[RFA] Should openp open directories?

[Joel Brobecker]

Hello,

Suppose you have a directory called "root", inside which you have a
directory called "foo". You also have an executable called "foo" in your
PATH that you would like to debug.

Suppose now that you launch gdb from "root" using the following command:
% gdb foo

Here is what is going to happen:
<<
GNU gdb 2002-04-17-cvs
[...]
This GDB was configured as "i686-pc-linux-gnu"..."/bonn.a/brobecke/gdb-public-ssh/gdb": not in executable format: Is a directory
>>

As you see, GDB found directory "foo" in the current directory, and
thought it was the executable it was asked to debug.

More generally, this problem can also happen if GDB finds in the PATH a
directory sharing the same name before the executable. For instance, say
your PATH is ~/bin:/usr/local/bin:/usr/bin, and that the directory
~/bin/sh exists, invoking GDB using the following command from your
home directory will also demonstrate the problem.
% gdb sh

This is because openp does not verify that the file it opens is a
regular file (ie not a directory, or a device, etc). From the
description of this function, and the name of the parameters, it seems
that this was the intent, and the attached patch fixes this.

2002-04-18  Joel Brobecker  <brobecker@gnat.com>

        * source.c (is_regular_file): New function.
        (openp): Check wether file to open is a regular file
        to avoid opening directories.

I verified that this patch does not introduce any regression:
Summary 1       2
FAIL    60      60
PASS    8242    8242
XFAIL   170     170
XPASS   11      11
Differences: 0

-- 
Joel
-------------- next part --------------
Index: source.c
===================================================================
RCS file: /cvs/src/src/gdb/source.c,v
retrieving revision 1.27
diff -c -3 -p -r1.27 source.c
*** source.c	12 Apr 2002 19:46:29 -0000	1.27
--- source.c	18 Apr 2002 10:23:55 -0000
*************** source_info (char *ignore, int from_tty)
*** 503,508 ****
--- 503,520 ----
  }
  
  
+ /* Return True if the file NAME exists and is a regular file */
+ static int
+ is_regular_file (const char *name)
+ {
+   struct stat st;
+   const int status = stat (name, &st);
+ 
+   if (status != 0)
+     return 0;
+ 
+   return S_ISREG (st.st_mode);
+ }
  
  /* Open a file named STRING, searching path PATH (dir names sep by some char)
     using mode MODE and protection bits PROT in the calls to open.
*************** openp (const char *path, int try_cwd_fir
*** 543,549 ****
    mode |= O_BINARY;
  #endif
  
!   if (try_cwd_first || IS_ABSOLUTE_PATH (string))
      {
        int i;
        filename = alloca (strlen (string) + 1);
--- 555,561 ----
    mode |= O_BINARY;
  #endif
  
!   if ((try_cwd_first || IS_ABSOLUTE_PATH (string)) && is_regular_file (string))
      {
        int i;
        filename = alloca (strlen (string) + 1);
*************** openp (const char *path, int try_cwd_fir
*** 601,609 ****
        strcat (filename + len, SLASH_STRING);
        strcat (filename, string);
  
!       fd = open (filename, mode);
!       if (fd >= 0)
! 	break;
      }
  
  done:
--- 613,624 ----
        strcat (filename + len, SLASH_STRING);
        strcat (filename, string);
  
!       if (is_regular_file (filename))
!       {
!         fd = open (filename, mode);
!         if (fd >= 0)
!           break;
!       }
      }
  
  done: