[PATCH 2/3] proc: Update get proc_pid_cmdline() to use mm.h helpers

[William Roberts]

Re-factor proc_pid_cmdline() to use get_cmdline_length() and
copy_cmdline() helpers from mm.h

Signed-off-by: William Roberts <wroberts at tresys.com>
---
 fs/proc/base.c |   35 ++++++++++-------------------------
 1 file changed, 10 insertions(+), 25 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 03c8d74..fb4eda5 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -203,37 +203,22 @@ static int proc_root_link(struct dentry *dentry, struct path *path)
 static int proc_pid_cmdline(struct task_struct *task, char * buffer)
 {
 	int res = 0;
-	unsigned int len;
+	unsigned int len = 0;
 	struct mm_struct *mm = get_task_mm(task);
 	if (!mm)
-		goto out;
-	if (!mm->arg_end)
-		goto out_mm;	/* Shh! No looking before we're done */
+		return 0;
 
- 	len = mm->arg_end - mm->arg_start;
- 
+	len = get_cmdline_length(mm);
+	if (!len)
+		goto mm_out;
+
+	/*The caller of this allocates a page */
 	if (len > PAGE_SIZE)
 		len = PAGE_SIZE;
- 
-	res = access_process_vm(task, mm->arg_start, buffer, len, 0);
-
-	// If the nul at the end of args has been overwritten, then
-	// assume application is using setproctitle(3).
-	if (res > 0 && buffer[res-1] != '\0' && len < PAGE_SIZE) {
-		len = strnlen(buffer, res);
-		if (len < res) {
-		    res = len;
-		} else {
-			len = mm->env_end - mm->env_start;
-			if (len > PAGE_SIZE - res)
-				len = PAGE_SIZE - res;
-			res += access_process_vm(task, mm->env_start, buffer+res, len, 0);
-			res = strnlen(buffer, res);
-		}
-	}
-out_mm:
+
+	res = copy_cmdline(task, mm, buffer, len);
+mm_out:
 	mmput(mm);
-out:
 	return res;
 }
 
-- 
1.7.9.5