Re: [PATCH] compat: convert modes to use portable file type values
From: Junio C Hamano <hidden>
Date: 2016-06-15 23:03:09
David Michael [off-list ref] writes:
This is my most recent attempt at solving the problem of z/OS using different file type values than every other OS. I believe it should be safe as long as the file type bits don't ever need to be converted back to their native values (and I didn't see any instances of that). I've been testing it by making commits to the same repositories on different operating systems and pushing those changes around, and so far there have been no issues. Can anyone foresee any problems with this method?
I cannot offhand comment on the last question above, but the reliance on exact S_IFxxx bit assignment was identified as a potential problem from very early days of Git that we have known about but didn't have need to address on any system that mattered. This is a long overdue issue and I am happy to see it getting tackled. The patch seems to be a sensible implementation of your design decision to use the one-way conversion.
quoted hunk
diff --git a/compat/stat.c b/compat/stat.c new file mode 100644 index 0000000..0ff1f2f --- /dev/null +++ b/compat/stat.c@@ -0,0 +1,49 @@ +#define _POSIX_SOURCE +#include <stddef.h> /* NULL */ +#include <sys/stat.h> /* *stat, S_IS* */ +#include <sys/types.h> /* mode_t */ + +static inline mode_t mode_native_to_git(mode_t native_mode) +{ + if (S_ISREG(native_mode)) + return 0100000 | (native_mode & 07777); + else if (S_ISDIR(native_mode)) + return 0040000 | (native_mode & 07777); + else if (S_ISLNK(native_mode)) + return 0120000 | (native_mode & 07777); + else if (S_ISBLK(native_mode)) + return 0060000 | (native_mode & 07777); + else if (S_ISCHR(native_mode)) + return 0020000 | (native_mode & 07777); + else if (S_ISFIFO(native_mode)) + return 0010000 | (native_mode & 07777); + else /* Non-standard type bits were given. */ + return native_mode & 07777; +}