Re: [PATCH v1 07/10] gdb/linux-tdep: migrate linux_find_memory_regions_full to file_reader_t

[Luis <luis.machado.foss@gmail.com>]

On 07/07/2026 16:48, Matthieu Longo wrote:
> The previous implementation of linux_find_memory_regions_full could
> still return success even when none of the /proc/PID/[s]maps files
> existed, or all reads returned 0 bytes (this last case can happen on
> Linux when the thread-group leader has exited).
> As a result, the function could incorrectly succeed, allowing core
> dump generation via the gcore command.
> This logical defect was allowing, by chance, the function to return
> success and hence, allowing fortuitously the codedump generation via

Typo: codedump -> coredump

> gcore command (see gcore-stale-thread test for more details).
> 
> A previous patch in this patch series fixed this issue by using the
> first LWP ID of the current inferior instead of relying on the PID.
> This patch adapts the code to use file_reader_t and makes the function
> return an error is reading any of the procfs files fails.
> ---
>   gdb/linux-tdep.c | 23 ++++++++++-------------
>   1 file changed, 10 insertions(+), 13 deletions(-)
> 
> diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
> index a2af1586d35..f1cea3040f9 100644
> --- a/gdb/linux-tdep.c
> +++ b/gdb/linux-tdep.c
> @@ -1777,25 +1777,22 @@ linux_find_memory_regions_full (struct gdbarch *gdbarch,
>   	}
>       }
>   
> -  std::string maps_filename = string_printf ("/proc/%ld/smaps", ptid.lwp ());
> -
> -  gdb::unique_xmalloc_ptr<char> data
> -    = target_fileio_read_stralloc (NULL, maps_filename.c_str ());
> +  std::vector<struct smaps_data> smaps;
>   
> -  if (data == NULL)
> +  file_reader_t<char> smaps_freader
> +    (string_printf ("/proc/%ld/smaps", ptid.lwp ()));
> +  if (smaps_freader)
> +    smaps = parse_smaps_data (smaps_freader);
> +  else
>       {
>         /* Older Linux kernels did not support /proc/PID/smaps.  */
> -      maps_filename = string_printf ("/proc/%ld/maps", ptid.lwp ());
> -      data = target_fileio_read_stralloc (NULL, maps_filename.c_str ());
> -
> -      if (data == nullptr)
> +      file_reader_t<char> maps_freader
> +	(string_printf ("/proc/%ld/maps", ptid.lwp ()));
> +      if (!maps_freader)
>   	return false;
> +      smaps = parse_smaps_data (maps_freader);
>       }
>   
> -  /* Parse the contents of smaps into a vector.  */
> -  std::vector<struct smaps_data> smaps
> -    = parse_smaps_data (data.get (), maps_filename);
> -
>     for (const struct smaps_data &map : smaps)
>       {
>         /* Invoke the callback function to create the corefile segment.  */