Complete the implementation + tests of compact common encoding lookup.

Resources/Tests/PLCrashAsyncCompactUnwindEncodingTests/test.c

@@ -4,6 +4,7 @@
 // Keep in sync with PLCrashAsyncCompactUnwindEncodingTests
 #define BASE_PC 0
 #define PC_COMPACT_COMMON (BASE_PC+1)
+#define PC_COMPACT_COMMON_ENCODING (UNWIND_X86_64_MODE_DWARF | 0xFF)
 
 
 struct unwind_sect_compressed_page {
@@ -50,7 +51,7 @@ struct unwind_sect data __attribute__((section("__TEXT,__unwind_info"))) = {
     },
     
     .common_encodings = {
-        0x0, // PC_COMPACT_COMMON
+        PC_COMPACT_COMMON_ENCODING,
     },
 
     .regular_page_1 = {
@@ -73,6 +74,7 @@ struct unwind_sect data __attribute__((section("__TEXT,__unwind_info"))) = {
             .entryCount = 1
         },
         .entries = {
+            /* Note that these are offsets from the first-level functionOffset */
             COMPRESSED(0, 0)
         },
     },

Source/PLCrashAsyncCompactUnwindEncoding.c

@@ -136,13 +136,17 @@ plcrash_error_t plcrash_async_cfe_reader_init (plcrash_async_cfe_reader_t *reade
 #define VERIFY_SIZE_T(_etype, _ecount) (SIZE_MAX / sizeof(_etype) < _ecount)
 
 /**
- * TODO
+ * Return the compact frame encoding entry for @a pc via @a encoding, if available.
  *
- * @param reader The initialized CFE reader.
+ * @param reader The initialized CFE reader which will be searched for the entry.
  * @param pc The PC value to search for within the CFE data. Note that this value must be relative to
  * the target Mach-O image's __TEXT vmaddr.
+ * @param encoding On success, will be populated with the compact frame encoding entry.
+ *
+ * @return Returns PLFRAME_ESUCCCESS on success, or one of the remaining error codes if a CFE parsing error occurs. If
+ * the entry can not be found, PLFRAME_ENOTFOUND will be returned.
  */
-plcrash_error_t plcrash_async_cfe_reader_find_pc (plcrash_async_cfe_reader_t *reader, pl_vm_address_t pc) {
+plcrash_error_t plcrash_async_cfe_reader_find_pc (plcrash_async_cfe_reader_t *reader, pl_vm_address_t pc, uint32_t *encoding) {
     const plcrash_async_byteorder_t *byteorder = reader->byteorder;
     const pl_vm_address_t base_addr = plcrash_async_mobject_base_address(reader->mobj);
 
@@ -266,18 +270,19 @@ plcrash_error_t plcrash_async_cfe_reader_find_pc (plcrash_async_cfe_reader_t *re
             /* Find the actual encoding */
             uint32_t c_entry = byteorder->swap32(*c_entry_ptr);
             uint8_t c_encoding_idx = UNWIND_INFO_COMPRESSED_ENTRY_ENCODING_INDEX(c_entry);
-            if (c_encoding_idx < common_enc_count) {
-                /* Found in the common table */
             
-            } else {
-                // TODO
-                __builtin_trap();
+            /* Handle common table entries */
+            if (c_encoding_idx < common_enc_count) {
+                /* Found in the common table. The offset is verified as being within the mapped memory range by
+                 * the < common_enc_count check above. */
+                *encoding = common_enc[c_encoding_idx];
+                return PLCRASH_ESUCCESS;
             }
 
-            
+            // TODO
+            __builtin_trap();
             PLCF_DEBUG("FOUND func_offset=%" PRIx32 " idx = %" PRIx32, base_foffset + UNWIND_INFO_COMPRESSED_ENTRY_FUNC_OFFSET(c_entry), UNWIND_INFO_COMPRESSED_ENTRY_ENCODING_INDEX(c_entry));
-            
-            break;
+            return PLCRASH_ESUCCESS;
         }
 
         default:
@@ -285,7 +290,9 @@ plcrash_error_t plcrash_async_cfe_reader_find_pc (plcrash_async_cfe_reader_t *re
             return PLCRASH_EINVAL;
     }
 
-    return PLCRASH_ESUCCESS;
+    // Unreachable
+    __builtin_trap();
+    return PLCRASH_ENOTFOUND;
 }
 
 /**

Source/PLCrashAsyncCompactUnwindEncoding.h

@@ -57,7 +57,7 @@ typedef struct plcrash_async_cfe_reader {
 
 plcrash_error_t plcrash_async_cfe_reader_init (plcrash_async_cfe_reader_t *reader, plcrash_async_mobject_t *mobj, cpu_type_t cputype);
 
-plcrash_error_t plcrash_async_cfe_reader_find_pc (plcrash_async_cfe_reader_t *reader, pl_vm_address_t pc);
+plcrash_error_t plcrash_async_cfe_reader_find_pc (plcrash_async_cfe_reader_t *reader, pl_vm_address_t pc, uint32_t *encoding);
 
 void plcrash_async_cfe_reader_free (plcrash_async_cfe_reader_t *reader);
 

Source/PLCrashAsyncCompactUnwindEncodingTests.m

@@ -51,6 +51,7 @@
 
 /** PC to use for the compact-common test */
 #define PC_COMPACT_COMMON (BASE_PC+1)
+#define PC_COMPACT_COMMON_ENCODING (UNWIND_X86_64_MODE_DWARF | 0xFF)
 
 /**
  * @internal
@@ -209,8 +210,10 @@
 - (void) testReadCompressedCommonEncoding {
     plcrash_error_t err;
 
-    err = plcrash_async_cfe_reader_find_pc(&_reader, PC_COMPACT_COMMON);
+    uint32_t encoding;
+    err = plcrash_async_cfe_reader_find_pc(&_reader, PC_COMPACT_COMMON, &encoding);
     STAssertEquals(PLCRASH_ESUCCESS, err, @"Failed to locate CFE entry");
+    STAssertEquals(encoding, (uint32_t)PC_COMPACT_COMMON_ENCODING, @"Incorrect encoding returned");
 }
 
 @end