Hi Bruno,
Bruno Haible <br...@clisp.org> writes:
>> However, I think that the correct way to write this would be to use
>> 'uintptr_t' which would work with large page sizes on more niche
>> architectures [1].
>
> Yes, the way to get rid of the warning is to cast from pointer to
> 'uintptr_t', not 'unsigned long'.
>
>> Can you check the attached patch before I push?
>
> The stdint.h part is right. What is not right, is to do a conversion
> from pointer to uintptr_t and then back from uintptr_t to pointer.
> That is inefficient on the CHERI architecture, IIRC.
> It's better to keep the addition on the 'char *' side.
Thanks for checking. I pushed the attached patch with those changes.
I assumed uintptr_t was correct for performing arithmetic on any
pointer. I know CHERI has some limitations, but I am not familiar with
them. Perhaps I will get around to reading the manual at some point [1].
Collin
[1] https://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-947.pdf
>From a5c7974191230a73c67926cb38d8539d9252f942 Mon Sep 17 00:00:00 2001
Message-ID: <a5c7974191230a73c67926cb38d8539d9252f942.1751821732.git.collin.fu...@gmail.com>
From: Collin Funk <collin.fu...@gmail.com>
Date: Sun, 6 Jul 2025 10:07:35 -0700
Subject: [PATCH] pagealign_alloc: Don't assume pointers fit in 'unsigned
long'.
* modules/pagealign_alloc (Depends-on): Add stdint-h.
* lib/pagealign_alloc.c: Include stdint.h.
(pagealign_alloc): Cast pointers to 'uintptr_t' instead of 'unsigned
long'.
---
ChangeLog | 8 ++++++++
lib/pagealign_alloc.c | 3 ++-
modules/pagealign_alloc | 1 +
3 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/ChangeLog b/ChangeLog
index c8d09b3dac..286d589d23 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2025-07-06 Collin Funk <collin.fu...@gmail.com>
+
+ pagealign_alloc: Don't assume pointers fit in 'unsigned long'.
+ * modules/pagealign_alloc (Depends-on): Add stdint-h.
+ * lib/pagealign_alloc.c: Include stdint.h.
+ (pagealign_alloc): Cast pointers to 'uintptr_t' instead of 'unsigned
+ long'.
+
2025-07-05 Collin Funk <collin.fu...@gmail.com>
strptime: Convert K&R definitions to ANSI C.
diff --git a/lib/pagealign_alloc.c b/lib/pagealign_alloc.c
index 3f3fc17169..e460356c3f 100644
--- a/lib/pagealign_alloc.c
+++ b/lib/pagealign_alloc.c
@@ -26,6 +26,7 @@
#include <fcntl.h>
#include <unistd.h>
+#include <stdint.h>
#if HAVE_MMAP
# include <sys/mman.h>
@@ -159,7 +160,7 @@ pagealign_alloc (size_t size)
return NULL;
}
ret = (char *) unaligned_ptr
- + ((- (unsigned long) unaligned_ptr) & (pagesize - 1));
+ + ((- (uintptr_t) unaligned_ptr) & (pagesize - 1));
new_memnode (ret, unaligned_ptr);
#endif /* HAVE_MMAP && HAVE_POSIX_MEMALIGN */
return ret;
diff --git a/modules/pagealign_alloc b/modules/pagealign_alloc
index 59afe866de..bd2d8f4cbc 100644
--- a/modules/pagealign_alloc
+++ b/modules/pagealign_alloc
@@ -17,6 +17,7 @@ open
stdlib-h
xalloc
unistd-h
+stdint-h
configure.ac:
gl_PAGEALIGN_ALLOC
--
2.50.0
