Constify target_pid_to_exec_file

This changes target_pid_to_exec_file and target_ops::pid_to_exec_file
to return a "const char *".  I couldn't build many of these targets,
but did examine the code by hand -- also, as this only affects the
return type, it's normally pretty safe.  This brings gdb and gdbserver
a bit closer, and allows for the removal of a const_cast as well.

gdb/darwin-nat.c

@@ -2373,7 +2373,7 @@ set_enable_mach_exceptions (const char *args, int from_tty,
     }
 }
 
-char *
+const char *
 darwin_nat_target::pid_to_exec_file (int pid)
 {
   static char path[PATH_MAX];

gdb/darwin-nat.h

@@ -100,7 +100,7 @@ class darwin_nat_target : public inf_child_target
 
   std::string pid_to_str (ptid_t) override;
 
-  char *pid_to_exec_file (int pid) override;
+  const char *pid_to_exec_file (int pid) override;
 
   enum target_xfer_status xfer_partial (enum target_object object,
 					const char *annex,

gdb/exec.c

@@ -314,7 +314,7 @@ validate_exec_file (int from_tty)
 void
 exec_file_locate_attach (int pid, int defer_bp_reset, int from_tty)
 {
-  char *exec_file_target;
+  const char *exec_file_target;
   symfile_add_flags add_flags = 0;
 
   /* Do nothing if we already have an executable filename.  */

gdb/fbsd-nat.c

@@ -57,7 +57,7 @@
 /* Return the name of a file that can be opened to get the symbols for
    the child process identified by PID.  */
 
-char *
+const char *
 fbsd_nat_target::pid_to_exec_file (int pid)
 {
   static char buf[PATH_MAX];

gdb/fbsd-nat.h

@@ -44,7 +44,7 @@
 class fbsd_nat_target : public inf_ptrace_target
 {
 public:
-  char *pid_to_exec_file (int pid) override;
+  const char *pid_to_exec_file (int pid) override;
 
   int find_memory_regions (find_memory_region_ftype func, void *data) override;
 

gdb/inf-child.c

@@ -220,7 +220,7 @@ inf_child_target::can_attach ()
   return true;
 }
 
-char *
+const char *
 inf_child_target::pid_to_exec_file (int pid)
 {
   /* This target doesn't support translation of a process ID to the

gdb/inf-child.h

@@ -71,7 +71,7 @@ public:
 
   void post_attach (int) override;
 
-  char *pid_to_exec_file (int pid) override;
+  const char *pid_to_exec_file (int pid) override;
 
   int fileio_open (struct inferior *inf, const char *filename,
 		   int flags, int mode, int warn_if_slow,

gdb/linux-nat.c

@@ -3764,7 +3764,7 @@ linux_nat_target::thread_name (struct thread_info *thr)
 /* Accepts an integer PID; Returns a string representing a file that
    can be opened to get the symbols for the child process.  */
 
-char *
+const char *
 linux_nat_target::pid_to_exec_file (int pid)
 {
   return linux_proc_pid_to_exec_file (pid);

gdb/linux-nat.h

@@ -123,7 +123,7 @@ public:
   int set_syscall_catchpoint (int pid, bool needed, int any_count,
 			      gdb::array_view<const int> syscall_counts) override;
 
-  char *pid_to_exec_file (int pid) override;
+  const char *pid_to_exec_file (int pid) override;
 
   void post_attach (int) override;
 

gdb/nat/linux-procfs.c

@@ -341,7 +341,7 @@ linux_proc_task_list_dir_exists (pid_t pid)
 
 /* See linux-procfs.h.  */
 
-char *
+const char *
 linux_proc_pid_to_exec_file (int pid)
 {
   static char buf[PATH_MAX];

gdb/nat/linux-procfs.h

@@ -78,7 +78,7 @@ extern int linux_proc_task_list_dir_exists (pid_t pid);
    to create the process PID.  The returned value persists until this
    function is next called.  */
 
-extern char *linux_proc_pid_to_exec_file (int pid);
+extern const char *linux_proc_pid_to_exec_file (int pid);
 
 /* Display possible problems on this system.  Display them only once
    per GDB execution.  */

gdb/netbsd-nat.c

@@ -34,10 +34,10 @@
 /* Return the name of a file that can be opened to get the symbols for
    the child process identified by PID.  */
 
-char *
+const char *
 nbsd_nat_target::pid_to_exec_file (int pid)
 {
-  return const_cast<char *> (netbsd_nat::pid_to_exec_file (pid));
+  return netbsd_nat::pid_to_exec_file (pid);
 }
 
 /* Return the current directory for the process identified by PID.  */

gdb/netbsd-nat.h

@@ -28,7 +28,7 @@ struct thread_info;
 
 struct nbsd_nat_target : public inf_ptrace_target
 {
-  char *pid_to_exec_file (int pid) override;
+  const char *pid_to_exec_file (int pid) override;
 
   bool thread_alive (ptid_t ptid) override;
   const char *thread_name (struct thread_info *thr) override;

gdb/nto-procfs.c

@@ -121,7 +121,7 @@ struct nto_procfs_target : public inf_child_target
 
   const char *extra_thread_info (struct thread_info *) override;
 
-  char *pid_to_exec_file (int pid) override;
+  const char *pid_to_exec_file (int pid) override;
 };
 
 /* For "target native".  */
@@ -664,7 +664,7 @@ nto_procfs_target::files_info ()
 
