Merge pull request #89 from p-x9/feature/improve-read-string-from-file

Improve null terminated string reading
p-x9 · Jun 13, 2024 · 9212cd2 · 9212cd2
2 parents 41f0bb3 + 1b21b68
commit 9212cd2
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Showing 6 changed files with 34 additions and 13 deletions.
diff --git a/Sources/MachOKit/Extension/FileHandle+.swift b/Sources/MachOKit/Extension/FileHandle+.swift
@@ -158,6 +158,24 @@ extension FileHandle {
         return String(cString: data)
     }
 
+    @_spi(Support)
+    public func readString(
+        offset: UInt64,
+        step: UInt64 = 10
+    ) -> String? {
+        var data = Data()
+        var offset = offset
+        while true {
+            let new = readData(offset: offset, size: Int(step))
+            if new.isEmpty { break }
+            data.append(new)
+            if new.contains(0) { break }
+            offset += UInt64(new.count)
+        }
+
+        return String(cString: data)
+    }
+
     @_spi(Support)
     public func readData(
         offset: UInt64,

diff --git a/Sources/MachOKit/Extension/UnsafePointer+.swift b/Sources/MachOKit/Extension/UnsafePointer+.swift
@@ -62,3 +62,12 @@ extension UnsafePointer<UInt8> {
         return (string, offset)
     }
 }
+
+extension UnsafePointer<CChar> {
+    func readString() -> (String, Int) {
+        let offset = Int(bitPattern: strchr(self, 0)) + 1 - Int(bitPattern: self)
+        let string = String(cString: self)
+
+        return (string, offset)
+    }
+}
diff --git a/Sources/MachOKit/MachOFile+Strings.swift b/Sources/MachOKit/MachOFile+Strings.swift
@@ -60,15 +60,12 @@ extension MachOFile.Strings {
 
                 let ptr = baseAddress
                     .advanced(by: nextOffset)
-                    .assumingMemoryBound(to: CChar.self)
-                let string = String(cString: ptr)
-
-                let nextPointer = UnsafePointer(strchr(ptr, 0))
-                    .advanced(by: 1)
+                    .assumingMemoryBound(to: UInt8.self)
+                let (string, offset) = ptr.readString()
 
                 let result = Element(string: string, offset: nextOffset)
 
-                nextOffset += Int(bitPattern: nextPointer) - Int(bitPattern: ptr)
+                nextOffset += offset
 
                 return  result
             }

diff --git a/Sources/MachOKit/MachOImage+Strings.swift b/Sources/MachOKit/MachOImage+Strings.swift
@@ -72,9 +72,8 @@ extension MachOImage.Strings {
             if offset >= tableSize {
                 return nil
             }
-            let string = String(cString: nextPointer)
-            nextPointer = UnsafePointer(strchr(nextPointer, 0))
-                .advanced(by: 1)
+            let (string, nextOffset) = nextPointer.readString()
+            nextPointer = nextPointer.advanced(by: nextOffset)
 
             return .init(string: string, offset: offset)
         }

diff --git a/Sources/MachOKit/Model/DyldCache/DyldCacheImageInfo.swift b/Sources/MachOKit/Model/DyldCache/DyldCacheImageInfo.swift
@@ -20,8 +20,7 @@ extension DyldCacheImageInfo {
     /// - Returns: Path for image
     public func path(in cache: DyldCache) -> String? {
         cache.fileHandle.readString(
-            offset: numericCast(layout.pathFileOffset),
-            size: 1000 // FIXME
+            offset: numericCast(layout.pathFileOffset)
         )
     }
 }
diff --git a/Sources/MachOKit/Model/DyldCache/DyldCacheImageTextInfo.swift b/Sources/MachOKit/Model/DyldCache/DyldCacheImageTextInfo.swift
@@ -25,8 +25,7 @@ extension DyldCacheImageTextInfo {
     /// - Returns: Path for image text
     public func path(in cache: DyldCache) -> String? {
         cache.fileHandle.readString(
-            offset: numericCast(layout.pathOffset),
-            size: 1000 // FIXME
+            offset: numericCast(layout.pathOffset)
         )
     }
 }