Gcc Makefile Solaris Ffmpeg

Understanding How `gcc` on Solaris Locates Its Libraries

When working with gcc on Solaris, many users face challenges in getting the compiler to find the necessary libraries and headers that their projects depend on. This issue can be particularly frustrating, especially when you’re trying to install a library that relies on others, such as ffmpeg. In this blog post, we’ll explore how gcc finds its libraries on Solaris and provide you with the steps needed to adjust its search paths correctly.

The Problem

Imagine you’re trying to build a library called quadrupel, which depends on ffmpeg. You’ve successfully compiled ffmpeg, and its libraries are installed in /opt/gnu/lib, with header files included in /opt/gnu/include. However, upon attempting to build quadrupel, you encounter an error indicating that the compiler cannot find the ffmpeg headers. This predicament highlights the need to configure the compiler properly to locate your libraries and includes.

The Solution

Fortunately, there are a few straightforward steps you can take to resolve this issue. The primary method involves adjusting the library and include paths so that gcc recognizes them during compilation. Here’s how to do it:

Setting Up Library Paths

Use the LD_LIBRARY_PATH Environment Variable
- One way to let gcc know where to find the libraries is by setting the LD_LIBRARY_PATH environment variable. Though effective, this method affects only the current user session.
Permanent Modification with crle
- To avoid changing settings for each user, a more permanent solution is to modify system paths. You can do this using the command crle (the runtime linker configuration).
- Here’s the command:
```
crle -l -c /var/ld/ld.config -l /usr/lib:/usr/local/lib:/opt/gnu/lib
```
- This command tells Solaris to include the specified directories (/usr/lib, /usr/local/lib, and /opt/gnu/lib) for library searches at all times.

Setting Up Include Paths

To ensure that your gcc compiler can find the necessary header files, you must adjust the CFLAGS variable:

Edit CFLAGS for Includes
- When compiling your code, include the path to your header files using the -I flag.
- Here’s how to add it:
```
export CFLAGS="-I/opt/gnu/include"
```
- This command updates the CFLAGS variable, allowing gcc to locate the include files in the /opt/gnu/include directory correctly.

Conclusion

Configuring gcc on Solaris to find libraries and header files effectively is crucial for successful compilation and installation of dependent libraries like quadrupel. By modifying both the library paths with crle and setting the CFLAGS for includes, you can ensure that your build process runs smoothly without encountering unnecessary errors.