n";
++        } else if ((!strcmp(argv[i], "-xpath0")) ||
++                   (!strcmp(argv[i], "--xpath0"))) {
++	    i++;
++	    noout++;
++	    xpathquery = argv[i];
++	    xpathsep = "\0";
+ #endif
+ 	} else if ((!strcmp(argv[i], "-oldxml10")) ||
+ 	           (!strcmp(argv[i], "--oldxml10"))) {
+@@ -3712,6 +3721,11 @@ main(int argc, char **argv) {
+ 	    i++;
+ 	    continue;
+ 	}
++        if ((!strcmp(argv[i], "-xpath0")) ||
++	    (!strcmp(argv[i], "--xpath0"))) {
++	    i++;
++	    continue;
++	}
+ #endif
+ 	if ((timing) && (repeat))
+ 	    startTimer();
+-- 
+2.30.2
+
diff --git a/gnu/packages/xml.scm b/gnu/packages/xml.scm
index ad5f35ef1e..d6a9b46e1d 100644
--- a/gnu/packages/xml.scm
+++ b/gnu/packages/xml.scm
@@ -177,7 +177,8 @@ hierarchical form with variable field lengths.")
                                  version ".tar.gz"))
              (sha256
               (base32
-               "07xynh8hcxb2yb1fs051xrgszjvj37wnxvxgsj10rzmqzy9y3zma"))))
+               "07xynh8hcxb2yb1fs051xrgszjvj37wnxvxgsj10rzmqzy9y3zma"))
+             (patches (list (search-patch "libxml2-Add-option-xpath0.patch")))))
     (build-system gnu-build-system)
     (outputs '("out" "static" "doc"))
     (arguments
-- 
2.30.2

[bug#47898] [PATCH] [core-updates] Add option --xpath0 to xmllint from libxml2

[Marius Bakke]

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david larsson <david.larsson@selfhosted.xyz> skriver:

> Hi!
> This patch adds the option to separate xpath results from xmllint by a 
> null delimiter when using the --xpath0 option-flag. It is something 
> that's been asked for for a long time by users on stackoverflow and 
> merge-attempts have been made to upstream without success.
>
> Examples:
>    - https://gitlab.gnome.org/GNOME/libxml2/-/issues/227
>    - https://gitlab.gnome.org/GNOME/libxml2/-/merge_requests/8

I'm reluctant to take a patch that has been rejected upstream,
especially for a core package such as libxml2.  Porting can be
time-consuming which delays security updates, and we'll have situations
where something "works on Guix" but not elsewhere (or vice versa).

Will adding it as a separate package be sufficient?  We could call it
"xmllint-xpath0" or similar and make it clear that it's just libxml2
with a patched xmllint in the description.

Thoughts?

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[bug#47898] [PATCH] [core-updates] Add option --xpath0 to xmllint from libxml2

[david larsson]

On 2021-05-13 14:41, Marius Bakke wrote:
> david larsson <david.larsson@selfhosted.xyz> skriver:
> 
>> Hi!
>> This patch adds the option to separate xpath results from xmllint by a
>> null delimiter when using the --xpath0 option-flag. It is something
>> that's been asked for for a long time by users on stackoverflow and
>> merge-attempts have been made to upstream without success.
>> 
>> Examples:
>>    - https://gitlab.gnome.org/GNOME/libxml2/-/issues/227
>>    - https://gitlab.gnome.org/GNOME/libxml2/-/merge_requests/8
> 
> I'm reluctant to take a patch that has been rejected upstream,
> especially for a core package such as libxml2.  Porting can be
> time-consuming which delays security updates, and we'll have situations
> where something "works on Guix" but not elsewhere (or vice versa).

I understand.

> 
> Will adding it as a separate package be sufficient?  We could call it
> "xmllint-xpath0" or similar and make it clear that it's just libxml2
> with a patched xmllint in the description.
> 
> Thoughts?

Yes, that would be nice. How about calling it libxml2-xpath0 instead? 
That would maintain libxml2 in the name, letting users know it's just a 
version of the original package and should show up when searching for 
libxml2. If calling it xmllint-xpath0, I feel that the package should 
remove other outputs than just the xmllint binary file, which is perhaps 
a good idea though?

Either option is fine for me.

