URL:
<http://savannah.gnu.org/bugs/?39934>
Summary: make closes a wrong FD, results in *** INTERNAL:
readdir: Bad file descriptor
Project: make
Submitted by: pmachata
Submitted on: Втр 03 Сен 2013 17:44:02
Severity: 3 - Normal
Item Group: Bug
Status: None
Privacy: Public
Assigned to: None
Open/Closed: Open
Discussion Lock: Any
Component Version: SCM
Operating System: None
Fixed Release: None
Triage Status: None
_______________________________________________________
Details:
This was filed in Red Hat bugzilla here:
https://bugzilla.redhat.com/show_bug.cgi?id=885474
To reproduce this, use the following Makefile:
default:
/home/petr/src/make/build/make -f Makefile2
And the following Makefile2 (note: the path in vpath must exist):
vpath %.c /home/petr/
foo:
Then run make:
$ make -j 2
/home/petr/src/make/build/make -f Makefile2
make[1]: Entering directory `/home/petr/tmp/tst'
make[1]: warning: jobserver unavailable: using -j1. Add `+' to parent make
rule.
make[1]: *** INTERNAL: readdir: Bad file descriptor
. Stop.
make[1]: Makefile2: Field 'stem' not cached: Makefile2
make[1]: Leaving directory `/home/petr/tmp/tst'
make: *** [default] Error 2
The following excerpt from an ltrace run illustrates the problem:
18706 16:46:43.945567 opendir("/home/petr" <unfinished ...>
18706 16:46:43.945713 SYS_open("/home/petr", 591872, 0172204710) = 4
18706 16:46:43.945785 SYS_brk(0) = 0x1e9d000
18706 16:46:43.945824 SYS_brk(0x1ec5000) = 0x1ec5000
18706 16:46:43.945870 <... opendir resumed> ) = { 4 }
[...]
18706 16:46:44.347777 close(4 <unfinished ...>
18706 16:46:44.347882 SYS_close(4) = 0
18706 16:46:44.347927 <... close resumed> ) = 0
[...]
18706 16:46:45.718922 readdir({ 4 } <unfinished ...>
18706 16:46:45.719037 SYS_getdents(4, 0x161f008, 32768) = -9
18706 16:46:45.719103 <... readdir resumed> ) = 0
The problem arises when parental make passes down jobserver FDs in the
environment, but the child make is not run as part of this jobsever batch.
Child make notices JOB_FDS numbers passed down, and tries to dup, which fails,
because JOB_FDS[0] is invalid. In then switches to -j1, and proceeds to close
JOB_FDS. But in the meantime make managed to reuse one of those descriptors
for a directory stream for vpath. When that is closed it later causes the
error message seen in the subject.
The immediate idea is not to close JOB_FDS if the dup fails. That's certainly
part of the solution (because otherwise we end up calling close over invalid
file descriptors). But that it fails is pure luck: make gets FD 3 for
Makefile2, then FD 4 for vpath dirstream, and then closes 3 after it's done
with it. Had --jobserver-fds been 4 and 5, we would dup it without trouble.
But perhaps it's possible to move read_all_makefiles down beyond the JOB_FDS
business. Then there would be no file operations except those in the dynamic
linker, and those don't leak descriptors. Then we can use the dup as a
reliable test. However I don't know whether there are interactions that I
don't see, and whether it's safe and desirable to postpone the parsing to a
later time like this. The test suite passes with this FWIW.
_______________________________________________________
File Attachments:
-------------------------------------------------------
Date: Втр 03 Сен 2013 17:44:02 Name:
0001-Don-t-close-JOB_FDS-if-we-know-they-are-invalid.patch Size: 2kB By:
pmachata
A fix
<http://savannah.gnu.org/bugs/download.php?file_id=28997>
_______________________________________________________
Reply to this item at:
<http://savannah.gnu.org/bugs/?39934>
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