/* Shared utility routines for GDB to interact with agent.

  Copyright (C) 2009-2024 Free Software Foundation, Inc.

  This file is part of GDB.

  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/>.  */

#include "target/target.h"
#include "gdbsupport/symbol.h"
#include <unistd.h>
#include "filestuff.h"

#define IPA_SYM_STRUCT_NAME ipa_sym_addresses_common
#include "agent.h"

bool debug_agent = false;

/* A stdarg wrapper for debug_vprintf.  */

static void ATTRIBUTE_PRINTF (1, 2)
debug_agent_printf (const char *fmt, ...)
{
 va_list ap;

 if (!debug_agent)
   return;
 va_start (ap, fmt);
 debug_vprintf (fmt, ap);
 va_end (ap);
}

#define DEBUG_AGENT debug_agent_printf

/* Global flag to determine using agent or not.  */
bool use_agent = false;

/* Addresses of in-process agent's symbols both GDB and GDBserver cares
  about.  */

struct ipa_sym_addresses_common
{
 CORE_ADDR addr_helper_thread_id;
 CORE_ADDR addr_cmd_buf;
 CORE_ADDR addr_capability;
};

/* Cache of the helper thread id.  FIXME: this global should be made
  per-process.  */
static uint32_t helper_thread_id = 0;

static struct
{
 const char *name;
 int offset;
} symbol_list[] = {
 IPA_SYM(helper_thread_id),
 IPA_SYM(cmd_buf),
 IPA_SYM(capability),
};

static struct ipa_sym_addresses_common ipa_sym_addrs;

static bool all_agent_symbols_looked_up = false;

bool
agent_loaded_p (void)
{
 return all_agent_symbols_looked_up;
}

/* Look up all symbols needed by agent.  Return 0 if all the symbols are
  found, return non-zero otherwise.  */

int
agent_look_up_symbols (void *arg)
{
 all_agent_symbols_looked_up = false;

 for (int i = 0; i < sizeof (symbol_list) / sizeof (symbol_list[0]); i++)
   {
     CORE_ADDR *addrp =
       (CORE_ADDR *) ((char *) &ipa_sym_addrs + symbol_list[i].offset);
     struct objfile *objfile = (struct objfile *) arg;

     if (find_minimal_symbol_address (symbol_list[i].name, addrp,
                                      objfile) != 0)
       {
         DEBUG_AGENT ("symbol `%s' not found\n", symbol_list[i].name);
         return -1;
       }
   }

 all_agent_symbols_looked_up = true;
 return 0;
}

static unsigned int
agent_get_helper_thread_id (void)
{
 if  (helper_thread_id == 0)
   {
     if (target_read_uint32 (ipa_sym_addrs.addr_helper_thread_id,
                             &helper_thread_id))
       warning (_("Error reading helper thread's id in lib"));
   }

 return helper_thread_id;
}

#ifdef HAVE_SYS_UN_H
#include <sys/socket.h>
#include <sys/un.h>
#define SOCK_DIR P_tmpdir

#ifndef UNIX_PATH_MAX
#define UNIX_PATH_MAX sizeof(((struct sockaddr_un *) NULL)->sun_path)
#endif

#endif

/* Connects to synchronization socket.  PID is the pid of inferior, which is
  used to set up the connection socket.  */

static int
gdb_connect_sync_socket (int pid)
{
#ifdef HAVE_SYS_UN_H
 struct sockaddr_un addr = {};
 int res, fd;
 char path[UNIX_PATH_MAX];

 res = xsnprintf (path, UNIX_PATH_MAX, "%s/gdb_ust%d", P_tmpdir, pid);
 if (res >= UNIX_PATH_MAX)
   return -1;

 res = fd = gdb_socket_cloexec (PF_UNIX, SOCK_STREAM, 0);
 if (res == -1)
   {
     warning (_("error opening sync socket: %s"), safe_strerror (errno));
     return -1;
   }

 addr.sun_family = AF_UNIX;

 res = xsnprintf (addr.sun_path, UNIX_PATH_MAX, "%s", path);
 if (res >= UNIX_PATH_MAX)
   {
     warning (_("string overflow allocating socket name"));
     close (fd);
     return -1;
   }

 res = connect (fd, (struct sockaddr *) &addr, sizeof (addr));
 if (res == -1)
   {
     warning (_("error connecting sync socket (%s): %s. "
                "Make sure the directory exists and that it is writable."),
                path, safe_strerror (errno));
     close (fd);
     return -1;
   }

 return fd;
#else
 return -1;
#endif
}

/* Execute an agent command in the inferior.  PID is the value of pid
  of the inferior.  CMD is the buffer for command.  It is assumed to
  be at least IPA_CMD_BUF_SIZE bytes long.  GDB or GDBserver will
  store the command into it and fetch the return result from CMD.
  The interaction between GDB/GDBserver and the agent is synchronized
  by a synchronization socket.  Return zero if success, otherwise
  return non-zero.  */

int
agent_run_command (int pid, char *cmd, int len)
{
 int fd;
 int tid = agent_get_helper_thread_id ();
 ptid_t ptid = ptid_t (pid, tid);

 int ret = target_write_memory (ipa_sym_addrs.addr_cmd_buf,
                                (gdb_byte *) cmd, len);

 if (ret != 0)
   {
     warning (_("unable to write"));
     return -1;
   }

 DEBUG_AGENT ("agent: resumed helper thread\n");

 /* Resume helper thread.  */
 target_continue_no_signal (ptid);

 fd = gdb_connect_sync_socket (pid);
 if (fd >= 0)
   {
     char buf[1] = "";

     DEBUG_AGENT ("agent: signalling helper thread\n");

     do
       {
         ret = write (fd, buf, 1);
       } while (ret == -1 && errno == EINTR);

       DEBUG_AGENT ("agent: waiting for helper thread's response\n");

     do
       {
         ret = read (fd, buf, 1);
       } while (ret == -1 && errno == EINTR);

     close (fd);

     DEBUG_AGENT ("agent: helper thread's response received\n");
   }
 else
   return -1;

 /* Need to read response with the inferior stopped.  */
 if (ptid != null_ptid)
   {
     /* Stop thread PTID.  */
     DEBUG_AGENT ("agent: stop helper thread\n");
     target_stop_and_wait (ptid);
   }

 if (fd >= 0)
   {
     if (target_read_memory (ipa_sym_addrs.addr_cmd_buf, (gdb_byte *) cmd,
                             IPA_CMD_BUF_SIZE))
       {
         warning (_("Error reading command response"));
         return -1;
       }
   }

 return 0;
}

/* Each bit of it stands for a capability of agent.  */
static uint32_t agent_capability = 0;

/* Return true if agent has capability AGENT_CAP, otherwise return false.  */

bool
agent_capability_check (enum agent_capa agent_capa)
{
 if (agent_capability == 0)
   {
     if (target_read_uint32 (ipa_sym_addrs.addr_capability,
                             &agent_capability))
       warning (_("Error reading capability of agent"));
   }
 return (agent_capability & agent_capa) != 0;
}

/* Invalidate the cache of agent capability, so we'll read it from inferior
  again.  Call it when launches a new program or reconnect to remote stub.  */

void
agent_capability_invalidate (void)
{
 agent_capability = 0;
}

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