hash: provide hash_xinitialize

hash: provide hash_xinitialize

[Akim Demaille]

Hi Jim,

Recently in Bison I had to check all my calls to hash_initialize for memory exhaustion.  Coreutils do it by hand for some of the calls, but we could just as well provide a simple wrapper?

commit 73f0aa2e58b1dabbe075ab6bf5644da36d7c72d2
Author: Akim Demaille <akim.demaille@gmail.com>
Date:   Mon Sep 9 08:31:33 2019 +0200

    hash: provide hash_xinitialize.
    
    Suggested by Egor Pugin <egor.pugin@gmail.com>
    https://lists.gnu.org/archive/html/bison-patches/2019-09/msg00026.html
    
    * modules/hash (Depends-on): Add xalloc.
    * lib/hash.h, lib/hash.c (hash_xinitialize): New.

diff --git a/ChangeLog b/ChangeLog
index 5c226ce43..ca12b170b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2019-09-09  Akim Demaille  <akim@lrde.epita.fr>
+
+	hash: provide hash_xinitialize.
+	Suggested by Egor Pugin <egor.pugin@gmail.com>
+	https://lists.gnu.org/archive/html/bison-patches/2019-09/msg00026.html
+	* modules/hash (Depends-on): Add xalloc.
+	* lib/hash.h, lib/hash.c (hash_xinitialize): New.
+
 2019-09-06  Akim Demaille  <akim@lrde.epita.fr>
 
 	bitset: style changes
diff --git a/lib/hash.c b/lib/hash.c
index 9e1f8e841..ca1d04044 100644
--- a/lib/hash.c
+++ b/lib/hash.c
@@ -27,6 +27,7 @@
 #include "hash.h"
 
 #include "bitrotate.h"
+#include "xalloc.h"
 #include "xalloc-oversized.h"
 
 #include <stdint.h>
@@ -645,6 +646,22 @@ hash_initialize (size_t candidate, const Hash_tuning *tuning,
   return NULL;
 }
 
+
+/* Same as hash_initialize, but invokes xalloc_die on memory
+   exhaustion.  */
+
+Hash_table *
+hash_xinitialize (size_t candidate, const Hash_tuning *tuning,
+                  Hash_hasher hasher, Hash_comparator comparator,
+                  Hash_data_freer data_freer)
+{
+  Hash_table *res =
+    hash_initialize (candidate, tuning, hasher, comparator, data_freer);
+  if (!res)
+    xalloc_die ();
+  return res;
+}
+
 /* Make all buckets empty, placing any chained entries on the free list.
    Apply the user-specified function data_freer (if any) to the datas of any
    affected entries.  */
diff --git a/lib/hash.h b/lib/hash.h
index a1a483a35..8f2e4591f 100644
--- a/lib/hash.h
+++ b/lib/hash.h
@@ -89,6 +89,9 @@ void hash_reset_tuning (Hash_tuning *);
 Hash_table *hash_initialize (size_t, const Hash_tuning *,
                              Hash_hasher, Hash_comparator,
                              Hash_data_freer) _GL_ATTRIBUTE_WUR;
+Hash_table *hash_xinitialize (size_t, const Hash_tuning *,
+                              Hash_hasher, Hash_comparator,
+                              Hash_data_freer) _GL_ATTRIBUTE_WUR;
 void hash_clear (Hash_table *);
 void hash_free (Hash_table *);
 
diff --git a/modules/hash b/modules/hash
index 42502e749..31303c1a8 100644
--- a/modules/hash
+++ b/modules/hash
@@ -9,6 +9,7 @@ Depends-on:
 bitrotate
 stdbool
 stdint
+xalloc
 xalloc-oversized
 
 configure.ac:

Re: hash: provide hash_xinitialize

[Bruno Haible]

Hi Akim,

>     * modules/hash (Depends-on): Add xalloc.
>     * lib/hash.h, lib/hash.c (hash_xinitialize): New.

This patch produces gnulib-tool warnings:

$ ./gnulib-tool --test hash
gnulib-tool: warning: module hash depends on a module with an incompatible license: error
gnulib-tool: warning: module hash depends on a module with an incompatible license: getprogname
gnulib-tool: warning: module hash depends on a module with an incompatible license: xalloc
gnulib-tool: warning: module hash depends on a module with an incompatible license: xalloc-die
...

What gnulib-tool is telling you is that the module 'hash' has a license
that makes it suitable for use in libraries. Adding a dependency to 'xalloc'
to it can't be done in this module, because library code should never
call xalloc_die().

The fix is to create a new module, with prefix 'x', that adds the
function. You can leave it declared in hash.h; this is not a problem.
But it needs to be defined in a different compilation unit.

For a model of this idiom, look at the modules 'concat-filename'
and 'xconcat-filename'.

Bruno

Re: hash: provide hash_xinitialize

[Akim Demaille]

> Le 9 sept. 2019 à 16:05, Bruno Haible <bruno@clisp.org> a écrit :
> 
> Hi Akim,

Hi!

>>    * modules/hash (Depends-on): Add xalloc.
>>    * lib/hash.h, lib/hash.c (hash_xinitialize): New.
> 
> This patch produces gnulib-tool warnings:
> 
> $ ./gnulib-tool --test hash
> gnulib-tool: warning: module hash depends on a module with an incompatible license: error
> gnulib-tool: warning: module hash depends on a module with an incompatible license: getprogname
> gnulib-tool: warning: module hash depends on a module with an incompatible license: xalloc
> gnulib-tool: warning: module hash depends on a module with an incompatible license: xalloc-die
> ...
> 
> What gnulib-tool is telling you is that the module 'hash' has a license
> that makes it suitable for use in libraries. Adding a dependency to 'xalloc'
> to it can't be done in this module, because library code should never
> call xalloc_die().

