refactor(buildtool): use list for OpenSSL ./Configure flags (ooni#1367)

We currently have a string variable in `cBuildEnv` named
`OPENSSL_API_DEFINE` that we append to OpenSSL's `./Configure`
invocation to force using the proper Android API. However, for building
for iOS (a need documented by
ooni/probe#2564), we need a list of strings,
because there is more than a single scalar that we need to append to the
`./Configure` invocation (as shown by the MVP implementation at
ooni#1366).

Hence, this diff, which introduces a string list named
`OPENSSL_POST_COMPILER_FLAGS` that contains strings to append to the
`./Configure` command line _after_ the OS/compiler flag. We specifically
named the variable "post compiler" because there is another variable in
the same `cBuildEnv` struct called `OPENSSL_COMPILER`.

internal/cmd/buildtool/android.go

@@ -26,20 +26,23 @@ func androidSubcommand() *cobra.Command {
 		Use:   "android",
 		Short: "Builds ooniprobe, miniooni, and oonimkall for android",
 	}
+
 	cmd.AddCommand(&cobra.Command{
 		Use:   "gomobile",
 		Short: "Builds oonimkall for android using gomobile",
 		Run: func(cmd *cobra.Command, args []string) {
 			androidBuildGomobile(&buildDeps{})
 		},
 	})
+
 	cmd.AddCommand(&cobra.Command{
 		Use:   "cli",
 		Short: "Builds ooniprobe and miniooni for usage within termux",
 		Run: func(cmd *cobra.Command, args []string) {
 			androidBuildCLIAll(&buildDeps{})
 		},
 	})
+
 	cmd.AddCommand(&cobra.Command{
 		Use:   "cdeps {zlib|openssl|libevent|tor} [zlib|openssl|libevent|tor...]",
 		Short: "Cross compiles C dependencies for Android",
@@ -50,6 +53,7 @@ func androidSubcommand() *cobra.Command {
 		},
 		Args: cobra.MinimumNArgs(1),
 	})
+
 	return cmd
 }
 
@@ -161,7 +165,7 @@ func androidBuildCLIProductArch(
 	androidHome string,
 	ndkDir string,
 ) {
-	cgo := newAndroidCBuildEnv(androidHome, ndkDir, ooniArch)
+	cgo := androidNewCBuildEnv(androidHome, ndkDir, ooniArch)
 
 	log.Infof("building %s for android/%s", product.Pkg, ooniArch)
 
@@ -203,33 +207,33 @@ func androidBuildCLIProductArch(
 	runtimex.Try0(shellx.RunEx(defaultShellxConfig(), argv, envp))
 }
 
-// newAndroidCBuildEnv creates a new [cBuildEnv] for the
+// androidNewCBuildEnv creates a new [cBuildEnv] for the
 // given ooniArch ("arm", "arm64", "386", "amd64").
-func newAndroidCBuildEnv(androidHome, ndkDir, ooniArch string) *cBuildEnv {
+func androidNewCBuildEnv(androidHome, ndkDir, ooniArch string) *cBuildEnv {
 	binpath := androidNDKBinPath(ndkDir)
 	destdir := runtimex.Try1(filepath.Abs(filepath.Join( // must be absolute
 		"internal", "libtor", "android", ooniArch,
 	)))
 	out := &cBuildEnv{
-		ANDROID_HOME:       androidHome,
-		ANDROID_NDK_ROOT:   ndkDir,
-		AS:                 "", // later
-		AR:                 filepath.Join(binpath, "llvm-ar"),
-		BINPATH:            binpath,
-		CC:                 "", // later
-		CFLAGS:             androidCflags(ooniArch),
-		CONFIGURE_HOST:     "", // later
-		DESTDIR:            destdir,
-		CXX:                "", // later
-		CXXFLAGS:           androidCflags(ooniArch),
-		GOARCH:             ooniArch,
-		GOARM:              "", // maybe later
-		LD:                 filepath.Join(binpath, "ld"),
-		LDFLAGS:            []string{}, // empty
-		OPENSSL_API_DEFINE: "-D__ANDROID_API__=21",
-		OPENSSL_COMPILER:   "", // later
-		RANLIB:             filepath.Join(binpath, "llvm-ranlib"),
-		STRIP:              filepath.Join(binpath, "llvm-strip"),
+		ANDROID_HOME:                androidHome,
+		ANDROID_NDK_ROOT:            ndkDir,
+		AS:                          "", // later
+		AR:                          filepath.Join(binpath, "llvm-ar"),
+		BINPATH:                     binpath,
+		CC:                          "", // later
+		CFLAGS:                      androidCflags(ooniArch),
+		CONFIGURE_HOST:              "", // later
+		DESTDIR:                     destdir,
+		CXX:                         "", // later
+		CXXFLAGS:                    androidCflags(ooniArch),
+		GOARCH:                      ooniArch,
+		GOARM:                       "", // maybe later
+		LD:                          filepath.Join(binpath, "ld"),
+		LDFLAGS:                     []string{}, // empty
+		OPENSSL_COMPILER:            "",         // later
+		OPENSSL_POST_COMPILER_FLAGS: []string{"-D__ANDROID_API__=21"},
+		RANLIB:                      filepath.Join(binpath, "llvm-ranlib"),
+		STRIP:                       filepath.Join(binpath, "llvm-strip"),
 	}
 	switch ooniArch {
 	case "arm":
@@ -395,7 +399,7 @@ func androidCdepsBuildArch(
 	ndkDir string,
 	name string,
 ) {
-	cdenv := newAndroidCBuildEnv(androidHome, ndkDir, arch)
+	cdenv := androidNewCBuildEnv(androidHome, ndkDir, arch)
 	switch name {
 	case "libevent":
 		cdepsLibeventBuildMain(cdenv, deps)

