Remove any uses of file ranges.

The text bytes are only used by macOS "Compact Unwind Info"-guided
unwinding. Before #11, we were computing `offset_from_base` in that
code based on the text segment/section start SVMA and the base SVMA.
In #11 this code was changed to use the file range, but this is actually
incorrect; file offsets are not always equivalent to relative-to-base
addresses, for example in the dyld shared cache. Furthermore, in samply's
case, we're getting these bytes straight from the other process's memory,
so we're not interested in any information about the file anyway.

This PR changes things back to deal in terms of SVMAs.

Author: mstange

Readme.md

@@ -86,7 +86,7 @@ let module = Module::new(
         unwind_info: Some(vec![/* __unwind_info */]),
         eh_frame_svma: Some(0x100237f80..0x100237ffc),
         eh_frame: Some(vec![/* __eh_frame */]),
-        text_segment_file_range: Some(0x1003fc000..0x100634000),
+        text_segment_svma: Some(0x1003fc000..0x100634000),
         text_segment: Some(vec![/* __TEXT */]),
         ..Default::default()
     },

src/lib.rs

@@ -70,7 +70,7 @@
 //!         unwind_info: Some(vec![/* __unwind_info */]),
 //!         eh_frame_svma: Some(0x100237f80..0x100237ffc),
 //!         eh_frame: Some(vec![/* __eh_frame */]),
-//!         text_segment_file_range: Some(0x1003fc000..0x100634000),
+//!         text_segment_svma: Some(0x1003fc000..0x100634000),
 //!         text_segment: Some(vec![/* __TEXT */]),
 //!         ..Default::default()
 //!     },

src/unwinder.rs

@@ -395,7 +395,8 @@ impl<
             } => {
                 // eprintln!("unwinding with cui and eh_frame in module {}", module.name);
                 let text_bytes = text_data.as_ref().and_then(|data| {
-                    let offset_from_base = u32::try_from(data.svma_range.start).ok()?;
+                    let offset_from_base =
+                        u32::try_from(data.svma_range.start.checked_sub(module.base_svma)?).ok()?;
                     Some(TextBytes::new(offset_from_base, &data.bytes[..]))
                 });
                 let stubs_range = if let Some(stubs_range) = stubs {
@@ -618,15 +619,19 @@ impl<D: Deref<Target = [u8]>> ModuleUnwindDataInternal<D> {
             // multiple executable sections such as `__text`, `__stubs`, and `__stub_helper`. If we
             // don't have the full `__TEXT` segment contents, we can fall back to the contents of
             // just the `__text` section.
-            let text_data = section_info
-                .segment_data(b"__TEXT")
-                .zip(section_info.segment_file_range(b"__TEXT"))
-                .or_else(|| {
-                    section_info
-                        .section_data(b"__text")
-                        .zip(section_info.section_file_range(b"__text"))
-                })
-                .map(|(bytes, svma_range)| TextByteData { bytes, svma_range });
+            let text_data = if let (Some(bytes), Some(svma_range)) = (
+                section_info.segment_data(b"__TEXT"),
+                section_info.segment_svma_range(b"__TEXT"),
+            ) {
+                Some(TextByteData { bytes, svma_range })
+            } else if let (Some(bytes), Some(svma_range)) = (
+                section_info.section_data(b"__text"),
+                section_info.section_svma_range(b"__text"),
+            ) {
+                Some(TextByteData { bytes, svma_range })
+            } else {
+                None
+            };
             ModuleUnwindDataInternal::CompactUnwindInfoAndEhFrame {
                 unwind_info,
                 eh_frame: eh_frame.map(Arc::new),
@@ -763,14 +768,11 @@ pub trait ModuleSectionInfo<D> {
     /// Get the given section's memory range, as stated in the module.
     fn section_svma_range(&mut self, name: &[u8]) -> Option<Range<u64>>;
 
-    /// Get the given section's file range in the module.
-    fn section_file_range(&mut self, name: &[u8]) -> Option<Range<u64>>;
-
     /// Get the given section's data.
     fn section_data(&mut self, name: &[u8]) -> Option<D>;
 
-    /// Get the given segment's file range in the module.
-    fn segment_file_range(&mut self, _name: &[u8]) -> Option<Range<u64>> {
+    /// Get the given segment's memory range, as stated in the module.
+    fn segment_svma_range(&mut self, _name: &[u8]) -> Option<Range<u64>> {
         None
     }
 