Best regards,
David

[bug#47898] [PATCH] [core-updates] Add option --xpath0 to xmllint from libxml2

[Marius Bakke]

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david larsson <david.larsson@selfhosted.xyz> skriver:

> On 2021-05-13 14:41, Marius Bakke wrote:
>> david larsson <david.larsson@selfhosted.xyz> skriver:
>> 
>> Will adding it as a separate package be sufficient?  We could call it
>> "xmllint-xpath0" or similar and make it clear that it's just libxml2
>> with a patched xmllint in the description.
>> 
>> Thoughts?
>
> Yes, that would be nice. How about calling it libxml2-xpath0 instead? 
> That would maintain libxml2 in the name, letting users know it's just a 
> version of the original package and should show up when searching for 
> libxml2. If calling it xmllint-xpath0, I feel that the package should 
> remove other outputs than just the xmllint binary file, which is perhaps 
> a good idea though?

libxml2-xpath0 is probably better indeed, I don't have a strong opinion.
Can you send an updated patch?  :-)

Thanks,
Marius

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[bug#47898] [PATCH] [core-updates] Add option --xpath0 to xmllint from libxml2

[david larsson]

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> libxml2-xpath0 is probably better indeed, I don't have a strong 
> opinion.
> Can you send an updated patch?  :-)
> 
> Thanks,
> Marius

Updated patch attached!

Best regards,
David

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From f3f3ff5e1553363a3c46335d418eed314646d38e Mon Sep 17 00:00:00 2001
From: David Larsson <david.larsson@selfhosted.xyz>
Date: Sat, 15 May 2021 11:35:11 +0200
Subject: [PATCH] gnu: libxml2-xpath0: New package with patch for xpath0 option
 to xmllint.

gnu/packages/patches/libxml2-Add-option-xpath0.patch: New file...
gnu/packages/xml.scm (libxml2-xpath0) [source]: ...apply it.
---
 .../patches/libxml2-Add-option-xpath0.patch   | 139 ++++++++++++++++++
 gnu/packages/xml.scm                          |  52 +++++++
 2 files changed, 191 insertions(+)
 create mode 100644 gnu/packages/patches/libxml2-Add-option-xpath0.patch

