Use fallocate instead of ftruncate

Even if the ftruncate() system call succeeds, this does not guarantee that the underlying filesystem has enough free blocks to support whatever increase in file size that was requested. This can cause SIGBUS errors if writes are attempted in the file. The fallocate() call does guarantee that there is enough space available. Signed-off-by: Christian Despres <[email protected]>
eclipse-openj9 · Oct 22, 2024 · f440e51 · f440e51
1 parent 56cbcb6
commit f440e51
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/port/linux/omrvmem.c b/port/linux/omrvmem.c
@@ -1164,8 +1164,8 @@ reserve_memory_with_mmap(struct OMRPortLibrary *portLibrary, void *address, uint
 			fd = mkostemp(filename, 0);
 			if (OMRPORT_INVALID_FD != fd) {
 				unlink(filename);
-				/* Set the file size with ftruncate. */
-				if (OMRPORT_INVALID_FD == ftruncate(fd, byteAmount)) {
+				/* Set the file size with fallocate . */
+				if (OMRPORT_INVALID_FD == fallocate(fd, 0, 0, byteAmount)) {
 					close(fd);
 					fd = OMRPORT_INVALID_FD;
 				}