[PATCH v2 3/6] dyxlat: building xlat dynamically

[Masatake YAMATO]

xlat tables are generating in built-time of strace.

printxval is suitable for printing `family' field of Netlink GENERIC
protocol. However, contents of the xlat table cannot be defined in
build-time because the values for the field are given by Linux kernel.

dyxlat functions are for building xlat in run-time. Decoding the
field is the primary use case of functions but they can be used
another purpose.

* defs.h (dyxlat_new, dyxlat_delete, dyxlat_may_add_pair): New functions
declarations.
(struct dyxlat): New opaque data type.

* dyxlat.c: New file.

Signed-off-by: Masatake YAMATO <yamato at redhat.com>
---
 Makefile.am |   1 +
 defs.h      |   7 ++++
 dyxlat.c    | 119 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 127 insertions(+)
 create mode 100644 dyxlat.c

diff --git a/Makefile.am b/Makefile.am
index 3d6eba1..3a76b85 100644
--- 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 6449bce..05958fd 100644
--- a/defs.h
+++ b/defs.h
@@ -1018,4 +1018,11 @@ scno_is_valid(kernel_ulong_t scno)
 #define PRI__u64 PRI__64"u"
 #define PRI__x64 PRI__64"x"
 
+/* Dynamic Xlat */
+struct dyxlat;
+
+struct dyxlat *dyxlat_new(int allocation);
+void dyxlat_delete(struct dyxlat *dyxlat);
+struct xlat *dyxlat_get(struct dyxlat *dyxlat);
+void dyxlat_may_add_pair(struct dyxlat *dyxlat, uint64_t val, const char *str);
 #endif /* !STRACE_DEFS_H */
diff --git a/dyxlat.c b/dyxlat.c
new file mode 100644
index 0000000..98e505c
--- /dev/null
+++ b/dyxlat.c
@@ -0,0 +1,119 @@
+/*
+ * 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 {
+	int used;
+	int allocated;
+	struct xlat *xlat;
+};
+
+#define MARK_END(xlat)				\
+	do {					\
+		(xlat).val = 0;			\
+		(xlat).str = 0;			\
+	} while (0)
+
+static void
+dyxlat_init(struct dyxlat *dyxlat, int allocation)
+{
+	dyxlat->used = 1;
+	dyxlat->allocated = allocation ? allocation : 10;
+	dyxlat->xlat = xcalloc(dyxlat->allocated, sizeof(struct xlat));
+	MARK_END(dyxlat->xlat[0]);
+}
+
+static void
+dyxlat_fini(struct dyxlat *dyxlat)
+{
+	int 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;
+}
+
+struct dyxlat *
+dyxlat_new(int allocation)
+{
+	struct dyxlat *dyxlat;
+
+	dyxlat = xmalloc(sizeof(*dyxlat));
+	dyxlat_init(dyxlat, allocation);
+	return dyxlat;
+}
+
+void
+dyxlat_delete(struct dyxlat *dyxlat)
+{
+	dyxlat_fini(dyxlat);
+	free(dyxlat);
+}
+
+struct xlat *
+dyxlat_get(struct dyxlat *dyxlat)
+{
+	return dyxlat->xlat;
+}
+
+static void
+dyxlat_add_pair(struct dyxlat *dyxlat, uint64_t val, const char *str)
+{
+	dyxlat->used++;
+
+	if (dyxlat->used == dyxlat->allocated) {
+		dyxlat->allocated *= 2;
+		dyxlat->xlat = xreallocarray(dyxlat->xlat, dyxlat->allocated,
+					     sizeof(struct xlat));
+	}
+
+	dyxlat->xlat[dyxlat->used - 2].val = val;
+	dyxlat->xlat[dyxlat->used - 2].str = xstrdup(str);
+	MARK_END(dyxlat->xlat[dyxlat->used - 1]);
+}
+
+void
+dyxlat_may_add_pair(struct dyxlat *dyxlat, uint64_t val, const char *str)
+{
+	int i;
+
+	for (i = 0; i < dyxlat->used - 1; i++) {
+		if (dyxlat->xlat[i].val == val) {
+			if (strcmp(dyxlat->xlat[i].str, str) == 0)
+				return;
+
+			free((void *)(dyxlat->xlat[i].str));
+			dyxlat->xlat[i].str = xstrdup(str);
+			return;
+		}
+	}
+	dyxlat_add_pair(dyxlat, val, str);
+}
-- 
2.9.4