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

Simon Marchi
2020-04-11T21:05:53Z

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