From 7da0d28318c97f1f3d629f13daad9ec824254709 Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@tavianator.com>
Date: Fri, 15 Dec 2017 12:40:37 -0500
Subject: Keep track of required FDs per-expr

---
 cmdline.h |  4 ----
 eval.c    |  4 +++-
 expr.h    |  5 +++++
 opt.c     | 13 +++++++++++++
 parse.c   | 25 ++++++++++++++-----------
 5 files changed, 35 insertions(+), 16 deletions(-)

diff --git a/cmdline.h b/cmdline.h
index 09500ce..e9731f9 100644
--- a/cmdline.h
+++ b/cmdline.h
@@ -98,10 +98,6 @@ 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 d13b548..88616cc 100644
--- a/eval.c
+++ b/eval.c
@@ -1195,7 +1195,9 @@ static int infer_fdlimit(const struct cmdline *cmdline) {
 		closedir(dir);
 	}
 
-	ret -= nopen + cmdline->persistent_fds + cmdline->ephemeral_fds;
+	ret -= nopen;
+	ret -= cmdline->expr->persistent_fds;
+	ret -= cmdline->expr->ephemeral_fds;
 
 	// bftw() needs at least 2 available fds
 	if (ret < 2) {
diff --git a/expr.h b/expr.h
index 5581bf4..0cd08ce 100644
--- a/expr.h
+++ b/expr.h
@@ -192,6 +192,11 @@ struct expr {
 
 	/** Optional string data for this expression. */
 	const char *sdata;
+
+	/** The number of files this expression keeps open between evaluations. */
+	int persistent_fds;
+	/** The number of files this expression opens during evaluation. */
+	int ephemeral_fds;
 };
 
 /** Singleton true expression instance. */
diff --git a/opt.c b/opt.c
index 405f995..a7ebbe2 100644
--- a/opt.c
+++ b/opt.c
@@ -571,6 +571,19 @@ static struct expr *optimize_expr_recursive(struct opt_state *state, struct expr
 		goto done;
 	}
 
+	struct expr *lhs = expr->lhs;
+	struct expr *rhs = expr->rhs;
+	if (rhs) {
+		expr->persistent_fds = rhs->persistent_fds;
+		expr->ephemeral_fds = rhs->ephemeral_fds;
+	}
+	if (lhs) {
+		expr->persistent_fds += lhs->persistent_fds;
+		if (lhs->ephemeral_fds > expr->ephemeral_fds) {
+			expr->ephemeral_fds = lhs->ephemeral_fds;
+		}
+	}
+
 	if (expr->always_true) {
 		set_facts_impossible(&state->facts_when_false);
 	}
diff --git a/parse.c b/parse.c
index e173d10..0e4eaad 100644
--- a/parse.c
+++ b/parse.c
@@ -124,6 +124,8 @@ struct expr *new_expr(eval_fn *eval, size_t argc, char **argv) {
 	expr->regex = NULL;
 	expr->execbuf = NULL;
 	expr->printf = NULL;
+	expr->persistent_fds = 0;
+	expr->ephemeral_fds = 0;
 	return expr;
 }
 
@@ -138,6 +140,8 @@ static struct expr *new_unary_expr(eval_fn *eval, struct expr *rhs, char **argv)
 	}
 
 	expr->rhs = rhs;
+	expr->persistent_fds = rhs->persistent_fds;
+	expr->ephemeral_fds = rhs->ephemeral_fds;
 	return expr;
 }
 
@@ -154,6 +158,12 @@ static struct expr *new_binary_expr(eval_fn *eval, struct expr *lhs, struct expr
 
 	expr->lhs = lhs;
 	expr->rhs = rhs;
+	expr->persistent_fds = lhs->persistent_fds + rhs->persistent_fds;
+	if (lhs->ephemeral_fds > rhs->ephemeral_fds) {
+		expr->ephemeral_fds = lhs->ephemeral_fds;
+	} else {
+		expr->ephemeral_fds = rhs->ephemeral_fds;
+	}
 	return expr;
 }
 
@@ -1073,9 +1083,7 @@ static struct expr *parse_empty(struct parser_state *state, int arg1, int arg2)
 		expr->pure = false;
 	}
 
-	if (cmdline->ephemeral_fds < 1) {
-		cmdline->ephemeral_fds = 1;
-	}
+	expr->ephemeral_fds = 1;
 
 	return expr;
 }
@@ -1105,17 +1113,14 @@ static struct expr *parse_exec(struct parser_state *state, int flags, int arg2)
 		expr->cost = 1000000.0;
 	}
 
-	int ephemeral_fds = 2;
+	expr->ephemeral_fds = 2;
 	if (execbuf->flags & BFS_EXEC_CHDIR) {
 		if (execbuf->flags & BFS_EXEC_MULTI) {
-			++cmdline->persistent_fds;
+			expr->persistent_fds = 1;
 		} else {
-			++ephemeral_fds;
+			++expr->ephemeral_fds;
 		}
 	}
-	if (cmdline->ephemeral_fds < ephemeral_fds) {
-		cmdline->ephemeral_fds = ephemeral_fds;
-	}
 
 	return expr;
 }
@@ -3051,8 +3056,6 @@ 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) {
-- 
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