[PATCH 1/2] hash, mgetgroups: drop xalloc dependency

[Eric Blake]

Merely including xalloc.h can drag in some unwanted link
dependencies on some platforms.  safe-alloc.c is already
one example of a file that broke the cycle by duplicating
the xalloc_oversized macro.

* lib/hash.c (hash_oversized): Copy from xalloc.h.
* lib/mgetgroups.c (mgetgroups_oversized): Likewise.
(xgetgroups): Move...
* lib/xgetgroups.c: ...to new file.
* modules/xgetgroups: New file, split from...
* modules/mgetgroups: ...here.
* modules/hash (Depends-on): Drop xalloc.

Signed-off-by: Eric Blake <address@hidden>
---

Perhaps an alternate approach would be to list just Files: of
xalloc.h, along with a preprocessor macro that a .c file can
define to get just the xalloc_oversized macro without also
getting the inline definitions of functions that pull in a
link dependency on xalloc_die.

 ChangeLog          |    9 +++++++++
 lib/hash.c         |   21 +++++++++++++++++++--
 lib/mgetgroups.c   |   33 ++++++++++++++++++++-------------
 lib/xgetgroups.c   |   37 +++++++++++++++++++++++++++++++++++++
 modules/hash       |    3 +--
 modules/mgetgroups |    1 -
 modules/xgetgroups |   24 ++++++++++++++++++++++++
 7 files changed, 110 insertions(+), 18 deletions(-)
 create mode 100644 lib/xgetgroups.c
 create mode 100644 modules/xgetgroups

diff --git a/ChangeLog b/ChangeLog
index c75e8f4..a610358 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,14 @@
 2011-04-26  Eric Blake  <address@hidden>

+       hash, mgetgroups: drop xalloc dependency
+       * lib/hash.c (hash_oversized): Copy from xalloc.h.
+       * lib/mgetgroups.c (mgetgroups_oversized): Likewise.
+       (xgetgroups): Move...
+       * lib/xgetgroups.c: ...to new file.
+       * modules/xgetgroups: New file, split from...
+       * modules/mgetgroups: ...here.
+       * modules/hash (Depends-on): Drop xalloc.
+
        fchdir: avoid extra chdir and fix test
        * modules/fchdir (Depends-on): Add dosname, filenamecat-lgpl,
        getcwd-lgpl.
diff --git a/lib/hash.c b/lib/hash.c
index f3de2aa..1efdb6c 100644
--- a/lib/hash.c
+++ b/lib/hash.c
@@ -27,7 +27,6 @@
 #include "hash.h"

 #include "bitrotate.h"
-#include "xalloc.h"

 #include <stdint.h>
 #include <stdio.h>
@@ -43,6 +42,24 @@
 # endif
 #endif

+/* Return 1 if an array of N objects, each of size S, cannot exist due
+   to size arithmetic overflow.  S must be positive and N must be
+   nonnegative.  This is a macro, not an inline function, so that it
+   works correctly even when SIZE_MAX < N.
+
+   By gnulib convention, SIZE_MAX represents overflow in size
+   calculations, so the conservative dividend to use here is
+   SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value.
+   However, malloc (SIZE_MAX) fails on all known hosts where
+   sizeof (ptrdiff_t) <= sizeof (size_t), so do not bother to test for
+   exactly-SIZE_MAX allocations on such hosts; this avoids a test and
+   branch when S is known to be 1.
+
+   This is the same as xalloc_oversized from xalloc.h
+*/
+#define hash_oversized(n, s)                                            \
+  ((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n))
+
 struct hash_entry
   {
     void *data;
@@ -551,7 +568,7 @@ compute_bucket_size (size_t candidate, const Hash_tuning 
*tuning)
       candidate = new_candidate;
     }
   candidate = next_prime (candidate);
-  if (xalloc_oversized (candidate, sizeof (struct hash_entry *)))
+  if (hash_oversized (candidate, sizeof (struct hash_entry *)))
     return 0;
   return candidate;
 }
diff --git a/lib/mgetgroups.c b/lib/mgetgroups.c
index 5c79915..77ab542 100644
--- a/lib/mgetgroups.c
+++ b/lib/mgetgroups.c
@@ -31,12 +31,30 @@
 #endif

