From 93da5d2be5ec3a3680449e186780ff7a08cec6d9 Mon Sep 17 00:00:00 2001
From: Stefan Seefeld <stefan_seefeld@mentor.com>
Date: Sat, 27 Jul 2013 01:10:23 -0400
Subject: [PATCH] Add trace support for calloc and realloc.

Signed-off-by: Stefan Seefeld <stefan_seefeld@mentor.com>
---
 liblttng-ust-libc-wrapper/lttng-ust-malloc.c | 68 +++++++++++++++++++++++++++-
 liblttng-ust-libc-wrapper/ust_libc.h         | 18 ++++++++
 2 files changed, 84 insertions(+), 2 deletions(-)

diff --git a/liblttng-ust-libc-wrapper/lttng-ust-malloc.c b/liblttng-ust-libc-wrapper/lttng-ust-malloc.c
index 3212ff0..81beb78 100644
--- a/liblttng-ust-libc-wrapper/lttng-ust-malloc.c
+++ b/liblttng-ust-libc-wrapper/lttng-ust-malloc.c
@@ -26,9 +26,25 @@
 #define TRACEPOINT_CREATE_PROBES
 #include "ust_libc.h"
 
+#define STATIC_CALLOC_LEN 4096
+static char static_calloc_buf[STATIC_CALLOC_LEN];
+static size_t static_calloc_buf_offset;
+
+static void *static_calloc(size_t nmemb, size_t size)
+{
+	size_t prev_offset;
+
+	if (nmemb * size > sizeof(static_calloc_buf) - static_calloc_buf_offset) {
+		return NULL;
+	}
+	prev_offset = static_calloc_buf_offset;
+	static_calloc_buf_offset += nmemb * size;
+	return &static_calloc_buf[prev_offset];
+}
+
 void *malloc(size_t size)
 {
-	static void *(*plibc_malloc)(size_t size) = NULL;
+	static void *(*plibc_malloc)(size_t size);
 	void *retval;
 
 	if (plibc_malloc == NULL) {
@@ -45,7 +61,16 @@ void *malloc(size_t size)
 
 void free(void *ptr)
 {
-	static void *(*plibc_free)(void *ptr) = NULL;
+	static void (*plibc_free)(void *ptr);
+
+	/* Check whether the memory was allocated with
+	 * static_calloc, in which case there is nothing
+	 * to free.
+	 */
+	if ((char *)ptr >= static_calloc_buf &&
+	    (char *)ptr < static_calloc_buf + STATIC_CALLOC_LEN) {
+		return;
+	}
 
 	if (plibc_free == NULL) {
 		plibc_free = dlsym(RTLD_NEXT, "free");
@@ -57,3 +82,42 @@ void free(void *ptr)
 	tracepoint(ust_libc, free, ptr);
 	plibc_free(ptr);
 }
+
+void *calloc(size_t nmemb, size_t size)
+{
+	static void *(*volatile plibc_calloc)(size_t nmemb, size_t size);
+	void *retval;
+
+	if (plibc_calloc == NULL) {
+		/*
+		 * Temporarily redirect to static_calloc,
+		 * until the dlsym lookup has completed.
+		 */
+		plibc_calloc = static_calloc;
+		plibc_calloc = dlsym(RTLD_NEXT, "calloc");
+		if (plibc_calloc == NULL) {
+			fprintf(stderr, "callocwrap: unable to find calloc\n");
+			return NULL;
+		}
+	}
+	retval = plibc_calloc(nmemb, size);
+	tracepoint(ust_libc, calloc, nmemb, size, retval);
+	return retval;
+}
+
+void *realloc(void *ptr, size_t size)
+{
+	static void *(*plibc_realloc)(void *ptr, size_t size);
+	void *retval;
+
+	if (plibc_realloc == NULL) {
+		plibc_realloc = dlsym(RTLD_NEXT, "realloc");
+		if (plibc_realloc == NULL) {
+			fprintf(stderr, "reallocwrap: unable to find realloc\n");
+			return NULL;
+		}
+	}
+	retval = plibc_realloc(ptr, size);
+	tracepoint(ust_libc, realloc, ptr, size, retval);
+	return retval;
+}
diff --git a/liblttng-ust-libc-wrapper/ust_libc.h b/liblttng-ust-libc-wrapper/ust_libc.h
index af705aa..6b03a4d 100644
--- a/liblttng-ust-libc-wrapper/ust_libc.h
+++ b/liblttng-ust-libc-wrapper/ust_libc.h
@@ -47,6 +47,24 @@ TRACEPOINT_EVENT(ust_libc, free,
 	)
 )
 
+TRACEPOINT_EVENT(ust_libc, calloc,
+	TP_ARGS(size_t, nmemb, size_t, size, void *, ptr),
+	TP_FIELDS(
+		ctf_integer(size_t, nmemb, nmemb)
+		ctf_integer(size_t, size, size)
+		ctf_integer_hex(unsigned long, ptr, (unsigned long) ptr)
+	)
+)
+
+TRACEPOINT_EVENT(ust_libc, realloc,
+	TP_ARGS(void *, in_ptr, size_t, size, void *, ptr),
+	TP_FIELDS(
+		ctf_integer_hex(unsigned long, in_ptr, (unsigned long) in_ptr)
+		ctf_integer(size_t, size, size)
+		ctf_integer_hex(unsigned long, ptr, (unsigned long) ptr)
+	)
+)
+
 #endif /* _TRACEPOINT_UST_LIBC_H */
 
 #undef TRACEPOINT_INCLUDE
-- 
1.8.3.1