The first crude version of tracing across libraries

- the patch will be sliced later

1 files changed, 149 insertions, 0 deletions

diff --git a/library.h b/library.h
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--- /dev/null
+++ b/library.h
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+/*
+ * This file is part of ltrace.
+ * Copyright (C) 2012 Petr Machata, Red Hat Inc.
+ * Copyright (C) 2006 Paul Gilliam
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#ifndef _LIBRARY_H_
+#define _LIBRARY_H_
+
+#include <stdint.h>
+#include <gelf.h> // XXX 
+
+struct Process;
+struct library;
+
+enum toplt {
+	LS_TOPLT_NONE = 0,	/* PLT not used for this symbol. */
+	LS_TOPLT_EXEC,		/* PLT for this symbol is executable. */
+	LS_TOPLT_POINT		/* PLT for this symbol is a non-executable. */
+};
+
+/* We should in general be able to trace 64-bit processes with 32-bit
+ * ltrace.  (At least PPC has several PTRACE requests related to
+ * tracing 64-on-32, so presumably it should be possible.)  But ltrace
+ * is currently hopelessly infested with using void* for host address.
+ * So keep with it, for now.  */
+typedef void *target_address_t;
+
+struct library_symbol {
+	struct library_symbol *next;
+	const char *name;
+	target_address_t enter_addr;
+	enum toplt plt_type;
+	char needs_init;
+	char is_weak;
+	char own_name;
+};
+
+/* Init LIBSYM.  NAME will be freed when LIBSYM is destroyed if
+ * OWN_NAME.  */
+/* XXX note that we shouldn't use GElf_Addr for ADDR either.  The fact
+ * that Elf is used is a back-end detail.  At least ltrace pretends
+ * that it would like to be cross-platform like that one day.  */
+void library_symbol_init(struct library_symbol *libsym,
+			 GElf_Addr addr, const char *name, int own_name,
+			 enum toplt type_of_plt, int is_weak);
+
+/* Copy library symbol SYM into the area pointed-to by RETP.  Return 0
+ * on success or a negative value on failure.  */
+int library_symbol_clone(struct library_symbol *retp,
+			 struct library_symbol *sym);
+
+/* Destroy library symbol.  This essentially just frees name if it's
+ * owned.  It doesn't free the memory associated with SYM pointer
+ * itself.  Returns 0 on success or a negative value in case of an
+ * error (which would be an out of memory condition).  */
+void library_symbol_destroy(struct library_symbol *sym);
+
+/* Compare two library symbols.  Returns a negative value, 0, or a
+ * positive value, much like strcmp.  The function compares symbol
+ * addresses, and if those are equal, it compares symbol names.  If
+ * those are equal, too, the symbols are considered equal.  */
+int library_symbol_cmp(struct library_symbol *a, struct library_symbol *b);
+
+/* A function that can be used as library_each_symbol callback.  Looks
+ * for a symbol SYM for which library_symbol_cmp(SYM, STANDARD)
+ * returns 0.  */
+enum callback_status library_symbol_equal_cb(struct library_symbol *libsym,
+					     void *standard);
+
+/* XXX we might consider sharing libraries across processes.  Things
+ * like libc will be opened by every single process, no point cloning
+ * these everywhere.  But for now, keep the ownership structure
+ * simple.  */
+struct library {
+	struct library *next;
+
+	/* Address where the library is mapped.  Two library objects
+	 * are considered equal, if they have the same base.  */
+	target_address_t base;
+
+	/* Absolute address of the entry point.  Useful for main
+	 * binary, though I the value might be useful for the dynamic
+	 * linker, too (in case we ever want to do early process
+	 * tracing).  */
+	target_address_t entry;
+
+	/* Symbols associated with the library.  */
+	struct library_symbol *symbols;
+	const char *name;
+	char own_name;
+};
+
+/* Init LIB.  NAME will be freed when LIB is destroyed if
+ * OWN_NAME.  */
+void library_init(struct library *lib, const char *name, int own_name);
+
+/* Initialize RETP to a library identical to LIB.  Symbols are not
+ * shared, but copied over.  Returns 0 on success and a negative value
+ * in case of failure.  */
+int library_clone(struct library *retp, struct library *lib);
+
+/* Destroy library.  Doesn't free LIB itself.  */
+void library_destroy(struct library *lib);
+
+/* Set library name.  Frees the old name if necessary.  */
+void library_set_name(struct library *lib, const char *new_name, int own_name);
+
+/* Iterate through list of symbols of library LIB.  Restarts are
+ * supported via START (see each_process for details of iteration
+ * interface).  */
+struct library_symbol *library_each_symbol
+	(struct library *lib, struct library_symbol *start,
+	 enum callback_status (*cb)(struct library_symbol *, void *),
+	 void *data);
+
+/* Add a new symbol SYM to LIB.  SYM is assumed owned, we need to
+ * overwrite SYM->next.  */
+void library_add_symbol(struct library *lib, struct library_symbol *sym);
+
+/* A function that can be used as proc_each_library callback.  Looks
+ * for a library with the name passed in DATA.  PROC is ignored.  */
+enum callback_status library_named_cb(struct Process *proc,
+				      struct library *lib, void *name);
+
+/* A function that can be used as proc_each_library callback.  Looks
+ * for a library with given base.
+ *
+ * NOTE: The base is passed as a POINTER to target_address_t (that
+ * because in general, target_address_t doesn't fit in void*). */
+enum callback_status library_with_base_cb(struct Process *proc,
+					  struct library *lib, void *basep);
+
+#endif /* _LIBRARY_H_ */