1 files changed, 25 insertions, 127 deletions
diff --git a/lib/libc/sys/ptrace.2 b/lib/libc/sys/ptrace.2
index 69477e9..37eca05 100644
--- a/lib/libc/sys/ptrace.2
+++ b/lib/libc/sys/ptrace.2
@@ -1,9 +1,10 @@
+.\" $FreeBSD$
 .\"	$NetBSD: ptrace.2,v 1.2 1995/02/27 12:35:37 cgd Exp $
 .\"
 .\" This file is in the public domain.
-.Dd November 7, 1994
+.Dd January 20, 1996
 .Dt PTRACE 2
-.Os NetBSD 1.0BETA
+.Os FreeBSD 2
 .Sh NAME
 .Nm ptrace
 .Nd process tracing and debugging
@@ -74,7 +75,9 @@ and data, which is why there are two requests: conceptually,
 .Dv PT_READ_I
 reads from the instruction space and
 .Dv PT_READ_D
-reads from the data space.  In the current NetBSD implementation, these
+reads from the data space.  In the current
+.Tn FreeBSD
+implementation, these
 two requests are completely identical.  The
 .Fa addr
 argument specifies the address (in the traced process' virtual address
@@ -163,7 +166,7 @@ succeeds, the traced process is no longer traced and continues
 execution normally.
 .El
 .Pp
-Additionally, machine-specific requests can exist.  On the SPARC, these
+Additionally, machine-specific requests can exist.  On the i386, these
 are:
 .Bl -tag -width 12n
 .It Dv PT_GETREGS
@@ -199,114 +202,25 @@ it loads the traced process' floating-point registers from the
 .Aq Pa machine/reg.h )
 pointed to by
 .Fa addr .
-.It Dv PT_SYSCALL
-This request is like
-.Dv PT_CONTINUE
-except that the process will stop next time it executes any system
-call.  Information about the system call can be examined with
-.Dv PT_READ_U
-and potentially modified with
-.Dv PT_WRITE_U
-through the
-.Li u_kproc.kp_proc.p_md
-element of the user structure (see below).  If the process is continued
-with another
-.Dv PT_SYSCALL
-request, it will stop again on exit from the syscall, at which point
-the return values can be examined and potentially changed.  The
-.Li u_kproc.kp_proc.p_md
-element is of type
-.Dq Li "struct mdproc" ,
-which should be declared by including
-.Aq Pa sys/param.h ,
-.Aq Pa sys/user.h ,
-and
-.Aq Pa machine/proc.h ,
-and contains the following fields (among others):
-.Bl -item -compact -offset indent
-.It
-.Li syscall_num
-.It
-.Li syscall_nargs
-.It
-.Li syscall_args[8]
-.It
-.Li syscall_err
-.It
-.Li syscall_rv[2]
-.El
-When a process stops on entry to a syscall,
-.Li syscall_num
-holds the number of the syscall,
-.Li syscall_nargs
-holds the number of arguments it expects, and
-.Li syscall_args
-holds the arguments themselves.  (Only the first
-.Li syscall_nargs
-elements of
-.Li syscall_args
-are guaranteed to be useful.)  When a process stops on exit from a
-syscall,
-.Li syscall_num
-is
-.Eo \&
-.Li -1
-.Ec ,
-.Li syscall_err
-holds the error number
-.Po
-see
-.Xr errno 2
-.Pc ,
-or 0 if no error occurred, and
-.Li syscall_rv
-holds the return values.  (If the syscall returns only one value, only
-.Li syscall_rv[0]
-is useful.)  The tracing process can modify any of these with
-.Dv PT_WRITE_U ;
-only some modifications are useful.
-.Pp
-On entry to a syscall,
-.Li syscall_num
-can be changed, and the syscall actually performed will correspond to
-the new number (it is the responsibility of the tracing process to fill
-in
-.Li syscall_args
-appropriately for the new call, but there is no need to modify
-.Eo \&
-.Li syscall_nargs
-.Ec ).
-If the new syscall number is 0, no syscall is actually performed;
-instead,
-.Li syscall_err
-and
-.Li syscall_rv
-are passed back to the traced process directly (and therefore should be
-filled in).  If the syscall number is otherwise out of range, a dummy
-syscall which simply produces an
-.Er ENOSYS
-error is effectively performed.
-.Pp
-On exit from a syscall, only
-.Li syscall_err
-and
-.Li syscall_rv
-can usefully be changed; they are set to the values returned by the
-syscall and will be passed back to the traced process by the normal
-syscall return mechanism.
 .El
-.Sh ERRORS
+.Sh RETURN VALUES
 Some requests can cause
 .Fn ptrace
 to return
 .Li -1
 as a non-error value; to disambiguate,
 .Va errno
-can be set to 0 before the call and checked afterwards.  The possible
-errors are:
+can be set to 0 before the call and checked afterwards.
+.Sh ERRORS
+The
+.Fn ptrace
+function may fail if:
 .Bl -tag -width 4n
 .It Bq Er ESRCH
+.Bl -bullet -compact
+.It
 No process having the specified process ID exists.
+.El
 .It Bq Er EINVAL
 .Bl -bullet -compact
 .It
@@ -331,8 +245,6 @@ The signal number (in
 .Fa data )
 to
 .Dv PT_CONTINUE
-or
-.Dv PT_SYSCALL
 was neither 0 nor a legal signal number.
 .It
 .Dv PT_GETREGS ,
@@ -369,27 +281,13 @@ on a process in violation of the requirements listed under
 .Dv PT_ATTACH
 above.
 .El
-.Sh BUGS
-On the SPARC, the PC is set to the provided PC value for
-.Dv PT_CONTINUE
-and similar calls, but the NPC is set willy-nilly to 4 greater than the
-PC value.  Using
-.Dv PT_GETREGS
-and
-.Dv PT_SETREGS
-to modify the PC, passing
-.Li (caddr_t)1
-to
-.Eo \&
+.Sh SEE ALSO
+.Xr execve 2 ,
+.Xr sigaction 2 ,
+.Xr wait 2 ,
+.Xr execv 3
+.Sh HISTORY
+A
 .Fn ptrace
-.Ec ,
-should be able to sidestep this.
-.Pp
-Single-stepping is not available.
-.Pp
-When using
-.Dv PT_SYSCALL ,
-there is no easy way to tell whether the traced process stopped because
-it made a syscall or because a signal was sent at a moment that it just
-happened to have valid-looking garbage in its
-.Dq Li "struct mdproc" .
+function call appeared in
+.At v7 .