Constify get_exec_file

I noticed that get_exec_file could return a "const char *".  This
patch implements this change.

I couldn't build all the code -- but I did build Linux native and a
mingw cross.

Consequently, the NTO code has a hack, where it casts away const.  I
think this can be removed, but that required more work there, and
since I couldn't compile it, I felt it best not to try.

Let me know what you think.

gdb/ChangeLog
2019-12-16  Tom Tromey  <tromey@adacore.com>

	* windows-nat.c (windows_nat_target::attach): Update.
	* remote.c (extended_remote_target::attach): Update.
	* procfs.c (procfs_target::attach): Update.
	* nto-procfs.c (nto_procfs_target::attach): Update.
	(nto_procfs_target::create_inferior): Update.
	* inf-ptrace.c (inf_ptrace_target::attach): Update.
	* gnu-nat.c (gnu_nat_target::attach): Update.
	(gnu_nat_target::detach): Update.
	* darwin-nat.c (darwin_nat_target::attach): Update.
	* corefile.c (get_exec_file): Constify result.  Remove extraneous
	return.
	* bsd-kvm.c (bsd_kvm_target_open): Update.
	* gdbsupport/common-inferior.h (get_exec_file): Constify result.

gdb/gdbserver/ChangeLog
2019-12-16  Tom Tromey  <tromey@adacore.com>

	* server.c (get_exec_file): Constify result.

Change-Id: I29c60f7313a7def0dcb290ff0c2a4c1dea4f981f

13 files changed, 33 insertions, 18 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 2ecc2aa..d2660cc 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,19 @@
+2019-12-16  Tom Tromey  <tromey@adacore.com>
+
+	* windows-nat.c (windows_nat_target::attach): Update.
+	* remote.c (extended_remote_target::attach): Update.
+	* procfs.c (procfs_target::attach): Update.
+	* nto-procfs.c (nto_procfs_target::attach): Update.
+	(nto_procfs_target::create_inferior): Update.
+	* inf-ptrace.c (inf_ptrace_target::attach): Update.
+	* gnu-nat.c (gnu_nat_target::attach): Update.
+	(gnu_nat_target::detach): Update.
+	* darwin-nat.c (darwin_nat_target::attach): Update.
+	* corefile.c (get_exec_file): Constify result.  Remove extraneous
+	return.
+	* bsd-kvm.c (bsd_kvm_target_open): Update.
+	* gdbsupport/common-inferior.h (get_exec_file): Constify result.
+
 2019-12-16  Christian Biesinger  <cbiesinger@google.com>
 
 	* gdbsupport/common-defs.h: Remove workaround for a gnulib bug
diff --git a/gdb/bsd-kvm.c b/gdb/bsd-kvm.c
index 895686e..74c044f 100644
--- a/gdb/bsd-kvm.c
+++ b/gdb/bsd-kvm.c
@@ -106,7 +106,7 @@ static void
 bsd_kvm_target_open (const char *arg, int from_tty)
 {
   char errbuf[_POSIX2_LINE_MAX];
-  char *execfile = NULL;
+  const char *execfile = NULL;
   kvm_t *temp_kd;
   char *filename = NULL;
 
diff --git a/gdb/corefile.c b/gdb/corefile.c
index f22c154..c4735ad 100644
--- a/gdb/corefile.c
+++ b/gdb/corefile.c
@@ -141,7 +141,7 @@ validate_files (void)
 
 /* See gdbsupport/common-inferior.h.  */
 
-char *
+const char *
 get_exec_file (int err)
 {
   if (exec_filename)
@@ -151,7 +151,6 @@ get_exec_file (int err)
 
   error (_("No executable file specified.\n\
 Use the \"file\" or \"exec-file\" command."));
-  return NULL;
 }
 
 
diff --git a/gdb/darwin-nat.c b/gdb/darwin-nat.c
index ecc7fc0..c3905d1 100644
--- a/gdb/darwin-nat.c
+++ b/gdb/darwin-nat.c
@@ -2045,7 +2045,7 @@ darwin_nat_target::attach (const char *args, int from_tty)
 
   if (from_tty)
     {
-      char *exec_file = get_exec_file (0);
+      const char *exec_file = get_exec_file (0);
 
       if (exec_file)
 	printf_unfiltered (_("Attaching to program: %s, %s\n"), exec_file,
diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 36dece6..ecc3db5 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,7 @@
+2019-12-16  Tom Tromey  <tromey@adacore.com>
+
+	* server.c (get_exec_file): Constify result.
+
 2019-12-10  Christian Biesinger  <cbiesinger@google.com>
 
 	* Makefile.in: Add safe-strerror.c to gdbreplay and IPA, and change
diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index c5f7176..a425fba 100644
--- a/gdb/gdbserver/server.c
+++ b/gdb/gdbserver/server.c
@@ -265,7 +265,7 @@ get_exec_wrapper ()
 
 /* See gdbsupport/common-inferior.h.  */
 
-char *
+const char *
 get_exec_file (int err)
 {
   if (err && program_path.get () == NULL)
diff --git a/gdb/gdbsupport/common-inferior.h b/gdb/gdbsupport/common-inferior.h
index 77d4ad9..0ee554e 100644
--- a/gdb/gdbsupport/common-inferior.h
+++ b/gdb/gdbsupport/common-inferior.h
@@ -28,7 +28,7 @@ extern const char *get_exec_wrapper ();
 /* Return the name of the executable file as a string.
    ERR nonzero means get error if there is none specified;
    otherwise return 0 in that case.  */
-extern char *get_exec_file (int err);
+extern const char *get_exec_file (int err);
 
