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Re: [PATCH v2 1/9] xenstored: use fread() instead of mmap() for reading live update state
- To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- From: Jürgen Groß <jgross@xxxxxxxx>
- Date: Wed, 30 Jul 2025 08:18:43 +0200
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- Cc: Julien Grall <julien@xxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, Jason Andryuk <jason.andryuk@xxxxxxx>
- Delivery-date: Wed, 30 Jul 2025 06:19:04 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 29.07.25 21:25, Andrew Cooper wrote:
On 29/07/2025 8:21 pm, Andrew Cooper wrote:
On 29/07/2025 12:01 pm, Juergen Gross wrote:
diff --git a/tools/xenstored/lu.c b/tools/xenstored/lu.c
index 77e0d377c5..f2c8b92d07 100644
--- a/tools/xenstored/lu.c
+++ b/tools/xenstored/lu.c
@@ -27,9 +27,11 @@ struct live_update *lu_status;
struct lu_dump_state {
void *buf;
+ unsigned int buf_size;
unsigned int size;
- int fd;
+ unsigned int offset;
char *filename;
+ FILE *fp;
I know there's already one unsigned int size here, but life is too short
to not use size_t from the get-go.
That said, offset really needs to be an offs64_t if you want 32bit
guests to 9P safely on a modern filesystem.
For 32bit guests I don't see a problem here, as this would mean the Xenstore
state would exceed 4GB, which seems unlikely using an in-memory data base in
a system supporting less than 2GB of memory (the Mini-OS limit for 32bit is
1GB, while a 32bit daemon can use max. 2GB of virtual memory).
Using unsigned int is a potential problem in 64bit mode, though. So switching
to size_t for size and off64_t for offset seems sensible.
Juergen
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