Date: Tue, 7 May 2013 13:58:12 -0700 From: Garrett Cooper <yaneurabeya@gmail.com> To: dim@FreeBSD.org Cc: toolchain@freebsd.org Subject: clang doesn't make temporary files in all instances, causes build races by not using mk*temp(3) in /tmp Message-ID: <CAGHfRMCnmViGvJadmmmKyE=mAdgWFbX5woPUbGb3mdUVkUbFeQ@mail.gmail.com>
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Hi Dimitriy,
I ran into the following error when trying to execute make
tinderbox with FreeBSD svn head with ATF changes I'm going to push to
benno@:
cc -O -pipe -DHAVE_CONFIG_H
-I/scratch/freebsd/head-svn/gnu/lib/libgomp -I.
-I/scratch/freebsd/head-svn/gnu/lib/libgomp/../../../contrib/gcclibs/libgomp
-I/scratch/freebsd/head-svn/gnu/lib/libgomp/../../../contrib/gcclibs/libgomp/config/posix
-std=gnu99 -Qunused-arguments -c
/scratch/freebsd/head-svn/gnu/lib/libgomp/../../../contrib/gcclibs/libgomp/config/posix/bar.c
-o bar.o
cc: error: unable to make temporary file: /tmp/bar: can't make unique
filename: Permission denied
*** [bar.o] Error code 1
Did some poking around in the clang source and it looks like it's
doing some less than intelligent things when generating "temporary"
paths (from contrib/llvm/tools/clang/lib/Driver/Driver.cpp ):
1598 std::string Driver::GetTemporaryPath(StringRef Prefix, const char *Suffix)
1599 const {
1600 // FIXME: This is lame; sys::Path should provide this function
(in particular,
1601 // it should know how to find the temporary files dir).
1602 std::string Error;
1603 const char *TmpDir = ::getenv("TMPDIR");
1604 if (!TmpDir)
1605 TmpDir = ::getenv("TEMP");
1606 if (!TmpDir)
1607 TmpDir = ::getenv("TMP");
1608 if (!TmpDir)
1609 TmpDir = "/tmp";
1610 llvm::sys::Path P(TmpDir);
1611 P.appendComponent(Prefix);
1612 if (P.makeUnique(false, &Error)) {
1613 Diag(clang::diag::err_unable_to_make_temp) << Error;
1614 return "";
1615 }
1616
1617 // FIXME: Grumble, makeUnique sometimes leaves the file around!? PR3837.
1618 P.eraseFromDisk(false, 0);
1619
1620 if (Suffix)
1621 P.appendSuffix(Suffix);
1622 return P.str();
This logic (line 1612) is racy and incorrect.
This _needs_ to be fixed in clang to properly prefix and rename to
the target path in the filesystem where the compilation is being done
in order to avoid races with partial compilations, etc.
Thanks,
-Garrett
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