zig

commit 947a3a1be92e0d5ddc5ad263d9434b31e8c170db (tree)
parent b7889f262a5bee642460eb33b1ae7f2b1f87864c
Author: Andrew Kelley <andrew@ziglang.org>
Date:   Mon, 27 May 2024 15:55:32 -0700

std.process.Child: fix spawning child proc with new cwd fd

Before this fix, the dup2 of the progress pipe was clobbering the cwd
fd, causing the fchdir to return ENOTDIR in between fork() and exec().

Diffstat:
M
lib/std/process/Child.zig
 | 
5
++++-

1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/lib/std/process/Child.zig b/lib/std/process/Child.zig
@@ -654,7 +654,6 @@ fn spawnPosix(self: *ChildProcess) SpawnError!void {
         setUpChildIo(self.stdin_behavior, stdin_pipe[0], posix.STDIN_FILENO, dev_null_fd) catch |err| forkChildErrReport(err_pipe[1], err);
         setUpChildIo(self.stdout_behavior, stdout_pipe[1], posix.STDOUT_FILENO, dev_null_fd) catch |err| forkChildErrReport(err_pipe[1], err);
         setUpChildIo(self.stderr_behavior, stderr_pipe[1], posix.STDERR_FILENO, dev_null_fd) catch |err| forkChildErrReport(err_pipe[1], err);
-        if (prog_pipe[1] != -1) posix.dup2(prog_pipe[1], prog_fileno) catch |err| forkChildErrReport(err_pipe[1], err);
 
         if (self.cwd_dir) |cwd| {
             posix.fchdir(cwd.fd) catch |err| forkChildErrReport(err_pipe[1], err);
@@ -662,6 +661,10 @@ fn spawnPosix(self: *ChildProcess) SpawnError!void {
             posix.chdir(cwd) catch |err| forkChildErrReport(err_pipe[1], err);
         }
 
+        // Must happen after fchdir above, the cwd file descriptor might be
+        // equal to prog_fileno and be clobbered by this dup2 call.
+        if (prog_pipe[1] != -1) posix.dup2(prog_pipe[1], prog_fileno) catch |err| forkChildErrReport(err_pipe[1], err);
+
         if (self.gid) |gid| {
             posix.setregid(gid, gid) catch |err| forkChildErrReport(err_pipe[1], err);
         }