@@ -804,7 +806,7 @@ pub struct ExplicitModuleSectionInfo<D> {
     /// This is used to detect whether we need to do instruction analysis for an address.
     pub text_svma: Option<Range<u64>>,
     /// The data of the `__text` or `.text` section. This is where most of the compiled code is
-    /// stored.
+    /// stored. For mach-O binaries, this does not need to be supplied if `text_segment` is supplied.
     ///
     /// This is used to handle function prologues and epilogues in some cases.
     pub text: Option<D>,
@@ -844,11 +846,9 @@ pub struct ExplicitModuleSectionInfo<D> {
     pub eh_frame_hdr: Option<D>,
     /// The data of the `.debug_frame` section. The related address range is not needed.
     pub debug_frame: Option<D>,
-    /// The file range of the `__TEXT` segment of mach-O binaries, or the `__text` section if the
-    /// segment is unavailable.
-    pub text_segment_file_range: Option<Range<u64>>,
-    /// The data of the `__TEXT` segment of mach-O binaries, or the `__text` section if the segment
-    /// is unavailable.
+    /// The address range of the `__TEXT` segment of mach-O binaries, if available.
+    pub text_segment_svma: Option<Range<u64>>,
+    /// The data of the `__TEXT` segment of mach-O binaries, if available.
     pub text_segment: Option<D>,
 }
 
@@ -871,9 +871,6 @@ where
             _ => None,
         }
     }
-    fn section_file_range(&mut self, _name: &[u8]) -> Option<Range<u64>> {
-        None
-    }
     fn section_data(&mut self, name: &[u8]) -> Option<D> {
         match name {
             b"__text" | b".text" => self.text.take(),
@@ -884,9 +881,9 @@ where
             _ => None,
         }
     }
-    fn segment_file_range(&mut self, name: &[u8]) -> Option<Range<u64>> {
+    fn segment_svma_range(&mut self, name: &[u8]) -> Option<Range<u64>> {
         match name {
-            b"__TEXT" => self.text_segment_file_range.take(),
+            b"__TEXT" => self.text_segment_svma.take(),
             _ => None,
         }
     }
@@ -926,21 +923,14 @@ mod object {
             Some(section.address()..section.address() + section.size())
         }
 
-        fn section_file_range(&mut self, name: &[u8]) -> Option<Range<u64>> {
-            let section = self.section_by_name_bytes(name)?;
-            let (start, size) = section.file_range()?;
-            Some(start..start + size)
-        }
-
         fn section_data(&mut self, name: &[u8]) -> Option<D> {
             let section = self.section_by_name_bytes(name)?;
             section.data().ok().map(|data| data.into())
         }
 
-        fn segment_file_range(&mut self, name: &[u8]) -> Option<Range<u64>> {
+        fn segment_svma_range(&mut self, name: &[u8]) -> Option<Range<u64>> {
             let segment = self.segments().find(|s| s.name_bytes() == Ok(Some(name)))?;
-            let (start, size) = segment.file_range();
-            Some(start..start + size)
+            Some(segment.address()..segment.address() + segment.size())
         }
 
         fn segment_data(&mut self, name: &[u8]) -> Option<D> {

tests/integration_tests/common.rs

@@ -26,12 +26,6 @@ where
             Some(section.address()..section.address() + section.size())
         }
 
-        fn section_file_range(&mut self, name: &[u8]) -> Option<Range<u64>> {
-            let section = self.0.section_by_name_bytes(name)?;
-            let (start, size) = section.file_range()?;
-            Some(start..start + size)
-        }
-
         fn section_data(&mut self, name: &[u8]) -> Option<Vec<u8>> {
             match self.0.section_by_name_bytes(name) {
                 Some(section) => section.data().ok().map(|data| data.to_owned()),
@@ -43,13 +37,12 @@ where
             }
         }
 
-        fn segment_file_range(&mut self, name: &[u8]) -> Option<Range<u64>> {
+        fn segment_svma_range(&mut self, name: &[u8]) -> Option<Range<u64>> {
             let segment = self
                 .0
                 .segments()
                 .find(|s| s.name_bytes() == Ok(Some(name)))?;
-            let (start, size) = segment.file_range();
-            Some(start..start + size)
+            Some(segment.address()..segment.address() + segment.size())
         }
 
         fn segment_data(&mut self, name: &[u8]) -> Option<Vec<u8>> {

tests/integration_tests/macos.rs

@@ -92,7 +92,7 @@ fn test_root_doc_comment() {
             stub_helper_svma: Some(0x1001d309c..0x1001d3438),
             eh_frame_svma: Some(0x100237f80..0x100237ffc),
             got_svma: Some(0x100238000..0x100238010),
-            text_segment_file_range: Some(0x1003fc000..0x100634000),
+            text_segment_svma: Some(0x1003fc000..0x100634000),
             text_segment: Some(vec![]),
             ..Default::default()
         },