fdset: Introduce new fdsets

Current fdsets are ugly, limited (bitmask will exhaust in several months) and
suffer from unknown problems with fdsets reuse :(

With new approach (this set) the images management is simple. The basic function
is open_image, which gives you an fd for an image. If you want to pre-open several
images at once instead of calling open_image every single time, you can use the
new fdsets.

Images CR_FD_ descriptors should be grouped like

_CR_FD_FOO_FROM,
CR_FD_FOO_ITEM1,
CR_FD_FOO_ITEM2,
..
CR_FD_FOO_ITEMN,
_CR_FD_FOO_TO,

After this you can call cr_fd_open() specifying ranges -- _FROM and _TO macros,
it will give you an cr_fdset object. Then the fdset_fd(set, type) will give you
the descriptor of the open "set" group corresponding to the "type" type.

3 groups are introduced in this set -- tasks, ns and global.

That's it.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

crtools.c

@@ -145,15 +145,22 @@ struct cr_fd_desc_tmpl fdset_template[CR_FD_MAX] = {
 	},
 };
 
-static struct cr_fdset *alloc_cr_fdset(void)
+static struct cr_fdset *alloc_cr_fdset(int nr)
 {
 	struct cr_fdset *cr_fdset;
 	unsigned int i;
 
 	cr_fdset = xmalloc(sizeof(*cr_fdset));
-	if (cr_fdset)
-		for (i = 0; i < CR_FD_PID_MAX; i++)
-			cr_fdset->_fds[i] = -1;
+	if (cr_fdset == NULL)
+		return NULL;
+
+	cr_fdset->_fds = xmalloc(nr * sizeof(int));
+	if (cr_fdset->_fds == NULL) {
+		xfree(cr_fdset);
+		return NULL;
+	}
+
+	cr_fdset->fd_nr = nr;
 	return cr_fdset;
 }
 
@@ -164,7 +171,7 @@ static void __close_cr_fdset(struct cr_fdset *cr_fdset)
 	if (!cr_fdset)
 		return;
 
-	for (i = 0; i < CR_FD_PID_MAX; i++) {
+	for (i = 0; i < cr_fdset->fd_nr; i++) {
 		if (cr_fdset->_fds[i] == -1)
 			continue;
 		close_safe(&cr_fdset->_fds[i]);
@@ -179,30 +186,25 @@ void close_cr_fdset(struct cr_fdset **cr_fdset)
 
 	__close_cr_fdset(*cr_fdset);
 
+	xfree((*cr_fdset)->_fds);
 	xfree(*cr_fdset);
 	*cr_fdset = NULL;
 }
 
-#define CR_FD_DESC_USE(type)		((1 << (type)))
-
-static struct cr_fdset *cr_fdset_open(int pid, unsigned long use_mask,
+static struct cr_fdset *cr_fdset_open(int pid, int from, int to,
 			       unsigned long flags)
 {
 	struct cr_fdset *fdset;
 	unsigned int i;
 	int ret = -1;
 
-	fdset = alloc_cr_fdset();
+	fdset = alloc_cr_fdset(to - from);
 	if (!fdset)
 		goto err;
 
-	for (i = 0; i < CR_FD_PID_MAX; i++) {
-		if (!(use_mask & CR_FD_DESC_USE(i)))
-			continue;
-
-		if (fdset->_fds[i] != -1)
-			continue;
-
+	from++;
+	fdset->fd_off = from;
+	for (i = from; i < to; i++) {
 		ret = open_image(i, flags, pid);
 		if (ret < 0) {
 			if (!(flags & O_CREAT))
@@ -211,7 +213,7 @@ static struct cr_fdset *cr_fdset_open(int pid, unsigned long use_mask,
 			goto err;
 		}
 
