URL:
<https://savannah.gnu.org/bugs/?57242>
Summary: Non-recursive command passes invalid jobserver file
descriptors
Project: make
Submitted by: stefanbruens
Submitted on: Fri 15 Nov 2019 07:41:39 PM UTC
Severity: 3 - Normal
Item Group: Bug
Status: None
Privacy: Public
Assigned to: None
Open/Closed: Open
Discussion Lock: Any
Component Version: 4.2.1
Operating System: POSIX-Based
Fixed Release: None
Triage Status: None
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Details:
The problem can be reproduced using the following trivial
Makefile:
---
all:
env | grep FLAGS
---
Using strace to get some diagnostics:
$> env -i strace -epipe,dup2,execve,fcntl -v -f -o nonrecursive.txt
/usr/bin/make -j2 -f Makefile
Obivously, the jobserver file descriptors (3,4) are closed on exec by
fcntl({3,4}, F_SETFD, FD_CLOEXEC), but are still exported via
MFLAGS/MAKEFLAGS=--jobserver-auth=3,4.
When the "env | grep FLAGS" command is invoked via shell, the shell creates a
new pipe, reusing the no longer used file descriptors 3 and 4.
I.e. "env" (which serves as a placeholder here for some command implementing
the jobserver protocol) receives some file descriptors which are no jobserver
fds.
This does not happen when the command is marked as a recursive one (using the
'+' marker), but this is non-trivial to achieve in practice:
1. the Makefile may come from some generator
2. the command itself may be some script invoking "gmake" again.
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