Support latent and delayed symbols

Neither latent, nor delayed symbols are given a breakpoint.  The difference
is in who's responsible for the state.  Latent symbols are (will be) used
by ltrace core.  Delayed symbols are used by backends.  Only when both of
these flags are cleared is a breakpoint enabled for the symbol.

1 files changed, 39 insertions, 9 deletions

diff --git a/proc.c b/proc.c
index 99bf31b..eb3e552 100644
--- a/proc.c
+++ b/proc.c
@@ -629,11 +629,10 @@ destroy_event_handler(Process * proc)
 	proc->event_handler = NULL;
 }
 
-static enum callback_status
-breakpoint_for_symbol(struct library_symbol *libsym, void *data)
+static int
+breakpoint_for_symbol(struct library_symbol *libsym, struct Process *proc)
 {
 	arch_addr_t bp_addr;
-	struct Process *proc = data;
 	assert(proc->leader == proc);
 
 	bp_addr = sym2addr(proc, libsym);
@@ -644,11 +643,16 @@ breakpoint_for_symbol(struct library_symbol *libsym, void *data)
 	 *
 	 * Allow the backend to add these into the process representation
 	 * but don't put breakpoints at this point. Let the backend fix that
-	 * up later.  */
+	 * up later.
+	 *
+	 * XXX This should be changed to delayed symbols.  */
 	if (bp_addr == 0 && libsym->plt_type == LS_TOPLT_GOTONLY) {
 		/* Don't add breakpoints yet.  */
 		return CBS_CONT;
 	}
+	/* Don't enable latent or delayed symbols.  */
+	if (libsym->latent || libsym->delayed)
+		return 0;
 
 	/* If there is an artificial breakpoint on the same address,
 	 * its libsym will be NULL, and we can smuggle our libsym
@@ -667,7 +671,7 @@ breakpoint_for_symbol(struct library_symbol *libsym, void *data)
 	if (bp != NULL) {
 		assert(bp->libsym == NULL);
 		bp->libsym = libsym;
-		return CBS_CONT;
+		return 0;
 	}
 
 	bp = malloc(sizeof(*bp));
@@ -675,7 +679,7 @@ breakpoint_for_symbol(struct library_symbol *libsym, void *data)
 	    || breakpoint_init(bp, proc, bp_addr, libsym) < 0) {
 	fail:
 		free(bp);
-		return CBS_FAIL;
+		return -1;
 	}
 	if (proc_add_breakpoint(proc, bp) < 0) {
 		breakpoint_destroy(bp);
@@ -688,7 +692,31 @@ breakpoint_for_symbol(struct library_symbol *libsym, void *data)
 		goto fail;
 	}
 
-	return CBS_CONT;
+	return 0;
+}
+
+static enum callback_status
+cb_breakpoint_for_symbol(struct library_symbol *libsym, void *data)
+{
+	return breakpoint_for_symbol(libsym, data) < 0 ? CBS_FAIL : CBS_CONT;
+}
+
+static int
+proc_activate_latent_symbol(struct Process *proc,
+			    struct library_symbol *libsym)
+{
+	assert(libsym->latent);
+	libsym->latent = 0;
+	return breakpoint_for_symbol(libsym, proc);
+}
+
+int
+proc_activate_delayed_symbol(struct Process *proc,
+			     struct library_symbol *libsym)
+{
+	assert(libsym->delayed);
+	libsym->delayed = 0;
+	return breakpoint_for_symbol(libsym, proc);
 }
 
 void
@@ -700,10 +728,12 @@ proc_add_library(struct Process *proc, struct library *lib)
 	debug(DEBUG_PROCESS, "added library %s@%p (%s) to %d",
 	      lib->soname, lib->base, lib->pathname, proc->pid);
 
+	/* Insert breakpoints for all active (non-latent) symbols.  */
 	struct library_symbol *libsym = NULL;
-	while ((libsym = library_each_symbol(lib, libsym, breakpoint_for_symbol,
+	while ((libsym = library_each_symbol(lib, libsym,
+					     cb_breakpoint_for_symbol,
 					     proc)) != NULL)
-		fprintf(stderr, "couldn't insert breakpoint for %s to %d: %s",
+		fprintf(stderr, "Couldn't insert breakpoint for %s to %d: %s.",
 			libsym->name, proc->pid, strerror(errno));
 }