[PATCH v2 3/5] src/t_dir_offset2: Add option to create or unlink file

[Amir Goldstein <amir73il@gmail.com>]

Will be used to test missing/stale entries after modifications to
an open dirfd.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 src/t_dir_offset2.c | 56 ++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 53 insertions(+), 3 deletions(-)

diff --git a/src/t_dir_offset2.c b/src/t_dir_offset2.c
index 7af24519..75b41c1a 100644
--- a/src/t_dir_offset2.c
+++ b/src/t_dir_offset2.c
@@ -34,13 +34,13 @@ static uint64_t d_ino_history[HISTORY_LEN];
 
 void usage()
 {
-	fprintf(stderr, "usage: t_dir_offset2: <dir> [[bufsize] <filename> [-v]]\n");
+	fprintf(stderr, "usage: t_dir_offset2: <dir> [[bufsize] [-|+]<filename> [-v]]\n");
 	exit(EXIT_FAILURE);
 }
 
 int main(int argc, char *argv[])
 {
-	int fd;
+	int fd, fd2 = -1;
 	char buf[BUF_SIZE];
 	int nread, bufsize = BUF_SIZE;
 	struct linux_dirent64 *d;
@@ -49,7 +49,7 @@ int main(int argc, char *argv[])
 	int retval = EXIT_SUCCESS;
 	const char *filename = NULL;
 	int exists = 0, found = 0;
-	int verbose = 0;
+	int modify = 0, verbose = 0;
 
 	if (argc > 2) {
 		bufsize = atoi(argv[2]);
@@ -60,6 +60,13 @@ int main(int argc, char *argv[])
 
 		if (argc > 3) {
 			filename = argv[3];
+			/* +<filename> creates, -<filename> removes */
+			if (filename[0] == '+')
+				modify = 1;
+			else if (filename[0] == '-')
+				modify = -1;
+			if (modify)
+				filename++;
 			if (argc > 4 && !strcmp(argv[4], "-v"))
 				verbose = 1;
 		}
@@ -89,6 +96,49 @@ int main(int argc, char *argv[])
 			exit(EXIT_FAILURE);
 		}
 
+		if (modify && fd2 < 0 && total == 0) {
+			printf("getdents at offset 0 returned %d bytes\n", nread);
+
+			/* create/unlink entry after first getdents */
+			if (modify > 0) {
+				if (openat(fd, filename, O_CREAT, 0600) < 0) {
+					perror("openat");
+					exit(EXIT_FAILURE);
+				}
+				exists = 1;
+				printf("created entry %s\n", filename);
+			} else if (modify < 0) {
+				if (unlinkat(fd, filename, 0) < 0) {
+					perror("unlinkat");
+					exit(EXIT_FAILURE);
+				}
+				exists = 0;
+				printf("unlinked entry %s\n", filename);
+			}
+
+			/*
+			 * Old fd may not return new entry and may return stale
+			 * entries which is allowed.  Keep old fd open and open
+			 * a new fd to check for stale or missing entries later.
+			 */
+			fd2 = open(argv[1], O_RDONLY | O_DIRECTORY);
+			if (fd2 < 0) {
+				perror("open fd2");
+				exit(EXIT_FAILURE);
+			}
+		}
+
+		if (nread == 0) {
+			if (fd2 < 0 || fd == fd2)
+				break;
+
+			/* Re-iterate with new fd leaving old fd open */
+			fd = fd2;
+			total = 0;
+			found = 0;
+			continue;
+		}
+
 		if (nread == 0)
 			break;
 
-- 
2.31.1