Re: [Qemu-arm] [PATCH v5 3/8] device_tree: introduce qemu_fdt_node_path

[Peter Maydell]

On 18 January 2016 at 15:16, Eric Auger <address@hidden> wrote:
> This new helper routine returns a NULL terminated array of
> node paths matching a node name and a compat string.
>
> Signed-off-by: Eric Auger <address@hidden>
>
> ---
>
> v4 -> v5:
> - support the case where several nodes exist, ie.
>   return an array of node paths. Also add Error **
>   parameter
>
> v1 -> v2:
> - move doc comment in header file
> - do not use a fixed size buffer
> - break on errors in while loop
> - use strcmp instead of strncmp
>
> RFC -> v1:
> - improve error handling according to Alex' comments
> ---
>  device_tree.c                | 49 
> ++++++++++++++++++++++++++++++++++++++++++++
>  include/sysemu/device_tree.h | 14 +++++++++++++
>  2 files changed, 63 insertions(+)
>
> diff --git a/device_tree.c b/device_tree.c
> index b262c2d..3c88a37 100644
> --- a/device_tree.c
> +++ b/device_tree.c
> @@ -231,6 +231,55 @@ static int findnode_nofail(void *fdt, const char 
> *node_path)
>      return offset;
>  }
>
> +char **qemu_fdt_node_path(void *fdt, const char *name, char *compat,
> +                          Error **errp)
> +{
> +    int offset, len, ret;
> +    const char *iter_name;
> +    unsigned int path_len = 16, n = 0;
> +    GSList *path_list = NULL, *iter;
> +    char **path_array;
> +
> +    offset = fdt_node_offset_by_compatible(fdt, -1, compat);
> +
> +    while (offset >= 0) {
> +        iter_name = fdt_get_name(fdt, offset, &len);
> +        if (!iter_name) {
> +            offset = len;
> +            break;
> +        }
> +        if (!strcmp(iter_name, name)) {
> +            char *path;
> +
> +            path = g_malloc(path_len);
> +            while ((ret = fdt_get_path(fdt, offset, path, path_len))
> +                  == -FDT_ERR_NOSPACE) {
> +                path_len += 16;
> +                path = g_realloc(path, path_len);
> +            }
> +            path_list = g_slist_prepend(path_list, path);
> +            n++;
> +        }
> +        offset = fdt_node_offset_by_compatible(fdt, offset, compat);
> +    }
> +
> +    if (offset < 0 && offset != -FDT_ERR_NOTFOUND) {
> +        error_setg(errp, "%s: abort parsing dt for %s/%s: %s",
> +                   __func__, name, compat, fdt_strerror(offset));

Needs to bail out (freeing memory).

> +    }
> +
> +    path_array = g_new(char *, n + 1);
> +    path_array[n--] = NULL;

0, or '\0'. NULL is a pointer, not the NUL character. (This is a
style issue, not a correctness one.)

> +
> +    for (iter = path_list; iter; iter = iter->next) {
> +        path_array[n--] = iter->data;
> +    }
> +
> +    g_slist_free(path_list);
> +
> +    return path_array;
> +}
> +
>  int qemu_fdt_setprop(void *fdt, const char *node_path,
>                       const char *property, const void *val, int size)
>  {
> diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h
> index fdf25a4..436b5dd 100644
> --- a/include/sysemu/device_tree.h
> +++ b/include/sysemu/device_tree.h
> @@ -20,6 +20,20 @@ void *load_device_tree(const char *filename_path, int 
> *sizep);
>  void *load_device_tree_from_sysfs(void);
>  #endif
>
> +/**
> + * qemu_fdt_node_path: return the paths of nodes matching a given
> + * name and compat string
> + * @fdt: pointer to the dt blob
> + * @name: node name
> + * @compat: compatibility string
> + * @errp: handle to an error object
> + *
> + * returns a newly allocated NULL-terminated array of node paths.

Should say what we return on error (NULL ?)

> + * Use g_strfreev() to free it.
> + */
> +char **qemu_fdt_node_path(void *fdt, const char *name, char *compat,
> +                          Error **errp);
> +
>  int qemu_fdt_setprop(void *fdt, const char *node_path,
>                       const char *property, const void *val, int size);
>  int qemu_fdt_setprop_cell(void *fdt, const char *node_path,
> --
> 1.9.1
>

thanks
-- PMM