Re: [PATCH 2/6] dump/win_dump: Improve error messages on write error

[Philippe Mathieu-Daudé]

On 13/5/24 16:16, Markus Armbruster wrote:
> create_win_dump() and write_run report qemu_write_full() failure to
> their callers as
>
>      An IO error has occurred
>
> The errno set by qemu_write_full() is lost.
>
> Improve this to
>
>      win-dump: failed to write header: <description of errno>
>
> and
>
>      win-dump: failed to save memory: <description of errno>
>
> This matches how dump.c reports similar errors.
>
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---
>   dump/win_dump.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/dump/win_dump.c b/dump/win_dump.c
> index b7bfaff379..0e4fe692ce 100644
> --- a/dump/win_dump.c
> +++ b/dump/win_dump.c
> @@ -12,7 +12,6 @@
>   #include "sysemu/dump.h"
>   #include "qapi/error.h"
>   #include "qemu/error-report.h"
> -#include "qapi/qmp/qerror.h"
>   #include "exec/cpu-defs.h"
>   #include "hw/core/cpu.h"
>   #include "qemu/win_dump_defs.h"
> @@ -52,6 +51,7 @@ static size_t write_run(uint64_t base_page, uint64_t 
> page_count,
>       uint64_t addr = base_page << TARGET_PAGE_BITS;
>       uint64_t size = page_count << TARGET_PAGE_BITS;
>       uint64_t len, l;
> +    int eno;
>       size_t total = 0;
>   
>       while (size) {
> @@ -65,9 +65,10 @@ static size_t write_run(uint64_t base_page, uint64_t 
> page_count,
>           }
>   
>           l = qemu_write_full(fd, buf, len);
> +        eno = errno;

Hmm this show the qemu_write_full() API isn't ideal.
Maybe we could pass &l as argument and return errno.
There are only 20 calls.

>           cpu_physical_memory_unmap(buf, addr, false, len);
>           if (l != len) {
> -            error_setg(errp, QERR_IO_ERROR);
> +            error_setg_errno(errp, eno, "win-dump: failed to save memory");
>               return 0;
>           }
>   
> @@ -459,7 +460,7 @@ void create_win_dump(DumpState *s, Error **errp)
>   
>       s->written_size = qemu_write_full(s->fd, h, hdr_size);
>       if (s->written_size != hdr_size) {
> -        error_setg(errp, QERR_IO_ERROR);
> +        error_setg_errno(errp, errno, "win-dump: failed to write header");
>           goto out_restore;
>       }
>