-		fdset->_fds[i] = ret;
+		fdset->_fds[i - from] = ret;
 	}
 
 	return fdset;
@@ -221,33 +223,14 @@ err:
 	return NULL;
 }
 
-#define CR_FD_DESC_TASK				(\
-	CR_FD_DESC_USE(CR_FD_FDINFO)		|\
-	CR_FD_DESC_USE(CR_FD_PAGES)		|\
-	CR_FD_DESC_USE(CR_FD_CORE)		|\
-	CR_FD_DESC_USE(CR_FD_VMAS)		|\
-	CR_FD_DESC_USE(CR_FD_PIPES)		|\
-	CR_FD_DESC_USE(CR_FD_SIGACT)		|\
-	CR_FD_DESC_USE(CR_FD_UNIXSK)		|\
-	CR_FD_DESC_USE(CR_FD_INETSK)		|\
-	CR_FD_DESC_USE(CR_FD_ITIMERS)		|\
-	CR_FD_DESC_USE(CR_FD_CREDS)		)
-
 struct cr_fdset *cr_task_fdset_open(int pid, int mode)
 {
-	return cr_fdset_open(pid, CR_FD_DESC_TASK, mode);
+	return cr_fdset_open(pid, _CR_FD_TASK_FROM, _CR_FD_TASK_TO, mode);
 }
 
-#define CR_FD_DESC_NS				(\
-	CR_FD_DESC_USE(CR_FD_UTSNS)		|\
-	CR_FD_DESC_USE(CR_FD_IPCNS_VAR)		|\
-	CR_FD_DESC_USE(CR_FD_IPCNS_MSG)		|\
-	CR_FD_DESC_USE(CR_FD_IPCNS_SEM)		|\
-	CR_FD_DESC_USE(CR_FD_IPCNS_SHM)		)
-
 struct cr_fdset *cr_ns_fdset_open(int pid, int mode)
 {
-	return cr_fdset_open(pid, CR_FD_DESC_NS, mode);
+	return cr_fdset_open(pid, _CR_FD_NS_FROM, _CR_FD_NS_TO, mode);
 }
 
 static int parse_ns_string(const char *ptr, unsigned int *flags)

include/crtools.h

@@ -5,7 +5,7 @@
 
 #include "types.h"
 #include "list.h"
-
+#include "util.h"
 #include "image.h"
 
 extern struct page_entry zero_page_entry;
@@ -19,6 +19,7 @@ enum {
 	 * Task entries
 	 */
 
+	_CR_FD_TASK_FROM,
 	CR_FD_FDINFO,
 	CR_FD_PAGES,
 	CR_FD_CORE,
@@ -29,18 +30,19 @@ enum {
 	CR_FD_INETSK,
 	CR_FD_ITIMERS,
 	CR_FD_CREDS,
+	_CR_FD_TASK_TO,
 
 	/*
-	 * Global entries
+	 * NS entries
 	 */
 
+	_CR_FD_NS_FROM,
 	CR_FD_UTSNS,
 	CR_FD_IPCNS_VAR,
 	CR_FD_IPCNS_SHM,
 	CR_FD_IPCNS_MSG,
 	CR_FD_IPCNS_SEM,
-
-	CR_FD_PID_MAX, /* fmt, pid */
+	_CR_FD_NS_TO,
 
 	CR_FD_PSTREE,
 	CR_FD_SHMEM_PAGES,
@@ -112,12 +114,19 @@ extern int open_image_ro_nocheck(const char *fmt, ...);
 #define LAST_PID_PERM		0666
 
 struct cr_fdset {
-	int _fds[CR_FD_PID_MAX];
+	int fd_off;
+	int fd_nr;
+	int *_fds;
 };
 
 static inline int fdset_fd(const struct cr_fdset *fdset, int type)
 {
-	return fdset->_fds[type];
+	int idx;
+
+	idx = type - fdset->fd_off;
+	BUG_ON(idx > fdset->fd_nr);
+
+	return fdset->_fds[idx];
 }
 
 int cr_dump_tasks(pid_t pid, const struct cr_options *opts);