Add support for copyoutstr() subroutine

Move tests to their own copyoutstr/ subdirectory to mimic other copy*
tests.

Signed-off-by: Eugene Loh <eugene.loh@oracle.com>
Reviewed-by: Kris Van Hees <kris.van.hees@oracle.com>

libdtrace/dt_cg.c

@@ -4769,6 +4769,79 @@ dt_cg_subr_copyout(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
 	TRACE_REGSET("    subr-copyout:End  ");
 }
 
+static void
+dt_cg_subr_copyoutstr(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
+{
+	dt_node_t	*src = dnp->dn_args;
+	dt_node_t	*dst = src->dn_list;
+	dt_node_t	*size = dst->dn_list;
+	size_t		strsize = yypcb->pcb_hdl->dt_options[DTRACEOPT_STRSIZE];
+	uint64_t	off;
+	uint_t		L1 = dt_irlist_label(dlp);
+	uint_t		L2 = dt_irlist_label(dlp);
+	uint_t		L3 = dt_irlist_label(dlp);
+
+	dt_cg_clsflags(yypcb, DTRACEACT_PROC_DESTRUCTIVE, dnp);
+
+	TRACE_REGSET("    subr-copyoutstr:Begin");
+
+	dt_cg_node(src, dlp, drp);
+	dt_cg_node(dst, dlp, drp);
+	dt_cg_node(size, dlp, drp);
+
+	/* if (size > strsize) size = strsize */
+	emit(dlp,  BPF_BRANCH_IMM(BPF_JLE, size->dn_reg, strsize, L1));
+	emit(dlp,  BPF_MOV_IMM(size->dn_reg, strsize));
+	emitl(dlp, L1,
+		   BPF_NOP());
+
+	/* validate the pointers */
+	dt_cg_check_ptr_arg(dlp, drp, src, size);
+	dt_cg_check_notnull(dlp, drp, dst->dn_reg);
+
+	/* copy into a temporary string to determine the string length */
+	if (dt_regset_xalloc_args(drp) == -1)
+		longjmp(yypcb->pcb_jmpbuf, EDT_NOREG);
+	emit(dlp, BPF_MOV_REG(BPF_REG_2, size->dn_reg));
+	dt_regset_free(drp, size->dn_reg);
+	emit(dlp, BPF_MOV_REG(BPF_REG_3, src->dn_reg));
+	off = dt_cg_tstring_xalloc(yypcb);
+	emit(dlp,  BPF_LOAD(BPF_DW, BPF_REG_1, BPF_REG_FP, DT_STK_DCTX));
+	emit(dlp,  BPF_LOAD(BPF_DW, BPF_REG_1, BPF_REG_1, DCTX_MEM));
+	emit(dlp,  BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, off));
+	dt_regset_xalloc(drp, BPF_REG_0);
+	emit(dlp, BPF_CALL_HELPER(BPF_FUNC_probe_read_str));
+	dt_regset_free_args(drp);
+	dt_cg_tstring_xfree(yypcb, off);
+
+	/* check that we could read the string */
+	emit(dlp,  BPF_BRANCH_IMM(BPF_JSGT, BPF_REG_0, 0, L2));
+	dt_cg_probe_error(yypcb, DTRACEFLT_BADADDR, DT_ISREG, src->dn_reg);  // FIXME: is this right?
+	emitl(dlp, L2,
+		   BPF_NOP());
+
+	/* copy with the measured size */
+	if (dt_regset_xalloc_args(drp) == -1)
+		longjmp(yypcb->pcb_jmpbuf, EDT_NOREG);
+	emit(dlp,  BPF_MOV_REG(BPF_REG_1, dst->dn_reg));
+	emit(dlp,  BPF_MOV_REG(BPF_REG_2, src->dn_reg));
+	emit(dlp,  BPF_MOV_REG(BPF_REG_3, BPF_REG_0));
+	emit(dlp,  BPF_CALL_HELPER(BPF_FUNC_probe_write_user));
+	dt_regset_free_args(drp);
+
+	/* since src was validated, any problem must be with dst */
+	emit(dlp,  BPF_BRANCH_IMM(BPF_JEQ, BPF_REG_0, 0, L3));
+	dt_regset_free(drp, BPF_REG_0);
+	dt_cg_probe_error(yypcb, DTRACEFLT_BADADDR, DT_ISREG, dst->dn_reg);
+	emitl(dlp, L3,
+		   BPF_NOP());
+
+	dt_regset_free(drp, src->dn_reg);
+	dt_regset_free(drp, dst->dn_reg);
+
+	TRACE_REGSET("    subr-copyoutstr:End  ");
+}
+
 static void
 dt_cg_subr_strchr(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
 {
@@ -5246,7 +5319,7 @@ static dt_cg_subr_f *_dt_cg_subr[DIF_SUBR_MAX + 1] = {
 	[DIF_SUBR_PROGENYOF]		= &dt_cg_subr_progenyof,
 	[DIF_SUBR_STRLEN]		= &dt_cg_subr_strlen,
 	[DIF_SUBR_COPYOUT]		= &dt_cg_subr_copyout,
-	[DIF_SUBR_COPYOUTSTR]		= NULL,
+	[DIF_SUBR_COPYOUTSTR]		= &dt_cg_subr_copyoutstr,
 	[DIF_SUBR_ALLOCA]		= &dt_cg_subr_alloca,
 	[DIF_SUBR_BCOPY]		= &dt_cg_subr_bcopy,
 	[DIF_SUBR_COPYINTO]		= &dt_cg_subr_copyinto,

