3

I develop for Linux and OpenBSD and sometimes I get the error can't preload library - do you know what it means?

The exact output I got was:

: can't preload library

When I try to run scripts and/or binaries. It seems to have to do with quoting but I'm not sure.

This problem does not occur on Linux, only OpenBSD.

enter image description here

The code is here but I don't know what it does:

void
_dl_dopreload(char *paths)
{
    char        *cp, *dp;
    elf_object_t    *shlib;

    dp = paths = _dl_strdup(paths);
    if (dp == NULL) {
        _dl_printf("preload: out of memory");
        _dl_exit(1);
    }

    while ((cp = _dl_strsep(&dp, ":")) != NULL) {
        shlib = _dl_load_shlib(cp, _dl_objects, OBJTYPE_LIB,
        _dl_objects->obj_flags);
        if (shlib == NULL) {
            _dl_printf("%s: can't preload library '%s'\n",
                __progname, cp);
            _dl_exit(4);
        }
        _dl_add_object(shlib);
        _dl_link_child(shlib, _dl_objects);
    }
    _dl_free(paths);
    return;
}

This is my script, which works with dash and Linux, that I try to run with OpenBSD:s Korn shell.

#!/bin/sh
echo "-- Testing our implementation of OpenShell --"
echo ""
echo "- If you have any problem in passing a test read the corresponding"
echo "- source file to understand what the test is checking"
echo ""
printf "********************* PRESS ENTER TO RUN TESTS  ... "
read _

# Key pressed, do something
printf "********************* TEST WILDCARDS \n***** Press any key to listing all files in current directory...\nYou should see filesnames *.* below "
read _
valgrind --leak-check=full -v ./shell << EOF
ls -al *.*
EOF
printf "********************* TEST ALGORITHMS ...  \n***** Press any key to run the algorithms... .\nYou should see the output from top -b -n1|head -8|tail -1 "
read _
top -b -n1|head -8|tail -1|sort -n|wc -l
valgrind --leak-check=full -v ./shell << EOF
ls|grep open
EOF

printf "********************* TEST ALGORITHMS Part II.  ... .\nYou should see the output from who|awk '{print \$4 ; print \$3}'|sort -n|wc -l. "
read _
valgrind --leak-check=full ./shell << EOF
who|awk '{print \$4 ; print \$3}'|sort -n|wc -l
EOF

printf "********************* TEST CHECKENV.  ..... .\nYou should see the output checkenv below "
read _
valgrind ./shell << EOF
checkenv
EOF
printf "********************* TEST DONE. YOU SHOULD SEE OUTPUT FROM TEST ABOVE ... "
read _

1 Answer 1

3
+50

openbsd has a distinct concept of memory management in terms of security. Therefore, statically linked libraries can not be preloaded.

The code reads:

        shlib = _dl_load_shlib(cp, _dl_objects, OBJTYPE_LIB,
        _dl_objects->obj_flags);
        if (shlib == NULL) {
            _dl_printf("%s: can't preload library '%s'\n",
                __progname, cp);
            _dl_exit(4);
        }

Accordingly, the value of shlib should not be tested as NULL.

Please try loading a dynamically linked library instead, that should work.

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