[libcamera-devel] [PATCH LIBCAMERA v3] libcamera: utils: adapt libcameraPath to match use cases

[Laurent Pinchart]

Hi Kaaira,

Thank you for the patch.

On Thu, Mar 19, 2020 at 06:12:52PM +0530, Kaaira Gupta wrote:
> The two callers of functions libcameraPath() and isLibcameraInstalled()
> end up using the same process and finally use the path with
> libcamera.so. Hence write a function libcameraBuildPath() which
> combines their functions and returns the root of the build sources
> when the library has not been installed, but is running,thereby making

s/running,/running, /

We don't charge extra for white space :-)

> call sites simpler.
> 
> When the library is imstalled, libcameraBuildPath() will return an empty

s/imstalled/installed/

> string.
> 
> Make changes in the call sites accordingly.
> 
> Signed-off-by: Kaaira Gupta <kgupta at es.iitr.ac.in>
> ---
> Changes since v2:
> 	- rename subject line and add necessary details in commit
> 	  message.
> 	- Solve whitespace issues.
> 	- specify the final 'slash' for directory path in return
> 	  statement itself.
> 
> Changes since v1:
>         - rename function to libcameraBuildPath() instead, and return
>           the root of libcamera source, and not the source directory
>           root.
>         - Return empty string instead of nullptr when ret==0
> 
>  src/libcamera/include/utils.h |  2 +-
>  src/libcamera/ipa_manager.cpp |  5 +++--
>  src/libcamera/ipa_proxy.cpp   |  6 +++---
>  src/libcamera/utils.cpp       | 16 +++++++++-------
>  4 files changed, 16 insertions(+), 13 deletions(-)
> 
> diff --git a/src/libcamera/include/utils.h b/src/libcamera/include/utils.h
> index bc96e79..5dea8d2 100644
> --- a/src/libcamera/include/utils.h
> +++ b/src/libcamera/include/utils.h
> @@ -145,7 +145,7 @@ details::StringSplitter split(const std::string &str, const std::string &delim);
>  
>  bool isLibcameraInstalled();

This function isn't used externally anymore, I would drop it from the
header.

>  
> -std::string libcameraPath();
> +std::string libcameraBuildPath();
>  
>  } /* namespace utils */
>  
> diff --git a/src/libcamera/ipa_manager.cpp b/src/libcamera/ipa_manager.cpp
> index 0bd280c..bcaae35 100644
> --- a/src/libcamera/ipa_manager.cpp
> +++ b/src/libcamera/ipa_manager.cpp
> @@ -119,8 +119,9 @@ IPAManager::IPAManager()
>  	 * path for the IPA from that point. We need to recurse one level of
>  	 * sub-directories to match the build tree.
>  	 */
> -	if (!utils::isLibcameraInstalled()) {
> -		std::string ipaBuildPath = utils::dirname(utils::libcameraPath()) + "/../ipa";
> +	std::string root = utils::libcameraBuildPath();
> +	if (!root.empty()) {
> +		std::string ipaBuildPath = root + "src/ipa";

Very neat :-)

>  		constexpr int maxDepth = 1;
>  
>  		LOG(IPAManager, Info)
> diff --git a/src/libcamera/ipa_proxy.cpp b/src/libcamera/ipa_proxy.cpp
> index 2f866cc..5fd88a4 100644
> --- a/src/libcamera/ipa_proxy.cpp
> +++ b/src/libcamera/ipa_proxy.cpp
> @@ -97,9 +97,9 @@ std::string IPAProxy::resolvePath(const std::string &file) const
>  	 * This requires identifying the path of the libcamera.so, and
>  	 * referencing a relative path for the proxy workers from that point.
>  	 */
> -	if (!utils::isLibcameraInstalled()) {
> -		std::string ipaProxyDir = utils::dirname(utils::libcameraPath())
> -					  + "/proxy/worker";
> +	std::string root = utils::libcameraBuildPath();
> +	if (!root.empty()) {
> +		std::string ipaProxyDir = root + "src/libcamera/proxy/worker";
>  
>  		LOG(IPAProxy, Info)
>  			<< "libcamera is not installed. Loading proxy workers from'"
> diff --git a/src/libcamera/utils.cpp b/src/libcamera/utils.cpp
> index 7e118fa..42c5c76 100644
> --- a/src/libcamera/utils.cpp
> +++ b/src/libcamera/utils.cpp
> @@ -347,16 +347,18 @@ bool isLibcameraInstalled()
>   *
>   * \return A string stating the path
>   */
> -std::string libcameraPath()
> +std::string libcameraBuildPath()
>  {
> -	Dl_info info;
> +	if (!isLibcameraInstalled()) {
> +		Dl_info info;
>  
> -	/* Look up our own symbol. */
> -	int ret = dladdr(reinterpret_cast<void *>(libcameraPath), &info);
> -	if (ret == 0)
> -		return nullptr;
> +		/* Look up our own symbol. */
> +		int ret = dladdr(reinterpret_cast<void *>(libcameraBuildPath), &info);
> +		if (ret)
> +			return dirname(info.dli_fname) + "/../../";
> +	}
>  
> -	return info.dli_fname;
> +	return std::string();

Maybe it's my personal preference, but I find code easier to read when
dealing away with errors immediately:

	if (isLibcameraInstalled())
		return std::string();

	Dl_info info;

	/* Look up our own symbol. */
	int ret = dladdr(reinterpret_cast<void *>(libcameraBuildPath), &info);
	if (!ret)
		return std::string();

	return dirname(info.dli_fname) + "/../../";

This way you can reduce indentation for most of the code that implements
the real logic.

If you're fine with this, I'm sure Kieran can change it while applying.

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

>  }
>  
>  } /* namespace utils */

-- 
Regards,

Laurent Pinchart