libtool.m4: fix nm BSD flag detection
Libtool needs to get BSD-format (or MS-format) output out of the system nm, so that it can scan generated object files for symbol names for -export-symbols-regex support. Some nms need specific flags to turn on BSD-formatted output, so libtool checks for this in its AC_PATH_NM. Unfortunately the code to do this has a pair of interlocking flaws: - it runs the test by doing an nm of /dev/null. Some platforms reasonably refuse to do an nm on a device file, but before now this has only been worked around by assuming that the error message has a specific textual form emitted by Tru64 nm, and that getting this error means this is Tru64 nm and that nm -B would work to produce BSD-format output, even though the test never actually got anything but an error message out of nm -B. This is fixable by nm'ing *nm itself* (since we necessarily have a path to it). - the test is entirely skipped if NM is set in the environment, on the grounds that the user has overridden the test: but the user cannot reasonably be expected to know that libtool wants not only nm but also flags forcing BSD-format output. Worse yet, one such "user" is the top-level Cygnus configure script, which neither tests for nor specifies any BSD-format flags. So platforms needing BSD-format flags always fail to set them when run in a Cygnus tree, breaking -export-symbols-regex on such platforms. Libtool also needs to augment $LD on some platforms, but this is done unconditionally, augmenting whatever the user specified: the nm check should do the same. One wrinkle: if the user has overridden $NM, a path might have been provided: so we use the user-specified path if there was one, and otherwise do the path search as usual. (If the nm specified doesn't work, this might lead to a few extra pointless path searches -- but the test is going to fail anyway, so that's not a problem.) (Tested with NM unset, and set to nm, /usr/bin/nm, my-nm where my-nm is a symlink to /usr/bin/nm on the PATH, and /not-on-the-path/my-nm where *that* is a symlink to /usr/bin/nm.) ChangeLog 2021-09-27 Nick Alcock <nick.alcock@oracle.com> PR libctf/27967 * libtool.m4 (LT_PATH_NM): Try BSDization flags with a user-provided NM, if there is one. Run nm on itself, not on /dev/null, to avoid errors from nms that refuse to work on non-regular files. Remove other workarounds for this problem. Strip out blank lines from the nm output.
This commit is contained in:
Nick Alcock
parent
bc4b140112
commit
bef9ef8ca0
2 changed files with 54 additions and 43 deletions
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@ -1,3 +1,12 @@
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2021-09-27 Nick Alcock <nick.alcock@oracle.com>
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PR libctf/27967
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* libtool.m4 (LT_PATH_NM): Try BSDization flags with a user-provided
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NM, if there is one. Run nm on itself, not on /dev/null, to avoid
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errors from nms that refuse to work on non-regular files. Remove
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other workarounds for this problem. Strip out blank lines from the
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nm output.
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2021-09-27 Nick Alcock <nick.alcock@oracle.com>
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PR libctf/27967
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88
libtool.m4
vendored
88
libtool.m4
vendored
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@ -3200,53 +3200,55 @@ _LT_DECL([], [file_magic_cmd], [1],
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# LT_PATH_NM
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# ----------
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# find the pathname to a BSD- or MS-compatible name lister
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# find the pathname to a BSD- or MS-compatible name lister, and any flags
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# needed to make it compatible
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AC_DEFUN([LT_PATH_NM],
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[AC_REQUIRE([AC_PROG_CC])dnl
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AC_CACHE_CHECK([for BSD- or MS-compatible name lister (nm)], lt_cv_path_NM,
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[if test -n "$NM"; then
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# Let the user override the test.
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lt_cv_path_NM="$NM"
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else
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lt_nm_to_check="${ac_tool_prefix}nm"
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if test -n "$ac_tool_prefix" && test "$build" = "$host"; then
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lt_nm_to_check="$lt_nm_to_check nm"
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fi
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for lt_tmp_nm in $lt_nm_to_check; do
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lt_save_ifs="$IFS"; IFS=$PATH_SEPARATOR
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for ac_dir in $PATH /usr/ccs/bin/elf /usr/ccs/bin /usr/ucb /bin; do
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IFS="$lt_save_ifs"
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test -z "$ac_dir" && ac_dir=.
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tmp_nm="$ac_dir/$lt_tmp_nm"
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if test -f "$tmp_nm" || test -f "$tmp_nm$ac_exeext" ; then
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# Check to see if the nm accepts a BSD-compat flag.
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# Adding the `sed 1q' prevents false positives on HP-UX, which says:
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# nm: unknown option "B" ignored
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# Tru64's nm complains that /dev/null is an invalid object file
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case `"$tmp_nm" -B /dev/null 2>&1 | sed '1q'` in
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*/dev/null* | *'Invalid file or object type'*)
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lt_cv_path_NM="$tmp_nm -B"
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break
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;;
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*)
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case `"$tmp_nm" -p /dev/null 2>&1 | sed '1q'` in
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*/dev/null*)
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lt_cv_path_NM="$tmp_nm -p"
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break
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;;
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*)
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lt_cv_path_NM=${lt_cv_path_NM="$tmp_nm"} # keep the first match, but
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continue # so that we can try to find one that supports BSD flags
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;;
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esac
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;;
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esac
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fi
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done
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IFS="$lt_save_ifs"
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done
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: ${lt_cv_path_NM=no}
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fi])
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# Let the user override the nm to test.
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lt_nm_to_check="$NM"
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else
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lt_nm_to_check="${ac_tool_prefix}nm"
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if test -n "$ac_tool_prefix" && test "$build" = "$host"; then
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lt_nm_to_check="$lt_nm_to_check nm"
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fi
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fi
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for lt_tmp_nm in $lt_nm_to_check; do
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lt_save_ifs="$IFS"; IFS=$PATH_SEPARATOR
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for ac_dir in $PATH /usr/ccs/bin/elf /usr/ccs/bin /usr/ucb /bin; do
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IFS="$lt_save_ifs"
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test -z "$ac_dir" && ac_dir=.
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case "$lt_tmp_nm" in
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*/*|*\\*) tmp_nm="$lt_tmp_nm";;
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*) tmp_nm="$ac_dir/$lt_tmp_nm";;
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esac
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if test -f "$tmp_nm" || test -f "$tmp_nm$ac_exeext" ; then
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# Check to see if the nm accepts a BSD-compat flag.
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# Adding the `sed 1q' prevents false positives on HP-UX, which says:
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# nm: unknown option "B" ignored
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case `"$tmp_nm" -B "$tmp_nm" 2>&1 | grep -v '^ *$' | sed '1q'` in
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*$tmp_nm*) lt_cv_path_NM="$tmp_nm -B"
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break
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;;
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*)
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case `"$tmp_nm" -p "$tmp_nm" 2>&1 | grep -v '^ *$' | sed '1q'` in
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*$tmp_nm*)
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lt_cv_path_NM="$tmp_nm -p"
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break
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;;
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*)
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lt_cv_path_NM=${lt_cv_path_NM="$tmp_nm"} # keep the first match, but
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continue # so that we can try to find one that supports BSD flags
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;;
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esac
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;;
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esac
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fi
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done
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IFS="$lt_save_ifs"
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done
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: ${lt_cv_path_NM=no}])
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if test "$lt_cv_path_NM" != "no"; then
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NM="$lt_cv_path_NM"
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else
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