diff --git a/gnu/packages/patches/libxml2-Add-option-xpath0.patch b/gnu/packages/patches/libxml2-Add-option-xpath0.patch
new file mode 100644
index 0000000000..3337374a8c
--- /dev/null
+++ b/gnu/packages/patches/libxml2-Add-option-xpath0.patch
@@ -0,0 +1,139 @@
+From e1df743329bdfd94fbfdea18303c5c6c6fe13403 Mon Sep 17 00:00:00 2001
+From: methuselah-0 <david.larsson@selfhosted.xyz>
+Date: Thu, 1 Apr 2021 08:33:56 +0200
+Subject: [PATCH] Add option --xpath0
+
+---
+ doc/xmllint.xml | 16 ++++++++++++++++
+ xmllint.c       | 32 +++++++++++++++++++++++---------
+ 2 files changed, 39 insertions(+), 9 deletions(-)
+
+diff --git a/doc/xmllint.xml b/doc/xmllint.xml
+index 1008179b..fcdc237e 100644
+--- a/doc/xmllint.xml
++++ b/doc/xmllint.xml
+@@ -70,6 +70,7 @@
+ 			<arg choice="plain"><option>--debug</option></arg>
+ 			<arg choice="plain"><option>--shell</option></arg>
+ 			<arg choice="plain"><option>--xpath "<replaceable class="option">XPath_expression</replaceable>"</option></arg>
++			<arg choice="plain"><option>--xpath0 "<replaceable class="option">XPath_expression</replaceable>"</option></arg>
+ 			<arg choice="plain"><option>--debugent</option></arg>
+ 			<arg choice="plain"><option>--copy</option></arg>
+ 			<arg choice="plain"><option>--recover</option></arg>
+@@ -537,6 +538,21 @@
+ 			node set is serialized in full in the output. In case
+ 			of an empty node set the "XPath set is empty" result
+ 			will be shown and an error exit code will be returned.
++			Results are separated by the newline character.
++		</para>
++	</listitem>
++		</varlistentry>
++
++		<varlistentry>
++	<term><option>--xpath0 "<replaceable class="option">XPath_expression</replaceable>"</option></term>
++	<listitem>
++		<para>
++			Run an XPath expression given as argument and print the
++			result. In case of a nodeset result, each node in the
++			node set is serialized in full in the output. In case
++			of an empty node set the "XPath set is empty" result
++			will be shown and an error exit code will be returned.
++			Results are separated by the null character.
+ 		</para>
+ 	</listitem>
+ 		</varlistentry>
+diff --git a/xmllint.c b/xmllint.c
+index 6ca1bf54..a60e1f4f 100644
+--- a/xmllint.c
++++ b/xmllint.c
+@@ -194,6 +194,7 @@ static int sax1 = 0;
+ #endif /* LIBXML_SAX1_ENABLED */
+ #ifdef LIBXML_XPATH_ENABLED
+ static const char *xpathquery = NULL;
++static const char *xpathsep = "\n";
+ #endif
+ static int options = XML_PARSE_COMPACT | XML_PARSE_BIG_LINES;
+ static int sax = 0;
+@@ -2095,7 +2096,7 @@ static void doXPathDump(xmlXPathObjectPtr cur) {
+             for (i = 0;i < cur->nodesetval->nodeNr;i++) {
+                 node = cur->nodesetval->nodeTab[i];
+                 xmlNodeDumpOutput(buf, NULL, node, 0, 0, NULL);
+-                xmlOutputBufferWrite(buf, 1, "\n");
++		xmlOutputBufferWrite(buf, 1, xpathsep);
+             }
+             xmlOutputBufferClose(buf);
+ #else
+@@ -2104,27 +2105,27 @@ static void doXPathDump(xmlXPathObjectPtr cur) {
+ 	    break;
+         }
+         case XPATH_BOOLEAN:
+-	    if (cur->boolval) printf("true\n");
+-	    else printf("false\n");
++	    if (cur->boolval) printf("true%s", xpathsep);
++	    else printf("false%s", xpathsep);
+ 	    break;
+         case XPATH_NUMBER:
+ 	    switch (xmlXPathIsInf(cur->floatval)) {
+ 	    case 1:
+-		printf("Infinity\n");
++	        printf("Infinity%s", xpathsep);
+ 		break;
+ 	    case -1:
+-		printf("-Infinity\n");
++	        printf("-Infinity%s", xpathsep);
+ 		break;
+ 	    default:
+ 		if (xmlXPathIsNaN(cur->floatval)) {
+-		    printf("NaN\n");
++		    printf("NaN%s", xpathsep);
+ 		} else {
+-		    printf("%0g\n", cur->floatval);
++		    printf("%0g%s", cur->floatval, xpathsep);
+ 		}
+ 	    }
+ 	    break;
+         case XPATH_STRING:
+-	    printf("%s\n", (const char *) cur->stringval);
++	    printf("%s%s", (const char *) cur->stringval, xpathsep);
+ 	    break;
+         case XPATH_UNDEFINED:
+ 	    fprintf(stderr, "XPath Object is uninitialized\n");
+@@ -3098,7 +3099,8 @@ static void usage(FILE *f, const char *name) {
+     fprintf(f, "\t--sax: do not build a tree but work just at the SAX level\n");
+     fprintf(f, "\t--oldxml10: use XML-1.0 parsing rules before the 5th edition\n");
+ #ifdef LIBXML_XPATH_ENABLED
+-    fprintf(f, "\t--xpath expr: evaluate the XPath expression, imply --noout\n");
++    fprintf(f, "\t--xpath expr: evaluate the XPath expression, results are separated by \\n, imply --noout\n");
++    fprintf(f, "\t--xpath0 expr: evaluate the XPath expression, results are separated by \\0, imply --noout\n");
+ #endif
+ 
+     fprintf(f, "\nLibxml project home page: http://xmlsoft.org/\n");
+@@ -3480,6 +3482,13 @@ main(int argc, char **argv) {
+ 	    i++;
+ 	    noout++;
+ 	    xpathquery = argv[i];
++	    xpathsep = "\n";
++        } else if ((!strcmp(argv[i], "-xpath0")) ||
++                   (!strcmp(argv[i], "--xpath0"))) {
++	    i++;
++	    noout++;
++	    xpathquery = argv[i];
++	    xpathsep = "\0";
+ #endif
+ 	} else if ((!strcmp(argv[i], "-oldxml10")) ||
+ 	           (!strcmp(argv[i], "--oldxml10"))) {
+@@ -3712,6 +3721,11 @@ main(int argc, char **argv) {
+ 	    i++;
+ 	    continue;
+ 	}
++        if ((!strcmp(argv[i], "-xpath0")) ||
++	    (!strcmp(argv[i], "--xpath0"))) {
++	    i++;
++	    continue;
++	}
+ #endif
+ 	if ((timing) && (repeat))
+ 	    startTimer();
+-- 
+2.30.2
+
diff --git a/gnu/packages/xml.scm b/gnu/packages/xml.scm
index 931698a575..12cad65154 100644
--- a/gnu/packages/xml.scm
+++ b/gnu/packages/xml.scm
@@ -167,6 +167,58 @@ binary extension of XML for the purpose of storing and manipulating data in a
 hierarchical form with variable field lengths.")
     (license license:lgpl2.1)))
 
