cmdline: Account for files opened during/between evaluations more carefully

3 files changed, 26 insertions, 9 deletions

diff --git a/cmdline.h b/cmdline.h
index e9731f9..09500ce 100644
--- a/cmdline.h
+++ b/cmdline.h
@@ -98,6 +98,10 @@ struct cmdline {
 	struct open_file *open_files;
 	/** The number of open files owned by the command line. */
 	int nopen_files;
+	/** The number of files that may stay open between evaluations. */
+	int persistent_fds;
+	/** The number of files that mau be opened during evaluations. */
+	int ephemeral_fds;
 };
 
 /**
diff --git a/eval.c b/eval.c
index fe89225..1c9ae50 100644
--- a/eval.c
+++ b/eval.c
@@ -1191,8 +1191,7 @@ static int infer_fdlimit(const struct cmdline *cmdline) {
 		closedir(dir);
 	}
 
-	// 1 extra fd needed by -empty
-	ret -= nopen + 1;
+	ret -= nopen + cmdline->persistent_fds + cmdline->ephemeral_fds;
 
 	// bftw() needs at least 2 available fds
 	if (ret < 2) {
diff --git a/parse.c b/parse.c
index 9d533ab..9054af7 100644
--- a/parse.c
+++ b/parse.c
@@ -1064,13 +1064,19 @@ static struct expr *parse_empty(struct parser_state *state, int arg1, int arg2)
 	expr->cost = 2000.0;
 	expr->probability = 0.01;
 
-	if (state->cmdline->optlevel < 4) {
+	struct cmdline *cmdline = state->cmdline;
+
+	if (cmdline->optlevel < 4) {
 		// Since -empty attempts to open and read directories, it may
 		// have side effects such as reporting permission errors, and
 		// thus shouldn't be re-ordered without aggressive optimizations
 		expr->pure = false;
 	}
 
+	if (cmdline->ephemeral_fds < 1) {
+		cmdline->ephemeral_fds = 1;
+	}
+
 	return expr;
 }
 
@@ -1078,28 +1084,34 @@ static struct expr *parse_empty(struct parser_state *state, int arg1, int arg2)
  * Parse -exec(dir)?/-ok(dir)?.
  */
 static struct expr *parse_exec(struct parser_state *state, int flags, int arg2) {
-	struct bfs_exec *execbuf = parse_bfs_exec(state->argv, flags, state->cmdline);
+	struct cmdline *cmdline = state->cmdline;
+
+	struct bfs_exec *execbuf = parse_bfs_exec(state->argv, flags, cmdline);
 	if (!execbuf) {
 		return NULL;
 	}
 
-	if ((execbuf->flags & BFS_EXEC_CHDIR) && (execbuf->flags & BFS_EXEC_MULTI)) {
-		++state->cmdline->nopen_files;
-	}
-
 	struct expr *expr = parse_action(state, eval_exec, execbuf->tmpl_argc + 2);
 	if (!expr) {
 		free_bfs_exec(execbuf);
 		return NULL;
 	}
 
+	expr->execbuf = execbuf;
+
 	if (execbuf->flags & BFS_EXEC_MULTI) {
 		expr_set_always_true(expr);
 	} else {
 		expr->cost = 1000000.0;
 	}
 
-	expr->execbuf = execbuf;
+	if (execbuf->flags & BFS_EXEC_CHDIR) {
+		if (execbuf->flags & BFS_EXEC_MULTI) {
+			++cmdline->persistent_fds;
+		} else if (cmdline->ephemeral_fds < 1) {
+			cmdline->ephemeral_fds = 1;
+		}
+	}
 
 	return expr;
 }
@@ -3035,6 +3047,8 @@ struct cmdline *parse_cmdline(int argc, char *argv[]) {
 	cmdline->expr = &expr_true;
 	cmdline->open_files = NULL;
 	cmdline->nopen_files = 0;
+	cmdline->persistent_fds = 0;
+	cmdline->ephemeral_fds = 0;
 
 	cmdline->argv = malloc((argc + 1)*sizeof(*cmdline->argv));
 	if (!cmdline->argv) {