test/unittest/funcs/copyoutstr/err.D_PROTO_LEN.copyoutstrbadarg.r

@@ -0,0 +1,2 @@
+-- @@stderr --
+dtrace: failed to compile script test/unittest/funcs/copyoutstr/err.D_PROTO_LEN.copyoutstrbadarg.d: [D_PROTO_LEN] line 19: copyoutstr( ) prototype mismatch: 2 args passed, 3 expected

test/unittest/funcs/copyoutstr/err.D_PROTO_LEN.copyoutstrtoofew.r

@@ -0,0 +1,2 @@
+-- @@stderr --
+dtrace: failed to compile script test/unittest/funcs/copyoutstr/err.D_PROTO_LEN.copyoutstrtoofew.d: [D_PROTO_LEN] line 19: copyoutstr( ) prototype mismatch: 1 arg passed, 3 expected

test/unittest/funcs/copyoutstr/tst.copyoutstr.r

@@ -0,0 +1,6 @@
+size is longer than the string; expect full string with terminating byte
+HELLO WORLD; YOU HAVE A LONG MESSAGE TO DELIVER|---------------
+
+size is shorter than the string; expect 32 chars without terminating byte
+HELLO WORLD; YOU HAVE A LONG MES-------------------------------
+

test/unittest/funcs/copyoutstr/tst.copyoutstr.sh

@@ -0,0 +1,73 @@
+#!/bin/bash
+#
+# Oracle Linux DTrace.
+# Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+# Licensed under the Universal Permissive License v 1.0 as shown at
+# http://oss.oracle.com/licenses/upl.
+
+dtrace=$1
+DIRNAME="$tmpdir/copyoutstr.$$.$RANDOM"
+mkdir -p $DIRNAME
+cd $DIRNAME
+
+# Construct a C program that:
+# - initializes a user buffer
+# - passes that buffer to a syscall (where DTrace will overwrite the buffer)
+# - checks the buffer
+cat << EOF > main.c
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+int main(int c, char **v) {
+	int i, fd = open("/dev/null", O_WRONLY);
+	char s[64];
+
+	/* initialize buffer */
+	memset(s, '-', sizeof(s));
+	s[sizeof(s) - 1] = '\0';
+
+	/* write buffer to /dev/null (the D script will overwrite s) */
+	write(fd, s, strlen(s));
+	close(fd);
+
+	/* turn NUL chars (except last one) into printable '|' */
+	for (i = 0; i < sizeof(s) - 1; i++)
+		if (s[i] == '\0')
+			s[i] = '|';
+
+	/* print buffer contents */
+	printf("%s\n", s);
+	return 0;
+}
+EOF
+
+gcc main.c
+if [ $? -ne 0 ]; then
+	echo "compilation error"
+	exit 1
+fi
+
+# $1 is copyoutstr() size
+# $2 is DTrace options
+# $3 is description of test
+function mytest() {
+	echo $3
+	$dtrace $dt_flags $2 -qwn '
+	syscall::write:entry
+	/pid == $target/
+	{
+		s = "HELLO WORLD; YOU HAVE A LONG MESSAGE TO DELIVER";
+		copyoutstr(s, arg1, '$1');
+		exit(0);
+	}' -c ./a.out
+	if [ $? -ne 0 ]; then
+		echo "DTrace error"
+		exit 1
+	fi
+}
+
+mytest  64       " "      "size is longer than the string; expect full string with terminating byte"
+mytest  32       " "      "size is shorter than the string; expect 32 chars without terminating byte"
+
+exit 0

test/unittest/speculation/err.D_ACT_SPEC.SpeculateWithCopyOutStr.d

@@ -1,11 +1,11 @@
 #!/usr/sbin/dtrace -ws
 /*
  * Oracle Linux DTrace.
- * Copyright (c) 2006, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2006, 2023, Oracle and/or its affiliates. All rights reserved.
  * Licensed under the Universal Permissive License v 1.0 as shown at
  * http://oss.oracle.com/licenses/upl.
  */
-/* @@skip: dtv2, no copyoutstr yet */
+
 /*
  * ASSERTION: Destructive actions may never be speculative.
  *