confile: use mmap() to parse config file

src/lxc/Makefile.am

@@ -278,7 +278,7 @@ lxc_checkpoint_SOURCES = tools/lxc_checkpoint.c tools/arguments.c tools/tool_uti
 # Binaries shipping with liblxc
 init_lxc_SOURCES = cmd/lxc_init.c
 lxc_monitord_SOURCES = cmd/lxc_monitord.c
-lxc_user_nic_SOURCES = cmd/lxc_user_nic.c namespace.c network.c
+lxc_user_nic_SOURCES = cmd/lxc_user_nic.c namespace.c network.c parse.c
 lxc_usernsexec_SOURCES = cmd/lxc_usernsexec.c
 
 if ENABLE_DEPRECATED

src/lxc/cmd/lxc_user_nic.c

@@ -48,6 +48,7 @@
 #include "config.h"
 #include "namespace.h"
 #include "network.h"
+#include "parse.h"
 #include "utils.h"
 
 #define usernic_debug_stream(stream, format, ...)                              \

src/lxc/confile.c

@@ -2334,7 +2334,7 @@ int lxc_config_read(const char *file, struct lxc_conf *conf, bool from_include)
 	if (!conf->rcfile)
 		conf->rcfile = strdup(file);
 
-	return lxc_file_for_each_line(file, parse_line, &c);
+	return lxc_file_for_each_line_mmap(file, parse_line, &c);
 }
 
 int lxc_config_define_add(struct lxc_list *defines, char *arg)

src/lxc/lxccontainer.c

@@ -57,6 +57,7 @@
 #include "monitor.h"
 #include "namespace.h"
 #include "network.h"
+#include "parse.h"
 #include "start.h"
 #include "state.h"
 #include "storage.h"

src/lxc/parse.c

@@ -20,13 +20,15 @@
  * License along with this library; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
+
 #define _GNU_SOURCE
 #include <stdio.h>
 #undef _GNU_SOURCE
-#include <string.h>
-#include <stdlib.h>
-#include <errno.h>
 #include <dirent.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
 
 #include "parse.h"
 #include "config.h"
@@ -35,6 +37,77 @@
 
 lxc_log_define(lxc_parse, lxc);
 
+void *lxc_strmmap(void *addr, size_t length, int prot, int flags, int fd,
+		  off_t offset)
+{
+	void *tmp = NULL, *overlap = NULL;
+
+	/* We establish an anonymous mapping that is one byte larger than the
+	 * underlying file. The pages handed to us are zero filled. */
+	tmp = mmap(addr, length + 1, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (tmp == MAP_FAILED)
+		return tmp;
+
+	/* Now we establish a fixed-address mapping starting at the address we
+	 * received from our anonymous mapping and replace all bytes excluding
+	 * the additional \0-byte with the file. This allows us to use normal
+	 * string-handling functions. */
+	overlap = mmap(tmp, length, prot, MAP_FIXED | flags, fd, offset);
+	if (overlap == MAP_FAILED)
+		munmap(tmp, length + 1);
+
+	return overlap;
+}
+
+int lxc_strmunmap(void *addr, size_t length)
+{
+	return munmap(addr, length + 1);
+}
+
+int lxc_file_for_each_line_mmap(const char *file, lxc_file_cb callback,
+				void *data)
+{
+	int fd, ret;
+	char *buf, *line;
+	struct stat st;
+	char *saveptr = NULL;
+
+	fd = open(file, O_RDONLY | O_CLOEXEC);
+	if (fd < 0)
+		return -1;
+
+	ret = fstat(fd, &st);
+	if (ret < 0) {
+		close(fd);
+		return -1;
+	}
+
+	if (st.st_size == 0)
+		return 0;
+
+	buf = lxc_strmmap(NULL, st.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+	if (buf == MAP_FAILED) {
+		close(fd);
+		return -1;
+	}
+
+	for (; (line = strtok_r(buf, "\n\0", &saveptr)); buf = NULL) {
+		ret = callback(line, data);
+		if (ret) {
+			/* Callback rv > 0 means stop here callback rv < 0 means
+			 * error.
+			 */
+			if (ret < 0)
+				ERROR("Failed to parse config: %s", line);
+			break;
+		}
+	}
+
+	lxc_strmunmap(buf, st.st_size);
+	close(fd);
+	return 0;
+}
+
 int lxc_file_for_each_line(const char *file, lxc_file_cb callback, void *data)
 {
 	FILE *f;