+(define-public libxml2-xpath0
+  (package
+    (name "libxml2-xpath0")
+    (version "2.9.10")
+    (source (origin
+             (method url-fetch)
+             (uri (string-append "ftp://xmlsoft.org/libxml2/libxml2-"
+                                 version ".tar.gz"))
+             (sha256
+              (base32
+               "07xynh8hcxb2yb1fs051xrgszjvj37wnxvxgsj10rzmqzy9y3zma"))
+             (patches (list (search-patch "libxml2-Add-option-xpath0.patch")))))
+    (build-system gnu-build-system)
+    (outputs '("out" "static"))
+    (arguments
+     `(#:phases (modify-phases %standard-phases
+                  (add-after 'install 'move-static-libs
+                    (lambda* (#:key outputs #:allow-other-keys)
+                      (let ((src (string-append (assoc-ref outputs "out") "/lib"))
+                            (dst (string-append (assoc-ref outputs "static")
+                                                "/lib")))
+                        (mkdir-p dst)
+                        (for-each (lambda (ar)
+                                    (rename-file ar (string-append dst "/"
+                                                                   (basename ar))))
+                                  (find-files src "\\.a$"))
+
+                        ;; Remove reference to the static library from the .la
+                        ;; file such that Libtool does the right thing when both
+                        ;; the shared and static variants are available.
+                        (substitute* (string-append src "/libxml2.la")
+                          (("^old_library='libxml2.a'") "old_library=''"))
+                        #t))))))
+    (home-page "http://www.xmlsoft.org/")
+    (synopsis "C parser for XML")
+    (inputs `(("xz" ,xz)))
+    (propagated-inputs `(("zlib" ,zlib))) ; libxml2.la says '-lz'.
+    (native-inputs `(("perl" ,perl)))
+    ;; $XML_CATALOG_FILES lists 'catalog.xml' files found in under the 'xml'
+    ;; sub-directory of any given package.
+    (native-search-paths (list (search-path-specification
+                                (variable "XML_CATALOG_FILES")
+                                (separator " ")
+                                (files '("xml"))
+                                (file-pattern "^catalog\\.xml$")
+                                (file-type 'regular))))
+    (search-paths native-search-paths)
+    (description
+     "Libxml2 is the XML C parser and toolkit developed for the Gnome
+project (but it is usable outside of the Gnome platform).")
+    (license license:x11)))
+
 (define-public libxml2
   (package
     (name "libxml2")
-- 
2.31.0

[bug#47898] [PATCH] [core-updates] Add option --xpath0 to xmllint from libxml2

[Marius Bakke]

[-- Attachment #1: Type: text/plain, Size: 1988 bytes --]

david larsson <david.larsson@selfhosted.xyz> skriver:

>> libxml2-xpath0 is probably better indeed, I don't have a strong 
>> opinion.
>> Can you send an updated patch?  :-)
>> 
>> Thanks,
>> Marius
>
> Updated patch attached!

Thanks!

[...]

> gnu/packages/patches/libxml2-Add-option-xpath0.patch: New file...
> gnu/packages/xml.scm (libxml2-xpath0) [source]: ...apply it.
> ---
>  .../patches/libxml2-Add-option-xpath0.patch   | 139 ++++++++++++++++++
>  gnu/packages/xml.scm                          |  52 +++++++
>  2 files changed, 191 insertions(+)
>  create mode 100644 gnu/packages/patches/libxml2-Add-option-xpath0.patch

Please also register this patch in gnu/local.mk.  Can you also add your
copyright at the top of xml.scm?

