From: Michael Tremer <michael.tremer@ipfire.org>
Date: Sun, 6 Oct 2024 14:58:27 +0000 (+0000)
Subject: pty: Re-open standard input/output
X-Git-Tag: 0.9.30~1132
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=759ad7fbbd1c2db8860eaf65f6ab5ac602466d53;p=pakfire.git

pty: Re-open standard input/output

This is helpful so that we don't have to worry about resetting the
original file descriptors in case we crash unintentionally.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---

diff --git a/src/libpakfire/pty.c b/src/libpakfire/pty.c
index 67b49e173..6e3d2a798 100644
--- a/src/libpakfire/pty.c
+++ b/src/libpakfire/pty.c
@@ -29,6 +29,7 @@
 
 #include <pakfire/ctx.h>
 #include <pakfire/pty.h>
+#include <pakfire/string.h>
 #include <pakfire/util.h>
 
 struct pakfire_pty_stdio {
@@ -473,6 +474,45 @@ static int pakfire_pty_enable_raw_mode(struct pakfire_pty* pty, struct pakfire_p
 	return 0;
 }
 
+static int pakfire_pty_reopen(struct pakfire_pty* pty, int fd, int flags) {
+	char path[PATH_MAX];
+	int existing_flags;
+	off_t offset;
+	int r;
+
+	// Make the path
+	r = pakfire_string_format(path, "/proc/self/fd/%d", fd);
+	if (r < 0)
+		return r;
+
+	// Fetch flags
+	existing_flags = fcntl(fd, F_GETFL);
+	if (existing_flags < 0)
+		return -errno;
+
+	// Apply O_APPEND if set before
+	flags |= existing_flags & O_APPEND;
+
+	// Fetch the offset
+	offset = lseek(fd, 0, SEEK_CUR);
+
+	// Duplicate the file descriptor
+	fd = open(path, flags);
+	if (fd < 0)
+		return fd;
+
+	CTX_DEBUG(pty->ctx, "Re-opened %s as fd %d\n", path, fd);
+
+	// Try to re-apply the offset to the new file descriptor
+	if (offset > 0) {
+		r = lseek(fd, offset, SEEK_SET);
+		if (r < 0)
+			CTX_DEBUG(pty->ctx, "Failed to apply offset: %m\n");
+	}
+
+	return fd;
+}
+
 /*
 	Sets up PTY forwarding...
 */
@@ -485,9 +525,21 @@ static int pakfire_pty_setup_forwarding(struct pakfire_pty* pty) {
 	// Mark as forwarding
 	pty->state = PAKFIRE_PTY_STATE_FORWARDING;
 
-	// Connect to standard input/output
-	pty->stdin.fd  = STDIN_FILENO;
-	pty->stdout.fd = STDOUT_FILENO;
+	// Connect to standard input
+	if (!pakfire_pty_has_flag(pty, PAKFIRE_PTY_READ_ONLY)) {
+		pty->stdin.fd = pakfire_pty_reopen(pty, STDIN_FILENO, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
+		if (pty->stdin.fd < 0) {
+			CTX_ERROR(pty->ctx, "Could not re-open standard input: %s\n", strerror(-pty->stdin.fd));
+			return -pty->stdin.fd;
+		}
+	}
+
+	// Connect to standard output
+	pty->stdout.fd = pakfire_pty_reopen(pty, STDOUT_FILENO, O_WRONLY|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
+	if (pty->stdout.fd < 0) {
+		CTX_ERROR(pty->ctx, "Could not re-open standard output: %s\n", strerror(-pty->stdout.fd));
+		return -pty->stdout.fd;
+	}
 
 	// Copy the terminal dimensions to the PTY
 	if (isatty(pty->stdout.fd)) {