Messages in this thread Patch in this message | | | Date | Mon, 16 Feb 2004 14:34:18 +0100 | From | Hansjoerg Lipp <> | Subject | [PATCH] Linux 2.6: shebang handling in fs/binfmt_script.c |
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Hi!
In a newsgroup about unix shells we had a discussion, why it is not possible to pass more than one argument to an interpreter using the shebang line of a script. We found, that this behaviour is rather OS dependent. See Sven Mascheck's page for details: http://www.in-ulm.de/~mascheck/various/shebang/
As I'm really missing this feature in Linux and changing this would not break anything (unless someone uses rather unportable "#!cmd x y" to pass _one_ argument "x y" containing spaces), I'd like to know if it's possible to apply the patch below to the kernel.
It also allows to pass whitespace by using '\' as escape character: "\t" => TAB "\n" => LF "\ " => SPC "\\" => backslash All other backslashes are discarded.
This allows something like #!/usr/bin/awk -F \t -f
This part could break old scripts if the interpreter's path/filename or the arguments contain backslashes. Although I don't consider this a real problem, this feature can be deactivated by removing the if (c=='\\') { ... } part from the patch.
Another change: -ENOEXEC is returned, if the shebang line is too long. So, excessive characters are not dropped silently any more.
The patch is tested for 2.6.1, but also applies cleanly to 2.6.2. I can also send a tested patch for 2.4.24.
[ CC me on replies, please, as I'm not subscribed. ]
Kind regards Hansjoerg Lipp
--- linux-2.6.1/fs/binfmt_script.c.orig 2004-02-06 22:21:30.000000000 +0100 +++ linux-2.6.1/fs/binfmt_script.c 2004-02-06 22:21:30.000000000 +0100 @@ -18,10 +18,16 @@ static int load_script(struct linux_binprm *bprm,struct pt_regs *regs) { - char *cp, *i_name, *i_arg; + char *cp; struct file *file; char interp[BINPRM_BUF_SIZE]; int retval; + char *argv[(BINPRM_BUF_SIZE-1)/2]; + char **cur_arg; + unsigned argc; + int in_arg; + char *end, *dest; + char c; if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!') || (bprm->sh_bang)) return -ENOEXEC; @@ -35,51 +41,47 @@ fput(bprm->file); bprm->file = NULL; - bprm->buf[BINPRM_BUF_SIZE - 1] = '\0'; - if ((cp = strchr(bprm->buf, '\n')) == NULL) - cp = bprm->buf+BINPRM_BUF_SIZE-1; - *cp = '\0'; - while (cp > bprm->buf) { - cp--; - if ((*cp == ' ') || (*cp == '\t')) - *cp = '\0'; - else - break; + in_arg=0; + cur_arg=argv; + argc=0; + dest=bprm->buf+2; + end=bprm->buf+BINPRM_BUF_SIZE; + for (cp=bprm->buf+2;cp<end;++cp) { + c=*cp; + if (c==' '|| c=='\t' || c=='\n' || !c) { + if (in_arg) { + in_arg=0; + *dest++=0; + } + if (c=='\n' || !c) break; + } else { + if (c=='\\') { + if (++cp>=end) return -ENOEXEC; + c=*cp; + if (c=='\n' || !c) return -ENOEXEC; + if (c=='t') + c='\t'; + else if (c=='n') + c='\n'; + } + if (!in_arg) { + in_arg=1; + argc++; + *cur_arg++=dest; + } + *dest++=c; + } } - for (cp = bprm->buf+2; (*cp == ' ') || (*cp == '\t'); cp++); - if (*cp == '\0') - return -ENOEXEC; /* No interpreter name found */ - i_name = cp; - i_arg = 0; - for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++) - /* nothing */ ; - while ((*cp == ' ') || (*cp == '\t')) - *cp++ = '\0'; - if (*cp) - i_arg = cp; - strcpy (interp, i_name); - /* - * OK, we've parsed out the interpreter name and - * (optional) argument. - * Splice in (1) the interpreter's name for argv[0] - * (2) (optional) argument to interpreter - * (3) filename of shell script (replace argv[0]) - * - * This is done in reverse order, because of how the - * user environment and arguments are stored. - */ + if (cp>=end||!argc) return -ENOEXEC; + + strcpy (interp, argv[0]); remove_arg_zero(bprm); retval = copy_strings_kernel(1, &bprm->interp, bprm); - if (retval < 0) return retval; - bprm->argc++; - if (i_arg) { - retval = copy_strings_kernel(1, &i_arg, bprm); - if (retval < 0) return retval; - bprm->argc++; - } - retval = copy_strings_kernel(1, &i_name, bprm); - if (retval) return retval; + if (retval < 0) return retval; bprm->argc++; + retval = copy_strings_kernel(argc, argv, bprm); + if (retval < 0) return retval; + bprm->argc += argc; bprm->interp = interp; /* - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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