[...]

> +(define-public libxml2-xpath0
> +  (package
> +    (name "libxml2-xpath0")
> +    (version "2.9.10")
> +    (source (origin
> +             (method url-fetch)
> +             (uri (string-append "ftp://xmlsoft.org/libxml2/libxml2-"
> +                                 version ".tar.gz"))
> +             (sha256
> +              (base32
> +               "07xynh8hcxb2yb1fs051xrgszjvj37wnxvxgsj10rzmqzy9y3zma"))
> +             (patches (list (search-patch "libxml2-Add-option-xpath0.patch")))))

You can inherit another record in Scheme to avoid duplicating all the
fields.  Then the package can be shortened to:

  (define-public libxml2-xpath0
    (package/inherit libxml2
      (name "libxml2-xpath0")
      (source (origin
                (inherit (package-source libxml2))
                (patches (append (search-patches "libxml2-Add-option-xpath0.patch")
                                 (origin-patches (package-source libxml2))))))
      (description
       "...")))

We should fill out that description to mention how it differs from the
regular libxml2.  Can you give it a try?  I can make the other changes
on your behalf, but not sure what to write.

Thanks,
Marius

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[bug#47898] [PATCH] [core-updates] Add option --xpath0 to xmllint from libxml2

[david larsson]

On 2021-05-15 18:12, Marius Bakke wrote:
> david larsson <david.larsson@selfhosted.xyz> skriver:
> 
>>> libxml2-xpath0 is probably better indeed, I don't have a strong
>>> opinion.
>>> Can you send an updated patch?  :-)
>>> 
>>> Thanks,
>>> Marius
>> 
>> Updated patch attached!
> 
> Thanks!
> 
> [...]
> 
>> gnu/packages/patches/libxml2-Add-option-xpath0.patch: New file...
>> gnu/packages/xml.scm (libxml2-xpath0) [source]: ...apply it.
>> ---
>>  .../patches/libxml2-Add-option-xpath0.patch   | 139 
>> ++++++++++++++++++
>>  gnu/packages/xml.scm                          |  52 +++++++
>>  2 files changed, 191 insertions(+)
>>  create mode 100644 
>> gnu/packages/patches/libxml2-Add-option-xpath0.patch
> 
> Please also register this patch in gnu/local.mk.  Can you also add your
> copyright at the top of xml.scm?
> 
> [...]
> 
>> +(define-public libxml2-xpath0
>> +  (package
>> +    (name "libxml2-xpath0")
>> +    (version "2.9.10")
>> +    (source (origin
>> +             (method url-fetch)
>> +             (uri (string-append "ftp://xmlsoft.org/libxml2/libxml2-"
>> +                                 version ".tar.gz"))
>> +             (sha256
>> +              (base32
>> +               
>> "07xynh8hcxb2yb1fs051xrgszjvj37wnxvxgsj10rzmqzy9y3zma"))
>> +             (patches (list (search-patch 
>> "libxml2-Add-option-xpath0.patch")))))
> 
> You can inherit another record in Scheme to avoid duplicating all the
> fields.  Then the package can be shortened to:
> 
>   (define-public libxml2-xpath0
>     (package/inherit libxml2
>       (name "libxml2-xpath0")
>       (source (origin
>                 (inherit (package-source libxml2))
>                 (patches (append (search-patches
> "libxml2-Add-option-xpath0.patch")
>                                  (origin-patches (package-source 
> libxml2))))))
>       (description
>        "...")))
> 
> We should fill out that description to mention how it differs from the
> regular libxml2.  Can you give it a try?  I can make the other changes
> on your behalf, but not sure what to write.
> 
> Thanks,
> Marius

I can fix all of it and send an updated patch again.

Best regards,
David

[bug#47898] [PATCH] [core-updates] Add option --xpath0 to xmllint from libxml2

[david larsson]

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> Please also register this patch in gnu/local.mk.  Can you also add your
> copyright at the top of xml.scm?

Done!

