[binutils-gdb] Fix constness problem in ioscm_make_gdb_stdio_port

[Simon Marchi <simark at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=48ffa2b8cd986527a41654c3b27755bbf6762048

commit 48ffa2b8cd986527a41654c3b27755bbf6762048
Author: Simon Marchi <simon.marchi@polymtl.ca>
Date:   Mon Oct 26 08:41:38 2015 -0400

    Fix constness problem in ioscm_make_gdb_stdio_port
    
    ioscm_make_gdb_stdio_port passes const char pointers (literal strings) to
    scm_mode_bits, which takes a non-const char pointer.  Ideally, we would
    change scm_mode_bits to take a const char pointer, but it's not part of
    an API we control.
    
    Instead, it's easy enough to build the string to pass to scm_mode_bits in
    a (non-const) char array and pass that.
    
    gdb/ChangeLog:
    
    	* guile/scm-ports.c (ioscm_make_gdb_stdio_port): Pass non-const
    	char pointer to scm_mode_bits.

Diff:
---
 gdb/ChangeLog         |  5 +++++
 gdb/guile/scm-ports.c | 15 +++++++++++----
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index da09f5b..f26f233 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,10 @@
 2015-10-26  Simon Marchi  <simon.marchi@polymtl.ca>
 
+	* guile/scm-ports.c (ioscm_make_gdb_stdio_port): Pass non-const
+	char pointer to scm_mode_bits.
+
+2015-10-26  Simon Marchi  <simon.marchi@polymtl.ca>
+
 	* symtab.c (default_make_symbol_completion_list_break_on_1): Add
 	cast.
 
diff --git a/gdb/guile/scm-ports.c b/gdb/guile/scm-ports.c
index 10d7ee2..5d529b3 100644
--- a/gdb/guile/scm-ports.c
+++ b/gdb/guile/scm-ports.c
@@ -357,29 +357,36 @@ ioscm_init_stdio_buffers (SCM port, long mode_bits)
 static SCM
 ioscm_make_gdb_stdio_port (int fd)
 {
-  int is_a_tty = isatty (fd);
   const char *name;
   long mode_bits;
   SCM port;
+  char buf[3];
+
+  memset (buf, 0, sizeof (buf));
 
   switch (fd)
     {
     case 0:
       name = input_port_name;
-      mode_bits = scm_mode_bits (is_a_tty ? "r0" : "r");
+      buf[0] = 'r';
       break;
     case 1:
       name = output_port_name;
-      mode_bits = scm_mode_bits (is_a_tty ? "w0" : "w");
+      buf[0] = 'w';
       break;
     case 2:
       name = error_port_name;
-      mode_bits = scm_mode_bits (is_a_tty ? "w0" : "w");
+      buf[0] = 'w';
       break;
     default:
       gdb_assert_not_reached ("bad stdio file descriptor");
     }
 
+  if (isatty (fd))
+    buf[1] = '0';
+
+  mode_bits = scm_mode_bits (buf);
+
   port = ioscm_open_port (stdio_port_desc, mode_bits);
 
   scm_set_port_filename_x (port, gdbscm_scm_from_c_string (name));