Re: echo "${HOME#$*/}" segfaults

[Dennis Williamson]

But not when $* is not empty:

$ set -- foo
$ echo "${HOME#$*/}"
/home/username

On Tue, Nov 30, 2010 at 7:43 PM, David Rochberg <rochberg@google.com> wrote:
> Configuration Information [Automatically generated, do not change]:
> Machine: x86_64
> OS: linux-gnu
> Compiler: gcc
> Compilation CFLAGS:  -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64'
> -DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-pc-linux-gnu'
> -DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash'
> -DSHELL -DHAVE_CONFIG_H   -I.  -I../bash -I../bash/include
> -I../bash/lib   -g -O2 -Wall
> Machine Type: x86_64-pc-linux-gnu
>
> Bash Version: 4.1
> Patch Level: 5
> Release Status: release
>
> Description:
>
>    echo "${HOME#$*/}" segfaults
>
>    Here's a stack trace from a -g -O0 build of bash 4.1
>
>      $ echo "${HOME#$*/}"
>
>      Program received signal SIGSEGV, Segmentation fault.
>      0x0000000000454ef1 in quote_string (string=0x0) at subst.c:3490
>      3490        if (*string == 0)
>      (gdb) where
>      #0  0x0000000000454ef1 in quote_string (string=0x0) at subst.c:3490
>      #1  0x000000000045c85b in param_expand (string=0x715c68 "$*/",
> sindex=0x7fffffffdb64, quoted=8, expanded_something=0x0,
> contains_dollar_at=0x7fffffffdb54,
>          quoted_dollar_at_p=0x7fffffffdb60,
> had_quoted_null_p=0x7fffffffdb58, pflags=0) at subst.c:7228
>      #2  0x000000000045d93d in expand_word_internal
> (word=0x7fffffffdc10, quoted=8, isexp=1, contains_dollar_at=0x0,
> expanded_something=0x0) at subst.c:7802
>      #3  0x000000000045450b in call_expand_word_internal
> (w=0x7fffffffdc10, q=8, i=1, c=0x0, e=0x0) at subst.c:3129
>      #4  0x00000000004549fd in expand_string_for_rhs (string=0x715c68
> "$*/", quoted=8, dollar_at_p=0x0, has_dollar_at=0x0) at subst.c:3315
>      #5  0x000000000045694f in getpattern (value=0x715c68 "$*/",
> quoted=1, expandpat=1) at subst.c:4277
>      #6  0x0000000000456d41 in parameter_brace_remove_pattern
> (varname=0x75f0a8 "HOME",
>          value=0xa23388
> "\001/\001h\001o\001m\001e\001/\001r\001o\001c\001h\001b\001e\001r\001g",
> patstr=0x773f58 "$*/", rtype=35, quoted=1) at subst.c:4411
>      #7  0x000000000045c298 in parameter_brace_expand
> (string=0x757888 "${HOME#$*/}", indexp=0x7fffffffde6c, quoted=1,
> pflags=0, quoted_dollar_atp=0x7fffffffdfa0,
>          contains_dollar_at=0x7fffffffdf94) at subst.c:6990
>      #8  0x000000000045c99f in param_expand (string=0x757888
> "${HOME#$*/}", sindex=0x7fffffffdfa4, quoted=1,
> expanded_something=0x0,
>          contains_dollar_at=0x7fffffffdf94,
> quoted_dollar_at_p=0x7fffffffdfa0, had_quoted_null_p=0x7fffffffdf98,
> pflags=0) at subst.c:7314
>      #9  0x000000000045d93d in expand_word_internal (word=0xa202a8,
> quoted=1, isexp=0, contains_dollar_at=0x7fffffffe0d4,
> expanded_something=0x0) at subst.c:7802
>      #10 0x000000000045dfc5 in expand_word_internal (word=0xa8b948,
> quoted=0, isexp=0, contains_dollar_at=0x7fffffffe168,
> expanded_something=0x7fffffffe16c)
>          at subst.c:7933
>      #11 0x000000000045f725 in shell_expand_word_list
> (tlist=0xa84f48, eflags=31) at subst.c:8893
>      #12 0x000000000045f9df in expand_word_list_internal
> (list=0x9eda48, eflags=31) at subst.c:9010
>      #13 0x000000000045f04a in expand_words (list=0x9eda48) at subst.c:8632
>      #14 0x000000000043ad49 in execute_simple_command
> (simple_command=0x71fd88, pipe_in=-1, pipe_out=-1, async=0,
> fds_to_close=0x764d08) at execute_cmd.c:3645
>      #15 0x0000000000435a49 in execute_command_internal
> (command=0xa23108, asynchronous=0, pipe_in=-1, pipe_out=-1,
> fds_to_close=0x764d08) at execute_cmd.c:730
>      #16 0x0000000000435221 in execute_command (command=0xa23108) at
> execute_cmd.c:375
>      #17 0x0000000000421d75 in reader_loop () at eval.c:152
>      #18 0x000000000041fbed in main (argc=1, argv=0x7fffffffe4a8,
> env=0x7fffffffe4b8) at shell.c:749
>
>