modecanon - canonical file mode representation

POSIX threw out the file type bit macros and replaced them with function-like macros that test file type. This is bad in many ways, the worst of which is that it provides no way for a user program to synthesize file types in the mode bits. pax(1), tar(1) and cpio(1) are examples of user programs that must convert between the internal mode representation and a private external representation. These routines provide a canonical external representation with macros to access and synthesize the bits in the external representation.

modei takes an external mode representation external and returns the equivalent internal representation.

modex takes an internal mode representation internal and returns the equivalent external representation.

The traditional bit access macro (S_ prefix changes to X_) are: X_IFMT , X_IFSOCK , X_IFLNK , X_IFCTG , X_IFREG , X_IFBLK , X_IFDIR , X_IFCHR , X_IFIFO , X_IPERM , X_ISUID , X_ISGID , X_ISVTX , X_IRUSR , X_IWUSR , X_IXUSR , X_IRGRP , X_IWGRP , X_IXGRP , X_IROTH , X_IWOTH , X_IXOTH , X_IRWXU , X_IRWXG and X_IRWXO . X_ITYPE(mode) returns the type bits for mode.

pax(1), stat(2)