vtgl

Commit: a5a679470ba738a710e43b04dfc5de04f6361c1d
Parent: 9cfa730cbaf2d69ddb25dd22c2230b11fd36c151
Author: Randy Palamar
Date:   Wed,  4 Dec 2024 18:18:39 -0700

drop unnecessary fcntl call in fork_child

Since we are opening the file descriptor ourselves we can just set
the flags we want to begin with.

Diffstat:
M
os_unix.c
 | 
47
++---------------------------------------------
M
platform_linux_common.c
 | 
43
+++++++++++++++++++++++++++++++++++++++++--

2 files changed, 43 insertions(+), 47 deletions(-)
diff --git a/os_unix.c b/os_unix.c
@@ -1,10 +1,9 @@
 /* See LICENSE for copyright details */
-#include <fcntl.h>
-#include <pty.h>
 #include <pwd.h>
 #include <sys/select.h>
 #include <unistd.h>
 
+__attribute__((noreturn))
 static void
 execsh(char *defcmd)
 {
@@ -28,47 +27,5 @@ execsh(char *defcmd)
 	execvp(sh, argv);
 
 	syscall1(SYS_exit_group, 1);
-}
-
-static linux_platform_process
-os_fork_child(char *cmd)
-{
-	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"));
-
-	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);
-
-	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);
-	}
-	syscall1(SYS_close, s);
-
-	/* 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(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 = m};
+	__builtin_unreachable();
 }
diff --git a/platform_linux_common.c b/platform_linux_common.c
@@ -37,8 +37,8 @@
 
 #define TIOCSCTTY  0x540E
 #define TIOCSWINSZ 0x5414
-#define TIOCSPTLCK 0x145431 /* (un)lock pty   */
-#define TIOCGPTN   0x245430 /* get pty number */
+#define TIOCSPTLCK 0x40045431 /* (un)lock pty   */
+#define TIOCGPTN   0x80045430 /* get pty number */
 
 #ifndef VERSION
 #define VERSION "unknown"
@@ -289,6 +289,45 @@ os_child_exited(iptr pid)
 	return r == pid && W_IF_EXITED(status);
 }
 
+static void execsh(char *);
+static linux_platform_process
+os_fork_child(char *cmd)
+{
+	i32 n = 0;
+
+	/* NOTE: we open in non-blocking mode so that we can try and fully drain the pipe
+	 * before processing. Otherwise a single read will be limited to the page size */
+	i64 m = syscall3(SYS_open, (iptr)"/dev/ptmx", O_RDWR|O_NOCTTY|O_NONBLOCK|O_CLOEXEC, 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"));
+
+	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);
+
+	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_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);
+	}
+	syscall1(SYS_close, s);
+
+	return (linux_platform_process){.process_id = pid, .handle = m};
+}
+
 static PLATFORM_SET_TERMINAL_SIZE_FN(os_set_terminal_size)
 {
 	u16 win_size[4];