merge revision(s) c15cddd1d515c5bd8dfe8fb2725e3f723aec63b8: [Backport #16787]

	Allow Dir.home to work for non-login procs when $HOME not set

	Allow the 'Dir.home' method to reliably locate the user's home directory when
	all three of the following are true at the same time:

	1. Ruby is running on a Unix-like OS
	2. The $HOME environment variable is not set
	3. The process is not a descendant of login(1) (or a work-alike)

	The prior behavior was that the lookup could only work for login-descended
	processes.

	This is accomplished by looking up the user's record in the password database
	by uid (getpwuid_r(3)) as a fallback to the lookup by name (getpwname_r(3))
	which is still attempted first (based on the name, if any, returned by
	getlogin_r(3)).

	If getlogin_r(3), getpwnam_r(3), and/or getpwuid_r(3) is not available at
	compile time, will fallback on using their respective non-*_r() variants:
	getlogin(3), getpwnam(3), and/or getpwuid(3).

	The rationale for attempting to do the lookup by name prior to doing it by uid
	is to accommodate the possibility of multiple login names (each with its own
	record in the password database, so each with a potentially different home
	directory) being mapped to the same uid (as is explicitly allowed for by
	POSIX; see getlogin(3posix)).

	Preserves the existing behavior for login-descended processes, and adds the
	new capability of having Dir.home being able to find the user's home directory
	for non-login-descended processes.

	Fixes [Bug #16787]

	Related discussion:
	https://bugs.ruby-lang.org/issues/16787
	https://github.com/ruby/ruby/pull/3034


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_6@67931 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 6 insertions, 0 deletions

diff --git a/internal.h b/internal.h
index 9583e8388e..37e5c73d18 100644
--- a/internal.h
+++ b/internal.h
@@ -2303,6 +2303,12 @@ void rb_write_error_str(VALUE mesg);
 /* numeric.c (export) */
 VALUE rb_int_positive_pow(long x, unsigned long y);
 
+#ifdef HAVE_PWD_H
+VALUE rb_getlogin(void);
+VALUE rb_getpwdirnam_for_login(VALUE login);  /* read as: "get pwd db home dir by username for login" */
+VALUE rb_getpwdiruid(void);                   /* read as: "get pwd db home dir for getuid()" */
+#endif
+
 /* process.c (export) */
 int rb_exec_async_signal_safe(const struct rb_execarg *e, char *errmsg, size_t errmsg_buflen);
 rb_pid_t rb_fork_async_signal_safe(int *status, int (*chfunc)(void*, char *, size_t), void *charg, VALUE fds, char *errmsg, size_t errmsg_buflen);