Add a global cmdline file

* main.c (argp_parser, main): Add the --kernel-pid option.
* main.h: Publish it.
* rootdir.c (rootdir_gc_cmdline): New function.

3 files changed, 56 insertions, 0 deletions

diff --git a/main.c b/main.c
index 26f5248..fee4867 100644
--- a/main.c
+++ b/main.c
@@ -14,6 +14,7 @@
 int opt_clk_tck;
 mode_t opt_stat_mode;
 pid_t opt_fake_self;
+pid_t opt_kernel_pid;
 
 static error_t
 argp_parser (int key, char *arg, struct argp_state *state)
@@ -44,6 +45,12 @@ argp_parser (int key, char *arg, struct argp_state *state)
       else
 	opt_fake_self = 1;
       break;
+
+    case 'k':
+      opt_kernel_pid = strtol (arg, &endp, 0);
+      if (*endp || ! *arg || (signed) opt_kernel_pid < 0)
+	error (1, 0, "--kernel-process: PID must be a positive integer");
+      break;
   }
 
   return 0;
@@ -64,6 +71,9 @@ struct argp argp = {
 	"Provide a fake \"self\" symlink to the given PID, for compatibility "
 	"purposes.  If PID is omitted, \"self\" will point to init.  "
 	"(default: no self link)" },
+    { "kernel-process", 'k', "PID", 0,
+	"Process identifier for the kernel, used to retreive its command line "
+	"(default: 2)" },
     {}
   },
   .parser = argp_parser,
@@ -112,6 +122,7 @@ int main (int argc, char **argv)
   opt_clk_tck = sysconf(_SC_CLK_TCK);
   opt_stat_mode = 0400;
   opt_fake_self = -1;
+  opt_kernel_pid = 2;
   argp_parse (&argp, argc, argv, 0, 0, 0);
 
   task_get_bootstrap_port (mach_task_self (), &bootstrap);
diff --git a/main.h b/main.h
index 361380b..6ada229 100644
--- a/main.h
+++ b/main.h
@@ -2,3 +2,4 @@
 extern int opt_clk_tck;
 extern mode_t opt_stat_mode;
 extern pid_t opt_fake_self;
+extern pid_t opt_kernel_pid;
diff --git a/rootdir.c b/rootdir.c
index f5b43ff..865342c 100644
--- a/rootdir.c
+++ b/rootdir.c
@@ -5,6 +5,7 @@
 #include <sys/time.h>
 #include <sys/utsname.h>
 #include <sys/stat.h>
+#include <argz.h>
 #include <ps.h>
 #include "procfs.h"
 #include "procfs_dir.h"
@@ -231,6 +232,41 @@ rootdir_gc_vmstat (void *hook, void **contents, size_t *contents_len)
 }
 
 static error_t
+rootdir_gc_cmdline (void *hook, void **contents, size_t *contents_len)
+{
+  struct ps_context *pc = hook;
+  struct proc_stat *ps;
+  error_t err;
+
+  err = _proc_stat_create (opt_kernel_pid, pc, &ps);
+  if (err)
+    return EIO;
+
+  err = proc_stat_set_flags (ps, PSTAT_ARGS);
+  if (err || ! (proc_stat_flags (ps) & PSTAT_ARGS))
+    {
+      err = EIO;
+      goto out;
+    }
+
+  *contents_len = proc_stat_args_len (ps);
+  *contents = malloc (*contents_len);
+  if (! *contents)
+    {
+      err = ENOMEM;
+      goto out;
+    }
+
+  memcpy (*contents, proc_stat_args (ps), *contents_len);
+  argz_stringify (*contents, *contents_len, ' ');
+  ((char *) *contents)[*contents_len - 1] = '\n';
+
+out:
+  _proc_stat_free (ps);
+  return err;
+}
+
+static error_t
 rootdir_gc_fakeself (void *hook, void **contents, size_t *contents_len)
 {
   *contents_len = asprintf ((char **) contents, "%d", opt_fake_self);
@@ -310,6 +346,14 @@ static const struct procfs_dir_entry rootdir_entries[] = {
       .cleanup_contents = procfs_cleanup_contents_with_free,
     },
   },
+  {
+    .name = "cmdline",
+    .make_node = rootdir_file_make_node,
+    .hook = & (struct procfs_node_ops) {
+      .get_contents = rootdir_gc_cmdline,
+      .cleanup_contents = procfs_cleanup_contents_with_free,
+    },
+  },
   {}
 };