From cca4ece0a8910fd032fb9219687c6516e331a6cc Mon Sep 17 00:00:00 2001
From: Sushant Pandurangi <sushpa@alumni.ethz.ch>
Date: Tue, 6 Jul 2021 22:48:38 +0200
Subject: [PATCH] macOS: get active SDK path from xcode-select

---
 libtcc.c | 29 ++++++++++++++++++++++++++++-
 tcc.h    | 24 +++++++++---------------
 2 files changed, 37 insertions(+), 16 deletions(-)

diff --git a/libtcc.c b/libtcc.c
index db109886..11999d2c 100644
--- a/libtcc.c
+++ b/libtcc.c
@@ -855,6 +855,29 @@ LIBTCCAPI void tcc_delete(TCCState *s1)
 #endif
 }
 
+/* Looks for the active developer SDK set by xcode-select (or the default
+   one set during installation.) */
+#define SZPAIR(s) s "", sizeof(s)-1
+ST_FUNC int tcc_add_macos_sdkpath(TCCState* s)
+{
+    char *sdkroot = NULL, *pos = NULL;
+    void* xcs = dlopen("libxcselect.dylib", RTLD_GLOBAL | RTLD_LAZY);
+    CString path = {};
+    int (*f)(unsigned int, char**) = dlsym(xcs, "xcselect_host_sdk_path");
+
+    if (f) f(1, &sdkroot);
+    if (!sdkroot) return -1;
+    pos = strstr(sdkroot,"SDKs/MacOSX");
+    if (!pos) return -1;
+    cstr_cat(&path, sdkroot, pos-sdkroot);
+    cstr_cat(&path, SZPAIR("SDKs/MacOSX.sdk/usr/lib\0") );
+    tcc_add_library_path(s, (char*)path.data);
+    cstr_free(&path);
+    tcc_free(sdkroot);
+    return 0;
+}
+#undef SZPAIR
+
 LIBTCCAPI int tcc_set_output_type(TCCState *s, int output_type)
 {
     s->output_type = output_type;
@@ -881,7 +904,11 @@ LIBTCCAPI int tcc_set_output_type(TCCState *s, int output_type)
     }
 
     tcc_add_library_path(s, CONFIG_TCC_LIBPATHS);
-
+#ifdef TCC_TARGET_MACHO
+    if (tcc_add_macos_sdkpath(s) != 0) {
+        tcc_add_library_path(s, CONFIG_OSX_SDK_FALLBACK);
+    }
+#endif
 #ifdef TCC_TARGET_PE
 # ifdef _WIN32
     if (!s->nostdlib && output_type != TCC_OUTPUT_OBJ)
diff --git a/tcc.h b/tcc.h
index 5650aee9..cc8a2f82 100644
--- a/tcc.h
+++ b/tcc.h
@@ -247,12 +247,6 @@ extern long double strtold (const char *__nptr, char **__endptr);
 # define ALSO_TRIPLET(s) s
 #endif
 
-/* FIXME: do this at runtime instead; check output of `xcode-select -p`. libxcselect provides this stuff */
-#ifndef CONFIG_OSX_SDK1
-# define CONFIG_OSX_SDK1 "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk"
-# define CONFIG_OSX_SDK2 "/Applications/Xcode.app/Developer/SDKs/MacOSX.sdk"
-#endif
-
 /* path to find crt1.o, crti.o and crtn.o */
 #ifndef CONFIG_TCC_CRTPREFIX
 # define CONFIG_TCC_CRTPREFIX USE_TRIPLET(CONFIG_SYSROOT "/usr/" CONFIG_LDDIR)
@@ -281,18 +275,18 @@ extern long double strtold (const char *__nptr, char **__endptr);
 # ifdef TCC_TARGET_PE
 #  define CONFIG_TCC_LIBPATHS "{B}/lib"
 # else
-#  ifdef TCC_TARGET_MACHO
-#   define CONFIG_TCC_LIBPATHS \
-        ALSO_TRIPLET(CONFIG_SYSROOT "/usr/" CONFIG_LDDIR) \
-    ":" ALSO_TRIPLET(CONFIG_SYSROOT "/" CONFIG_LDDIR) \
-    ":" ALSO_TRIPLET(CONFIG_SYSROOT "/usr/local/" CONFIG_LDDIR)\
-    ":" ALSO_TRIPLET(CONFIG_OSX_SDK1 "/usr/" CONFIG_LDDIR) \
-    ":" ALSO_TRIPLET(CONFIG_OSX_SDK2 "/usr/" CONFIG_LDDIR)
-#  else
-#   define CONFIG_TCC_LIBPATHS \
+#  define CONFIG_TCC_LIBPATHS \
         ALSO_TRIPLET(CONFIG_SYSROOT "/usr/" CONFIG_LDDIR) \
     ":" ALSO_TRIPLET(CONFIG_SYSROOT "/" CONFIG_LDDIR) \
     ":" ALSO_TRIPLET(CONFIG_SYSROOT "/usr/local/" CONFIG_LDDIR)
+#  ifdef TCC_TARGET_MACHO
+#   define CONFIG_OSX_SDK1 \
+        "/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk"
+#   define CONFIG_OSX_SDK2 \
+        "/Applications/Xcode.app/Developer/SDKs/MacOSX.sdk"
+#   define CONFIG_OSX_SDK_FALLBACK \
+        ALSO_TRIPLET(CONFIG_OSX_SDK1 "/usr/" CONFIG_LDDIR) \
+    ":" ALSO_TRIPLET(CONFIG_OSX_SDK2 "/usr/" CONFIG_LDDIR)
 #  endif
 # endif
 #endif