os: add a posix_set_permission_bit function (#7754)

vlib/os/const.v

@@ -1,18 +1 @@
 module os
-
-// (Must be realized in Syscall) (Must be specified)
-// ref: http://www.ccfit.nsu.ru/~deviv/courses/unix/unix/ng7c229.html
-const (
-	s_ifmt  = 0xF000 // type of file
-	s_ifdir = 0x4000 // directory
-	s_iflnk = 0xa000 // link
-	s_ixusr = 0o100 // is executable by the owner
-	s_ixgrp = 0o010 // is executable by group
-	s_ixoth = 0o001 // is executable by others
-)
-
-const (
-	std_input_handle  = -10
-	std_output_handle = -11
-	std_error_handle  = -12
-)

vlib/os/os_c.v

@@ -472,7 +472,7 @@ pub fn get_raw_line() string {
 		unsafe {
 			max_line_chars := 256
 			buf := malloc(max_line_chars * 2)
-			h_input := C.GetStdHandle(std_input_handle)
+			h_input := C.GetStdHandle(C.STD_INPUT_HANDLE)
 			mut bytes_read := 0
 			if is_atty(0) > 0 {
 				C.ReadConsole(h_input, buf, max_line_chars * 2, C.LPDWORD(&bytes_read),
@@ -514,7 +514,7 @@ pub fn get_raw_stdin() []byte {
 		unsafe {
 			block_bytes := 512
 			mut buf := malloc(block_bytes)
-			h_input := C.GetStdHandle(std_input_handle)
+			h_input := C.GetStdHandle(C.STD_INPUT_HANDLE)
 			mut bytes_read := 0
 			mut offset := 0
 			for {

vlib/os/os_nix.c.v

@@ -17,6 +17,26 @@ const (
 	stderr_value = 2
 )
 
+// (Must be realized in Syscall) (Must be specified)
+// ref: http://www.ccfit.nsu.ru/~deviv/courses/unix/unix/ng7c229.html
+pub const (
+	s_ifmt  = 0xF000 // type of file
+	s_ifdir = 0x4000 // directory
+	s_iflnk = 0xa000 // link
+	s_isuid = 0o4000 // SUID
+	s_isgid = 0o2000 // SGID
+	s_isvtx = 0o1000 // Sticky
+	s_irusr = 0o0400 // Read by owner
+	s_iwusr = 0o0200 // Write by owner
+	s_ixusr = 0o0100 // Execute by owner
+	s_irgrp = 0o0040 // Read by group
+	s_iwgrp = 0o0020 // Write by group
+	s_ixgrp = 0o0010 // Execute by group
+	s_iroth = 0o0004 // Read by others
+	s_iwoth = 0o0002 // Write by others
+	s_ixoth = 0o0001 // Execute by others
+)
+
 struct C.utsname {
 mut:
 	sysname  charptr
@@ -264,3 +284,19 @@ pub fn is_writable_folder(folder string) ?bool {
 pub fn getpid() int {
 	return C.getpid()
 }
+
+// Turns the given bit on or off, depending on the `enable` parameter
+pub fn posix_set_permission_bit(path_s string, mode u32, enable bool) {
+	mut s := C.stat{}
+	mut new_mode := u32(0)
+	path := charptr(path_s.str)
+	unsafe {
+		C.stat(path, &s)
+		new_mode = s.st_mode
+	}
+	match enable {
+		true { new_mode |= mode }
+		false { new_mode &= (0o7777 - mode) }
+	}
+	C.chmod(path, int(new_mode))
+}

vlib/os/os_test.v

@@ -465,3 +465,53 @@ for !cmd.eof {
 cmd.close()
 	*/
 }
+
+fn test_posix_set_bit() {
+	$if windows {
+		assert true
+	} $else {
+		fpath := '/tmp/permtest'
+		create(fpath) or { panic("Couldn't create file") }
+		chmod(fpath, 0o7777)
+		c_fpath := charptr(fpath.str)
+		mut s := C.stat{}
+		unsafe {
+			C.stat(c_fpath, &s)
+		}
+		// Take the permissions part of the mode
+		mut mode := u32(s.st_mode) & 0o7777
+		assert mode == 0o7777
+		// `chmod u-r`
+		posix_set_permission_bit(fpath, os.s_irusr, false)
+		unsafe {
+			C.stat(c_fpath, &s)
+		}
+		mode = u32(s.st_mode) & 0o7777
+		assert mode == 0o7377
+		// `chmod u+r`
+		posix_set_permission_bit(fpath, os.s_irusr, true)
+		unsafe {
+			C.stat(c_fpath, &s)
+		}
+		mode = u32(s.st_mode) & 0o7777
+		assert mode == 0o7777
+		// `chmod -s -g -t`
+		posix_set_permission_bit(fpath, os.s_isuid, false)
+		posix_set_permission_bit(fpath, os.s_isgid, false)
+		posix_set_permission_bit(fpath, os.s_isvtx, false)
+		unsafe {
+			C.stat(c_fpath, &s)
+		}
+		mode = u32(s.st_mode) & 0o7777
+		assert mode == 0o0777
+		// `chmod g-w o-w`
+		posix_set_permission_bit(fpath, os.s_iwgrp, false)
+		posix_set_permission_bit(fpath, os.s_iwoth, false)
+		unsafe {
+			C.stat(c_fpath, &s)
+		}
+		mode = u32(s.st_mode) & 0o7777
+		assert mode == 0o0755
+		rm(fpath)
+	}
+}

vlib/os/os_windows.c.v

@@ -391,3 +391,7 @@ fn C._getpid() int
 pub fn getpid() int {
 	return C._getpid()
 }
+
+pub fn posix_set_permission_bit(path_s string, mode u32, enable bool) {
+	// windows has no concept of a permission mask, so do nothing
+}