1 files changed, 146 insertions, 0 deletions
diff --git a/lib/tdb/test/lock-tracking.c b/lib/tdb/test/lock-tracking.c
new file mode 100644
index 0000000000..18f2ab08f6
--- /dev/null
+++ b/lib/tdb/test/lock-tracking.c
@@ -0,0 +1,146 @@
+/* We save the locks so we can reaquire them. */
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <ccan/tap/tap.h>
+#include "../common/tdb_private.h"
+#include "lock-tracking.h"
+
+struct lock {
+	struct lock *next;
+	unsigned int off;
+	unsigned int len;
+	int type;
+};
+static struct lock *locks;
+int locking_errors = 0;
+bool suppress_lockcheck = false;
+bool nonblocking_locks;
+int locking_would_block = 0;
+void (*unlock_callback)(int fd);
+
+int fcntl_with_lockcheck(int fd, int cmd, ... /* arg */ )
+{
+	va_list ap;
+	int ret, arg3;
+	struct flock *fl;
+	bool may_block = false;
+
+	if (cmd != F_SETLK && cmd != F_SETLKW) {
+		/* This may be totally bogus, but we don't know in general. */
+		va_start(ap, cmd);
+		arg3 = va_arg(ap, int);
+		va_end(ap);
+
+		return fcntl(fd, cmd, arg3);
+	}
+
+	va_start(ap, cmd);
+	fl = va_arg(ap, struct flock *);
+	va_end(ap);
+
+	if (cmd == F_SETLKW && nonblocking_locks) {
+		cmd = F_SETLK;
+		may_block = true;
+	}
+	ret = fcntl(fd, cmd, fl);
+
+	/* Detect when we failed, but might have been OK if we waited. */
+	if (may_block && ret == -1 && (errno == EAGAIN || errno == EACCES)) {
+		locking_would_block++;
+	}
+
+	if (fl->l_type == F_UNLCK) {
+		struct lock **l;
+		struct lock *old = NULL;
+
+		for (l = &locks; *l; l = &(*l)->next) {
+			if ((*l)->off == fl->l_start
+			    && (*l)->len == fl->l_len) {
+				if (ret == 0) {
+					old = *l;
+					*l = (*l)->next;
+					free(old);
+				}
+				break;
+			}
+		}
+		if (!old && !suppress_lockcheck) {
+			diag("Unknown unlock %u@%u - %i",
+			     (int)fl->l_len, (int)fl->l_start, ret);
+			locking_errors++;
+		}
+	} else {
+		struct lock *new, *i;
+		unsigned int fl_end = fl->l_start + fl->l_len;
+		if (fl->l_len == 0)
+			fl_end = (unsigned int)-1;
+
+		/* Check for overlaps: we shouldn't do this. */
+		for (i = locks; i; i = i->next) {
+			unsigned int i_end = i->off + i->len;
+			if (i->len == 0)
+				i_end = (unsigned int)-1;
+
+			if (fl->l_start >= i->off && fl->l_start < i_end)
+				break;
+			if (fl_end >= i->off && fl_end < i_end)
+				break;
+
+			/* tdb_allrecord_lock does this, handle adjacent: */
+			if (fl->l_start == i_end && fl->l_type == i->type) {
+				if (ret == 0) {
+					i->len = fl->l_len
+						? i->len + fl->l_len
+						: 0;
+				}
+				goto done;
+			}
+		}
+		if (i) {
+			/* Special case: upgrade of allrecord lock. */
+			if (i->type == F_RDLCK && fl->l_type == F_WRLCK
+			    && i->off == FREELIST_TOP
+			    && fl->l_start == FREELIST_TOP
+			    && i->len == 0
+			    && fl->l_len == 0) {
+				if (ret == 0)
+					i->type = F_WRLCK;
+				goto done;
+			}
+			if (!suppress_lockcheck) {
+				diag("%s lock %u@%u overlaps %u@%u",
+				     fl->l_type == F_WRLCK ? "write" : "read",
+				     (int)fl->l_len, (int)fl->l_start,
+				     i->len, (int)i->off);
+				locking_errors++;
+			}
+		}
+
+		if (ret == 0) {
+			new = malloc(sizeof *new);
+			new->off = fl->l_start;
+			new->len = fl->l_len;
+			new->type = fl->l_type;
+			new->next = locks;
+			locks = new;
+		}
+	}
+done:
+	if (ret == 0 && fl->l_type == F_UNLCK && unlock_callback)
+		unlock_callback(fd);
+	return ret;
+}
+
+unsigned int forget_locking(void)
+{
+	unsigned int num = 0;
+	while (locks) {
+		struct lock *next = locks->next;
+		free(locks);
+		locks = next;
+		num++;
+	}
+	return num;
+}