[PATCH v3 2/4] selftests: cgroup: return the errno of write() in cg_write() on failure

From: Yosry Ahmed
Date: Fri Apr 08 2022 - 00:58:04 EST


Currently, cg_write() returns 0 on success and -1 on failure. Modify it
to return the errno of write() syscall when write() fails.

Signed-off-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
---
tools/testing/selftests/cgroup/cgroup_util.c | 32 +++++++++++---------
1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/cgroup_util.c
index dbaa7aabbb4a..3b6bb09985fa 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.c
+++ b/tools/testing/selftests/cgroup/cgroup_util.c
@@ -38,23 +38,23 @@ static ssize_t read_text(const char *path, char *buf, size_t max_len)
return len;
}

-static ssize_t write_text(const char *path, char *buf, ssize_t len)
+/*
+ * Returns:
+ * success -> 0
+ * open() failure -> -1
+ * write() failure -> errno
+ */
+static int write_text(const char *path, char *buf, ssize_t len)
{
- int fd;
+ int fd, ret;

fd = open(path, O_WRONLY | O_APPEND);
if (fd < 0)
return fd;

- len = write(fd, buf, len);
- if (len < 0) {
- close(fd);
- return len;
- }
-
+ ret = write(fd, buf, len) < 0 ? errno : 0;
close(fd);
-
- return len;
+ return ret;
}

char *cg_name(const char *root, const char *name)
@@ -177,17 +177,19 @@ long cg_read_lc(const char *cgroup, const char *control)
return cnt;
}

+/*
+ * Returns:
+ * success -> 0
+ * open() failure -> -1
+ * write() failure -> errno
+ */
int cg_write(const char *cgroup, const char *control, char *buf)
{
char path[PATH_MAX];
ssize_t len = strlen(buf);

snprintf(path, sizeof(path), "%s/%s", cgroup, control);
-
- if (write_text(path, buf, len) == len)
- return 0;
-
- return -1;
+ return write_text(path, buf, len);
}

int cg_find_unified_root(char *root, size_t len)
--
2.35.1.1178.g4f1659d476-goog