 /* Return the inferior's current working directory.  If nothing has
    been set, then return NULL.  */
diff --git a/gdb/gnu-nat.c b/gdb/gnu-nat.c
index 93a50be..cf42af4 100644
--- a/gdb/gnu-nat.c
+++ b/gdb/gnu-nat.c
@@ -2195,7 +2195,6 @@ void
 gnu_nat_target::attach (const char *args, int from_tty)
 {
   int pid;
-  char *exec_file;
   struct inf *inf = cur_inf ();
   struct inferior *inferior;
 
@@ -2206,7 +2205,7 @@ gnu_nat_target::attach (const char *args, int from_tty)
 
   if (from_tty)
     {
-      exec_file = (char *) get_exec_file (0);
+      const char *exec_file = get_exec_file (0);
 
       if (exec_file)
 	printf_unfiltered ("Attaching to program `%s', pid %d\n",
@@ -2260,7 +2259,7 @@ gnu_nat_target::detach (inferior *inf, int from_tty)
 
   if (from_tty)
     {
-      char *exec_file = get_exec_file (0);
+      const char *exec_file = get_exec_file (0);
 
       if (exec_file)
 	printf_unfiltered ("Detaching from program `%s' pid %d\n",
diff --git a/gdb/inf-ptrace.c b/gdb/inf-ptrace.c
index 4a8e732..fd18146 100644
--- a/gdb/inf-ptrace.c
+++ b/gdb/inf-ptrace.c
@@ -186,7 +186,6 @@ inf_ptrace_target::mourn_inferior ()
 void
 inf_ptrace_target::attach (const char *args, int from_tty)
 {
-  char *exec_file;
   pid_t pid;
   struct inferior *inf;
 
@@ -210,7 +209,7 @@ inf_ptrace_target::attach (const char *args, int from_tty)
 
   if (from_tty)
     {
-      exec_file = get_exec_file (0);
+      const char *exec_file = get_exec_file (0);
 
       if (exec_file)
 	printf_unfiltered (_("Attaching to program: %s, %s\n"), exec_file,
diff --git a/gdb/nto-procfs.c b/gdb/nto-procfs.c
index dcb0494..42b2348 100644
--- a/gdb/nto-procfs.c
+++ b/gdb/nto-procfs.c
@@ -693,7 +693,6 @@ nto_procfs_target::pid_to_exec_file (const int pid)
 void
 nto_procfs_target::attach (const char *args, int from_tty)
 {
-  char *exec_file;
   int pid;
   struct inferior *inf;
 
@@ -704,7 +703,7 @@ nto_procfs_target::attach (const char *args, int from_tty)
 
   if (from_tty)
     {
-      exec_file = (char *) get_exec_file (0);
+      const char *exec_file = get_exec_file (0);
 
       if (exec_file)
 	printf_unfiltered ("Attaching to program `%s', %s\n", exec_file,
@@ -1215,7 +1214,7 @@ nto_procfs_target::create_inferior (const char *exec_file,
 
   argv = xmalloc ((allargs.size () / (unsigned) 2 + 2) *
 		  sizeof (*argv));
-  argv[0] = get_exec_file (1);
+  argv[0] = const_cast<char *> (get_exec_file (1));
   if (!argv[0])
     {
       if (exec_file)
diff --git a/gdb/procfs.c b/gdb/procfs.c
index 57d4b8f..ccc5e26 100644
--- a/gdb/procfs.c
+++ b/gdb/procfs.c
@@ -1870,7 +1870,6 @@ procfs_debug_inferior (procinfo *pi)
 void
 procfs_target::attach (const char *args, int from_tty)
 {
-  char *exec_file;
   int   pid;
 
   pid = parse_pid_to_attach (args);
@@ -1880,7 +1879,7 @@ procfs_target::attach (const char *args, int from_tty)
 
   if (from_tty)
     {
-      exec_file = get_exec_file (0);
+      const char *exec_file = get_exec_file (0);
 
       if (exec_file)
 	printf_filtered (_("Attaching to program `%s', %s\n"),
diff --git a/gdb/remote.c b/gdb/remote.c
index e7a8bb6..3c54450 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -5792,7 +5792,7 @@ extended_remote_target::attach (const char *args, int from_tty)
 
   if (from_tty)
     {
-      char *exec_file = get_exec_file (0);
+      const char *exec_file = get_exec_file (0);
 
       if (exec_file)
 	printf_unfiltered (_("Attaching to program: %s, %s\n"), exec_file,
diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c
index d778282..10d5c95 100644
--- a/gdb/windows-nat.c
+++ b/gdb/windows-nat.c
@@ -1990,7 +1990,7 @@ windows_nat_target::attach (const char *args, int from_tty)
 
   if (from_tty)
     {
-      char *exec_file = (char *) get_exec_file (0);
+      const char *exec_file = get_exec_file (0);
 
       if (exec_file)
 	printf_unfiltered ("Attaching to program `%s', %s\n", exec_file,