1 files changed, 161 insertions, 0 deletions
diff --git a/src/chattymalloc.c b/src/chattymalloc.c
new file mode 100644
index 0000000..54708d6
--- /dev/null
+++ b/src/chattymalloc.c
@@ -0,0 +1,161 @@
+#define _GNU_SOURCE
+#include <dlfcn.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+static char tmpbuff[1024];
+static unsigned long tmppos = 0;
+static unsigned long tmpallocs = 0;
+
+static int out = -1;
+static int prevent_recursion = 0;
+
+/*=========================================================
+ *  * interception points
+ *  */
+
+static void * (*myfn_malloc)(size_t size);
+static void (*myfn_free)(void* ptr);
+static void * (*myfn_calloc)(size_t nmemb, size_t size);
+static void * (*myfn_realloc)(void* ptr, size_t size);
+static void * (*myfn_memalign)(size_t alignment, size_t size);
+
+static void write_output(const char* fmt, ...)
+{
+	if (!prevent_recursion)
+	{
+		prevent_recursion = 1;
+
+		/* lockf(out, F_LOCK, 0); */
+
+		va_list args;
+		va_start(args, fmt);
+		vdprintf(out, fmt, args);
+		va_end(args);
+
+		/* lockf(out, F_ULOCK, 0); */
+		prevent_recursion = 0;
+	}
+}
+
+static void init()
+{
+	out = open("chattymalloc.data", O_WRONLY | O_TRUNC | O_CREAT, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+	if (out == -1)
+	{
+		fprintf(stderr, "failed to open output file with %d\n", errno);
+		exit(1);
+	}
+
+	myfn_malloc     = dlsym(RTLD_NEXT, "malloc");
+	myfn_free       = dlsym(RTLD_NEXT, "free");
+	myfn_calloc     = dlsym(RTLD_NEXT, "calloc");
+	myfn_realloc    = dlsym(RTLD_NEXT, "realloc");
+	myfn_memalign   = dlsym(RTLD_NEXT, "memalign");
+
+	if (!myfn_malloc || !myfn_free || !myfn_calloc || !myfn_realloc || !myfn_memalign)
+	{
+		fprintf(stderr, "Error in `dlsym`: %s\n", dlerror());
+		exit(1);
+	}
+}
+
+void *malloc(size_t size)
+{
+	static int initializing = 0;
+
+	if (myfn_malloc == NULL)
+	{
+		if (!initializing)
+		{
+			initializing = 1;
+			init();
+			initializing = 0;
+
+		}
+		else
+		{
+			if (tmppos + size < sizeof(tmpbuff))
+			{
+				void *retptr = tmpbuff + tmppos;
+				tmppos += size;
+				++tmpallocs;
+				return retptr;
+			}
+			else
+			{
+				fprintf(stderr, "%d in %d allocs\n", tmppos, tmpallocs);
+				fprintf(stderr, "jcheck: too much memory requested during initialisation - increase tmpbuff size\n");
+				exit(1);
+			}
+		}
+	}
+
+	void *ptr = myfn_malloc(size);
+	write_output("m %zu %p\n", size, ptr);
+	return ptr;
+}
+
+void free(void *ptr)
+{
+	// something wrong if we call free before one of the allocators!
+	if (myfn_malloc == NULL)
+		init();
+	if (!(ptr >= (void*) tmpbuff && ptr <= (void*)(tmpbuff + tmppos)))
+	{
+		write_output("f %p\n", ptr);
+		myfn_free(ptr);
+	}
+}
+
+void* realloc(void *ptr, size_t size)
+{
+	if (myfn_realloc == NULL)
+	{
+		void *nptr = malloc(size);
+		if (nptr && ptr)
+		{
+			memmove(nptr, ptr, size);
+			free(ptr);
+		}
+		return nptr;
+	}
+
+	void* nptr =  myfn_realloc(ptr, size);
+	write_output("r %p %zu %p\n", ptr, size, nptr);
+	return nptr;
+}
+
+void* calloc(size_t nmemb, size_t size)
+{
+	if (myfn_calloc == NULL)
+	{
+		void *ptr = malloc(nmemb*size);
+		if (ptr)
+			memset(ptr, 0, nmemb*size);
+		return ptr;
+	}
+
+	void* ptr = myfn_calloc(nmemb, size);
+	write_output("c %zu %zu %p\n", nmemb, size, ptr);
+	return ptr;
+}
+
+void* memalign(size_t alignment, size_t size)
+{
+	if (myfn_memalign == NULL)
+	{
+		fprintf(stderr, "called memalign before or during init");
+		exit(1);
+	}
+
+	void* ptr = myfn_memalign(alignment, size);
+	write_output("mm %zu %zu %p\n", alignment, size, ptr);
+	return ptr;
+}