 /* Target to_pid_to_exec_file implementation.  */
 
-char *
+const char *
 nto_procfs_target::pid_to_exec_file (const int pid)
 {
   int proc_fd;

gdb/procfs.c

@@ -127,7 +127,7 @@ public:
 
   std::string pid_to_str (ptid_t) override;
 
-  char *pid_to_exec_file (int pid) override;
+  const char *pid_to_exec_file (int pid) override;
 
   thread_control_capabilities get_thread_control_capabilities () override
   { return tc_schedlock; }
@@ -2927,7 +2927,7 @@ procfs_target::pid_to_str (ptid_t ptid)
 /* Accepts an integer PID; Returns a string representing a file that
    can be opened to get the symbols for the child process.  */
 
-char *
+const char *
 procfs_target::pid_to_exec_file (int pid)
 {
   static char buf[PATH_MAX];

gdb/remote.c

@@ -508,7 +508,7 @@ public:
 
   void rcmd (const char *command, struct ui_file *output) override;
 
-  char *pid_to_exec_file (int pid) override;
+  const char *pid_to_exec_file (int pid) override;
 
   void log_command (const char *cmd) override
   {
@@ -14353,7 +14353,7 @@ remote_target::load (const char *name, int from_tty)
    can be opened on the remote side to get the symbols for the child
    process.  Returns NULL if the operation is not supported.  */
 
-char *
+const char *
 remote_target::pid_to_exec_file (int pid)
 {
   static gdb::optional<gdb::char_vector> filename;

gdb/target-delegates.c

@@ -94,7 +94,7 @@ struct dummy_target : public target_ops
   void interrupt () override;
   void pass_ctrlc () override;
   void rcmd (const char *arg0, struct ui_file *arg1) override;
-  char *pid_to_exec_file (int arg0) override;
+  const char *pid_to_exec_file (int arg0) override;
   void log_command (const char *arg0) override;
   const target_section_table *get_section_table () override;
   thread_control_capabilities get_thread_control_capabilities () override;
@@ -268,7 +268,7 @@ struct debug_target : public target_ops
   void interrupt () override;
   void pass_ctrlc () override;
   void rcmd (const char *arg0, struct ui_file *arg1) override;
-  char *pid_to_exec_file (int arg0) override;
+  const char *pid_to_exec_file (int arg0) override;
   void log_command (const char *arg0) override;
   const target_section_table *get_section_table () override;
   thread_control_capabilities get_thread_control_capabilities () override;
@@ -1983,28 +1983,28 @@ debug_target::rcmd (const char *arg0, struct ui_file *arg1)
   gdb_puts (")\n", gdb_stdlog);
 }
 
-char *
+const char *
 target_ops::pid_to_exec_file (int arg0)
 {
   return this->beneath ()->pid_to_exec_file (arg0);
 }
 
-char *
+const char *
 dummy_target::pid_to_exec_file (int arg0)
 {
   return NULL;
 }
 
-char *
+const char *
 debug_target::pid_to_exec_file (int arg0)
 {
-  char * result;
+  const char * result;
   gdb_printf (gdb_stdlog, "-> %s->pid_to_exec_file (...)\n", this->beneath ()->shortname ());
   result = this->beneath ()->pid_to_exec_file (arg0);
   gdb_printf (gdb_stdlog, "<- %s->pid_to_exec_file (", this->beneath ()->shortname ());
   target_debug_print_int (arg0);
   gdb_puts (") = ", gdb_stdlog);
-  target_debug_print_char_p (result);
+  target_debug_print_const_char_p (result);
   gdb_puts ("\n", gdb_stdlog);
   return result;
 }

gdb/target.c

@@ -423,7 +423,7 @@ target_extra_thread_info (thread_info *tp)
 
 /* See target.h.  */
 
-char *
+const char *
 target_pid_to_exec_file (int pid)
 {
   return current_inferior ()->top_target ()->pid_to_exec_file (pid);

gdb/target.h

@@ -688,7 +688,7 @@ struct target_ops
       TARGET_DEFAULT_FUNC (default_target_pass_ctrlc);
     virtual void rcmd (const char *command, struct ui_file *output)
       TARGET_DEFAULT_FUNC (default_rcmd);
-    virtual char *pid_to_exec_file (int pid)
+    virtual const char *pid_to_exec_file (int pid)
       TARGET_DEFAULT_RETURN (NULL);
     virtual void log_command (const char *)
       TARGET_DEFAULT_IGNORE ();
@@ -1951,7 +1951,7 @@ extern gdb::byte_vector target_thread_info_to_thread_handle
    the client if the string will not be immediately used, or if
    it must persist.  */
 
-extern char *target_pid_to_exec_file (int pid);
+extern const char *target_pid_to_exec_file (int pid);
 
 /* See the to_thread_architecture description in struct target_ops.  */
 

gdb/windows-nat.c

@@ -276,7 +276,7 @@ struct windows_nat_target final : public x86_nat_target<inf_child_target>
 
   void interrupt () override;
 
-  char *pid_to_exec_file (int pid) override;
+  const char *pid_to_exec_file (int pid) override;
 
   ptid_t get_ada_task_ptid (long lwp, ULONGEST thread) override;
 
@@ -2005,7 +2005,7 @@ windows_get_exec_module_filename (char *exe_name_ret, size_t exe_name_max_len)
 
 /* The pid_to_exec_file target_ops method for this platform.  */
 
-char *
+const char *
 windows_nat_target::pid_to_exec_file (int pid)
 {
   static char path[__PMAX];