printstr_ex: fix decoding of non-NUL-terminated strings when len == -1

Do not treat len == -1 in any special way.  All users who need the
string to be handled as a NUL-terminated string set QUOTE_0_TERMINATED
bit in user_style flags already.

* util.c (printstr_ex): Remove (len == -1) check.
* tests/printstr.c: New file.
* tests/printstr.test: New test.
* tests/.gitignore: Add printstr.
* tests/Makefile.am (check_PROGRAMS): Likewise.
(DECODER_TESTS): Add printstr.test.

diff --git a/tests/.gitignore b/tests/.gitignore
index 3b04590a617f33398bfbed718fb5d07e8bddf749..2f2c5d9e9d3fb1b49cab1821bbdcc70a77c66d5d 100644 (file)
--- a/tests/.gitignore
+++ b/tests/.gitignore
@@ -223,6 +223,7 @@ preadv
 preadv-pwritev
 preadv2-pwritev2
 print_maxfd
+printstr
 prlimit64
 process_vm_readv
 process_vm_writev

diff --git a/tests/Makefile.am b/tests/Makefile.am
index 7a8b411cfb28646f42308935fda092518c432163..793a0dc920d5a376f147aa54f8989de10afd8587 100644 (file)
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -283,6 +283,7 @@ check_PROGRAMS = \
        preadv-pwritev \
        preadv2-pwritev2 \
        print_maxfd \
+       printstr \
        prlimit64 \
        process_vm_readv \
        process_vm_writev \
@@ -667,6 +668,7 @@ DECODER_TESTS = \
        preadv-pwritev.test \
        preadv2-pwritev2.test \
        preadv.test \
+       printstr.test \
        prlimit64.test \
        process_vm_readv.test \
        process_vm_writev.test \

diff --git a/tests/printstr.c b/tests/printstr.c
new file mode 100644 (file)
index 0000000..330234f
--- /dev/null
+++ b/tests/printstr.c
@@ -0,0 +1,69 @@
+/*
+ * Check decoding of non-NUL-terminated strings when len == -1.
+ *
+ * Copyright (c) 2016 Dmitry V. Levin <ldv@altlinux.org>
+ * 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 "tests.h"
+
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/uio.h>
+
+#define DEFAULT_STRLEN 32
+
+int
+main(void)
+{
+       char *const buf = tail_alloc(DEFAULT_STRLEN + 1);
+       const struct iovec io = {
+               .iov_base = buf,
+               .iov_len = -1
+       };
+       int rc;
+
+       buf[0] = 0;
+
+       tprintf("%s", "");
+
+       memset(buf + 1, 'X', DEFAULT_STRLEN);
+       buf[DEFAULT_STRLEN - 1] = 0;
+
+       rc = writev(-1, &io, 1);
+       tprintf("writev(-1, [{iov_base=\"\\0%*s\\0\"..., iov_len=%lu}], 1)"
+               " = %s\n", DEFAULT_STRLEN - 2, buf + 1, -1UL, sprintrc(rc));
+
+       buf[DEFAULT_STRLEN - 1] = 'X';
+       buf[DEFAULT_STRLEN] = 0;
+
+       rc = writev(-1, &io, 1);
+       tprintf("writev(-1, [{iov_base=\"\\0%*s\"..., iov_len=%lu}], 1)"
+               " = %s\n", DEFAULT_STRLEN - 1, buf + 1, -1UL, sprintrc(rc));
+
+       tprintf("+++ exited with 0 +++\n");
+       return 0;
+}

diff --git a/tests/printstr.test b/tests/printstr.test
new file mode 100755 (executable)
index 0000000..5f164eb
--- /dev/null
+++ b/tests/printstr.test
@@ -0,0 +1,6 @@
+#!/bin/sh
+
+# Check decoding of non-NUL-terminated strings when len == -1.
+. "${srcdir=.}/init.sh"
+
+run_strace_match_diff -e trace=writev

diff --git a/util.c b/util.c
index bfc4134ec5e4d82439ecbf929ba8785ae5f42ad1..7dc6863ef3812f081785b86ba062a0527469b66e 100644 (file)
--- a/util.c
+++ b/util.c
@@ -850,12 +850,11 @@ printpath(struct tcb *const tcp, const kernel_ureg_t addr)
 
 /*
  * Print string specified by address `addr' and length `len'.
- * If `len' == -1, set QUOTE_0_TERMINATED bit in `user_style'.
  * If `user_style' has QUOTE_0_TERMINATED bit set, treat the string
  * as a NUL-terminated string.
  * Pass `user_style' on to `string_quote'.
  * Append `...' to the output if either the string length exceeds `max_strlen',
- * or `len' != -1 and the string length exceeds `len'.
+ * or QUOTE_0_TERMINATED bit is set and the string length exceeds `len'.
  */
 void
 printstr_ex(struct tcb *const tcp, const kernel_ureg_t addr, const long len,
@@ -882,22 +881,16 @@ printstr_ex(struct tcb *const tcp, const kernel_ureg_t addr, const long len,
                outstr = xmalloc(outstr_size);
        }
 
+       /* Fetch one byte more because string_quote may look one byte ahead. */
        size = max_strlen + 1;
-       if (len == -1) {
-               /*
-                * Treat as a NUL-terminated string: fetch one byte more
-                * because string_quote may look one byte ahead.
-                */
-               style |= QUOTE_0_TERMINATED;
+
+       if (size > (unsigned long) len)
+               size = (unsigned long) len;
+       if (style & QUOTE_0_TERMINATED)
                rc = umovestr(tcp, addr, size, str);
-       } else {
-               if (size > (unsigned long) len)
-                       size = (unsigned long) len;
-               if (style & QUOTE_0_TERMINATED)
-                       rc = umovestr(tcp, addr, size, str);
-               else
-                       rc = umoven(tcp, addr, size, str);
-       }
+       else
+               rc = umoven(tcp, addr, size, str);
+
        if (rc < 0) {
                printaddr(addr);
                return;