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.

1 files changed, 32 insertions, 0 deletions

diff --git a/procfs/process.c b/procfs/process.c
index ece37b70..59653b24 100644
--- a/procfs/process.c
+++ b/procfs/process.c
@@ -95,6 +95,19 @@ static int args_filename_length (const char *name)
 /* Actual content generators */
 
 static ssize_t
+process_file_gc_exe (struct proc_stat *ps, char **contents)
+{
+  if (proc_stat_exe_len (ps) == 0)
+    {
+      *contents = "-";
+      return 1;
+    }
+
+  *contents = proc_stat_exe(ps);
+  return proc_stat_exe_len(ps);
+}
+
+static ssize_t
 process_file_gc_cmdline (struct proc_stat *ps, char **contents)
 {
   *contents = proc_stat_args(ps);
@@ -410,6 +423,14 @@ process_file_make_node (void *dir_hook, const void *entry_hook)
   return np;
 }
 
+static struct node *
+process_file_symlink_make_node (void *dir_hook, const void *entry_hook)
+{
+  struct node *np = process_file_make_node (dir_hook, entry_hook);
+  if (np) procfs_node_chtype (np, S_IFLNK);
+  return np;
+}
+
 /* Stat needs its own constructor in order to set its mode according to
    the --stat-mode command-line option.  */
 static struct node *
@@ -425,6 +446,17 @@ process_stat_make_node (void *dir_hook, const void *entry_hook)
 
 static struct procfs_dir_entry entries[] = {
   {
+    .name = "exe",
+    .hook = & (struct process_file_desc) {
+      .get_contents = process_file_gc_exe,
+      .needs = PSTAT_EXE,
+      .no_cleanup = 1,
+    },
+    .ops = {
+      .make_node = process_file_symlink_make_node,
+    },
+  },
+  {
     .name = "cmdline",
     .hook = & (struct process_file_desc) {
       .get_contents = process_file_gc_cmdline,