fix memory overlap check (#39)

Author: kilograham

main.cpp

@@ -140,8 +140,25 @@ struct range {
         to = other.clamp(to);
     }
 
+    bool intersects(const range& other) const {
+        return !(other.from >= to || other.to < from);
+    }
+
 };
 
+static void __noreturn fail(int code, string msg) {
+    throw command_failure(code, std::move(msg));
+}
+
+static void __noreturn fail(int code, const char *format, ...) {
+    va_list args;
+    va_start(args, format);
+    static char error_msg[512];
+    vsnprintf(error_msg, sizeof(error_msg), format, args);
+    va_end(args);
+    fail(code, string(error_msg));
+}
+
 // ranges should not overlap
 template <typename T> struct range_map {
     struct mapping {
@@ -150,19 +167,20 @@ template <typename T> struct range_map {
         const uint32_t max_offset;
     };
 
-    void check_overlap(uint32_t p) {
-        auto f = m.lower_bound(p);
-        if (f != m.end()) {
-            assert(p >= f->first);
-            assert(p < f->second.first);
-        }
-    }
-
     void insert(const range& r, T t) {
         if (r.to != r.from) {
             assert(r.to > r.from);
-            check_overlap(r.from);
-            check_overlap(r.to);
+            // check we don't overlap any existing map entries
+
+            auto f = m.lower_bound(r.from); // first element that starts after r.from
+            if (f != m.begin()) f--; // back up, to catch element that starts on or before r.from
+            for(; f != m.end() && f->first <= r.from; f++) {
+                range r2(f->first, f->second.first);
+                if (r2.intersects(r)) {
+                    fail(ERROR_FORMAT, "Found overlapping memory ranges 0x%08x->0x%08x and 0x%08x->%08x\n",
+                         r.from, r.to, r2.from, r2.to);
+                }
+            }
             m.insert(std::make_pair(r.from, std::make_pair(r.to, t)));
         }
     }
@@ -695,10 +713,6 @@ struct memory_access {
     }
 };
 
-static void __noreturn fail(int code, string msg) {
-    throw command_failure(code, msg);
-}
-
 uint32_t bootrom_func_lookup(memory_access& access, uint16_t tag) {
     auto magic = access.read_int(BOOTROM_MAGIC_ADDR);
     magic &= 0xffffff; // ignore bootrom version
@@ -891,16 +905,6 @@ static void read_and_check_elf32_header(FILE *in, elf32_header& eh_out) {
     }
 }
 
-static char error_msg[512];
-
-static void __noreturn fail(int code, const char *format, ...) {
-    va_list args;
-    va_start(args, format);
-    vsnprintf(error_msg, sizeof(error_msg), format, args);
-    va_end(args);
-    fail(code, string(error_msg));
-}
-
 static void __noreturn fail_read_error() {
     fail(ERROR_READ_FAILED, "Failed to read input file");
 }