> 
> [...]
> 
>> +(define-public libxml2-xpath0
>> +  (package
>> +    (name "libxml2-xpath0")
>> +    (version "2.9.10")
>> +    (source (origin
>> +             (method url-fetch)
>> +             (uri (string-append "ftp://xmlsoft.org/libxml2/libxml2-"
>> +                                 version ".tar.gz"))
>> +             (sha256
>> +              (base32
>> +               
>> "07xynh8hcxb2yb1fs051xrgszjvj37wnxvxgsj10rzmqzy9y3zma"))
>> +             (patches (list (search-patch 
>> "libxml2-Add-option-xpath0.patch")))))
> 
> You can inherit another record in Scheme to avoid duplicating all the
> fields.  Then the package can be shortened to:
> 
>   (define-public libxml2-xpath0
>     (package/inherit libxml2
>       (name "libxml2-xpath0")
>       (source (origin
>                 (inherit (package-source libxml2))
>                 (patches (append (search-patches
> "libxml2-Add-option-xpath0.patch")
>                                  (origin-patches (package-source 
> libxml2))))))
>       (description
>        "...")))
> 
> We should fill out that description to mention how it differs from the
> regular libxml2.  Can you give it a try?  I can make the other changes
> on your behalf, but not sure what to write.
> 
> Thanks,
> Marius

Hi, new patch attached. There's a lint warning though: 
"libxml2-xpath0@2.9.10: no updater for libxml2-xpath0". I don't know 
what it means, maybe it should be fixed before committing?

Best regards,
David

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From 70c7a419f060256795737a7dc7122bfbcd456ae6 Mon Sep 17 00:00:00 2001
From: David Larsson <david.larsson@selfhosted.xyz>
Date: Sat, 15 May 2021 20:52:50 +0200
Subject: [PATCH] gnu: libxml2-xpath0: New package with patch for xpath0 option
 to xmllint.

* gnu/packages/patches/libxml2-xpath0-Add-option-xpath0.patch: New file...
* gnu/local.mk: register it.
* gnu/packages/xml.scm (libxml2-xpath0) [source]: ...apply it.
---
 gnu/local.mk                                  |   1 +
 .../libxml2-xpath0-Add-option-xpath0.patch    | 139 ++++++++++++++++++
 gnu/packages/xml.scm                          |  14 ++
 3 files changed, 154 insertions(+)
 create mode 100644 gnu/packages/patches/libxml2-xpath0-Add-option-xpath0.patch

