From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Thu, 23 Jan 2020 22:09:13 +0000 (-0500)
Subject: directory-handle: add an equals method
X-Git-Tag: v2.12.0-rc1~41
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=0e98551307eb5a7a59cc74982b386dc95f4c4f89;p=lttng-tools.git

directory-handle: add an equals method

Add an "equals" method to both implementations of directory-handle.
The "directory fd" implementation uses the underlying inode of
the directory to perform comparisons.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I9c97f75ea6a79168d772268fca490aee7c333ae2
---

diff --git a/src/common/compat/directory-handle.c b/src/common/compat/directory-handle.c
index d9d1e2337..15ee5b5de 100644
--- a/src/common/compat/directory-handle.c
+++ b/src/common/compat/directory-handle.c
@@ -93,6 +93,26 @@ void lttng_directory_handle_release(struct urcu_ref *ref);
 
 #ifdef COMPAT_DIRFD
 
+/*
+ * Special inode number reserved to represent the "current working directory".
+ * ino_t is spec'ed as being an unsigned integral type.
+ */
+#define RESERVED_AT_FDCWD_INO                      \
+	({                                         \
+		uint64_t reserved_val;             \
+		switch (sizeof(ino_t)) {           \
+		case 4:                            \
+			reserved_val = UINT32_MAX; \
+			break;                     \
+		case 8:                            \
+			reserved_val = UINT64_MAX; \
+			break;                     \
+		default:                           \
+			abort();                   \
+		}                                  \
+		(ino_t) reserved_val;              \
+	})
+
 LTTNG_HIDDEN
 struct lttng_directory_handle *lttng_directory_handle_create(const char *path)
 {
@@ -144,11 +164,23 @@ LTTNG_HIDDEN
 struct lttng_directory_handle *lttng_directory_handle_create_from_dirfd(
 		int dirfd)
 {
+	int ret;
 	struct lttng_directory_handle *handle = zmalloc(sizeof(*handle));
+	struct stat stat_buf;
 
 	if (!handle) {
 		goto end;
 	}
+
+	if (dirfd != AT_FDCWD) {
+		ret = fstat(dirfd, &stat_buf);
+		if (ret) {
+			PERROR("Failed to fstat directory file descriptor %i", dirfd);
+			lttng_directory_handle_release(&handle->ref);
+		}
+	} else {
+		handle->directory_inode = RESERVED_AT_FDCWD_INO;
+	}
 	handle->dirfd = dirfd;
 	urcu_ref_init(&handle->ref);
 end:
@@ -199,6 +231,13 @@ end:
 	return new_handle;
 }
 
+LTTNG_HIDDEN
+bool lttng_directory_handle_equals(const struct lttng_directory_handle *lhs,
+		const struct lttng_directory_handle *rhs)
+{
+	return lhs->directory_inode == rhs->directory_inode;
+}
+
 static
 void lttng_directory_handle_invalidate(struct lttng_directory_handle *handle)
 {
@@ -550,6 +589,13 @@ end:
 	return new_handle;
 }
 
+LTTNG_HIDDEN
+bool lttng_directory_handle_equals(const struct lttng_directory_handle *lhs,
+		const struct lttng_directory_handle *rhs)
+{
+	return strcmp(lhs->path, rhs->path) == 0;
+}
+
 static
 void lttng_directory_handle_invalidate(struct lttng_directory_handle *handle)
 {
diff --git a/src/common/compat/directory-handle.h b/src/common/compat/directory-handle.h
index 5974e36e3..0ad5c8510 100644
--- a/src/common/compat/directory-handle.h
+++ b/src/common/compat/directory-handle.h
@@ -37,6 +37,7 @@ enum lttng_directory_handle_rmdir_recursive_flags {
 #ifdef COMPAT_DIRFD
 struct lttng_directory_handle {
 	struct urcu_ref ref;
+	ino_t directory_inode;
 	int dirfd;
 };
 
@@ -256,4 +257,13 @@ int lttng_directory_handle_remove_subdirectory_recursive_as_user(
 		const struct lttng_credentials *creds,
 		int flags);
 
+/*
+ * Compare two directory handles.
+ *
+ * Returns true if the two directory handles are equal, false otherwise.
+ */
+LTTNG_HIDDEN
+bool lttng_directory_handle_equals(const struct lttng_directory_handle *lhs,
+		const struct lttng_directory_handle *rhs);
+
 #endif /* _COMPAT_PATH_HANDLE_H */