dyxlat: new interface for building xlat tables dynamically

xlat tables are usually generated at build time.

printxval is suitable for printing struct nlmsghdr.nlmsg_type for
NETLINK_GENERIC protocol.  However, the corresponding xlat table
cannot be defined at build time because the values are registered
by the kernel at run time.

This change introduces dyxlat functions for building xlat tables
dynamically.  The primary use case is decoding nlmsg_type but this
interface can be used for other purposes.

* defs.h (struct dyxlat): New opaque data type.
(dyxlat_alloc, dyxlat_free, dyxlat_add_pair): New function declarations.
* dyxlat.c: New file.
* Makefile.am (strace_SOURCES): Add it.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>

diff --git a/Makefile.am b/Makefile.am
index e22d4804ec59172ce6f958e2b7b1bd11e36a299f..f9e78ed19f4d0c39e3bf12bf0691b57a1b0249fc 100644 (file)
--- a/Makefile.am
+++ b/Makefile.am
@@ -104,6 +104,7 @@ strace_SOURCES =    \
        dirent.c        \
        dirent64.c      \
        dm.c            \
+       dyxlat.c        \
        empty.h         \
        epoll.c         \
        evdev.c         \

diff --git a/defs.h b/defs.h
index 5e054577e796706f8b5d3f3e00fc0d2337ec1cf8..f7b57090bd8f9e3812c0fa498e7a5a7819844af1 100644 (file)
--- a/defs.h
+++ b/defs.h
@@ -508,6 +508,12 @@ extern enum sock_proto getfdproto(struct tcb *, int);
 extern const char *xlookup(const struct xlat *, const uint64_t);
 extern const char *xlat_search(const struct xlat *, const size_t, const uint64_t);
 
+struct dyxlat;
+struct dyxlat *dyxlat_alloc(size_t nmemb);
+void dyxlat_free(struct dyxlat *);
+const struct xlat *dyxlat_get(const struct dyxlat *);
+void dyxlat_add_pair(struct dyxlat *, uint64_t val, const char *str, size_t len);
+
 extern unsigned long get_pagesize(void);
 extern int
 string_to_uint_ex(const char *str, char **endptr,

diff --git a/dyxlat.c b/dyxlat.c
new file mode 100644 (file)
index 0000000..ef6bef4
--- /dev/null
+++ b/dyxlat.c
@@ -0,0 +1,103 @@
+/*
+ * Copyright (c) 2017 The strace developers.
+ *
+ * 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"
+
+struct dyxlat {
+       size_t used;
+       size_t allocated;
+       struct xlat *xlat;
+};
+
+#define MARK_END(xlat)                         \
+       do {                                    \
+               (xlat).val = 0;                 \
+               (xlat).str = 0;                 \
+       } while (0)
+
+struct dyxlat *
+dyxlat_alloc(const size_t nmemb)
+{
+       struct dyxlat *const dyxlat = xmalloc(sizeof(*dyxlat));
+
+       dyxlat->used = 1;
+       dyxlat->allocated = nmemb ? nmemb : 16;
+       dyxlat->xlat = xcalloc(dyxlat->allocated, sizeof(struct xlat));
+       MARK_END(dyxlat->xlat[0]);
+
+       return dyxlat;
+}
+
+void
+dyxlat_free(struct dyxlat *const dyxlat)
+{
+       size_t i;
+
+       for (i = 0; i < dyxlat->used - 1; ++i) {
+               free((void *) dyxlat->xlat[i].str);
+               dyxlat->xlat[i].str = NULL;
+       }
+
+       free(dyxlat->xlat);
+       dyxlat->xlat = NULL;
+       free(dyxlat);
+}
+
+const struct xlat *
+dyxlat_get(const struct dyxlat *const dyxlat)
+{
+       return dyxlat->xlat;
+}
+
+void
+dyxlat_add_pair(struct dyxlat *const dyxlat, const uint64_t val,
+               const char *const str, const size_t len)
+{
+       size_t i;
+
+       for (i = 0; i < dyxlat->used - 1; ++i) {
+               if (dyxlat->xlat[i].val == val) {
+                       if (strncmp(dyxlat->xlat[i].str, str, len) == 0
+                           && dyxlat->xlat[i].str[len] == '\0')
+                               return;
+
+                       free((void *) dyxlat->xlat[i].str);
+                       dyxlat->xlat[i].str = xstrndup(str, len);
+                       return;
+               }
+       }
+
+       if (dyxlat->used >= dyxlat->allocated) {
+               dyxlat->allocated *= 2;
+               dyxlat->xlat = xreallocarray(dyxlat->xlat, dyxlat->allocated,
+                                            sizeof(struct xlat));
+       }
+
+       dyxlat->xlat[dyxlat->used - 1].val = val;
+       dyxlat->xlat[dyxlat->used - 1].str = xstrndup(str, len);
+       MARK_END(dyxlat->xlat[dyxlat->used]);
+       dyxlat->used++;
+}