diff --git a/gnu/local.mk b/gnu/local.mk
index c3b0274945..d3e8baf17e 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1366,6 +1366,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/libutils-remove-damaging-includes.patch	\
   %D%/packages/patches/libvdpau-va-gl-unbundle.patch		\
   %D%/packages/patches/libvpx-CVE-2016-2818.patch		\
+  %D%/packages/patches/libxml2-xpath0-Add-option-xpath0.patch	\
   %D%/packages/patches/libxslt-generated-ids.patch		\
   %D%/packages/patches/libxt-guix-search-paths.patch		\
   %D%/packages/patches/lierolibre-check-unaligned-access.patch	\
diff --git a/gnu/packages/patches/libxml2-xpath0-Add-option-xpath0.patch b/gnu/packages/patches/libxml2-xpath0-Add-option-xpath0.patch
new file mode 100644
index 0000000000..3337374a8c
--- /dev/null
+++ b/gnu/packages/patches/libxml2-xpath0-Add-option-xpath0.patch
@@ -0,0 +1,139 @@
+From e1df743329bdfd94fbfdea18303c5c6c6fe13403 Mon Sep 17 00:00:00 2001
+From: methuselah-0 <david.larsson@selfhosted.xyz>
+Date: Thu, 1 Apr 2021 08:33:56 +0200
+Subject: [PATCH] Add option --xpath0
+
+---
+ doc/xmllint.xml | 16 ++++++++++++++++
+ xmllint.c       | 32 +++++++++++++++++++++++---------
+ 2 files changed, 39 insertions(+), 9 deletions(-)
+
+diff --git a/doc/xmllint.xml b/doc/xmllint.xml
+index 1008179b..fcdc237e 100644
+--- a/doc/xmllint.xml
++++ b/doc/xmllint.xml
+@@ -70,6 +70,7 @@
+ 			<arg choice="plain"><option>--debug</option></arg>
+ 			<arg choice="plain"><option>--shell</option></arg>
+ 			<arg choice="plain"><option>--xpath "<replaceable class="option">XPath_expression</replaceable>"</option></arg>
++			<arg choice="plain"><option>--xpath0 "<replaceable class="option">XPath_expression</replaceable>"</option></arg>
+ 			<arg choice="plain"><option>--debugent</option></arg>
+ 			<arg choice="plain"><option>--copy</option></arg>
+ 			<arg choice="plain"><option>--recover</option></arg>
+@@ -537,6 +538,21 @@
+ 			node set is serialized in full in the output. In case
+ 			of an empty node set the "XPath set is empty" result
+ 			will be shown and an error exit code will be returned.
++			Results are separated by the newline character.
++		</para>
++	</listitem>
++		</varlistentry>
++
++		<varlistentry>
++	<term><option>--xpath0 "<replaceable class="option">XPath_expression</replaceable>"</option></term>
++	<listitem>
++		<para>
++			Run an XPath expression given as argument and print the
++			result. In case of a nodeset result, each node in the
++			node set is serialized in full in the output. In case
++			of an empty node set the "XPath set is empty" result
++			will be shown and an error exit code will be returned.
++			Results are separated by the null character.
+ 		</para>
+ 	</listitem>
+ 		</varlistentry>
+diff --git a/xmllint.c b/xmllint.c
+index 6ca1bf54..a60e1f4f 100644
+--- a/xmllint.c
++++ b/xmllint.c
+@@ -194,6 +194,7 @@ static int sax1 = 0;
+ #endif /* LIBXML_SAX1_ENABLED */
+ #ifdef LIBXML_XPATH_ENABLED
+ static const char *xpathquery = NULL;
++static const char *xpathsep = "\n";
+ #endif
+ static int options = XML_PARSE_COMPACT | XML_PARSE_BIG_LINES;
+ static int sax = 0;
+@@ -2095,7 +2096,7 @@ static void doXPathDump(xmlXPathObjectPtr cur) {
+             for (i = 0;i < cur->nodesetval->nodeNr;i++) {
+                 node = cur->nodesetval->nodeTab[i];
+                 xmlNodeDumpOutput(buf, NULL, node, 0, 0, NULL);
+-                xmlOutputBufferWrite(buf, 1, "\n");
++		xmlOutputBufferWrite(buf, 1, xpathsep);
+             }
+             xmlOutputBufferClose(buf);
+ #else
+@@ -2104,27 +2105,27 @@ static void doXPathDump(xmlXPathObjectPtr cur) {
+ 	    break;
+         }
+         case XPATH_BOOLEAN:
+-	    if (cur->boolval) printf("true\n");
+-	    else printf("false\n");
++	    if (cur->boolval) printf("true%s", xpathsep);
++	    else printf("false%s", xpathsep);
+ 	    break;
+         case XPATH_NUMBER:
+ 	    switch (xmlXPathIsInf(cur->floatval)) {
+ 	    case 1:
+-		printf("Infinity\n");
++	        printf("Infinity%s", xpathsep);
+ 		break;
+ 	    case -1:
+-		printf("-Infinity\n");
++	        printf("-Infinity%s", xpathsep);
+ 		break;
+ 	    default:
+ 		if (xmlXPathIsNaN(cur->floatval)) {
+-		    printf("NaN\n");
++		    printf("NaN%s", xpathsep);
+ 		} else {
+-		    printf("%0g\n", cur->floatval);
++		    printf("%0g%s", cur->floatval, xpathsep);
+ 		}
+ 	    }
+ 	    break;
+         case XPATH_STRING:
+-	    printf("%s\n", (const char *) cur->stringval);
++	    printf("%s%s", (const char *) cur->stringval, xpathsep);
+ 	    break;
+         case XPATH_UNDEFINED:
+ 	    fprintf(stderr, "XPath Object is uninitialized\n");
+@@ -3098,7 +3099,8 @@ static void usage(FILE *f, const char *name) {
+     fprintf(f, "\t--sax: do not build a tree but work just at the SAX level\n");
+     fprintf(f, "\t--oldxml10: use XML-1.0 parsing rules before the 5th edition\n");
+ #ifdef LIBXML_XPATH_ENABLED
+-    fprintf(f, "\t--xpath expr: evaluate the XPath expression, imply --noout\n");
++    fprintf(f, "\t--xpath expr: evaluate the XPath expression, results are separated by \\n, imply --noout\n");
++    fprintf(f, "\t--xpath0 expr: evaluate the XPath expression, results are separated by \\0, imply --noout\n");
+ #endif
+ 
+     fprintf(f, "\nLibxml project home page: http://xmlsoft.org/\n");
+@@ -3480,6 +3482,13 @@ main(int argc, char **argv) {
+ 	    i++;
+ 	    noout++;
+ 	    xpathquery = argv[i];
++	    xpathsep = "\n";
++        } else if ((!strcmp(argv[i], "-xpath0")) ||
++                   (!strcmp(argv[i], "--xpath0"))) {
++	    i++;
++	    noout++;
++	    xpathquery = argv[i];
++	    xpathsep = "\0";
+ #endif
+ 	} else if ((!strcmp(argv[i], "-oldxml10")) ||
+ 	           (!strcmp(argv[i], "--oldxml10"))) {
+@@ -3712,6 +3721,11 @@ main(int argc, char **argv) {
+ 	    i++;
+ 	    continue;
+ 	}
++        if ((!strcmp(argv[i], "-xpath0")) ||
++	    (!strcmp(argv[i], "--xpath0"))) {
++	    i++;
++	    continue;
++	}
+ #endif
+ 	if ((timing) && (repeat))
+ 	    startTimer();
+-- 
+2.30.2
+
diff --git a/gnu/packages/xml.scm b/gnu/packages/xml.scm
index 931698a575..28601f0d09 100644
--- a/gnu/packages/xml.scm
+++ b/gnu/packages/xml.scm
@@ -31,6 +31,7 @@
 ;;; Copyright © 2021 Julien Lepiller <julien@lepiller.eu>
 ;;; Copyright © 2021 Felix Gruber <felgru@posteo.net>
 ;;; Copyright © 2021 Guillaume Le Vaillant <glv@posteo.net>
+;;; Copyright © 2021 David Larsson <david.larsson@selfhosted.xyz>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -218,6 +219,19 @@ hierarchical form with variable field lengths.")
 project (but it is usable outside of the Gnome platform).")
     (license license:x11)))
 
