[PATCH v4 29/55] selftests/mm: move read_file(), read_num() and write_num() to vm_util

[Mike Rapoport <rppt@kernel.org>]

From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>

These are useful helpers for writing and reading sysfs and proc files.

Make them available to the tests that don't use thp_settings.

While on it make write_num() use "%lu" instead of "%ld" to match
'unsigned long num' argument type.

Tested-by: Luiz Capitulino <luizcap@redhat.com>
Tested-by: Sarthak Sharma <sarthak.sharma@arm.com>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
 .../testing/selftests/mm/hugepage_settings.c  | 41 -------------------
 .../testing/selftests/mm/hugepage_settings.h  |  4 --
 tools/testing/selftests/mm/vm_util.c          | 39 ++++++++++++++++++
 tools/testing/selftests/mm/vm_util.h          |  3 ++
 4 files changed, 42 insertions(+), 45 deletions(-)

diff --git a/tools/testing/selftests/mm/hugepage_settings.c b/tools/testing/selftests/mm/hugepage_settings.c
index 01a557f372d1..2eab2110ac6a 100644
--- a/tools/testing/selftests/mm/hugepage_settings.c
+++ b/tools/testing/selftests/mm/hugepage_settings.c
@@ -48,47 +48,6 @@ static const char * const shmem_enabled_strings[] = {
 	NULL
 };
 
-int read_file(const char *path, char *buf, size_t buflen)
-{
-	int fd;
-	ssize_t numread;
-
-	fd = open(path, O_RDONLY);
-	if (fd == -1)
-		return 0;
-
-	numread = read(fd, buf, buflen - 1);
-	if (numread < 1) {
-		close(fd);
-		return 0;
-	}
-
-	buf[numread] = '\0';
-	close(fd);
-
-	return (unsigned int) numread;
-}
-
-unsigned long read_num(const char *path)
-{
-	char buf[21];
-
-	if (read_file(path, buf, sizeof(buf)) < 0) {
-		perror("read_file()");
-		exit(EXIT_FAILURE);
-	}
-
-	return strtoul(buf, NULL, 10);
-}
-
-void write_num(const char *path, unsigned long num)
-{
-	char buf[21];
-
-	sprintf(buf, "%ld", num);
-	write_file(path, buf, strlen(buf) + 1);
-}
-
 int thp_read_string(const char *name, const char * const strings[])
 {
 	char path[PATH_MAX];
diff --git a/tools/testing/selftests/mm/hugepage_settings.h b/tools/testing/selftests/mm/hugepage_settings.h
index c07722b7f102..726c73c43c05 100644
--- a/tools/testing/selftests/mm/hugepage_settings.h
+++ b/tools/testing/selftests/mm/hugepage_settings.h
@@ -66,10 +66,6 @@ struct thp_settings {
 	struct shmem_hugepages_settings shmem_hugepages[NR_ORDERS];
 };
 
-int read_file(const char *path, char *buf, size_t buflen);
-unsigned long read_num(const char *path);
-void write_num(const char *path, unsigned long num);
-
 int thp_read_string(const char *name, const char * const strings[]);
 void thp_write_string(const char *name, const char *val);
 unsigned long thp_read_num(const char *name);
diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index 412e980cce9a..9256bbbe38ea 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -698,6 +698,27 @@ int unpoison_memory(unsigned long pfn)
 	return ret > 0 ? 0 : -errno;
 }
 
+int read_file(const char *path, char *buf, size_t buflen)
+{
+	int fd;
+	ssize_t numread;
+
+	fd = open(path, O_RDONLY);
+	if (fd == -1)
+		return 0;
+
+	numread = read(fd, buf, buflen - 1);
+	if (numread < 1) {
+		close(fd);
+		return 0;
+	}
+
+	buf[numread] = '\0';
+	close(fd);
+
+	return (unsigned int) numread;
+}
+
 void write_file(const char *path, const char *buf, size_t buflen)
 {
 	int fd, saved_errno;
@@ -721,3 +742,21 @@ void write_file(const char *path, const char *buf, size_t buflen)
 		ksft_exit_fail_msg("%s write(%.*s) is truncated, expected %zu bytes, got %zd bytes\n",
 				path, (int)(buflen - 1), buf, buflen - 1, numwritten);
 }
+
+unsigned long read_num(const char *path)
+{
+	char buf[21];
+
+	if (read_file(path, buf, sizeof(buf)) < 0)
+		ksft_exit_fail_perror("read_file()");
+
+	return strtoul(buf, NULL, 10);
+}
+
+void write_num(const char *path, unsigned long num)
+{
+	char buf[21];
+
+	sprintf(buf, "%lu", num);
+	write_file(path, buf, strlen(buf) + 1);
+}
diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
index 195bf2e26792..5fc9707f6b9a 100644
--- a/tools/testing/selftests/mm/vm_util.h
+++ b/tools/testing/selftests/mm/vm_util.h
@@ -165,3 +165,6 @@ int unpoison_memory(unsigned long pfn);
 #define PAGEMAP_PFN(ent)	((ent) & ((1ull << 55) - 1))
 
 void write_file(const char *path, const char *buf, size_t buflen);
+int read_file(const char *path, char *buf, size_t buflen);
+unsigned long read_num(const char *path);
+void write_num(const char *path, unsigned long num);
-- 
2.53.0