From f27aa8df3d71f6f30ec0cefe030f68a3537baa13 Mon Sep 17 00:00:00 2001
From: Simone Basso <bassosimone@gmail.com>
Date: Fri, 2 Aug 2019 14:04:11 +0200
Subject: [PATCH] Implement check_{function,symbol}_exists

Required by and used in https://github.com/measurement-kit/libndt/pull/108
---
 cmake/cmake.go               |  6 ++++++
 cmake/cmakefile/cmakefile.go | 27 +++++++++++++++++++++++++++
 pkginfo/pkginfo.go           | 27 +++++++++++++++++++++++++++
 3 files changed, 60 insertions(+)

diff --git a/cmake/cmake.go b/cmake/cmake.go
index a41afdf..4b96609 100644
--- a/cmake/cmake.go
+++ b/cmake/cmake.go
@@ -50,6 +50,12 @@ func sortedTestInfo(m map[string]pkginfo.TestInfo) []string {
 func Generate(pkginfo *pkginfo.PkgInfo) {
 	cmake := cmakefile.Open(pkginfo.Name)
 	defer cmake.Close()
+	for _, funcheck := range pkginfo.FunctionChecks {
+		cmake.CheckFunctionExists(funcheck.Name, funcheck.Define)
+	}
+	for _, symcheck := range pkginfo.SymbolChecks {
+		cmake.CheckSymbolExists(symcheck.Name, symcheck.Header, symcheck.Define)
+	}
 	for _, depname := range pkginfo.Dependencies {
 		handler, ok := deps.All[depname]
 		if !ok {
diff --git a/cmake/cmakefile/cmakefile.go b/cmake/cmakefile/cmakefile.go
index 46548fe..3a5f70c 100644
--- a/cmake/cmakefile/cmakefile.go
+++ b/cmake/cmakefile/cmakefile.go
@@ -104,6 +104,9 @@ func Open(name string) *CMakeFile {
 	cmake.WriteLine(`  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -L/usr/local/lib")`)
 	cmake.WriteLine(`  set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -L/usr/local/lib")`)
 	cmake.WriteLine(`endif()`)
+	cmake.writeEmptyLine()
+	cmake.WriteLine(`include(CheckFunctionExists)`)
+	cmake.WriteLine(`include(CheckSymbolExists)`)
 	return cmake
 }
 
@@ -154,6 +157,30 @@ func (cmake *CMakeFile) untar(filename, destdir string) {
 	cmake.unzip(filename, destdir)
 }
 
+// CheckFunctionExists checks whether |name| is a function and
+// defines the |define| preprocessor macro in such case.
+func (cmake *CMakeFile) CheckFunctionExists(name, define string) {
+	cmake.WriteLine(fmt.Sprintf("check_function_exists(%s %s)", name, define))
+	cmake.WriteLine(fmt.Sprintf("if(${%s})", define))
+	cmake.WithIndent("  ", func() {
+		cmake.WriteLine(fmt.Sprintf("add_definitions(-D%s)", define))
+	})
+	cmake.WriteLine("endif()")
+}
+
+// CheckSymbolExists checks whether |name| is a symbol in |header| and
+// defines the |define| preprocessor macro in such case.
+func (cmake *CMakeFile) CheckSymbolExists(name, header, define string) {
+	cmake.WriteLine(fmt.Sprintf(
+		"check_symbol_exists(%s %s %s)", name, header, define,
+	))
+	cmake.WriteLine(fmt.Sprintf("if(${%s})", define))
+	cmake.WithIndent("  ", func() {
+		cmake.WriteLine(fmt.Sprintf("add_definitions(-D%s)", define))
+	})
+	cmake.WriteLine("endif()")
+}
+
 // AddRequiredDefinition adds |definition| to the macro definitions
 func (cmake *CMakeFile) AddRequiredDefinition(definition string) {
 	cmake.WriteLine(fmt.Sprintf(
diff --git a/pkginfo/pkginfo.go b/pkginfo/pkginfo.go
index 9cc004d..d18b3a6 100644
--- a/pkginfo/pkginfo.go
+++ b/pkginfo/pkginfo.go
@@ -59,11 +59,38 @@ type TestInfo struct {
 	Command string
 }
 
+// FunctionCheck adds a check for a specific function
+type FunctionCheck struct {
+	// Name is the function name
+	Name string
+
+	// Define is the define to add to the build if function exists
+	Define string
+}
+
+// SymbolCheck adds a check for a specific symbol
+type SymbolCheck struct {
+	// Name is the symbol name
+	Name string
+
+	// Header is the header to include for checking for the symbol
+	Header string
+
+	// Define is the define to add to the build if symbol exists
+	Define string
+}
+
 // PkgInfo contains information on a package
 type PkgInfo struct {
 	// Name is the name of the package
 	Name string
 
+	// FunctionChecks contains all the checks for functions
+	FunctionChecks []FunctionCheck `yaml:"function_checks"`
+
+	// SymbolChecks contains all the checks for symbols
+	SymbolChecks []SymbolCheck `yaml:"symbol_checks"`
+
 	// Docker is the docker container to use for running tests
 	Docker string