vtgl

Commit: 9cfa730cbaf2d69ddb25dd22c2230b11fd36c151
Parent: b14e800a97c108805665b3a769d834a40463ea59
Author: Randy Palamar
Date:   Wed,  4 Dec 2024 07:53:47 -0700

replace forkpty

Diffstat:
M
os_unix.c
 | 
43
++++++++++++++++++++++++++++++-------------
M
platform_linux_amd64.c
 | 
3
+++
M
platform_linux_common.c
 | 
1
+

3 files changed, 34 insertions(+), 13 deletions(-)
diff --git a/os_unix.c b/os_unix.c
@@ -27,31 +27,48 @@ execsh(char *defcmd)
 
 	execvp(sh, argv);
 
-	_exit(1);
+	syscall1(SYS_exit_group, 1);
 }
 
 static linux_platform_process
 os_fork_child(char *cmd)
 {
-	i32 cfd;
+	i32 n = 0;
+	i64 m = syscall3(SYS_open, (iptr)"/dev/ptmx", O_RDWR|O_NOCTTY, 0);
+	if (m > -4096UL) os_fatal(s8("os_fork_child: failed to open master terminal\n"));
+	/* NOTE: first unlock the tty, then get a valid pty number */
+	if (syscall3(SYS_ioctl, m, TIOCSPTLCK, (iptr)&n) || syscall3(SYS_ioctl, m, TIOCGPTN, (iptr)&n))
+		os_fatal(s8("os_fork_child: failed to get a pty number\n"));
 
-	pid_t pid = forkpty(&cfd, NULL, NULL, NULL);
+	u8 buffer[20] = {"/dev/pts/"};
+	Stream sbuf = {.buf = buffer, .cap = 20, .widx = sizeof("/dev/pts/") - 1};
+	stream_push_i64(&sbuf, n);
+	stream_push_byte(&sbuf, 0);
 
-	switch (pid) {
-	case -1:
-		os_write_err_msg(s8("os_fork_child: failed to spawn child: "));
-		os_write_err_msg(c_str_to_s8(cmd));
-		os_fatal(s8("\n"));
-	case 0: /* child */
+	i64 s = syscall3(SYS_open, (iptr)sbuf.buf, O_RDWR|O_NOCTTY, 0);
+	if (s > -4096UL) os_fatal(s8("os_fork_child: failed to open slave terminal\n"));
+
+	i64 pid = syscall1(SYS_fork, 0);
+	if (pid > -4096UL) os_fatal(s8("os_fork_child: failed to fork a child\n"));
+
+	if (pid == 0) {
+		syscall1(SYS_close, m);
+		syscall1(SYS_setsid, 0);
+		syscall2(SYS_dup2, s, 0);
+		syscall2(SYS_dup2, s, 1);
+		syscall2(SYS_dup2, s, 2);
+		syscall3(SYS_ioctl, s, TIOCSCTTY, 0);
+		if (s > 2) syscall1(SYS_close, s);
 		execsh(cmd);
-		break;
 	}
+	syscall1(SYS_close, s);
 
-	i32 flags = fcntl(cfd, F_GETFL);
+	/* TODO: why is this needed? are we blocking on write? */
+	i32 flags = fcntl(m, F_GETFL);
 	if (flags == -1)
 		os_fatal(s8("os_fork_child: fcntl: F_GETFL\n"));
-	if (fcntl(cfd, F_SETFL, flags | O_NONBLOCK) == -1)
+	if (fcntl(m, F_SETFL, flags | O_NONBLOCK) == -1)
 		os_fatal(s8("os_fork_child: fcntl: F_SETFL\n"));
 
-	return (linux_platform_process){.process_id = pid, .handle = cfd};
+	return (linux_platform_process){.process_id = pid, .handle = m};
 }
diff --git a/platform_linux_amd64.c b/platform_linux_amd64.c
@@ -19,9 +19,12 @@
 #define SYS_ioctl              16
 #define SYS_pwrite             18
 #define SYS_madvise            28
+#define SYS_dup2               33
 #define SYS_clone              56
+#define SYS_fork               57
 #define SYS_wait4              61
 #define SYS_ftruncate          77
+#define SYS_setsid            112
 #define SYS_prctl             157
 #define SYS_futex             202
 #define SYS_getdents64        217
diff --git a/platform_linux_common.c b/platform_linux_common.c
@@ -35,6 +35,7 @@
 #define WNOHANG 1
 #define W_IF_EXITED(s) (!((s) & 0x7F))
 
+#define TIOCSCTTY  0x540E
 #define TIOCSWINSZ 0x5414
 #define TIOCSPTLCK 0x145431 /* (un)lock pty   */
 #define TIOCGPTN   0x245430 /* get pty number */