Hi. On Mon, Aug 27, 2018 at 12:01:23PM -0400, Greg Wooledge wrote: > On Mon, Aug 27, 2018 at 06:41:25PM +0300, Reco wrote: > > Last sentence says to me that wordexp output should be always sorted. > > This only tells us that it *reads* the config files in glob-sorted order. > And peeking into the actual source code of ifupdown, yes, it appears to > do this. (File config.c starting at line 436, in the stretch source.) > It even uses wordexp() as advertised. > > What's less clear to me at this moment is what happens *after* the > interface configuration file(s) have been read into memory. > > Moving over to main.c, it looks like it reads the interfaces (line 639), > and that function was called from line 1190. After line 1190, it loops > over the "target_iface" array, and processes them in the order they appear > in that array. > > So... next question is how they get packed into that array. > > Returning to the select_interfaces function, it looks like the ordering > is created by a call to find_allowup. > > And... this is where I stopped reading, because it got confusing. Maybe > someone else can take a stab at deciphering that part.
select_interfaces() is called on "ifup -a" invocation. read_interfaces() is called by it. read_interfaces() calls read_interfaces_defn(). read_interfaces_defn() parses "iface" and "source" directives, and calls read_interfaces_defn() once again on each file specified by "source" in order defined by wordexp(3). Therefore defn[] array should be filled in this order (assuming that one specifies "source" only at /e/n/i): 1) any interface definition at /e/n/i in order encountered, until "source" directive. 2) any interface definition provided by "source" directive in order defined by wordexp(3). 3) any interface definition at /e/n/i in order encountered, after the "source" directive. I'd use ltrace(1) to check it, but building test environment is something that I lack the time to do. Reco
