[Qemu-devel] [RFC v6 1/2] util: add memmem replacement function

[hw.claudio@gmail.com]

From: Claudio Fontana <claudio.fontana@huawei.com>

if the memmem function is missing, provide a trivial replacement.

Signed-off-by: Claudio Fontana <claudio.fontana@huawei.com>
---
 configure            | 15 +++++++++++++
 include/qemu/osdep.h |  4 ++++
 util/Makefile.objs   |  1 +
 util/memmem.c        | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 82 insertions(+)
 create mode 100644 util/memmem.c

diff --git a/configure b/configure
index 1f0f485..feb55b1 100755
--- a/configure
+++ b/configure
@@ -3078,6 +3078,17 @@ if compile_prog "" "" ; then
 fi
 
 ##########################################
+# memmem probe
+cat > $TMPC <<EOF
+#include <string.h>
+int main(int argc, char *argv[]) { return memmem(argv[0], 0, argv[0], 0) != argv[0]; }
+EOF
+memmem=no
+if compile_prog "" "" ; then
+  memmem=yes
+fi
+
+##########################################
 # fdt probe
 # fdt support is mandatory for at least some target architectures,
 # so insist on it if we're building those system emulators.
@@ -4431,6 +4442,7 @@ echo "RDMA support      $rdma"
 echo "TCG interpreter   $tcg_interpreter"
 echo "fdt support       $fdt"
 echo "preadv support    $preadv"
+echo "memmem support    $memmem"
 echo "fdatasync         $fdatasync"
 echo "madvise           $madvise"
 echo "posix_madvise     $posix_madvise"
@@ -4780,6 +4792,9 @@ fi
 if test "$preadv" = "yes" ; then
   echo "CONFIG_PREADV=y" >> $config_host_mak
 fi
+if test "$memmem" = "yes" ; then
+  echo "CONFIG_MEMMEM=y" >> $config_host_mak
+fi
 if test "$fdt" = "yes" ; then
   echo "CONFIG_FDT=y" >> $config_host_mak
 fi
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index b3300cc..d74ddff 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -201,6 +201,10 @@ ssize_t writev(int fd, const struct iovec *iov, int iov_cnt);
 #include <sys/uio.h>
 #endif
 
+#ifndef CONFIG_MEMMEM
+void *memmem(const void *hay, size_t hay_len, const void *s, size_t s_len);
+#endif /* !CONFIG_MEMMEM */
+
 #ifdef _WIN32
 static inline void qemu_timersub(const struct timeval *val1,
                                  const struct timeval *val2,
diff --git a/util/Makefile.objs b/util/Makefile.objs
index ceaba30..628242f 100644
--- a/util/Makefile.objs
+++ b/util/Makefile.objs
@@ -1,6 +1,7 @@
 util-obj-y = osdep.o cutils.o unicode.o qemu-timer-common.o
 util-obj-$(CONFIG_WIN32) += oslib-win32.o qemu-thread-win32.o event_notifier-win32.o
 util-obj-$(CONFIG_POSIX) += oslib-posix.o qemu-thread-posix.o event_notifier-posix.o qemu-openpty.o
+util-obj-$(call lnot,$(CONFIG_MEMMEM)) += memmem.o
 util-obj-y += envlist.o path.o module.o
 util-obj-$(call lnot,$(CONFIG_INT128)) += host-utils.o
 util-obj-y += bitmap.o bitops.o hbitmap.o
diff --git a/util/memmem.c b/util/memmem.c
new file mode 100644
index 0000000..32b58ba
--- /dev/null
+++ b/util/memmem.c
@@ -0,0 +1,62 @@
+/*
+ * memmem replacement function
+ *
+ * Copyright (C) 2015 Huawei Technologies Duesseldorf GmbH
+ * Written by Claudio Fontana <claudio.fontana@huawei.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <qemu-common.h>
+
+/*
+ * Search for the first occurrence of a binary string ("needle")
+ * in a memory region ("haystack").
+ *
+ * If needle length is 0, it returns the pointer to the haystack.
+ * Otherwise it returns the pointer to the first character of the first
+ * occurrence of the needle in the haystack, or NULL if none are found.
+ *
+ */
+void *memmem(const void *haystack, size_t hay_len, const void *needle, size_t s_len)
+{
+    const unsigned char *hay = (const unsigned char *)haystack;
+    const unsigned char *s = (const unsigned char *)needle;
+    const unsigned char *last = hay + (hay_len - s_len);
+
+    if (s_len == 0) {
+        return (void *)hay;
+    }
+
+    if (hay_len < s_len) {
+        return NULL;
+    }
+
+    if (s_len == 1) {
+        return memchr(hay, s[0], hay_len);
+    }
+
+    for (; hay <= last; hay++) {
+        if (hay[0] == s[0] && memcmp(hay, s, s_len) == 0) {
+            return (void *)hay;
+        }
+    }
+
+    return NULL;
+}
-- 
1.8.5.3