Invalid len argument type in NVS C++ API? (IDFGH-4275)

[hg]

Environment

• IDF version: v4.3-dev-1720-g494a124d9
• Compiler version: xtensa-esp32-elf-gcc (crosstool-NG esp-2020r3) 8.4.0

Problem Description

Hi,

I omitted most of the template as it doesn't really apply to this issue.

I think the NVSHandle::get_string method uses the wrong type for argument len:

esp-idf/components/nvs_flash/include/nvs_handle.hpp

Line 152 in 5aa2158

virtual esp_err_t get_string(const char *key, char* out_str, size_t len) = 0;

If we look at the docs, it is described as the pointer to the variable which receives the length of the string actually read from flash memory:

esp-idf/components/nvs_flash/include/nvs_handle.hpp

Lines 142 to 144 in 5aa2158

	* @param[inout] length A non-zero pointer to the variable holding the length of out_value.
	* It will be set to the actual length of the value
	* written. For nvs_get_str this includes the zero terminator.

And if we look at the C API, the corresponding function does receive a pointer:

esp-idf/components/nvs_flash/include/nvs.h

Line 346 in 5aa2158

esp_err_t nvs_get_str (nvs_handle_t handle, const char* key, char* out_value, size_t* length);

It can be worked around by using NVSHandle::get_item_size and then passing its result to NVSHandle::get_string, but I guess docs for NVSHandle::get_string could be improved if it's too late to change its signature.

Thank you!

[0xjakob]

@hg
Thanks a lot for being attentive!
We will change the documentation. This is in fact a documentation mistake from copy-pasting the docs over from the C API.

[0xjakob]

@hg A fix has been merged into our internal CI system. It should be pushed to the github master during the next few weeks.