CODEWITHSUNDEEP
cxcodemacosheader-filesmacos-mojave
Matthieu Brucher
Matthieu Brucher

Reputation: 22023

Where are the C headers in MacOS Mojave?

It seems that Apple keeps on moving their tools around and the old solution of installing the command line tools are with using xcode-select --install doesn't work.

In Mojave, xcode-select doesn't install anything anymore (the GUI always fails to find the package) and the command line tools don't install itself in /usr/ or /usr/local.

Upvotes: 17

Views: 35460

Answers (3)

Eric Postpischil
Eric Postpischil

Reputation: 222234

Xcode now supports multiple SDKs and multiple installations of Xcode in different locations. The SDKs are inside Xcode.app, and Xcode.app is installed by default in Applications but may be elsewhere.

xcrun --show-sdk-path will show a default SDK path, but there may be others. For example, one possible path is /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk. From there, usr/include holds common public headers such as the standard C headers, and various Apple headers are in frameworks under System.

In /Applications/Xcode.app/Contents/Developer/Platforms, you will likely find folders for other platforms, such as iPhoneOS.platform and AppleTVOS.platform. Within those, Developer/SDKs leads to SDKs for those platforms.

Upvotes: 9

mpmeyer
mpmeyer

Reputation: 6944

Per the following article: https://silvae86.github.io/sysadmin/mac/osx/mojave/beta/libxml2/2018/07/05/fixing-missing-headers-for-homebrew-in-mac-osx-mojave/

This will install the headers:

open /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg

Upvotes: 4

olehermanse
olehermanse

Reputation: 366

xcode-select --install did work for me in Mojave. Maybe you can try installing XCode from Mac App Store, and then install developer tools?

Regarding header locations, I have Apples headers in /Library/Developer/CommandLineTools/:

$ sudo find /Library -name stdio.h 
/Library/Developer/CommandLineTools/usr/include/c++/v1/stdio.h
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/sys/stdio.h
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/stdio.h
/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Frameworks/Kernel.framework/Versions/A/Headers/sys/stdio.h

And if you install gcc via brew, it will add headers in /usr/local/:

$ sudo find /usr -name stdio.h 
/usr/local/Cellar/gcc/8.2.0/include/c++/8.2.0/tr1/stdio.h
/usr/local/Cellar/gcc/8.2.0/lib/gcc/8/gcc/x86_64-apple-darwin17.7.0/8.2.0/include/ssp/stdio.h
/usr/local/Cellar/gcc/8.2.0/lib/gcc/8/gcc/x86_64-apple-darwin17.7.0/8.2.0/include-fixed/stdio.h
/usr/local/Cellar/gcc/8.1.0/include/c++/8.1.0/tr1/stdio.h
/usr/local/Cellar/gcc/8.1.0/lib/gcc/8/gcc/x86_64-apple-darwin17.5.0/8.1.0/include/ssp/stdio.h
/usr/local/Cellar/gcc/8.1.0/lib/gcc/8/gcc/x86_64-apple-darwin17.5.0/8.1.0/include-fixed/stdio.h
/usr/local/Cellar/gcc/7.3.0_1/include/c++/7.3.0/tr1/stdio.h
/usr/local/Cellar/gcc/7.3.0_1/lib/gcc/7/gcc/x86_64-apple-darwin17.3.0/7.3.0/include/ssp/stdio.h
/usr/local/Cellar/gcc@7/7.3.0/include/c++/7.3.0/tr1/stdio.h
/usr/local/Cellar/gcc@7/7.3.0/lib/gcc/7/gcc/x86_64-apple-darwin17.5.0/7.3.0/include/ssp/stdio.h
/usr/local/Cellar/gcc@7/7.3.0/lib/gcc/7/gcc/x86_64-apple-darwin17.5.0/7.3.0/include-fixed/stdio.h
/usr/local/include/c++/8.2.0/tr1/stdio.h
/usr/local/lib/gcc/8/gcc/x86_64-apple-darwin17.7.0/8.2.0/include/ssp/stdio.h
/usr/local/lib/gcc/8/gcc/x86_64-apple-darwin17.7.0/8.2.0/include-fixed/stdio.h

(Those are not Apple's headers, but GCC / GLIBC).

Using dtruss I can see that Apple clang uses the one in CommandLineTools/SDKs:

$ sudo dtruss -f sudo -u $USER clang test.c -o test 2>&1
3781/0x51d8:  pread(0x3, "#include <stdio.h>\n\nint main(void)\n{\n  printf(\"Hello, world\\n\");\n  return 0;\n}\n\0", 0x4F, 0x0)              = 79 0
3781/0x51d8:  __pthread_sigmask(0x3, 0x7FFEE3A7E768, 0x7FFEE3A7E76C)            = 0 0
3781/0x51d8:  close(0x3)                = 0 0
3781/0x51d8:  __pthread_sigmask(0x3, 0x7FFEE3A7E76C, 0x0)               = 0 0
3781/0x51d8:  open("/usr/local/include/stdio.h\0", 0x1000000, 0x1A)             = -1 Err#2
3781/0x51d8:  open("/Library/Developer/CommandLineTools/usr/lib/clang/10.0.0/include/stdio.h\0", 0x1000000, 0x48)               = -1 Err#2
3781/0x51d8:  open("/Library/Developer/CommandLineTools/usr/include/stdio.h\0", 0x1000000, 0x37)                = -1 Err#2
3781/0x51d8:  open("/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/stdio.h\0", 0x1000000, 0x47)                = 3 0

Upvotes: 22

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