internal/cmd/buildtool/cbuildenv.go

@@ -61,12 +61,12 @@ type cBuildEnv struct {
 	// LDFLAGS contains the LDFLAGS to use when compiling.
 	LDFLAGS []string
 
-	// OPENSSL_API_DEFINE is an extra define we need to add on Android.
-	OPENSSL_API_DEFINE string
-
 	// OPENSSL_COMPILER is the compiler name for OpenSSL.
 	OPENSSL_COMPILER string
 
+	// OPENSSL_POST_COMPILER_FLAGS contains extra flags to pass after OPENSSL_COMPILER
+	OPENSSL_POST_COMPILER_FLAGS []string
+
 	// RANLIB is the path to the ranlib tool.
 	RANLIB string
 
@@ -86,29 +86,30 @@ type cBuildEnv struct {
 // environment variables to CFLAGS, CXXFLAGS, etc.
 func cBuildMerge(global, local *cBuildEnv) *cBuildEnv {
 	out := &cBuildEnv{
-		ANDROID_HOME:       global.ANDROID_HOME,
-		ANDROID_NDK_ROOT:   global.ANDROID_NDK_ROOT,
-		AR:                 global.AR,
-		AS:                 global.AS,
-		BINPATH:            global.BINPATH,
-		CC:                 global.CC,
-		CFLAGS:             append([]string{}, global.CFLAGS...),
-		CONFIGURE_HOST:     global.CONFIGURE_HOST,
-		DESTDIR:            global.DESTDIR,
-		CXX:                global.CXX,
-		CXXFLAGS:           append([]string{}, global.CXXFLAGS...),
-		GOARCH:             global.GOARCH,
-		GOARM:              global.GOARM,
-		LD:                 global.LD,
-		LDFLAGS:            append([]string{}, global.LDFLAGS...),
-		OPENSSL_API_DEFINE: global.OPENSSL_API_DEFINE,
-		OPENSSL_COMPILER:   global.OPENSSL_COMPILER,
-		RANLIB:             global.RANLIB,
-		STRIP:              global.STRIP,
+		ANDROID_HOME:                global.ANDROID_HOME,
+		ANDROID_NDK_ROOT:            global.ANDROID_NDK_ROOT,
+		AR:                          global.AR,
+		AS:                          global.AS,
+		BINPATH:                     global.BINPATH,
+		CC:                          global.CC,
+		CFLAGS:                      append([]string{}, global.CFLAGS...),
+		CONFIGURE_HOST:              global.CONFIGURE_HOST,
+		DESTDIR:                     global.DESTDIR,
+		CXX:                         global.CXX,
+		CXXFLAGS:                    append([]string{}, global.CXXFLAGS...),
+		GOARCH:                      global.GOARCH,
+		GOARM:                       global.GOARM,
+		LD:                          global.LD,
+		LDFLAGS:                     append([]string{}, global.LDFLAGS...),
+		OPENSSL_COMPILER:            global.OPENSSL_COMPILER,
+		OPENSSL_POST_COMPILER_FLAGS: append([]string{}, global.OPENSSL_POST_COMPILER_FLAGS...),
+		RANLIB:                      global.RANLIB,
+		STRIP:                       global.STRIP,
 	}
 	out.CFLAGS = append(out.CFLAGS, local.CFLAGS...)
 	out.CXXFLAGS = append(out.CXXFLAGS, local.CXXFLAGS...)
 	out.LDFLAGS = append(out.LDFLAGS, local.LDFLAGS...)
+	out.OPENSSL_POST_COMPILER_FLAGS = append(out.OPENSSL_POST_COMPILER_FLAGS, local.OPENSSL_POST_COMPILER_FLAGS...)
 	return out
 }
 