 #include "getugroups.h"
-#include "xalloc.h"
+
+/* Return 1 if an array of N objects, each of size S, cannot exist due
+   to size arithmetic overflow.  S must be positive and N must be
+   nonnegative.  This is a macro, not an inline function, so that it
+   works correctly even when SIZE_MAX < N.
+
+   By gnulib convention, SIZE_MAX represents overflow in size
+   calculations, so the conservative dividend to use here is
+   SIZE_MAX - 1, since SIZE_MAX might represent an overflowed value.
+   However, malloc (SIZE_MAX) fails on all known hosts where
+   sizeof (ptrdiff_t) <= sizeof (size_t), so do not bother to test for
+   exactly-SIZE_MAX allocations on such hosts; this avoids a test and
+   branch when S is known to be 1.
+
+   This is the same as xalloc_oversized from xalloc.h
+*/
+#define mgetgroups_oversized(n, s)                                      \
+  ((size_t) (sizeof (ptrdiff_t) <= sizeof (size_t) ? -1 : -2) / (s) < (n))
+

 static gid_t *
 realloc_groupbuf (gid_t *g, size_t num)
 {
-  if (xalloc_oversized (num, sizeof *g))
+  if (mgetgroups_oversized (num, sizeof *g))
     {
       errno = ENOMEM;
       return NULL;
@@ -193,14 +211,3 @@ mgetgroups (char const *username, gid_t gid, gid_t 
**groups)

   return ng;
 }
-
-/* Like mgetgroups, but call xalloc_die on allocation failure.  */
-
-int
-xgetgroups (char const *username, gid_t gid, gid_t **groups)
-{
-  int result = mgetgroups (username, gid, groups);
-  if (result == -1 && errno == ENOMEM)
-    xalloc_die ();
-  return result;
-}
diff --git a/lib/xgetgroups.c b/lib/xgetgroups.c
new file mode 100644
index 0000000..41886c9
--- /dev/null
+++ b/lib/xgetgroups.c
@@ -0,0 +1,37 @@
+/* xgetgroups.c -- return a list of the groups a user or current process is in
+
+   Copyright (C) 2007-2011 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 <http://www.gnu.org/licenses/>.  */
+
+/* Extracted from coreutils' src/id.c. */
+
+#include <config.h>
+
+#include "mgetgroups.h"
+
+#include <errno.h>
+
+#include "xalloc.h"
+
+/* Like mgetgroups, but call xalloc_die on allocation failure.  */
+
+int
+xgetgroups (char const *username, gid_t gid, gid_t **groups)
+{
+  int result = mgetgroups (username, gid, groups);
+  if (result == -1 && errno == ENOMEM)
+    xalloc_die ();
+  return result;
+}
diff --git a/modules/hash b/modules/hash
index 75a99da..6ebca01 100644
--- a/modules/hash
+++ b/modules/hash
@@ -1,5 +1,5 @@
 Description:
-Parametrizable hash table.
+Parameterizable hash table.

 Files:
 lib/hash.c
@@ -10,7 +10,6 @@ Depends-on:
 bitrotate
 stdbool
 stdint
-xalloc

 configure.ac:
 gl_HASH
diff --git a/modules/mgetgroups b/modules/mgetgroups
index c404d01..eeb525c 100644
--- a/modules/mgetgroups
+++ b/modules/mgetgroups
@@ -10,7 +10,6 @@ Depends-on:
 getgroups
 getugroups
 realloc-gnu
-xalloc

 configure.ac:
 gl_MGETGROUPS
diff --git a/modules/xgetgroups b/modules/xgetgroups
new file mode 100644
index 0000000..0236a87
--- /dev/null
+++ b/modules/xgetgroups
@@ -0,0 +1,24 @@
+Description:
+Return the group IDs of a user or current process in malloc'd storage, with
+out-of-memory checking.
+
+Files:
+lib/xgetgroups.c
+
+Depends-on:
+mgetgroups
+xalloc
+
+configure.ac:
+
+Makefile.am:
+lib_SOURCES += xgetgroups.c
+
+Include:
+"mgetgroups.h"
+
+License:
+GPL
+
+Maintainer:
+Jim Meyering, Eric Blake
-- 
1.7.4.4