1 files changed, 56 insertions, 0 deletions
diff --git a/src/libmach/localaddr.c b/src/libmach/localaddr.c
new file mode 100644
index 00000000..1b1dea73
--- /dev/null
+++ b/src/libmach/localaddr.c
@@ -0,0 +1,56 @@
+#include <u.h>
+#include <libc.h>
+#include <bio.h>
+#include <mach.h>
+
+/*
+ * XXX could remove the rock by hiding it in a special regs.
+ * That would still be sleazy but would be thread-safe.
+ */
+
+static struct {
+	int found;
+	int nframe;
+	Loc l;
+	char *fn;
+	char *var;
+} rock;
+
+static int
+ltrace(Map *map, Regs *regs, ulong pc, ulong nextpc, Symbol *sym, int depth)
+{
+	ulong v;
+	Symbol s1;
+
+	USED(pc);
+	USED(nextpc);
+	USED(depth);
+
+	if(sym==nil || strcmp(sym->name, rock.fn) != 0)
+		return ++rock.nframe < 40;
+	if(lookuplsym(sym, rock.var, &s1) < 0)
+		return 0;
+	if(locsimplify(map, regs, s1.loc, &rock.l) < 0)
+		return 0;
+	if(rock.l.type == LREG && rget(regs, rock.l.reg, &v) >= 0)
+		rock.l = locconst(v);
+	if(rock.l.type != LADDR && rock.l.type != LCONST)
+		return 0;
+	rock.found = 1;
+	return 0;
+}
+
+int
+localaddr(Map *map, Regs *regs, char *fn, char *var, ulong *val)
+{
+	rock.found = 0;
+	rock.nframe = 0;
+	rock.fn = fn;
+	rock.var = var;
+	stacktrace(map, regs, ltrace);
+	if(rock.found){
+		*val = rock.l.addr;
+		return 0;
+	}
+	return -1;
+}