[PATCH v3] Implement "info proc mappings" for NetBSD

[Simon Marchi]

On 2020-04-06 5:37 a.m., Kamil Rytarowski wrote:
> @@ -39,3 +42,148 @@ nbsd_nat_target::pid_to_exec_file (int pid)
>      return NULL;
>    return buf;
>  }
> +
> +/* Retrieve all the memory regions in the specified process.  */
> +
> +static gdb::unique_xmalloc_ptr<struct kinfo_vmentry[]>
> +nbsd_kinfo_get_vmmap (pid_t pid, size_t *size)
> +{
> +  int mib[5] = {CTL_VM, VM_PROC, VM_PROC_MAP, pid,
> +		sizeof (struct kinfo_vmentry)};
> +
> +  size_t length = 0;
> +  if (sysctl (mib, ARRAY_SIZE (mib), NULL, &length, NULL, 0))
> +    {
> +      *size = 0;
> +      return NULL;
> +    }
> +
> +  /* Prereserve more space. */
> +  length = length * 5 / 3;

Why is this needed?

> +
> +  gdb::unique_xmalloc_ptr<struct kinfo_vmentry[]> kiv
> +    ((struct kinfo_vmentry *) xcalloc (length, 1));

Let's use XCNEWVAR here.  It doesn't matter in this case, but for consistency.  It does
check that we are not trying to allocate space for a non-POD type.  You can use like:

  XCNEWVAR (kinfo_vmentry, length)

You can also use XNEWVAR if you don't care about the buffer being initialized to zeros.

> diff --git a/gdb/nbsd-tdep.h b/gdb/nbsd-tdep.h
> index c99a8b537b6..81bdb2510f5 100644
> --- a/gdb/nbsd-tdep.h
> +++ b/gdb/nbsd-tdep.h
> @@ -25,4 +25,22 @@ struct link_map_offsets *nbsd_lp64_solib_svr4_fetch_link_map_offsets (void);
> 
>  int nbsd_pc_in_sigtramp (CORE_ADDR, const char *);
> 
> +/* Output the header for "info proc mappings".  ADDR_BIT is the size
> +   of a virtual address in bits.  */
> +
> +extern void nbsd_info_proc_mappings_header (int addr_bit);
> +
> +/* Output description of a single memory range for "info proc
> +   mappings".  ADDR_BIT is the size of a virtual address in bits.  The
> +   KVE_START, KVE_END, KVE_OFFSET, KVE_FLAGS, and KVE_PROTECTION
> +   parameters should contain the value of the corresponding fields in
> +   a 'struct kinfo_vmentry'.  The KVE_PATH parameter should contain a
> +   pointer to the 'kve_path' field in a 'struct kinfo_vmentry'. */
> +
> +extern void nbsd_info_proc_mappings_entry (int addr_bit, ULONGEST kve_start,
> +					   ULONGEST kve_end,
> +					   ULONGEST kve_offset,
> +					   int kve_flags, int kve_protection,
> +					   const void *kve_path);

I'd make the last parameter a `const char *` directly, since this is what the function
expects to receive.  And remove the reinterpret_casts.

Simon