Fix magic number printing (#53)

Author: topolarity

src/COFF/COFFHandle.jl

@@ -49,8 +49,8 @@ function readmeta(io::IO, ::Type{H}) where {H <: COFFHandle}
     magic = [read(io, UInt8) for idx in 1:4]
     if any(magic .!= PE_magic)
         msg = """
-        Magic Number 0x$(join(string.(magic, base=16),"")) does not match expected PE
-        magic number 0x$(join("", string.(PE_magic, base=16)))
+        Magic Number 0x$(join(string.(magic, base=16, pad=2),"")) does not match expected PE
+        magic number 0x$(join(string.(PE_magic, base=16, pad=2),""))
         """
         throw(MagicMismatch(replace(strip(msg), "\n" => " ")))
     end

src/ELF/ELFHandle.jl

@@ -38,8 +38,8 @@ function readmeta(io::IO, ::Type{H}) where {H <: ELFHandle}
     magic = [read(io, UInt8) for idx in 1:4]
     if any(magic .!= elven_magic)
         msg = """
-        Magic Number 0x$(join(string.(magic, base=16),"")) does not match expected ELF
-        magic number 0x$(join("", string.(elven_magic, base=16)))
+        Magic Number 0x$(join(string.(magic, base=16, pad=2),"")) does not match expected ELF
+        magic number 0x$(join(string.(elven_magic, base=16, pad=2),""))
         """
         throw(MagicMismatch(replace(strip(msg), "\n" => " ")))
     end

src/MachO/MachOHeader.jl

@@ -47,7 +47,7 @@ function macho_header_type(magic::UInt32)
     elseif magic in (METALLIB_MAGIC,)
         return MetallibHeader{MachOHandle}
     else
-        throw(MagicMismatch("Invalid Magic ($(string(magic, base=16)))!"))
+        throw(MagicMismatch("Invalid Magic (0x$(string(magic, base=16, pad=8)))!"))
     end
 end
 
@@ -63,7 +63,7 @@ function macho_is64bit(magic::UInt32)
     elseif magic in (MH_MAGIC, MH_CIGAM, FAT_MAGIC, FAT_CIGAM, FAT_MAGIC_METAL, FAT_CIGAM_METAL, METALLIB_MAGIC)
         return false
     else
-        throw(MagicMismatch("Invalid Magic ($(string(magic, base=16)))!"))
+        throw(MagicMismatch("Invalid Magic (0x$(string(magic, base=16, pad=8)))!"))
     end
 end
 
@@ -79,7 +79,7 @@ function macho_endianness(magic::UInt32)
     elseif magic in (MH_MAGIC, MH_MAGIC_64, FAT_MAGIC, FAT_MAGIC_METAL, METALLIB_MAGIC)
         return :LittleEndian
     else
-        throw(MagicMismatch("Invalid Magic ($(string(magic, base=16)))!"))
+        throw(MagicMismatch("Invalid Magic (0x$(string(magic, base=16, pad=8)))!"))
     end
 end
 

test/runtests.jl

@@ -12,6 +12,27 @@ using Test
     end
 end
 
+function check_magic_mismatch(path, HandleType)
+    err = try
+        readmeta(open(path, "r"), HandleType)
+    catch err
+        err
+    end
+
+    @test err isa MagicMismatch
+    if HandleType === ELFHandle
+        @test occursin(r"Magic Number 0x[a-f0-9]{8} does not match expected ELF magic number 0x7f454c46", repr(err))
+    elseif HandleType === COFFHandle
+        @test occursin(r"Magic Number 0x[a-f0-9]{8} does not match expected PE magic number 0x50450000", repr(err))
+    elseif HandleType === MachOHandle
+        @test occursin(r"Invalid Magic \(0x[a-f0-9]{8}\)\!", repr(err))
+    else
+        @assert false "unexpected handle type"
+    end
+
+    return nothing
+end
+
 function test_libfoo_and_fooifier(fooifier_path, libfoo_path)
     # Actually read it in
     oh_exe = only(readmeta(open(fooifier_path, "r")))
@@ -43,6 +64,12 @@ function test_libfoo_and_fooifier(fooifier_path, libfoo_path)
                 # Test that we got the right type
                 @test typeof(oh) <: H
 
+                # Test that the wrong types all error as expected
+                for MismatchedType in (ELFHandle, COFFHandle, MachOHandle)
+                    H === MismatchedType && continue
+                    check_magic_mismatch(fooifier_path, MismatchedType)
+                end
+
                 # Test that we got the right number of bits
                 @test is64bit(oh) == (bits == "64")
                 @test platforms_match(Platform(oh), platforms[dir_path])