[CRIU] Re: on servie fd handling code

[Cyrill Gorcunov]

Does the one attached look better?
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>From ef4458603b318a2295de2414aaedbd9ecab5ab75 Mon Sep 17 00:00:00 2001
From: Cyrill Gorcunov <gorcunov at openvz.org>
Date: Thu, 6 Sep 2012 12:07:56 +0400
Subject: [PATCH] service-fd: Rework helpers fd handling v2

While being addressing feedback from tty
c/r patch I found that service fd code could
be transferred to own .ch files and a bit reworked.

With this patch we move all code related to service
fd handling into service-fd.[ch] and add init_service_fd
helper which will fetch current limits from the tool
startup time. Thus instead of calling getrlimit
everytime we call for get_service_fd, we just do
that once.

v2 (by xemul@):
 - no need to carry the whole rlim structure
 - add is_service_fd helper

Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
---
 Makefile             |    1 +
 crtools.c            |    3 +++
 include/crtools.h    |   10 ----------
 include/service-fd.h |   22 ++++++++++++++++++++++
 include/util.h       |    2 ++
 service-fd.c         |   43 +++++++++++++++++++++++++++++++++++++++++++
 util.c               |   17 -----------------
 7 files changed, 71 insertions(+), 27 deletions(-)
 create mode 100644 include/service-fd.h
 create mode 100644 service-fd.c

diff --git a/Makefile b/Makefile
index c5ee775..aea0a8e 100644
--- a/Makefile
+++ b/Makefile
@@ -42,6 +42,7 @@ OBJS		+= inotify.o
 OBJS		+= signalfd.o
 OBJS		+= pstree.o
 OBJS		+= protobuf.o
+OBJS		+= service-fd.o
 
 PROTOBUF-LIB	:= protobuf/protobuf-lib.o
 
diff --git a/crtools.c b/crtools.c
index 901a6c7..1a5eb6d 100644
--- a/crtools.c
+++ b/crtools.c
@@ -73,6 +73,9 @@ int main(int argc, char *argv[])
 	opts.final_state = TASK_DEAD;
 	INIT_LIST_HEAD(&opts.veth_pairs);
 
+	if (init_service_fd())
+		return -1;
+
 	while (1) {
 		static struct option long_opts[] = {
 			{ "tree", required_argument, 0, 't' },
diff --git a/include/crtools.h b/include/crtools.h
index 8ad8ce8..a7ce246 100644
--- a/include/crtools.h
+++ b/include/crtools.h
@@ -98,16 +98,6 @@ struct cr_options {
 
 extern struct cr_options opts;
 
-enum {
-	LOG_FD_OFF = 1,
-	LOG_DIR_FD_OFF,
-	IMG_FD_OFF,
-	SELF_EXE_FD_OFF,
-	PROC_FD_OFF,
-};
-
-int get_service_fd(int type);
-
 /* file descriptors template */
 struct cr_fd_desc_tmpl {
 	const char	*fmt;			/* format for the name */
diff --git a/include/service-fd.h b/include/service-fd.h
new file mode 100644
index 0000000..836f8fd
--- /dev/null
+++ b/include/service-fd.h
@@ -0,0 +1,22 @@
+#ifndef SERVICE_FD_H__
+#define SERVICE_FD_H__
+
+#include "compiler.h"
+#include "types.h"
+
+enum {
+	LOG_FD_OFF	= 1,
+	LOG_DIR_FD_OFF,
+	IMG_FD_OFF,
+	SELF_EXE_FD_OFF,
+	PROC_FD_OFF,
+	CTL_TTY_OFF,
+
+	SERVICE_FD_OFF__MAX,
+};
+
+extern int init_service_fd(void);
+extern int get_service_fd(int type);
+extern bool is_service_fd(int fd, int type);
+
+#endif /* SERVICE_FD_H__ */
diff --git a/include/util.h b/include/util.h
index 1daf451..eaa3baf 100644
--- a/include/util.h
+++ b/include/util.h
@@ -16,6 +16,8 @@
 #include "types.h"
 #include "log.h"
 
+#include "service-fd.h"
+
 #include "../protobuf/vma.pb-c.h"
 
 #define PREF_SHIFT_OP(pref, op, size)	((size) op (pref ##BYTES_SHIFT))
diff --git a/service-fd.c b/service-fd.c
new file mode 100644
index 0000000..817b490
--- /dev/null
+++ b/service-fd.c
@@ -0,0 +1,43 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <limits.h>
+
+#include <sys/time.h>
+#include <sys/resource.h>
+
+#include <fcntl.h>
+
+#include "service-fd.h"
+#include "log.h"
+
+static int rlim_cur;
+static int rlim_min;
+
+int init_service_fd(void)
+{
+	struct rlimit rlimit;
+
+	/*
+	 * Service FDs are thouse that most likely won't
+	 * conflict with any 'real-life' ones
+	 */
+	if (getrlimit(RLIMIT_NOFILE, &rlimit)) {
+		pr_perror("Can't get rlimit");
+		return -1;
+	}
+
+	rlim_cur = (int)rlimit.rlim_cur;
+	rlim_min = rlim_cur - SERVICE_FD_OFF__MAX;
+	return 0;
+}
+
+int get_service_fd(int type)
+{
+	return rlim_cur - type;
+}
+
+bool is_service_fd(int fd, int type)
+{
+	return fd > rlim_min && fd == get_service_fd(type);
+}
diff --git a/util.c b/util.c
index 1fad14c..6f6cf6d 100644
--- a/util.c
+++ b/util.c
@@ -224,23 +224,6 @@ int do_open_proc(pid_t pid, int flags, const char *fmt, ...)
 	return openat(dirfd, path, flags);
 }
 
-int get_service_fd(int type)
-{
-	struct rlimit rlimit;
-
-	/*
-	 * Service FDs are thouse that most likely won't
-	 * conflict with any 'real-life' ones
-	 */
-
-	if (getrlimit(RLIMIT_NOFILE, &rlimit)) {
-		pr_perror("Can't get rlimit");
-		return -1;
-	}
-
-	return rlimit.rlim_cur - type;
-}
-
 int copy_file(int fd_in, int fd_out, size_t bytes)
 {
 	ssize_t written = 0;
-- 
1.7.7.6