[PATCH]: print missing interpreter name [Was: Re: binfmt_script and ^M]

[Jan Nieuwenhuizen]

"Richard B. Johnson" <root@chaos.analogic.com> writes:

> So why would you even consider breaking bash as a work-around for
> a broken script?

I don't.

> Somebody must have missed the boat entirely. Unix does not, never
> has, and never will end a text line with '\r'. It's Microsoft junk
> that does that, a throwback to CP/M, a throwback to MDS/200.

Yes, we all know that, but you missed the point.  As far as this patch
goes, it's got nothing to do with the '\r'.  It's meant to get a more
informative error message from bash, if ``#!INTERPRETER'' does not
exist.  Look:

    $ cat /bin/foo.sh
    #!/foo/bar/baz
    echo bar
    $ /bin/bash -c /bin/foo.sh 
    /bin/bash: /bin/foo.sh: No such file or directory
    $ ./build/bash -c /bin/foo.sh 
    ./build/bash: /foo/bar: No such file or directory

Maybe the message could even be better, but having `/foo/bar' printed,
ie, the file that the kernel says does not exist, iso `/bin/foo.sh',
the name of the script, that certainly does exist, may help.  Possibly
both should be printed.

Greetings,
Jan.

I made a silly mistake in previous patch, sorry.

--- ../bash-2.04.orig/ChangeLog Mon Mar  5 13:58:48 2001
+++ ./ChangeLog Mon Mar  5 15:28:19 2001
@@ -0,0 +1,5 @@
+2001-03-05  Jan Nieuwenhuizen  <jan@netland.nl>
+
+       * execute_cmd.c (extract_hash_bang_interpreter): New function.
+       (shell_execve): More informative error message.
+
--- ../bash-2.04.orig/execute_cmd.c     Tue Jan 25 17:29:11 2000
+++ ./execute_cmd.c     Mon Mar  5 15:29:37 2001
@@ -3035,6 +3035,42 @@
     }
 }
 
+/* Look for #!INTERPRETER in file COMMAND, and return INTERPRETER . */
+static char *
+extract_hash_bang_interpreter (char *command, char buf[80])
+{
+  int fd;
+  char *interpreter;
+
+  interpreter = "";
+  fd = open (command, O_RDONLY);
+  if (fd >= 0)
+    {
+      int len;
+             
+      len = read (fd, (char *)buf, 80);
+      close (fd);
+             
+      if (len > 0
+         && buf[0] == '#' && buf[1] == '!')
+       {
+         int i;
+         int start;
+                 
+         for (i = 2; whitespace (buf[i]) && i < len; i++)
+           ;
+         
+         for (start = i;
+              !whitespace (buf[i]) && buf[i] != '\n' && i < len;
+              i++)
+           ;
+
+         interpreter = substring ((char *)buf, start, i);
+       }
+    }
+  return interpreter;
+}
+
 /* Execute a simple command that is hopefully defined in a disk file
    somewhere.
 
@@ -3326,6 +3362,11 @@
       else
        {
          errno = i;
+         if (errno == ENOENT)
+           {
+             char buf[80];
+             command = extract_hash_bang_interpreter (command, buf);
+           }
          file_error (command);
        }
       return ((i == ENOENT) ? EX_NOTFOUND : EX_NOEXEC);        /* XXX Posix.2 
says that exit status is 126 */

-- 
Jan Nieuwenhuizen <janneke@gnu.org> | GNU LilyPond - The music typesetter
http://www.xs4all.nl/~jantien       | http://www.lilypond.org