malloca.c non-top variable declaration

[Simon Josefsson]

Hi

I noticed a build failure of libidn on an old architecture that doesn't
permit non-top variable declarations.  How about the patch below?  The
rest builds fine and passes self-tests on the platform, so presumably
this was a recently introduced regression in malloca.c related to
ckd_add.  Thoughts?

For readability, a 'diff -w' patch is easier to read:

diff --git a/lib/malloca.c b/lib/malloca.c
index e75c72df84..6938cdce7a 100644
--- a/lib/malloca.c
+++ b/lib/malloca.c
@@ -69,6 +69,7 @@ mmalloca (size_t n)
              theoretical platforms where UINTPTR_MAX <= INT_MAX.  */
           uintptr_t umemplus;
           ckd_add (&umemplus, umem, sizeof (small_t) + sa_alignment_max - 1);
+          {
             idx_t offset = (umemplus - umemplus % (2 * sa_alignment_max)
                             + sa_alignment_max - umem);
             void *p = mem + offset;
@@ -90,6 +91,7 @@ mmalloca (size_t n)
             return p;
           }
         }
+    }
   /* Out of memory.  */
   return NULL;
 #else

/Simon

From c162d25fde4cd3eecf8cb0645a831b894576c285 Mon Sep 17 00:00:00 2001
From: Simon Josefsson <simon@josefsson.org>
Date: Wed, 11 Sep 2024 09:12:25 +0200
Subject: [PATCH] malloca: Fix compilation on old compilers.

* lib/malloca.c (mmalloca): Add scope, for variable declaration.
---
 ChangeLog     |  5 +++++
 lib/malloca.c | 32 +++++++++++++++++---------------
 2 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 73d43cf40b..1ac9d6a257 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2024-09-11  Simon Josefsson  <simon@josefsson.org>
+
+       malloca: Fix compilation on old compilers.
+       * lib/malloca.c (mmalloca): Add scope, for variable declaration.
+
 2024-09-10  Bruno Haible  <bruno@clisp.org>
 
        mbrtoc16: Fix undefined behaviour.
diff --git a/lib/malloca.c b/lib/malloca.c
index e75c72df84..6938cdce7a 100644
--- a/lib/malloca.c
+++ b/lib/malloca.c
@@ -69,25 +69,27 @@ mmalloca (size_t n)
              theoretical platforms where UINTPTR_MAX <= INT_MAX.  */
           uintptr_t umemplus;
           ckd_add (&umemplus, umem, sizeof (small_t) + sa_alignment_max - 1);
-          idx_t offset = (umemplus - umemplus % (2 * sa_alignment_max)
-                          + sa_alignment_max - umem);
-          void *p = mem + offset;
-          /* Here p >= mem + sizeof (small_t),
-             and p <= mem + sizeof (small_t) + 2 * sa_alignment_max - 1
-             hence p + n <= mem + nplus.
-             So, the memory range [p, p+n) lies in the allocated memory range
-             [mem, mem + nplus).  */
-          small_t *sp = p;
+          {
+            idx_t offset = (umemplus - umemplus % (2 * sa_alignment_max)
+                            + sa_alignment_max - umem);
+            void *p = mem + offset;
+            /* Here p >= mem + sizeof (small_t),
+               and p <= mem + sizeof (small_t) + 2 * sa_alignment_max - 1
+               hence p + n <= mem + nplus.
+               So, the memory range [p, p+n) lies in the allocated memory range
+               [mem, mem + nplus).  */
+            small_t *sp = p;
 # if defined __CHERI_PURE_CAPABILITY__
-          sp[-1] = umem;
-          p = (char *) cheri_bounds_set ((char *) p - sizeof (small_t),
-                                         sizeof (small_t) + n)
+            sp[-1] = umem;
+            p = (char *) cheri_bounds_set ((char *) p - sizeof (small_t),
+                                           sizeof (small_t) + n)
               + sizeof (small_t);
 # else
-          sp[-1] = offset;
+            sp[-1] = offset;
 # endif
-          /* p ≡ sa_alignment_max mod 2*sa_alignment_max.  */
-          return p;
+            /* p ≡ sa_alignment_max mod 2*sa_alignment_max.  */
+            return p;
+          }
         }
     }
   /* Out of memory.  */
-- 
2.45.2

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