Wow!  Nice feature!

Note that the hash module claims LGPLv2+, but the header of hash.[ch] is about GPLv3+.

> The fix is to create a new module, with prefix 'x', that adds the
> function. You can leave it declared in hash.h; this is not a problem.
> But it needs to be defined in a different compilation unit.
> 
> For a model of this idiom, look at the modules 'concat-filename'
> and 'xconcat-filename'.


Thanks for the hint; below is my updated proposal (which passes its test :).  I see that xconcat-filename is about xconcat_filename; I stayed with hash_initialize instead of xhash_initialize, but I can change that, of course.  Also, contrary to the case of xconcat-filename, I have not put hash.h in the Files of xhash, because I see hash.h as a part of hash, not xhash.  And I shamelessly decided to put the maintenance burden on Jim's shoulders.


commit 734cd738f062ccbc53126d593e5ae977d77d6ee6
Author: Akim Demaille <akim.demaille@gmail.com>
Date:   Mon Sep 9 08:31:33 2019 +0200

    xhash: provide hash_xinitialize
    
    Suggested by Egor Pugin <egor.pugin@gmail.com>
    https://lists.gnu.org/archive/html/bison-patches/2019-09/msg00026.html
    
    * modules/xhash, lib/xhash.c: New.
    * lib/hash.h (hash_xinitialize): New.

diff --git a/ChangeLog b/ChangeLog
index 5c226ce43..6969156e3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2019-09-09  Akim Demaille  <akim@lrde.epita.fr>
+
+	xhash: provide hash_xinitialize.
+	Suggested by Egor Pugin <egor.pugin@gmail.com>
+	https://lists.gnu.org/archive/html/bison-patches/2019-09/msg00026.html
+	* modules/xhash, lib/xhash.c: New.
+	* lib/hash.h (hash_xinitialize): New.
+
 2019-09-06  Akim Demaille  <akim@lrde.epita.fr>
 
 	bitset: style changes
diff --git a/lib/hash.h b/lib/hash.h
index a1a483a35..8f2e4591f 100644
--- a/lib/hash.h
+++ b/lib/hash.h
@@ -89,6 +89,9 @@ void hash_reset_tuning (Hash_tuning *);
 Hash_table *hash_initialize (size_t, const Hash_tuning *,
                              Hash_hasher, Hash_comparator,
                              Hash_data_freer) _GL_ATTRIBUTE_WUR;
+Hash_table *hash_xinitialize (size_t, const Hash_tuning *,
+                              Hash_hasher, Hash_comparator,
+                              Hash_data_freer) _GL_ATTRIBUTE_WUR;
 void hash_clear (Hash_table *);
 void hash_free (Hash_table *);
 
diff --git a/lib/xhash.c b/lib/xhash.c
new file mode 100644
index 000000000..9b2bcdbb4
--- /dev/null
+++ b/lib/xhash.c
@@ -0,0 +1,38 @@
+/* hash - hashing table processing.
+
+   Copyright (C) 2019 Free Software Foundation, Inc.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include "hash.h"
+
+#include "xalloc.h"
+
+/* Same as hash_initialize, but invokes xalloc_die on memory
+   exhaustion.  */
+
+Hash_table *
+hash_xinitialize (size_t candidate, const Hash_tuning *tuning,
+                  Hash_hasher hasher, Hash_comparator comparator,
+                  Hash_data_freer data_freer)
+{
+  Hash_table *res =
+    hash_initialize (candidate, tuning, hasher, comparator, data_freer);
+  if (!res)
+    xalloc_die ();
+  return res;
+}
diff --git a/modules/xhash b/modules/xhash
new file mode 100644
index 000000000..2e74c718f
--- /dev/null
+++ b/modules/xhash
@@ -0,0 +1,23 @@
+Description:
+Parameterizable hash table, with out-of-memory checking.
+
+Files:
+lib/xhash.c
+
+Depends-on:
+hash
+xalloc
+
+configure.ac:
+
+Makefile.am:
+lib_SOURCES += xhash.c
+
+Include:
+"hash.h"
+
+License:
+GPLv3+
+
+Maintainer:
+Jim Meyering

Re: hash: provide hash_xinitialize

[Bruno Haible]

Hi Akim,

> Note that the hash module claims LGPLv2+, but the header of hash.[ch] is about GPLv3+.

This is explained here:
https://www.gnu.org/software/gnulib/manual/html_node/Gnulib-licensing.html

The gnulib-tool option --lgpl=2 will put LGPLv2+ headers on the files, for
people who use the modules to build an LGPLv2+ package.

> Thanks for the hint; below is my updated proposal (which passes its test :).

Looks perfect.

> Also, contrary to the case of xconcat-filename, I have not put hash.h in the
> Files of xhash, because I see hash.h as a part of hash, not xhash.

Either way is fine.

> And I shamelessly decided to put the maintenance burden on Jim's shoulders.

Don't be shy :)

Bruno

Re: hash: provide hash_xinitialize

[Jim Meyering]

On Mon, Sep 9, 2019 at 12:16 PM Bruno Haible <bruno@clisp.org> wrote:
...
> > And I shamelessly decided to put the maintenance burden on Jim's shoulders.
>
> Don't be shy :)

Indeed. Feel free to add your name.
Thank you both for the addition and improvements.