Transform fetch_old_mmap_args into fetch_indirect_syscall_args

As there are more than one old style syscall that take their arguments
via array, generalize fetch_old_mmap_args into a function that could
fetch variable number of arguments.

* mem.c (fetch_old_mmap_args): Transform into ...
* fetch_indirect_syscall_args.c: ... fetch_indirect_syscall_args
in this new file.
* Makefile.am (libstrace_a_SOURCES): Add it.
* defs.h [HAVE_ARCH_OLD_MMAP] (fetch_old_mmap_args): Remove.
(fetch_indirect_syscall_args): New prototype.
* pathtrace.c (pathtrace_match_set) [HAVE_ARCH_OLD_MMAP]: Use
fetch_indirect_syscall_args instead of fetch_old_mmap_args.

Makefile.am

@@ -70,6 +70,7 @@ noinst_LIBRARIES = libstrace.a
 libstrace_a_CPPFLAGS = $(strace_CPPFLAGS)
 libstrace_a_CFLAGS = $(strace_CFLAGS)
 libstrace_a_SOURCES =	\
+	fetch_indirect_syscall_args.c \
 	fstatfs.c \
 	fstatfs64.c \
 	getpagesize.c \

defs.h

@@ -554,9 +554,8 @@ extern void print_numeric_long_umask(unsigned long);
 extern void print_dev_t(unsigned long long dev);
 extern void print_abnormal_hi(kernel_ulong_t);
 
-#if HAVE_ARCH_OLD_MMAP
-extern kernel_ulong_t *fetch_old_mmap_args(struct tcb *tcp);
-#endif
+extern kernel_ulong_t *
+fetch_indirect_syscall_args(struct tcb *, kernel_ulong_t addr, unsigned int n_args);
 
 extern void
 dumpiov_in_msghdr(struct tcb *, kernel_ulong_t addr, kernel_ulong_t data_size);

fetch_indirect_syscall_args.c

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2018 The strace developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "defs.h"
+
+/*
+ * Fetch indirect syscall arguments that are provided as an array.
+ * Return a pointer to a static array of kernel_ulong_t elements,
+ * or NULL in case of fetch failure.
+ */
+kernel_ulong_t *
+fetch_indirect_syscall_args(struct tcb *const tcp,
+			    const kernel_ulong_t addr,
+			    const unsigned int n_args)
+{
+	static kernel_ulong_t u_arg[MAX_ARGS];
+
+	if (current_wordsize == sizeof(*u_arg)) {
+		if (umoven(tcp, addr, sizeof(*u_arg) * n_args, u_arg))
+			return NULL;
+	} else {
+		uint32_t narrow_arg[ARRAY_SIZE(u_arg)];
+
+		if (umoven(tcp, addr, sizeof(*narrow_arg) * n_args, narrow_arg))
+			return NULL;
+		for (unsigned int i = 0; i < n_args; ++i)
+			u_arg[i] = narrow_arg[i];
+	}
+
+	return u_arg;
+}

mem.c

@@ -108,33 +108,11 @@ print_mmap(struct tcb *tcp, kernel_ulong_t *u_arg, unsigned long long offset)
  */
 
 #if HAVE_ARCH_OLD_MMAP
-/**
- * Fetch old_mmap/old_mmap_pgoff arguments that are provided as a 6-element
- * array.  Return pointer to a static array or NULL in case of fetch failure.
- */
-kernel_ulong_t *
-fetch_old_mmap_args(struct tcb *tcp)
-{
-	static kernel_ulong_t u_arg[6];
-
-	if (current_wordsize == 4) {
-		unsigned int narrow_arg[6];
-		if (umove(tcp, tcp->u_arg[0], &narrow_arg))
-			return NULL;
-		for (unsigned int i = 0; i < 6; i++)
-			u_arg[i] = narrow_arg[i];
-	} else {
-		if (umove(tcp, tcp->u_arg[0], &u_arg))
-			return NULL;
-	}
-
-	return u_arg;
-}
-
 /* Params are pointed to by u_arg[0], offset is in bytes */
 SYS_FUNC(old_mmap)
 {
-	kernel_ulong_t *args = fetch_old_mmap_args(tcp);
+	kernel_ulong_t *args =
+		fetch_indirect_syscall_args(tcp, tcp->u_arg[0], 6);
 
 	if (args)
 		print_mmap(tcp, args, args[5]);
@@ -148,7 +126,8 @@ SYS_FUNC(old_mmap)
 /* Params are pointed to by u_arg[0], offset is in pages */
 SYS_FUNC(old_mmap_pgoff)
 {
-	kernel_ulong_t *args = fetch_old_mmap_args(tcp);
+	kernel_ulong_t *args =
+		fetch_indirect_syscall_args(tcp, tcp->u_arg[0], 6);
 
 	if (args) {
 		unsigned long long offset;

pathtrace.c

@@ -220,7 +220,8 @@ pathtrace_match_set(struct tcb *tcp, struct path_set *set)
 	case SEN_old_mmap_pgoff:
 # endif
 	{
-		kernel_ulong_t *args = fetch_old_mmap_args(tcp);
+		kernel_ulong_t *args =
+			fetch_indirect_syscall_args(tcp, tcp->u_arg[0], 6);
 
 		return args && fdmatch(tcp, args[4], set);
 	}