Add hooking functionality

This allows us to hook chosen functions and do interesting things there (in
particular: reentrancy checking).

include/jemalloc/internal/hooks.h

@@ -0,0 +1,19 @@
+#ifndef JEMALLOC_INTERNAL_HOOKS_H
+#define JEMALLOC_INTERNAL_HOOKS_H
+
+extern void (*hooks_arena_new_hook)();
+extern void (*hooks_libc_hook)();
+
+#define JEMALLOC_HOOK(fn, hook) ((void)(hook != NULL && (hook(), 0)), fn)
+
+#define open JEMALLOC_HOOK(open, hooks_libc_hook)
+#define read JEMALLOC_HOOK(read, hooks_libc_hook)
+#define write JEMALLOC_HOOK(write, hooks_libc_hook)
+#define readlink JEMALLOC_HOOK(readlink, hooks_libc_hook)
+#define close JEMALLOC_HOOK(close, hooks_libc_hook)
+#define creat JEMALLOC_HOOK(creat, hooks_libc_hook)
+#define secure_getenv JEMALLOC_HOOK(secure_getenv, hooks_libc_hook)
+/* Note that this is undef'd and re-define'd in src/prof.c. */
+#define _Unwind_Backtrace JEMALLOC_HOOK(_Unwind_Backtrace, hooks_libc_hook)
+
+#endif /* JEMALLOC_INTERNAL_HOOKS_H */

include/jemalloc/internal/jemalloc_internal.h.in

@@ -23,7 +23,14 @@ extern "C" {
 #  define JEMALLOC_N(n) @private_namespace@##n
 #  include "../jemalloc@install_suffix@.h"
 #endif
+
+/*
+ * Note that the ordering matters here; the hook itself is name-mangled.  We
+ * want the inclusion of hooks to happen early, so that we hook as much as
+ * possible.
+ */
 #include "jemalloc/internal/private_namespace.h"
+#include "jemalloc/internal/hooks.h"
 
 static const bool config_debug =
 #ifdef JEMALLOC_DEBUG

include/jemalloc/internal/malloc_io.h

@@ -56,7 +56,7 @@ size_t malloc_snprintf(char *str, size_t size, const char *format, ...)
     JEMALLOC_FORMAT_PRINTF(3, 4);
 void malloc_vcprintf(void (*write_cb)(void *, const char *), void *cbopaque,
     const char *format, va_list ap);
-void malloc_cprintf(void (*write)(void *, const char *), void *cbopaque,
+void malloc_cprintf(void (*write_cb)(void *, const char *), void *cbopaque,
     const char *format, ...) JEMALLOC_FORMAT_PRINTF(3, 4);
 void malloc_printf(const char *format, ...) JEMALLOC_FORMAT_PRINTF(1, 2);
 

include/jemalloc/internal/private_symbols.txt

@@ -232,6 +232,7 @@ hash_rotl_64
 hash_x64_128
 hash_x86_128
 hash_x86_32
+hooks_libc_hook
 iaalloc
 ialloc
 iallocztm

include/jemalloc/internal/stats_externs.h

@@ -3,7 +3,7 @@
 
 extern bool	opt_stats_print;
 
-void	stats_print(void (*write)(void *, const char *), void *cbopaque,
+void	stats_print(void (*write_cb)(void *, const char *), void *cbopaque,
     const char *opts);
 
 #endif /* JEMALLOC_INTERNAL_STATS_EXTERNS_H */