add test for ftruncate

test/Makefile

@@ -4,7 +4,7 @@ PROJECT_DIR := $(realpath $(CUR_DIR)/../)
 # Dependencies: need to be compiled but not to run by any Makefile target
 TEST_DEPS := dev_null
 # Tests: need to be compiled and run by test-% target
-TESTS := empty argv hello_world malloc file getpid spawn pipe time
+TESTS := empty argv hello_world malloc file getpid spawn pipe time truncate
 # Benchmarks: need to be compiled and run by bench-% target
 BENCHES := spawn_and_exit_latency pipe_throughput
 

test/truncate/Makefile

@@ -0,0 +1,5 @@
+include ../test_common.mk
+
+EXTRA_C_FLAGS :=
+EXTRA_LINK_FLAGS :=
+BIN_ARGS :=

test/truncate/main.c

@@ -0,0 +1,56 @@
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+#include <stdio.h>
+
+int main(int argc, const char* argv[]) {
+    const char* file_name = "tmp.txt";
+    const int TRUNC_LEN = 256;
+    const int MODE_MASK = 0777;
+
+    int ret;
+
+    int flags = O_WRONLY | O_CREAT| O_TRUNC;
+    int mode = 00666;
+    int fd = open(file_name, flags, mode);
+    if (fd < 0) {
+        printf("failed to open a file for write\n");
+        return fd;
+    }
+
+    ret = ftruncate(fd, TRUNC_LEN);
+    if (ret < 0) {
+        printf("failed to truncate the file\n");
+        return ret;
+    }
+
+    struct stat stat_buf;
+    ret = fstat(fd, &stat_buf);
+    if (ret < 0) {
+        printf("failed to fstat the file\n");
+        return ret;
+    }
+
+    int file_size = stat_buf.st_size;
+    if (file_size != TRUNC_LEN) {
+        printf("Incorrect file size %d. Expected %d\n", file_size, TRUNC_LEN);
+        return -1;
+    }
+    int file_mode = stat_buf.st_mode & MODE_MASK;
+	if (file_mode != mode) {
+		printf("Incorrect file mode %o. Expected %o\n", file_mode, mode);
+		return -1;
+	}
+	int file_type = stat_buf.st_mode & S_IFMT;
+	if (file_type != S_IFREG) {
+		printf("Incorrect file type %o. Expected %o\n", file_type, S_IFREG);
+		return -1;
+	}
+
+    close(fd);
+
+    printf("Truncate & fstat test succesful\n");
+    return 0;
+}