internal/cmd/buildtool/cdepsopenssl.go

@@ -67,9 +67,7 @@ func cdepsOpenSSLBuildMain(globalEnv *cBuildEnv, deps buildtoolmodel.Dependencie
 		"no-rc2", "no-rc4", "no-rc5", "no-rmd160", "no-whirlpool", "no-dso",
 		"no-ui-console", "no-shared", "no-unit-test", globalEnv.OPENSSL_COMPILER,
 	))
-	if globalEnv.OPENSSL_API_DEFINE != "" {
-		argv.Append(globalEnv.OPENSSL_API_DEFINE)
-	}
+	argv.Append(globalEnv.OPENSSL_POST_COMPILER_FLAGS...)
 	argv.Append("--libdir=lib", "--prefix=/", "--openssldir=/")
 	runtimex.Try0(shellx.RunEx(defaultShellxConfig(), argv, envp))
 

internal/cmd/buildtool/internal/buildtoolmodel/buildtoolmodel.go

@@ -18,6 +18,9 @@ type Dependencies interface {
 	// function returns the Android home path.
 	AndroidSDKCheck() string
 
+	// GOOS returns the current GOOS.
+	GOOS() string
+
 	// GOPATH returns the current GOPATH.
 	GOPATH() string
 
@@ -49,7 +52,4 @@ type Dependencies interface {
 	// WindowsMingwCheck makes sure we're using the
 	// expected version of mingw-w64.
 	WindowsMingwCheck()
-
-	// GOOS returns the current GOOS.
-	GOOS() string
 }

internal/cmd/buildtool/linuxcdeps.go

@@ -50,24 +50,24 @@ func linuxCdepsBuildMain(name string, deps buildtoolmodel.Dependencies) {
 		"internal", "libtor", "linux", runtime.GOARCH,
 	)))
 	globalEnv := &cBuildEnv{
-		ANDROID_HOME:       "",
-		ANDROID_NDK_ROOT:   "",
-		AR:                 "",
-		BINPATH:            "",
-		CC:                 "",
-		CFLAGS:             cflags,
-		CONFIGURE_HOST:     "",
-		DESTDIR:            destdir,
-		CXX:                "",
-		CXXFLAGS:           cflags,
-		GOARCH:             "",
-		GOARM:              "",
-		LD:                 "",
-		LDFLAGS:            []string{},
-		OPENSSL_API_DEFINE: "",
-		OPENSSL_COMPILER:   "linux-x86_64",
-		RANLIB:             "",
-		STRIP:              "",
+		ANDROID_HOME:                "",
+		ANDROID_NDK_ROOT:            "",
+		AR:                          "",
+		BINPATH:                     "",
+		CC:                          "",
+		CFLAGS:                      cflags,
+		CONFIGURE_HOST:              "",
+		DESTDIR:                     destdir,
+		CXX:                         "",
+		CXXFLAGS:                    cflags,
+		GOARCH:                      "",
+		GOARM:                       "",
+		LD:                          "",
+		LDFLAGS:                     []string{},
+		OPENSSL_COMPILER:            "linux-x86_64",
+		OPENSSL_POST_COMPILER_FLAGS: []string{},
+		RANLIB:                      "",
+		STRIP:                       "",
 	}
 	switch name {
 	case "libevent":