[PATCH v5 2/4] selftests: cgroup: return -errno from cg_read()/cg_write() on failure

Yosry Ahmed
2022-04-25T19:01:08Z

Currently, cg_read()/cg_write() returns 0 on success and -1 on failure.
Modify them to return the -errno on failure.

Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
---
tools/testing/selftests/cgroup/cgroup_util.c | 44 +++++++++-----------
1 file changed, 19 insertions(+), 25 deletions(-)

diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/cgroup_util.c
index dbaa7aabbb4a..e6f3679cdcc0 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.c
+++ b/tools/testing/selftests/cgroup/cgroup_util.c
@@ -19,6 +19,7 @@
#include "cgroup_util.h"
#include "../clone3/clone3_selftests.h"

+/* Returns read len on success, or -errno on failure. */
static ssize_t read_text(const char *path, char *buf, size_t max_len)
{
ssize_t len;
@@ -26,35 +27,29 @@ static ssize_t read_text(const char *path, char *buf, size_t max_len)

fd = open(path, O_RDONLY);
if (fd < 0)
- return fd;
+ return -errno;

len = read(fd, buf, max_len - 1);
- if (len < 0)
- goto out;

- buf[len] = 0;
-out:
+ if (len >= 0)
+ buf[len] = 0;
+
close(fd);
- return len;
+ return len < 0 ? -errno : len;
}

+/* Returns written len on success, or -errno on failure. */
static ssize_t write_text(const char *path, char *buf, ssize_t len)
{
int fd;

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

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

char *cg_name(const char *root, const char *name)
@@ -87,16 +82,16 @@ char *cg_control(const char *cgroup, const char *control)
return ret;
}

+/* Returns 0 on success, or -errno on failure. */
int cg_read(const char *cgroup, const char *control, char *buf, size_t len)
{
char path[PATH_MAX];
+ ssize_t ret;

snprintf(path, sizeof(path), "%s/%s", cgroup, control);

- if (read_text(path, buf, len) >= 0)
- return 0;
-
- return -1;
+ ret = read_text(path, buf, len);
+ return ret >= 0 ? 0 : ret;
}

int cg_read_strcmp(const char *cgroup, const char *control,
@@ -177,17 +172,15 @@ long cg_read_lc(const char *cgroup, const char *control)
return cnt;
}

+/* Returns 0 on success, or -errno on failure. */
int cg_write(const char *cgroup, const char *control, char *buf)
{
char path[PATH_MAX];
- ssize_t len = strlen(buf);
+ ssize_t len = strlen(buf), ret;

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

int cg_find_unified_root(char *root, size_t len)
@@ -545,7 +538,8 @@ ssize_t proc_read_text(int pid, bool thread, const char *item, char *buf, size_t
else
snprintf(path, sizeof(path), "/proc/%d/%s", pid, item);

- return read_text(path, buf, size);
+ size = read_text(path, buf, size);
+ return size < 0 ? -1 : size;
}

int proc_read_strstr(int pid, bool thread, const char *item, const char *needle)
--
2.36.0.rc2.479.g8af0fa9b8e-goog