feat(process): fork/exec/id/session + system/popen

src/process/session.c

@@ -0,0 +1,109 @@
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <unistd.h>
+
+#include "../internal/syscall.h"
+
+/* Foreground-process-group ioctls (x86_64 _IO/_IOR derivations). */
+#define VLIBC_PROC_TIOCGPGRP 0x540F
+#define VLIBC_PROC_TIOCSPGRP 0x5410
+
+/*
+ * Process group and session control (POSIX base): setpgid, getpgrp,
+ * setsid. The XSI/obsolescent extras (setpgrp, getpgid, getsid,
+ * tcgetpgrp, tcsetpgrp) are gated at level 2 below.
+ */
+
+/*
+ * setpgid: move pid (0 = the caller) into process group pgid (0 = pid's
+ * own value). A process can change groups for itself and its children;
+ * session leaders cannot change groups.
+ */
+int
+setpgid(pid_t pid, pid_t pgid)
+{
+    return syscall_ret(__syscall2(SYS_setpgid, pid, pgid));
+}
+
+/*
+ * getpgrp: the caller's process group.
+ */
+pid_t
+getpgrp(void)
+{
+    return (pid_t)syscall_ret(__syscall0(SYS_getpgrp));
+}
+
+/*
+ * setsid: make the caller the leader of a new session and process group,
+ * detaching it from the controlling terminal. Returns the new session id
+ * (the caller's pid), or -1 with errno EPERM when the caller is already
+ * a process group leader.
+ */
+pid_t
+setsid(void)
+{
+    return (pid_t)syscall_ret(__syscall0(SYS_setsid));
+}
+
+#if VLIBC_LEVEL_GE(2)
+
+/* Level 2 (muslmimic): XSI and obsolescent session extras. */
+
+/*
+ * setpgrp (obsolescent): setpgid(0, 0) — the caller becomes the leader
+ * of its own process group.
+ */
+int
+setpgrp(void)
+{
+    return setpgid(0, 0);
+}
+
+/*
+ * getpgid (XSI): the process group of pid (0 = the caller).
+ */
+pid_t
+getpgid(pid_t pid)
+{
+    return (pid_t)syscall_ret(__syscall1(SYS_getpgid, pid));
+}
+
+/*
+ * getsid (XSI): the session id of pid (0 = the caller).
+ */
+pid_t
+getsid(pid_t pid)
+{
+    return (pid_t)syscall_ret(__syscall1(SYS_getsid, pid));
+}
+
+/*
+ * tcgetpgrp (XSI): the foreground process group of the terminal on
+ * fildes, or -1 with errno set (ENOTTY when fildes is not a terminal).
+ */
+pid_t
+tcgetpgrp(int fildes)
+{
+    int pgrp = 0;
+
+    if (syscall_ret(__syscall3(SYS_ioctl, fildes, VLIBC_PROC_TIOCGPGRP, (long)&pgrp)) < 0)
+    {
+        return (pid_t)-1;
+    }
+    return (pid_t)pgrp;
+}
+
+/*
+ * tcsetpgrp (XSI): make pgid the foreground process group of the
+ * terminal on fildes.
+ */
+int
+tcsetpgrp(int fildes, pid_t pgid)
+{
+    return syscall_ret(__syscall3(SYS_ioctl, fildes, VLIBC_PROC_TIOCSPGRP, pgid));
+}
+
+#endif /* VLIBC_LEVEL_GE(2) */