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 d9d1e233757bdb76bbabdc51436ac13b02388574..15ee5b5de68902cc0933209337c41dd1122df898 100644 (file)
--- 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 5974e36e35538cac553dd22daf81b1d24aba9410..0ad5c851072ab68de75788aeeb42c657dbd19e8c 100644 (file)
--- 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 */