Don't increment the iterator while a Section/Relocation/Symbol is using it.

Fixes rust-lang#172.

Author: nlewycky

src/object_file.rs

@@ -48,6 +48,7 @@ impl Drop for ObjectFile {
 pub struct SectionIterator {
     section_iterator: LLVMSectionIteratorRef,
     object_file: LLVMObjectFileRef,
+    before_first: bool,
 }
 
 impl SectionIterator {
@@ -56,7 +57,8 @@ impl SectionIterator {
 
         SectionIterator {
             section_iterator,
-            object_file
+            object_file,
+            before_first: true
         }
     }
 }
@@ -65,7 +67,14 @@ impl Iterator for SectionIterator {
     type Item = Section;
 
     fn next(&mut self) -> Option<Self::Item> {
-        // REVIEW: Should it compare against 1? End checking order might also be off
+        if self.before_first {
+            self.before_first = false;
+        } else {
+            unsafe {
+                LLVMMoveToNextSection(self.section_iterator);
+            }
+        }
+
         let at_end = unsafe {
             LLVMIsSectionIteratorAtEnd(self.object_file, self.section_iterator) == 1
         };
@@ -76,10 +85,6 @@ impl Iterator for SectionIterator {
 
         let section = Section::new(self.section_iterator, self.object_file);
 
-        unsafe {
-            LLVMMoveToNextSection(self.section_iterator)
-        }
-
         Some(section)
     }
 }
@@ -151,6 +156,7 @@ pub struct RelocationIterator {
     relocation_iterator: LLVMRelocationIteratorRef,
     section_iterator: LLVMSectionIteratorRef,
     object_file: LLVMObjectFileRef,
+    before_first: bool,
 }
 
 impl RelocationIterator {
@@ -161,6 +167,7 @@ impl RelocationIterator {
             relocation_iterator,
             section_iterator,
             object_file,
+            before_first: true
         }
     }
 }
@@ -169,7 +176,14 @@ impl Iterator for RelocationIterator {
     type Item = Relocation;
 
     fn next(&mut self) -> Option<Self::Item> {
-        // REVIEW: Should it compare against 1? End checking order might also be off
+        if self.before_first {
+            self.before_first = false;
+        } else {
+            unsafe {
+                LLVMMoveToNextRelocation(self.relocation_iterator)
+            }
+        }
+
         let at_end = unsafe {
             LLVMIsRelocationIteratorAtEnd(self.section_iterator, self.relocation_iterator) == 1
         };
@@ -180,10 +194,6 @@ impl Iterator for RelocationIterator {
 
         let relocation = Relocation::new(self.relocation_iterator, self.object_file);
 
-        unsafe {
-            LLVMMoveToNextRelocation(self.relocation_iterator)
-        }
-
         Some(relocation)
     }
 }
@@ -249,6 +259,7 @@ impl Relocation {
 pub struct SymbolIterator {
     symbol_iterator: LLVMSymbolIteratorRef,
     object_file: LLVMObjectFileRef,
+    before_first: bool,
 }
 
 impl SymbolIterator {
@@ -258,6 +269,7 @@ impl SymbolIterator {
         SymbolIterator {
             symbol_iterator,
             object_file,
+            before_first: true
         }
     }
 }
@@ -266,7 +278,14 @@ impl Iterator for SymbolIterator {
     type Item = Symbol;
 
     fn next(&mut self) -> Option<Self::Item> {
-        // REVIEW: Should it compare against 1? End checking order might also be off
+        if self.before_first {
+            self.before_first = false;
+        } else {
+            unsafe {
+                LLVMMoveToNextSymbol(self.symbol_iterator)
+            }
+        }
+
         let at_end = unsafe {
             LLVMIsSymbolIteratorAtEnd(self.object_file, self.symbol_iterator) == 1
         };
@@ -277,10 +296,6 @@ impl Iterator for SymbolIterator {
 
         let symbol = Symbol::new(self.symbol_iterator);
 
-        unsafe {
-            LLVMMoveToNextSymbol(self.symbol_iterator)
-        }
-
         Some(symbol)
     }
 }