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gnu: glibc-final: Catch all cases of a glibc user not requesting 64-bit offsets and then using readdir regardless.

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* gnu/packages/commencement.scm (glibc-final): Catch all cases of a glibc user not
requesting 64-bit offsets and then using readdir.
This commit is contained in:
Danny Milosavljevic 2020-09-21 17:17:05 +02:00
parent c9cfcd5159
commit 51d13466bb
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1 changed files with 67 additions and 1 deletions
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68
gnu/packages/commencement.scm
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@ -3462,7 +3462,73 @@ (define glibc-final
,hurd-headers-boot0)
'())
,@(package-outputs glibc-final-with-bootstrap-bash))
,@(package-arguments glibc-final-with-bootstrap-bash)))))
,@(substitute-keyword-arguments
(package-arguments glibc-final-with-bootstrap-bash)
((#:phases phases)
`(modify-phases ,phases
(add-after 'unpack 'patch-dirent
(lambda* (#:key outputs #:allow-other-keys)
;; Linux kernel file offsets are always 64 bits.
;; But userspace can be built to use 32 bit offsets.
;;
;; "struct dirent", returned by readdir, uses d_off to store
;; such an "offset" that it got from the Linux kernel.
;; In the case of ext4 that "offset" is actually a 64 bit
;; hash value.
;;
;; Therefore, there are cases where such an offset that it got
;; from the Linux kernel does not fit in the "struct dirent"
;; field "d_off".
;;
;; If the guest system's glibc is 32 bit AND uses 32 bit
;; file offsets it is going to be very confused.
;; It does check whether d_off fits into the structure
;; it gives back to the user--and it doesn't fit. Hence readdir
;; fails, with errno == EOVERFLOW (which is undocumented and thus
;; an API error).
;; This manifests itself in simple directory reads not working
;; anymore in parts of cmake, for example.
;;
;; This manifested in Guix when building stuff for
;; ARMHF on a x86_64 build host using QEMU transparent emulation.
;;
;; There is a very simple and complete way to avoid this problem:
;; Just always use 64 bit offsets in user space programs (also
;; on 32 bit machines). The Linux kernel does that already
;; anyway.
;;
;; Note: We might want to avoid using 64 bit when bootstrapping
;; using mescc (since mescc doesn't directly support 64 bit
;; values)--but then bootstrapping has to be done on a
;; file system other than ext4, or on ext4 with the feature
;; "dir_index" disabled.
;;
;; The change below does not affect 64 bit users.
;;
;; See <https://issues.guix.gnu.org/43513>.
(let ((port (open-file "dirent/dirent.h" "a")))
(display "
#ifndef _LIBC
#if __SIZEOF_LONG__ < 8
#ifndef __USE_FILE_OFFSET64
#if defined(_FILE_OFFSET_BITS) && _FILE_OFFSET_BITS == 32
#warning \"Using -D_FILE_OFFSET_BITS=32 and using readdir is a bad idea, see <https://bugzilla.kernel.org/show_bug.cgi?id=205957>\"
#else
#undef readdir
#define readdir @READDIR_WITHOUT_FILE_OFFSET64_IS_A_REALLY_BAD_IDEA@
#endif
#endif
#endif
#endif
" port)
(close-port port))
;; This file includes <dirent.h> and thus checks sanity already.
;; TODO: Check dirent/scandir-tail.c, dirent/scandir64-tail.c.
(substitute* "posix/glob.c"
(("(#[ ]*define[ ][ ]*readdir)") "
#undef readdir
#define readdir"))
#t)))))))))
(define/system-dependent gcc-boot0-wrapped
;; Make the cross-tools GCC-BOOT0 and BINUTILS-BOOT0 available under the