parse: Take umask into account in parse_mode()

POSIX 2024 clarified that find(1) is meant to work exactly like chmod(1)
here, so for modes like +rw,-x with no "who" specified, apply the umask.

Link: https://www.austingroupbugs.net/view.php?id=1392

Author: tavianator

src/ctx.c

@@ -52,6 +52,9 @@ struct bfs_ctx *bfs_ctx_new(void) {
 
 	trie_init(&ctx->files);
 
+	ctx->umask = umask(0);
+	umask(ctx->umask);
+
 	if (getrlimit(RLIMIT_NOFILE, &ctx->orig_nofile) != 0) {
 		goto fail;
 	}

src/ctx.h

@@ -16,6 +16,7 @@
 #include "trie.h"
 #include <stddef.h>
 #include <sys/resource.h>
+#include <sys/types.h>
 #include <time.h>
 
 struct CFILE;
@@ -98,6 +99,9 @@ struct bfs_ctx {
 	/** The number of files owned by the context. */
 	int nfiles;
 
+	/** The current file creation mask. */
+	mode_t umask;
+
 	/** The initial RLIMIT_NOFILE limits. */
 	struct rlimit orig_nofile;
 	/** The current RLIMIT_NOFILE limits. */

src/parse.c

@@ -1901,6 +1901,8 @@ static int parse_mode(const struct bfs_parser *parser, const char *mode, struct
 		return 0;
 	}
 
+	mode_t umask = parser->ctx->umask;
+
 	expr->file_mode = 0;
 	expr->dir_mode = 0;
 
@@ -1938,6 +1940,7 @@ static int parse_mode(const struct bfs_parser *parser, const char *mode, struct
 	} op uninit(MODE_EQUALS);
 
 	mode_t who uninit(0);
+	mode_t mask uninit(0);
 	mode_t file_change uninit(0);
 	mode_t dir_change uninit(0);
 
@@ -1946,6 +1949,7 @@ static int parse_mode(const struct bfs_parser *parser, const char *mode, struct
 		switch (state) {
 		case MODE_CLAUSE:
 			who = 0;
+			mask = 0777;
 			state = MODE_WHO;
 			fallthru;
 
@@ -1989,6 +1993,9 @@ static int parse_mode(const struct bfs_parser *parser, const char *mode, struct
 		case MODE_ACTION:
 			if (who == 0) {
 				who = 0777;
+				mask = who & ~umask;
+			} else {
+				mask = who;
 			}
 
 			switch (*i) {
@@ -2048,27 +2055,27 @@ static int parse_mode(const struct bfs_parser *parser, const char *mode, struct
 			}
 
 			file_change |= (file_change << 6) | (file_change << 3);
-			file_change &= who;
+			file_change &= mask;
 			dir_change |= (dir_change << 6) | (dir_change << 3);
-			dir_change &= who;
+			dir_change &= mask;
 			state = MODE_ACTION_APPLY;
 			break;
 
 		case MODE_PERM:
 			switch (*i) {
 			case 'r':
-				file_change |= who & 0444;
-				dir_change |= who & 0444;
+				file_change |= mask & 0444;
+				dir_change |= mask & 0444;
 				break;
 			case 'w':
-				file_change |= who & 0222;
-				dir_change |= who & 0222;
+				file_change |= mask & 0222;
+				dir_change |= mask & 0222;
 				break;
 			case 'x':
-				file_change |= who & 0111;
+				file_change |= mask & 0111;
 				fallthru;
 			case 'X':
-				dir_change |= who & 0111;
+				dir_change |= mask & 0111;
 				break;
 			case 's':
 				if (who & 0700) {

tests/bfs/perm_leading_plus_symbolic.out

@@ -1,2 +1,3 @@
-perms/drwxrwxrwx
-perms/frwxrwxrwx
+perms
+perms/drwxr-xr-x
+perms/frwxr-xr-x

tests/posix/perm_leading_plus_symbolic_minus.out

@@ -1,2 +1,7 @@
+perms
+perms/drwxr-xr-x
+perms/drwxrwxr-x
 perms/drwxrwxrwx
+perms/frwxr-xr-x
+perms/frwxrwxr-x
 perms/frwxrwxrwx

tests/posix/perm_leading_plus_umask.out

@@ -0,0 +1,10 @@
+perms/drwxrwxr-x
+perms/drwxrwxrwx
+perms/f-w--w----
+perms/f-w--w--w-
+perms/f-wx-wx--x
+perms/f-wx-wx-wx
+perms/frw-rw-r--
+perms/frw-rw-rw-
+perms/frwxrwxr-x
+perms/frwxrwxrwx

tests/posix/perm_leading_plus_umask.sh

@@ -0,0 +1,3 @@
+# Test for https://www.austingroupbugs.net/view.php?id=1392
+umask 002
+bfs_diff perms -perm -+w