build: Cleanup cmake search paths

fbs · danobi · commit 17cc2ea0416b · 2021-05-17T16:18:24.000-05:00
PATHS are just additional paths to search after it's done searching the
default paths([1]) so these additional paths are useless. Comparing the
paths between old and new by changing the libname from `bcc` to
`pancake` and using:

```
/usr/local/bin/cmake .. -DCMAKE_FIND_DEBUG_MODE=true 2&gt;&amp;1 1&gt;/dev/null | \
  grep LIBBCC_LIBRARIES -A 40
```

Shows that the only diff is

```
➜  /tmp diff -u old new
--- old	2021-05-13 21:55:12.000000000 +0200
+++ new	2021-05-13 21:55:07.000000000 +0200
@@ -25,5 +25,3 @@
 /opt/lib/(lib)pancake(\.so|\.a)
 /opt/(lib)pancake(\.so|\.a)
 /usr/lib/X11/(lib)pancake(\.so|\.a)
-/opt/local/lib/(lib)pancake(\.so|\.a)
-/sw/lib/(lib)pancake(\.so|\.a)
```

The full list considered is:

```
/usr/local/sbin/(lib)pancake(\.so|\.a)
/usr/local/bin/(lib)pancake(\.so|\.a)
/usr/sbin/(lib)pancake(\.so|\.a)
/usr/bin/(lib)pancake(\.so|\.a)
/sbin/(lib)pancake(\.so|\.a)
/bin/(lib)pancake(\.so|\.a)
/usr/games/(lib)pancake(\.so|\.a)
/usr/local/games/(lib)pancake(\.so|\.a)
/snap/bin/(lib)pancake(\.so|\.a)
/usr/local/lib/x86_64-linux-gnu/(lib)pancake(\.so|\.a)
/usr/local/lib/(lib)pancake(\.so|\.a)
/usr/local/(lib)pancake(\.so|\.a)
/usr/lib/x86_64-linux-gnu/(lib)pancake(\.so|\.a)
/usr/lib/(lib)pancake(\.so|\.a)
/usr/(lib)pancake(\.so|\.a)
/lib/x86_64-linux-gnu/(lib)pancake(\.so|\.a)
/lib/(lib)pancake(\.so|\.a)
/usr/X11R6/lib/x86_64-linux-gnu/(lib)pancake(\.so|\.a)
/usr/X11R6/lib/(lib)pancake(\.so|\.a)
/usr/X11R6/(lib)pancake(\.so|\.a)
/usr/pkg/lib/x86_64-linux-gnu/(lib)pancake(\.so|\.a)
/usr/pkg/lib/(lib)pancake(\.so|\.a)
/usr/pkg/(lib)pancake(\.so|\.a)
/opt/lib/x86_64-linux-gnu/(lib)pancake(\.so|\.a)
/opt/lib/(lib)pancake(\.so|\.a)
/opt/(lib)pancake(\.so|\.a)
/usr/lib/X11/(lib)pancake(\.so|\.a)
```

When we want to also search a subdir we should set `PATH_SUFFIXES`
instead, for libelf this changes the searchpath from

```
/usr/local/sbin/(lib)elf(\.so|\.a)
/usr/local/bin/(lib)elf(\.so|\.a)
/usr/sbin/(lib)elf(\.so|\.a)
/usr/bin/(lib)elf(\.so|\.a)
/sbin/(lib)elf(\.so|\.a)
/bin/(lib)elf(\.so|\.a)
/usr/games/(lib)elf(\.so|\.a)
/usr/local/games/(lib)elf(\.so|\.a)
/snap/bin/(lib)elf(\.so|\.a)
/usr/local/lib/x86_64-linux-gnu/(lib)elf(\.so|\.a)
/usr/local/lib/(lib)elf(\.so|\.a)
/usr/local/(lib)elf(\.so|\.a)
```

```
/usr/local/sbin/libelf/(lib)elf(\.so|\.a)
/usr/local/sbin/(lib)elf(\.so|\.a)
/usr/local/bin/libelf/(lib)elf(\.so|\.a)
/usr/local/bin/(lib)elf(\.so|\.a)
/usr/sbin/libelf/(lib)elf(\.so|\.a)
/usr/sbin/(lib)elf(\.so|\.a)
/usr/bin/libelf/(lib)elf(\.so|\.a)
/usr/bin/(lib)elf(\.so|\.a)
/sbin/libelf/(lib)elf(\.so|\.a)
/sbin/(lib)elf(\.so|\.a)
/bin/libelf/(lib)elf(\.so|\.a)
/bin/(lib)elf(\.so|\.a)
/usr/games/libelf/(lib)elf(\.so|\.a)
/usr/games/(lib)elf(\.so|\.a)
/usr/local/games/libelf/(lib)elf(\.so|\.a)
/usr/local/games/(lib)elf(\.so|\.a)
/snap/bin/libelf/(lib)elf(\.so|\.a)
/snap/bin/(lib)elf(\.so|\.a)
/usr/local/lib/x86_64-linux-gnu/libelf/(lib)elf(\.so|\.a)
/usr/local/lib/x86_64-linux-gnu/(lib)elf(\.so|\.a)
/usr/local/lib/libelf/(lib)elf(\.so|\.a)
/usr/local/lib/(lib)elf(\.so|\.a)
/usr/local/libelf/(lib)elf(\.so|\.a)
/usr/local/(lib)elf(\.so|\.a)
/usr/lib/x86_64-linux-gnu/libelf/(lib)elf(\.so|\.a)
```

