Fix dev_minor()/dev_major()/dev_makedev() for Mac.

Major/minor device encoding is not portable. No two BSDs agree with
each other, and Darwin is different again.

Everyone does agree on having major()/minor()/makedev() macros, but
they disagree whether they should be in <sys/types.h> (the BSDs
including Darwin, and old versions of glibc) or <sys/sysmacros.h>
(glibc >= 2.26 and bionic).

This fixes `ls -l /dev/zero` and `stat /dev/zero` on Mac.

1 files changed, 33 insertions, 0 deletions

diff --git a/lib/portability.c b/lib/portability.c
index 0b5677cc..ae862c97 100644
--- a/lib/portability.c
+++ b/lib/portability.c
@@ -515,3 +515,36 @@ char *num_to_sig(int sig)
 
   return NULL;
 }
+
+int dev_minor(int dev)
+{
+#if defined(__linux__)
+  return ((dev&0xfff00000)>>12)|(dev&0xff);
+#elif defined(__APPLE__)
+  return dev&0xffffff;
+#else
+#error
+#endif
+}
+
+int dev_major(int dev)
+{
+#if defined(__linux__)
+  return (dev&0xfff00)>>8;
+#elif defined(__APPLE__)
+  return (dev>>24)&0xff;
+#else
+#error
+#endif
+}
+
+int dev_makedev(int major, int minor)
+{
+#if defined(__linux__)
+  return (minor&0xff)|((major&0xfff)<<8)|((minor&0xfff00)<<12);
+#elif defined(__APPLE__)
+  return (minor&0xffffff)|((major&0xff)<<24);
+#else
+#error
+#endif
+}