+(define-public libxml2-xpath0
+  (package/inherit libxml2
+    (name "libxml2-xpath0")
+    (source (origin
+              (inherit (package-source libxml2))
+              (patches (append (search-patches
+                                "libxml2-xpath0-Add-option-xpath0.patch")
+                               (origin-patches (package-source libxml2))))))
+    (description
+     "Libxml2-xpath0 is like libxml2 but with a patch applied that
+provides an --xpath0 option to xmllint that enables it to output xpath
+results with a null delimiter")))
+
 (define-public libxlsxwriter
   (package
     (name "libxlsxwriter")
-- 
2.31.0

bug#47898: [PATCH] [core-updates] Add option --xpath0 to xmllint from libxml2

[Marius Bakke]

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david larsson <david.larsson@selfhosted.xyz> skriver:

> Hi, new patch attached. There's a lint warning though: 
> "libxml2-xpath0@2.9.10: no updater for libxml2-xpath0". I don't know 
> what it means, maybe it should be fixed before committing?

That warning is harmless and affects a lot of packages.  I've applied
the patch with a couple minor tweaks:

> +From e1df743329bdfd94fbfdea18303c5c6c6fe13403 Mon Sep 17 00:00:00 2001
> +From: methuselah-0 <david.larsson@selfhosted.xyz>
> +Date: Thu, 1 Apr 2021 08:33:56 +0200
> +Subject: [PATCH] Add option --xpath0
> +
> +---
> + doc/xmllint.xml | 16 ++++++++++++++++
> + xmllint.c       | 32 +++++++++++++++++++++++---------
> + 2 files changed, 39 insertions(+), 9 deletions(-)

I replaced this git-style patch header with a short description and an
URL to the upstream issue, like we usually do.

> +(define-public libxml2-xpath0
> +  (package/inherit libxml2
> +    (name "libxml2-xpath0")
> +    (source (origin
> +              (inherit (package-source libxml2))
> +              (patches (append (search-patches
> +                                "libxml2-xpath0-Add-option-xpath0.patch")
> +                               (origin-patches (package-source libxml2))))))
> +    (description
> +     "Libxml2-xpath0 is like libxml2 but with a patch applied that
> +provides an --xpath0 option to xmllint that enables it to output xpath
> +results with a null delimiter")))

...and sprinkled some markup and punctuation into the description.

Pushed as b58efbc6611550ad9234163e198ff71ace5306ea, thank you!

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