* source.c (is_regular_file): New arg errno_ptr.

gdb/ChangeLog:

	* source.c (is_regular_file): New arg errno_ptr.
	All callers updated.

gdb/testsuite/ChangeLog:

	* gdb.base/bad-file.exp: New file.

gdb/ChangeLog

@@ -1,3 +1,8 @@
+2016-04-19  Doug Evans  <xdje42@gmail.com>
+
+	* source.c (is_regular_file): New arg errno_ptr.
+	All callers updated.
+
 2016-04-19  Andreas Arnez  <arnez@linux.vnet.ibm.com>
 
 	* linux-record.c (record_linux_system_call): Merge handling for

gdb/source.c

@@ -685,9 +685,12 @@ source_info (char *ignore, int from_tty)
 }
 
 
-/* Return True if the file NAME exists and is a regular file.  */
+/* Return True if the file NAME exists and is a regular file.
+   If the result is false then *ERRNO_PTR is set to a useful value assuming
+   we're expecting a regular file.  */
+
 static int
-is_regular_file (const char *name)
+is_regular_file (const char *name, int *errno_ptr)
 {
   struct stat st;
   const int status = stat (name, &st);
@@ -698,9 +701,21 @@ is_regular_file (const char *name)
      on obscure systems where stat does not work as expected.  */
 
   if (status != 0)
-    return (errno != ENOENT);
+    {
+      if (errno != ENOENT)
+	return 1;
+      *errno_ptr = ENOENT;
+      return 0;
+    }
 
-  return S_ISREG (st.st_mode);
+  if (S_ISREG (st.st_mode))
+    return 1;
+
+  if (S_ISDIR (st.st_mode))
+    *errno_ptr = EISDIR;
+  else
+    *errno_ptr = EINVAL;
+  return 0;
 }
 
 /* Open a file named STRING, searching path PATH (dir names sep by some char)
@@ -775,22 +790,23 @@ openp (const char *path, int opts, const char *string,
 
   if ((opts & OPF_TRY_CWD_FIRST) || IS_ABSOLUTE_PATH (string))
     {
-      int i;
+      int i, reg_file_errno;
 
-      if (is_regular_file (string))
+      if (is_regular_file (string, &reg_file_errno))
 	{
 	  filename = (char *) alloca (strlen (string) + 1);
 	  strcpy (filename, string);
 	  fd = gdb_open_cloexec (filename, mode, 0);
 	  if (fd >= 0)
 	    goto done;
+	  last_errno = errno;
 	}
       else
 	{
 	  filename = NULL;
 	  fd = -1;
+	  last_errno = reg_file_errno;
 	}
-      last_errno = errno;
 
       if (!(opts & OPF_SEARCH_IN_PATH))
 	for (i = 0; string[i]; i++)
@@ -821,6 +837,7 @@ openp (const char *path, int opts, const char *string,
   for (ix = 0; VEC_iterate (char_ptr, dir_vec, ix, dir); ++ix)
     {
       size_t len = strlen (dir);
+      int reg_file_errno;
 
       if (strcmp (dir, "$cwd") == 0)
 	{
@@ -879,13 +896,15 @@ openp (const char *path, int opts, const char *string,
       strcat (filename + len, SLASH_STRING);
       strcat (filename, string);
 
-      if (is_regular_file (filename))
+      if (is_regular_file (filename, &reg_file_errno))
 	{
 	  fd = gdb_open_cloexec (filename, mode, 0);
 	  if (fd >= 0)
 	    break;
 	  last_errno = errno;
 	}
+      else
+	last_errno = reg_file_errno;
     }
 
   do_cleanups (back_to);

gdb/testsuite/ChangeLog

@@ -1,3 +1,7 @@
+2016-04-19  Doug Evans  <xdje42@gmail.com>
+
+	* gdb.base/bad-file.exp: New file.
+
 2016-04-18  Martin Galvan  <martin.galvan@tallertechnologies.com>
 
 	* gdb.dwarf2/implref.exp: New file.

gdb/testsuite/gdb.base/bad-file.exp

@@ -0,0 +1,56 @@
+# Copyright 2015 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+# Test passing bad files to gdb.  PR symtab/17911
+
+# We watch for specific text for errno, so only test on systems we have
+# confidence in the error text.
+
+if { ! [ishost "*-*-linux*"] } {
+  return 0
+}
+
+# There is no such file, but we still use the normal mechanism to pick
+# its name and path.
+standard_testfile
+
+gdb_exit
+gdb_start
+
+set test "non-existent file"
+set bad_file $testfile
+remote_file host delete $bad_file
+gdb_test_multiple "file $bad_file" "$test" {
+    -re "No such file or directory.\[\r\n\]+$gdb_prompt $" {
+	pass $test
+    }
+}
+
+set test "directory"
+set bad_file [standard_output_file {}]
+remote_exec host "mkdir -p $bad_file"
+gdb_test_multiple "file $bad_file" "$test" {
+    -re "Is a directory.\[\r\n\]+$gdb_prompt $" {
+	pass $test
+    }
+}
+
+set test "neither file nor directory"
+set bad_file "/dev/null"
+gdb_test_multiple "file $bad_file" "$test" {
+    -re "Invalid argument.\[\r\n\]+$gdb_prompt $" {
+	pass $test
+    }
+}