From 3fa016dfdd7946e63f87da0c25b2e58a7b6dd258 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Sun, 10 May 2026 03:03:40 +0300
Subject: [PATCH] os: gc fix in fd_read

---
 vlib/os/fd.c.v     | 20 +++++++++++++++++++-
 vlib/os/os_nix.c.v |  9 ++++++++-
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/vlib/os/fd.c.v b/vlib/os/fd.c.v
index c0a0984a4..7580e50da 100644
--- a/vlib/os/fd.c.v
+++ b/vlib/os/fd.c.v
@@ -56,13 +56,31 @@ pub fn fd_slurp(fd int) []string {
 }
 
 // fd_read reads data from the file descriptor. It returns the read data, and how many bytes were read.
+// On signal interruption (EINTR), the read is retried so callers do not see spurious empty results
+// when a signal (for example a Boehm GC stop-the-world signal in a multi-threaded program) interrupts
+// a blocking read.
 pub fn fd_read(fd int, maxbytes int) (string, int) {
 	if fd == -1 {
 		return '', 0
 	}
 	unsafe {
 		mut buf := malloc_noscan(maxbytes + 1)
-		nbytes := int(C.read(fd, buf, maxbytes))
+		mut nbytes := 0
+		for {
+			$if !windows {
+				C.errno = 0
+			}
+			nbytes = int(C.read(fd, buf, maxbytes))
+			if nbytes >= 0 {
+				break
+			}
+			$if !windows {
+				if C.errno == C.EINTR {
+					continue
+				}
+			}
+			break
+		}
 		if nbytes < 0 {
 			free(buf)
 			return '', nbytes
diff --git a/vlib/os/os_nix.c.v b/vlib/os/os_nix.c.v
index 73e19cdc2..4d2a58d74 100644
--- a/vlib/os/os_nix.c.v
+++ b/vlib/os/os_nix.c.v
@@ -340,7 +340,14 @@ pub fn execute(cmd string) Result {
 	soutput := fd_slurp(read_fd).join('')
 	fd_close(read_fd)
 	mut status := 0
-	if C.waitpid(pid, &status, 0) == -1 {
+	for {
+		C.errno = 0
+		if C.waitpid(pid, &status, 0) != -1 {
+			break
+		}
+		if C.errno == C.EINTR {
+			continue
+		}
 		return Result{
 			exit_code: -1
 			output:    soutput
-- 
2.39.5