src/lxc/parse.h

@@ -23,6 +23,9 @@
 #ifndef __LXC_PARSE_H
 #define __LXC_PARSE_H
 
+#include <stdio.h>
+#include <sys/types.h>
+
 typedef int (*lxc_dir_cb)(const char *name, const char *directory,
 			  const char *file, void *data);
 
@@ -31,10 +34,20 @@ typedef int (*lxc_file_cb)(char *buffer, void *data);
 extern int lxc_file_for_each_line(const char *file, lxc_file_cb callback,
 				  void* data);
 
+extern int lxc_file_for_each_line_mmap(const char *file, lxc_file_cb callback,
+				       void *data);
+
 extern int lxc_char_left_gc(const char *buffer, size_t len);
 
 extern int lxc_char_right_gc(const char *buffer, size_t len);
 
 extern int lxc_is_line_empty(const char *line);
 
+/* mmap() wrapper. lxc_strmmap() will take care to \0-terminate files so that
+ * normal string-handling functions can be used on the buffer. */
+extern void *lxc_strmmap(void *addr, size_t length, int prot, int flags, int fd,
+			 off_t offset);
+/* munmap() wrapper. Use it to free memory mmap()ed with lxc_strmmap(). */
+extern int lxc_strmunmap(void *addr, size_t length);
+
 #endif

src/lxc/utils.c

@@ -1810,33 +1810,6 @@ int lxc_count_file_lines(const char *fn)
 	return n;
 }
 
-void *lxc_strmmap(void *addr, size_t length, int prot, int flags, int fd,
-		  off_t offset)
-{
-	void *tmp = NULL, *overlap = NULL;
-
-	/* We establish an anonymous mapping that is one byte larger than the
-	 * underlying file. The pages handed to us are zero filled. */
-	tmp = mmap(addr, length + 1, PROT_READ, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
-	if (tmp == MAP_FAILED)
-		return tmp;
-
-	/* Now we establish a fixed-address mapping starting at the address we
-	 * received from our anonymous mapping and replace all bytes excluding
-	 * the additional \0-byte with the file. This allows us to use normal
-	 * string-handling functions. */
-	overlap = mmap(tmp, length, prot, MAP_FIXED | flags, fd, offset);
-	if (overlap == MAP_FAILED)
-		munmap(tmp, length + 1);
-
-	return overlap;
-}
-
-int lxc_strmunmap(void *addr, size_t length)
-{
-	return munmap(addr, length + 1);
-}
-
 /* Check whether a signal is blocked by a process. */
 /* /proc/pid-to-str/status\0 = (5 + 21 + 7 + 1) */
 #define __PROC_STATUS_LEN (5 + (LXC_NUMSTRLEN64) + 7 + 1)

src/lxc/utils.h

@@ -426,13 +426,6 @@ extern size_t lxc_array_len(void **array);
 
 extern void **lxc_append_null_to_array(void **array, size_t count);
 
-/* mmap() wrapper. lxc_strmmap() will take care to \0-terminate files so that
- * normal string-handling functions can be used on the buffer. */
-extern void *lxc_strmmap(void *addr, size_t length, int prot, int flags, int fd,
-			 off_t offset);
-/* munmap() wrapper. Use it to free memory mmap()ed with lxc_strmmap(). */
-extern int lxc_strmunmap(void *addr, size_t length);
-
 /* initialize rand with urandom */
 extern int randseed(bool);