Add proc_find_symbol, use it to find corresponding symbols for clones

The code in breakpoint_clone was buggy--it looked through old_proc's
symbols.  It was also needlessly verbose, proc_find_symbol uses library
key to find the right library.  Instead use the new interface and call
it on new_proc to find the new symbol.

We also didn't relink symbols in stack elements of a cloned process in
process_clone.  Use proc_find_symbol for this as well.

3 files changed, 48 insertions, 29 deletions

diff --git a/breakpoints.c b/breakpoints.c
index 450472a..d77fefc 100644
--- a/breakpoints.c
+++ b/breakpoints.c
@@ -155,41 +155,16 @@ breakpoint_destroy(struct breakpoint *bp)
 	arch_breakpoint_destroy(bp);
 }
 
-struct find_symbol_data {
-	struct library_symbol *old_libsym;
-	struct library_symbol *found_libsym;
-};
-
-static enum callback_status
-find_sym_in_lib(struct Process *proc, struct library *lib, void *u)
-{
-	struct find_symbol_data *fs = u;
-	fs->found_libsym
-		= library_each_symbol(lib, NULL, library_symbol_equal_cb,
-				      fs->old_libsym);
-	return fs->found_libsym != NULL ? CBS_STOP : CBS_CONT;
-}
-
 int
 breakpoint_clone(struct breakpoint *retp, struct Process *new_proc,
 		 struct breakpoint *bp, struct Process *old_proc)
 {
-	/* Find library and symbol that this breakpoint was linked to.  */
-	struct library_symbol *libsym = bp->libsym;
-	struct library *lib = NULL;
-	if (libsym != NULL) {
-		struct find_symbol_data f_data = {
-			.old_libsym = libsym,
-		};
-		lib = proc_each_library(old_proc, NULL,
-					find_sym_in_lib, &f_data);
-		assert(lib != NULL);
-		libsym = f_data.found_libsym;
+	struct library_symbol *libsym = NULL;
+	if (bp->libsym != NULL) {
+		int rc = proc_find_symbol(new_proc, bp->libsym, NULL, &libsym);
+		assert(rc == 0);
 	}
 
-	/* LIB and LIBSYM now hold the new library and symbol that
-	 * correspond to the original breakpoint.  Now we can do the
-	 * clone itself.  */
 	breakpoint_init_base(retp, new_proc, bp->addr, libsym);
 	memcpy(retp->orig_value, bp->orig_value, sizeof(bp->orig_value));
 	retp->enabled = bp->enabled;
diff --git a/proc.c b/proc.c
index e601e15..d12faef 100644
--- a/proc.c
+++ b/proc.c
@@ -420,6 +420,16 @@ process_clone(struct Process *retp, struct Process *proc, pid_t pid)
 			}
 			retp->callstack[i].arguments = nargs;
 		}
+
+		/* If it's not a syscall, we need to find the
+		 * corresponding library symbol in the cloned
+		 * library.  */
+		if (!elem->is_syscall && elem->c_un.libfunc != NULL) {
+			struct library_symbol *libfunc = elem->c_un.libfunc;
+			int rc = proc_find_symbol(retp, libfunc,
+						  NULL, &elem->c_un.libfunc);
+			assert(rc == 0);
+		}
 	}
 
 	if (os_process_clone(retp, proc) < 0
@@ -949,3 +959,29 @@ proc_each_breakpoint(struct Process *proc, void *start,
 	dict_apply_to_all(proc->breakpoints, &each_breakpoint_cb, &dd);
 	return dd.end;
 }
+
+int
+proc_find_symbol(struct Process *proc, struct library_symbol *sym,
+		 struct library **retlib, struct library_symbol **retsym)
+{
+	struct library *lib = sym->lib;
+	assert(lib != NULL);
+
+	struct library *flib
+		= proc_each_library(proc, NULL, library_with_key_cb, &lib->key);
+	if (flib == NULL)
+		return -1;
+
+	struct library_symbol *fsym
+		= library_each_symbol(flib, NULL, library_symbol_named_cb,
+				      (char *)sym->name);
+	if (fsym == NULL)
+		return -1;
+
+	if (retlib != NULL)
+		*retlib = flib;
+	if (retsym != NULL)
+		*retsym = fsym;
+
+	return 0;
+}
diff --git a/proc.h b/proc.h
index ab8794b..68054b3 100644
--- a/proc.h
+++ b/proc.h
@@ -241,4 +241,12 @@ void *proc_each_breakpoint(struct Process *proc, void *start,
  * If tag is not found, return a negative value.  */
 int proc_find_dynamic_entry_addr(struct Process *proc, arch_addr_t src_addr,
 				 int d_tag, arch_addr_t *ret);
+
+/* Finds a symbol corresponding to LIBSYM in a process PROC.  Returns
+ * 0 and sets *RETLIB and *RETSYM if the corresponding pointer is
+ * non-NULL.  Returns a negative value when the symbols couldn't be
+ * found.  */
+int proc_find_symbol(struct Process *proc, struct library_symbol *sym,
+		     struct library **retlib, struct library_symbol **retsym);
+
 #endif /* _PROC_H_ */