[libc] Add FILENO related macros to unistd.h.

[c8ef]

Closes #124637.

This is necessary to build LLVM with LLVM-libc and align the behavior with other libc implementations.
ref: https://man7.org/linux/man-pages/man3/stdin.3.html

[llvmbot]

@llvm/pr-subscribers-libc

Author: None (c8ef)

Changes

Closes #124637.

This is necessary to build LLVM with LLVM-libc and align the behavior with other libc implementations.
ref: https://man7.org/linux/man-pages/man3/stdin.3.html

---

Full diff: https://github.com/llvm/llvm-project/pull/124688.diff

1 Files Affected:

• (modified) libc/include/llvm-libc-macros/unistd-macros.h (+4)

diff --git a/libc/include/llvm-libc-macros/unistd-macros.h b/libc/include/llvm-libc-macros/unistd-macros.h
index 4f27f075fcc61b..e09dada04a19d4 100644
--- a/libc/include/llvm-libc-macros/unistd-macros.h
+++ b/libc/include/llvm-libc-macros/unistd-macros.h
@@ -5,4 +5,8 @@
 #include "linux/unistd-macros.h"
 #endif
 
+#define STDIN_FILENO 0
+#define STDOUT_FILENO 1
+#define STDERR_FILENO 2
+
 #endif // LLVM_LIBC_MACROS_UNISTD_MACROS_H

[RossComputerGuy]

LGTM

[nickdesaulniers]

Thanks for the patch.

A better source to cite rather than the man page is POSIX itself, which mandates these symbolic constants have these specific values.

https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/unistd.h.html

[c8ef]

A better source to cite rather than the man page is POSIX itself, which mandates these symbolic constants have these specific values.

https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/unistd.h.html

Got it, thanks for your advice!