Implement /proc/<pid>/exe

by adding proc_set/get_exe to the proc server, making
exec call proc_set_exe, and libps call proc_get_exe. procfs can then just
retrieve the information to make the "exe" symlink.

* hurd/process.defs (proc_set_exe, proc_get_exe): New RPCs.
* hurd/process_request.defs: Likewise.
* hurd/process_reply.defs: Add skips for proc_set_exe and proc_get_exe RPCs.
* proc/proc.h (struct proc): Add `exe' field.
* proc/info.c (S_proc_set_exe, S_proc_get_exe): New functions.
* proc/mgt.c (process_has_exited): Free p->exe.
(S_proc_child): Duplicate parent `exe' into child's `exe'.
* exec/exec.c (do_exec): Call proc_set_exe when a filename is available.
* libps/ps.h (struct proc_stat): Add `exe_vm_alloced', `exe', and `exe_len'
field.
(PSTAT_EXE): New macro.
(PSTAT_USER_BASE): Change value to make room.
(proc_stat_exe, proc_stat_exe_len): New macros.
* libps/procstat.c (proc_stat_set_flags): Handle PSTAT_EXE case by calling
proc_get_exe.
* libps/spec.c (ps_get_exe): New function.
(ps_exe_getter): New structure.
(ps_fmt_spec): Add "Exe" specification.
* procfs/process.c (process_file_symlink_make_node, process_file_gc_exe): New
functions.
(procfs_dir_entry): Add "exe" entry.
* startup/startup.c (launch_core_servers): Set exe paths for startup, auth,
proc, and fs servers.
(frob_kernel_process): Set exe path for kernel task.
(S_startup_essential_task): Set exe path for exec server.

3 files changed, 37 insertions, 1 deletions

diff --git a/libps/procstat.c b/libps/procstat.c
index f6420eea..d0423410 100644
--- a/libps/procstat.c
+++ b/libps/procstat.c
@@ -956,6 +956,23 @@ proc_stat_set_flags (struct proc_stat *ps, ps_flags_t flags)
 	}
     }
 
+  /* The process's path to binary executable */
+  if (NEED (PSTAT_EXE, PSTAT_PID))
+    {
+      ps->exe = malloc (sizeof(string_t));
+      if (ps->exe)
+	{
+	  if (proc_get_exe (server, ps->pid, ps->exe))
+	    free (ps->exe);
+	  else
+	    {
+	      ps->exe_len = strlen(ps->exe);
+	      have |= PSTAT_EXE;
+	      ps->exe_vm_alloced = 0;
+	    }
+	}
+    }
+
   /* The ctty id port; note that this is just a magic cookie;
      we use it to fetch a port to the actual terminal -- it's not useful for
      much else.  */
diff --git a/libps/ps.h b/libps/ps.h
index 3ee142d0..2725b1f4 100644
--- a/libps/ps.h
+++ b/libps/ps.h
@@ -272,6 +272,7 @@ struct proc_stat
   unsigned thread_waits_vm_alloced : 1;
   unsigned args_vm_alloced : 1;
   unsigned env_vm_alloced : 1;
+  unsigned exe_vm_alloced : 1;
 
   /* Various libc ports:  */
 
@@ -305,6 +306,11 @@ struct proc_stat
   size_t env_len;
 
   unsigned num_ports;
+
+  /* The path to process's binary executable.  */
+  char *exe;
+  /* The length of EXE.  */
+  size_t exe_len;
 };
 
 /* Proc_stat flag bits; each bit is set in the FLAGS field if that
@@ -344,12 +350,13 @@ struct proc_stat
 #define PSTAT_HOOK	      0x800000 /* Has a non-zero hook */
 #define PSTAT_NUM_PORTS      0x4000000 /* Number of Mach ports in the task */
 #define PSTAT_TIMES          0x8000000 /* Task/thread user and system times */
+#define PSTAT_EXE           0x10000000 /* Path to binary executable */
 
 /* Flag bits that don't correspond precisely to any field.  */
 #define PSTAT_NO_MSGPORT     0x1000000 /* Don't use the msgport at all */
 
 /* Bits from PSTAT_USER_BASE on up are available for user-use.  */
-#define PSTAT_USER_BASE      0x10000000
+#define PSTAT_USER_BASE      0x20000000
 #define PSTAT_USER_MASK      ~(PSTAT_USER_BASE - 1)
 
 /* If the PSTAT_STATE flag is set, then the proc_stats state field holds a
@@ -448,6 +455,8 @@ extern char *proc_stat_state_tags;
 #define proc_stat_tty(ps) ((ps)->tty)
 #define proc_stat_task_events_info(ps) ((ps)->task_events_info)
 #define proc_stat_num_ports(ps) ((ps)->num_ports)
+#define proc_stat_exe(ps) ((ps)->exe)
+#define proc_stat_exe_len(ps) ((ps)->exe_len)
 #define proc_stat_has(ps, needs) (((ps)->flags & needs) == needs)
 
 /* True if PS refers to a thread and not a process.  */
diff --git a/libps/spec.c b/libps/spec.c
index 5e540f87..4760c431 100644
--- a/libps/spec.c
+++ b/libps/spec.c
@@ -358,6 +358,14 @@ ps_get_num_ports (struct proc_stat *ps)
 const struct ps_getter ps_num_ports_getter =
 {"num_ports", PSTAT_NUM_PORTS, (vf) ps_get_num_ports};
 
+static void
+ps_get_exe (struct proc_stat *ps, char **exe_p, int *exe_len_p)
+{
+  *exe_p = proc_stat_exe (ps);
+  *exe_len_p = proc_stat_exe_len (ps);
+}
+const struct ps_getter ps_exe_getter =
+{"exe", PSTAT_EXE, ps_get_exe};
 /* ---------------------------------------------------------------- */
 /* some printing functions */
 
@@ -1166,6 +1174,8 @@ static const struct ps_fmt_spec specs[] =
    &ps_zero_fills_getter,  ps_emit_int,	    ps_cmp_ints,   ps_nominal_zint},
   {"Ports",	0,	-5, -1, 0,
    &ps_num_ports_getter,       ps_emit_int,	    ps_cmp_ints,   0},
+  {"Exe",	0,	 0, -1, 0,
+   &ps_exe_getter,	   ps_emit_string,  ps_cmp_strings,ps_nominal_string},
   {0}
 };