[Devel] [PATCH VZ10 v3 2/3] 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-144504

Feature: ve selftests
Signed-off-by: Vladimir Riabchun <vladimir.riabchun@virtuozzo.com>
---
 tools/testing/selftests/ve/ve_selftest.h | 85 +++++++++++++++++++++++++++++---
 1 file changed, 78 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/ve/ve_selftest.h b/tools/testing/selftests/ve/ve_selftest.h
index 22c5c8dfc2d1..bf9b89b59a6c 100644
--- a/tools/testing/selftests/ve/ve_selftest.h
+++ b/tools/testing/selftests/ve/ve_selftest.h
@@ -171,6 +171,14 @@ 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[32];
+
+	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)
 {
@@ -201,14 +209,9 @@ static inline int read_u64_at(int dirfd, const char *path,
 			      unsigned long long *out)
 {
 	char buf[32] = {0}, *end;
-	int fd, ret;
-
-	fd = openat(dirfd, path, O_RDONLY);
-	if (fd < 0)
-		return -1;
+	int ret;
 
-	ret = read(fd, buf, sizeof(buf) - 1);
-	close(fd);
+	ret = read_file_at(dirfd, path, buf, sizeof(buf));
 	if (ret <= 0)
 		return -1;
 
@@ -219,6 +222,25 @@ static inline int read_u64_at(int dirfd, const char *path,
 	return 0;
 }
 
+static inline int read_s32_at(int dirfd, const char *path,
+			      int *out)
+{
+	char buf[32] = {0}, *end;
+	long tmp;
+	int ret;
+
+	ret = read_file_at(dirfd, path, buf, sizeof(buf));
+	if (ret <= 0)
+		return -1;
+
+	errno = 0;
+	tmp = strtol(buf, &end, 10);
+	if (errno || end == buf || tmp < INT_MIN || tmp > INT_MAX)
+		return -1;
+	*out = tmp;
+	return 0;
+}
+
 /* A fresh, private cgroup2 mount, returned as an fd to use with *at() calls. */
 static inline int mount_cg2_fd(void)
 {
@@ -262,6 +284,55 @@ static inline int enter_cgroup(int cgv2_fd, int ctid)
 	return ret;
 }
 
+/*
+ * Run function in VE cgroup and given namespaces.
+ *
+ * Namespaces are provided via namespace_ctx and entered based on flags mask.
+ *
+ * Return values:
+ *  -  0 if function returns zero
+ *  - -1 if function returns negative value
+ *  -  1 if function returns positive value
+ *  -  2 if setup fails
+ */
+static inline int run_in_ve(int cgv2_fd, int ctid, struct namespace_ctx *ctx,
+		int flags, int (*fn)(void *), void *arg)
+{
+	int status;
+	pid_t pid;
+
+	pid = fork();
+	if (pid < 0) {
+		fprintf(stderr, "%s: fork failed\n", __func__);
+		return 2;
+	}
+	if (pid == 0) {
+		int ret;
+
+		if (enter_cgroup(cgv2_fd, ctid) < 0) {
+			fprintf(stderr, "%s: enter_cgroup failed\n", __func__);
+			_exit(254);
+		}
+		if (enter_namespaces(ctx, flags) < 0)
+			_exit(254);
+
+		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) == 254)
+		return 2;
+	if (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

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