Users that do want their software in /opt or /sw for whatever reason
should instead modify the cmake search path, e.g. using
`-DCMAKE_LIBRARY_PATH=/sw/junk` the search turns into

```
  find_library considered the following locations:

    /sw/junk/(lib)bcc(\.so|\.a)
    /usr/local/sbin/(lib)bcc(\.so|\.a)
    /usr/local/bin/(lib)bcc(\.so|\.a)
```
diff --git a/cmake/FindLibBcc.cmake b/cmake/FindLibBcc.cmake
@@ -21,47 +21,26 @@ find_path (LIBBCC_INCLUDE_DIRS
   NAMES
     bcc/libbpf.h
   PATHS
-    /usr/include
-    /usr/include/bcc
-    /usr/local/include
-    /usr/local/include/libbcc
-    /usr/local/include/bcc
-    /opt/local/include
-    /opt/local/include/libbcc
-    /sw/include
-    /sw/include/libbcc
     ENV CPATH)
 
 find_library (LIBBCC_LIBRARIES
   NAMES
     bcc
   PATHS
-    /usr/lib
-    /usr/local/lib
-    /opt/local/lib
-    /sw/lib
     ENV LIBRARY_PATH
     ENV LD_LIBRARY_PATH)
 
 find_library (LIBBCC_BPF_LIBRARY_STATIC
   NAMES
     bcc_bpf
   PATHS
-    /usr/lib
-    /usr/local/lib
-    /opt/local/lib
-    /sw/lib
     ENV LIBRARY_PATH
     ENV LD_LIBRARY_PATH)
 
 find_library (LIBBCC_LOADER_LIBRARY_STATIC
   NAMES
     bcc-loader-static
   PATHS
-    /usr/lib
-    /usr/local/lib
-    /opt/local/lib
-    /sw/lib
     ENV LIBRARY_PATH
     ENV LD_LIBRARY_PATH)
 
diff --git a/cmake/FindLibBfd.cmake b/cmake/FindLibBfd.cmake
@@ -16,22 +16,12 @@ find_path (LIBBFD_INCLUDE_DIRS
   NAMES
     bfd.h
   PATHS
-    /usr/include
-    /usr/local/include
-    /opt/local/include
-    /sw/include
     ENV CPATH)
 
 find_library (LIBBFD_LIBRARIES
   NAMES
     bfd
   PATHS
-    /lib
-    /usr/lib
-    /usr/local/lib
-    /opt/local/lib
-    /usr/lib/x86_64-linux-gnu/
-    /sw/lib
     ENV LIBRARY_PATH
     ENV LD_LIBRARY_PATH)
 
@@ -42,12 +32,6 @@ find_library (LIBIBERTY_LIBRARIES
   NAMES
     libiberty.a
   PATHS
-    /lib
-    /usr/lib
-    /usr/local/lib
-    /opt/local/lib
-    /usr/lib/x86_64-linux-gnu/
-    /sw/lib
     ENV LIBRARY_PATH
     ENV LD_LIBRARY_PATH)
 
diff --git a/cmake/FindLibBpf.cmake b/cmake/FindLibBpf.cmake
@@ -16,20 +16,12 @@ find_path (LIBBPF_INCLUDE_DIRS
     bpf/btf.h
     bpf/libbpf.h
   PATHS
-    /usr/include
-    /usr/local/include
-    /opt/local/include
-    /sw/include
     ENV CPATH)
 
 find_library (LIBBPF_LIBRARIES
   NAMES
     bpf
   PATHS
-    /usr/lib
-    /usr/local/lib
-    /opt/local/lib
-    /sw/lib
     ENV LIBRARY_PATH
     ENV LD_LIBRARY_PATH)
 
diff --git a/cmake/FindLibElf.cmake b/cmake/FindLibElf.cmake
@@ -21,26 +21,17 @@ endif (LIBELF_LIBRARIES AND LIBELF_INCLUDE_DIRS)
 find_path (LIBELF_INCLUDE_DIRS
   NAMES
     libelf.h
+  PATH_SUFFIXES
+    libelf
   PATHS
-    /usr/include
-    /usr/include/libelf
-    /usr/local/include
-    /usr/local/include/libelf
-    /opt/local/include
-    /opt/local/include/libelf
-    /sw/include
-    /sw/include/libelf
     ENV CPATH)
 
 find_library (LIBELF_LIBRARIES
   NAMES
     elf
+  PATH_SUFFIXES
+    libelf
   PATHS
-    /usr/lib
-    /usr/local/lib
-    /opt/local/lib
-    /usr/lib/x86_64-linux-gnu/
-    /sw/lib
     ENV LIBRARY_PATH
     ENV LD_LIBRARY_PATH)
 
diff --git a/cmake/FindLibOpcodes.cmake b/cmake/FindLibOpcodes.cmake
@@ -14,22 +14,12 @@ find_path (LIBOPCODES_INCLUDE_DIRS
   NAMES
     dis-asm.h
   PATHS
-    /usr/include
-    /usr/local/include
-    /opt/local/include
-    /sw/include
     ENV CPATH)
 
 find_library (LIBOPCODES_LIBRARIES
   NAMES
     opcodes
   PATHS
-    /lib
-    /usr/lib
-    /usr/local/lib
-    /opt/local/lib
-    /usr/lib/x86_64-linux-gnu/
-    /sw/lib
     ENV LIBRARY_PATH
     ENV LD_LIBRARY_PATH)
 
diff --git a/cmake/FindLibZ.cmake b/cmake/FindLibZ.cmake
@@ -8,12 +8,6 @@ find_library(LIBZ_LIBRARIES
   NAMES
     libz.a
   PATHS
-    /lib
-    /usr/lib
-    /usr/local/lib
-    /opt/local/lib
-    /usr/lib/x86_64-linux-gnu/
-    /sw/lib
     ENV LIBRARY_PATH
     ENV LD_LIBRARY_PATH)
 
