[Devel] [PATCH VZ10 v5 8/9] selftests/ve: Add more helpers

[Vladimir Riabchun <vladimir.riabchun@virtuozzo.com>]

Some more read/write helpers may be useful.

Also, add a helper to execute functions in child process with
switched namespaces and cgroup.

https://virtuozzo.atlassian.net/browse/VSTOR-135520

Feature: per-ve failcounters
Signed-off-by: Vladimir Riabchun <vladimir.riabchun@virtuozzo.com>
---
v4 -> v5:
 - In run_in_ve helper CLONE_NEWVE flag is added to unshare_flags
   unconditionally.

 tools/testing/selftests/ve/ve_selftest.h | 81 ++++++++++++++++++++++--
 1 file changed, 75 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/ve/ve_selftest.h b/tools/testing/selftests/ve/ve_selftest.h
index 69c0a52dd7ef..48bb7d1871bd 100644
--- a/tools/testing/selftests/ve/ve_selftest.h
+++ b/tools/testing/selftests/ve/ve_selftest.h
@@ -43,6 +43,14 @@ static inline int write_file_at(int dirfd, const char *path, const char *val)
 	return (ret == (int)len) ? 0 : -1;
 }
 
+static inline int write_u64_at(int dirfd, const char *path, unsigned long long val)
+{
+	char s[20];
+
+	snprintf(s, sizeof(s), "%llu", val);
+	return write_file_at(dirfd, path, s);
+}
+
 static inline int read_file_at(int dirfd, const char *path, char *buf,
 			       size_t buflen)
 {
@@ -73,19 +81,31 @@ static inline int read_u64_at(int dirfd, const char *path,
 			      unsigned long long *out)
 {
 	char buf[32] = {0}, *end;
-	int fd, ret;
+	int ret;
 
-	fd = openat(dirfd, path, O_RDONLY);
-	if (fd < 0)
+	ret = read_file_at(dirfd, path, buf, sizeof(buf));
+	if (ret <= 0)
 		return -1;
 
-	ret = read(fd, buf, sizeof(buf) - 1);
-	close(fd);
+	errno = 0;
+	*out = strtoull(buf, &end, 10);
+	if (errno || end == buf)
+		return -1;
+	return 0;
+}
+
+static inline int read_s32_at(int dirfd, const char *path,
+			      int *out)
+{
+	char buf[32] = {0}, *end;
+	int ret;
+
+	ret = read_file_at(dirfd, path, buf, sizeof(buf));
 	if (ret <= 0)
 		return -1;
 
 	errno = 0;
-	*out = strtoull(buf, &end, 10);
+	*out = strtol(buf, &end, 10);
 	if (errno || end == buf)
 		return -1;
 	return 0;
@@ -134,6 +154,55 @@ static inline int enter_cgroup(int cgv2_fd, int ctid)
 	return ret;
 }
 
+/*
+ * Run function in VE cgroup and new namespaces.
+ *
+ * Namespaces are provided via unshare_flags.
+ * CLONE_NEWVE flag is set by this function.
+ * Return values:
+ *  -  0 if function returns zero
+ *  - -1 if function returns negative value
+ *  -  1 if setup fails or function returns positive value
+ */
+static inline int run_in_ve(int cgv2_fd, int ctid, int unshare_flags,
+		int (*fn)(void *), void *arg)
+{
+	int status;
+	pid_t pid;
+
+	unshare_flags |= CLONE_NEWVE;
+	pid = fork();
+	if (pid < 0) {
+		fprintf(stderr, "%s: fork failed\n", __func__);
+		return 1;
+	}
+	if (pid == 0) {
+		int ret;
+
+		if (enter_cgroup(cgv2_fd, ctid) < 0) {
+			fprintf(stderr, "%s: enter_cgroup failed\n", __func__);
+			_exit(255);
+		}
+		if (unshare(unshare_flags) < 0) {
+			fprintf(stderr, "%s: unshare(%d) failed\n",
+				__func__, unshare_flags);
+			_exit(255);
+		}
+		ret = fn(arg);
+		if (ret < 0)
+			ret = 1;
+		else if (ret > 0)
+			ret = 255;
+		_exit(ret);
+	}
+	if (waitpid(pid, &status, 0) < 0 || !WIFEXITED(status) || WEXITSTATUS(status) == 255)
+		return 1;
+	if (WEXITSTATUS(status))
+		return -1;
+	return 0;
+
+}
+
 /*
  * Create a fresh VE cgroup at the first free id at or after @from and unhide
  * its ve.* control files. Return the new id, or -1.
-- 
2.47.1