freestanding: add core linux syscalls and associated tests

vlib/builtin/bare/.checks/.gitignore

@@ -0,0 +1 @@
+checks

vlib/builtin/bare/.checks/checks.v

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+module main
+
+import os
+
+fn failed (msg string) {
+	println ("!!! failed: $msg")
+}
+
+fn passed (msg string) {
+	println (">>> passed: $msg")
+}
+
+
+fn vcheck(vfile string) {
+	run_check := "v -freestanding --enable-globals run "
+	if 0 == os.system("$run_check $vfile/${vfile}.v") {
+		passed(run_check)
+	} else {
+		failed(run_check)
+	}
+	os.system("rm -f $vfile/$vfile")
+}
+
+fn main() {
+	vcheck("string")
+	vcheck("linuxsys")
+	exit(0)
+}
+

vlib/builtin/bare/.checks/linuxsys/linuxsys.v

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+module main
+
+__global fd [2]int
+__global buffer [16]byte
+
+const (
+	sample_text_file1 = ""
+)
+
+fn check_read_write_pipe() {
+	/*
+		Checks the following system calls:
+			sys_pipe
+			sys_write
+			sys_read
+			sys_close
+	*/
+	println ("checking pipe read/write")
+	fd[0] = -1
+	fd[1] = -1
+
+	assert fd[0] == -1
+	assert fd[1] == -1
+
+	a := sys_pipe(intptr(fd))
+
+	assert a != -1
+
+	assert fd[0] != -1
+	assert fd[1] != -1
+
+	test_data := "test_data"
+	b := test_data.len + 1
+	mut c := sys_write (fd[1], test_data.str, u64(b))
+
+	assert c == b
+
+	c = sys_read(fd[0], byteptr(buffer), u64(b))
+
+	assert c == b
+
+	assert buffer[b-1] == 0
+
+	for i in 0..b {
+		assert test_data[i] == buffer[i]
+	}
+
+	assert 0 == sys_close(fd[0])
+	assert 0 == sys_close(fd[1])
+
+	assert 0 != sys_close(-1)
+
+	println ("pipe read/write passed")
+}
+
+fn check_read_file() {
+	/*
+		Checks the following system calls:
+			sys_read
+			sys_write
+			sys_close
+	*/
+	test_file := "sample_text1.txt"
+	sample_text := "Do not change this text.\n"
+	println ("checking read file")
+	fd := sys_open(test_file.str, int(fcntl.o_rdonly), 0)
+	assert fd > 0
+	n := sample_text.len
+	c := sys_read(fd, buffer, u64(n*2))
+	assert c == n
+	for i in 0..n {
+		assert sample_text[i] == buffer[i]
+	}
+	assert 0 == sys_close(fd)
+	println("read file passed")
+}
+
+fn main() {
+	check_read_write_pipe()
+	check_read_file()
+	sys_exit(0)
+}
+

vlib/builtin/bare/.checks/readme.md

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+In this directory:
+```
+v run checks.v
+```
+

vlib/builtin/bare/.checks/sample_text1.txt

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+Do not change this text.

vlib/builtin/bare/.checks/string/string.v

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+module main
+
+fn check_string_eq () {
+	println ("checking string_eq")
+	assert "monkey" != "rat"
+	some_animal := "a bird"
+	assert some_animal == "a bird"
+	println ("string_eq passed")
+}
+
+fn main () {
+	check_string_eq ()
+	sys_exit(0)
+}
+