Implement ELF subtype expression

README.md

@@ -30,9 +30,9 @@ make remove #remove from /bin/
 - Images:		BMP, PNG, JPEG, QOI, GIF, TIFF, WEBP
 - Audio:		WAV, MP3, OGG, QOA, AIFF, MIDI, FLAC
 - Video:		MP4, AVI
-- Multimedia:	PDF, Blender, glTF, MD2
+- Multimedia:	PDF, XCF, Blender, glTF, MD2
 - Fonts:		WOFF, WOFF2, OpenType
-- Executables:	ELF, EXE, WebAssembly, JAR, Luac
+- Executables:	ELF, EXE, WebAssembly, Luac
 - Archives:		Tar, ZIP, GZIP, XZ, LZIP, 7-Zip, RAR, BZip, CPIO, PAK, .deb, .rpm
 - Binary Data:	qcow, ISO
 - Other:		XML, Shebang scripts, SSH keys, Shortcuts

src/ext.h

@@ -0,0 +1 @@
+#include "ext/elf.h"

src/ext/elf.h

@@ -0,0 +1,108 @@
+typedef struct
+	{
+		unsigned char magic[4]; // 7F E L F
+		unsigned char bitclass;
+		unsigned char endian;
+		unsigned char elfversion; // Must be 1
+		unsigned char abi;
+		unsigned char abiversion; // ignore
+		unsigned char padding[7];
+		uint16_t type;
+		uint16_t machine;
+		uint32_t version;
+		// ... there's more we don't really care about in this context
+	}
+	elf_header_t;
+
+enum {
+	ELF_BITCLASS_NONE,
+	ELF_BITCLASS_32,
+	ELF_BITCLASS_64,
+	ELF_BITCLASS_OOB
+};
+enum {
+	ELF_ENDIAN_NONE,
+	ELF_ENDIAN_LITTLE,
+	ELF_ENDIAN_BIG,
+	ELF_ENDIAN_OOB
+};
+enum {
+	ELF_ABI_NONE,
+	ELF_ABI_SYSV,
+	ELF_ABI_HPUX,
+	ELF_ABI_NETBSD,
+	ELF_ABI_LINUX,
+	ELF_ABI_SOLARIS,
+	ELF_ABI_IRIX,
+	ELF_ABI_FREEBSD,
+	ELF_ABI_TRU64,
+	ELF_ABI_ARM,
+	ELF_ABI_STANDALONE,
+	ELF_ABI_OOB
+};
+enum {
+	ELF_TYPE_NONE,
+	ELF_TYPE_RELOCATABLE,
+	ELF_TYPE_EXECUTABLE,
+	ELF_TYPE_DYNAMIC,
+	ELF_TYPE_CORE,
+	ELF_TYPE_OOB,
+};
+enum {
+	ELF_MACH_NONE,
+	ELF_MACH_X86 = 0x03,
+	ELF_MACH_IA64 = 0x32,
+	ELF_MACH_AMDX86 = 0x3E,
+	ELF_MACH_ARM = 0x28,
+	ELF_MACH_AARM = 0xB7,
+	ELF_MACH_RISCV = 0xF3,
+	ELF_MACH_Z80 = 0xDC
+};
+
+char elf_endians[][8] = {
+	"Invalid", "Little", "Big" };
+
+char elf_bitclasses[][8] = {
+	"Invalid", "32", "64" };
+
+char elf_types[][16] = {
+	"Other", "Relocatable", "Executable", "Dynamic Object", "Core File" };
+
+char elf_abis[][16] = {
+	"Generic", "SYS-V", "HPUX", "NetBSD", "Linux", "Solaris", "Irix", "FreeBSD", "Tru64", "ARM", "Standalone" };
+
+char elf_machs[0xFF][16] = {
+	[ELF_MACH_NONE] = "None",
+	[ELF_MACH_X86] = "x86",
+	[ELF_MACH_IA64] = "IA-64 (Itanium)",
+	[ELF_MACH_AMDX86] = "x86 (AMD)",
+	[ELF_MACH_ARM] = "ARM",
+	[ELF_MACH_AARM] = "ARM (AArch64)",
+	[ELF_MACH_RISCV] = "RISC-V",
+	[ELF_MACH_Z80] = "Zilog Z80",
+};
+
+void elf_printer (void *filetype, char *in) {
+	static char buffer[128];
+	elf_header_t * header = (elf_header_t *) in;
+	filetype_t * self = (filetype_t *) filetype;
+
+	if ( header->abi >= ELF_ABI_OOB ) { header->abi = 0; }
+	if ( header->bitclass >= ELF_BITCLASS_OOB ) { header->bitclass = 0; }
+	if ( header->endian >= ELF_ENDIAN_OOB ) { header->endian = 0; }
+	if ( header->abi >= ELF_ABI_OOB ) { header->abi = 0; }
+	if ( header->type >= ELF_TYPE_OOB ) { header->type = 0; }
+	if ( header->machine >= 0xFF ) { header->type = 0; } // Prevent overflow
+	if ( elf_machs[header->machine][0] == 0 ) { header->type = 0; } // Prevent nulls
+
+	char * abi = elf_abis[header->abi];
+	char * bitclass = elf_bitclasses[header->bitclass];
+	char * endian = elf_endians[header->endian];
+	char * type = elf_types[header->type];
+	char * mach = elf_machs[header->machine];
+
+	snprintf(buffer, sizeof(buffer),
+		"ELF %.16s-bit %.16s endian %.16s, %.16s %.16s",
+		bitclass, endian, type, mach, abi
+	);	self->info = buffer;
+}

src/magic.c

@@ -24,6 +24,9 @@ int parse_magic(char *in) {
 		if ( status == 0 ) { type = test; break; }
 	}
 
+	if ( type != NULL && type->printer != NULL )
+		{ type->printer(type, (char *)buffer); }
+
 	fclose(target);
 	return 0;
 }

src/magic.h

@@ -1,21 +1,24 @@
 #ifndef MAGIC_H
 #define MAGIC_H
-#include <stdio.h>
-#include <string.h>
 
 	// Allows overriding the default printer function for certain types
-typedef void *type_parser(void *type, char *in);
+typedef void type_parser(void *type, char *in);
 void parser_default(void *type, char *in);
 int parse_magic(char *in);
 long parse_size(char *in);
 long get_size(FILE *f);
 int parse_scale(long in);
 
 typedef struct
-	{ char * name; char * magic; char * ext; int off; int len; type_parser *printer; }
+	{ char * name; char * magic; char * ext; int off; int len; type_parser *printer; char * info; }
 	filetype_t;
+	// the type_parser printer is used to set *info for file formats with important subtypes.
+	// they are passed in the first 32 bytes of the input file,
+	// which can be changed later if some formats (such as MacOS dmg files)
+	// require more data (and bounds checking logic)
 
 extern filetype_t * type;
+#include "ext.h"
 
 // https://en.wikipedia.org/wiki/List_of_file_formats
 #define magic_table_size ( sizeof(magic_table) / sizeof(magic_table[0]) )
@@ -35,8 +38,6 @@ filetype_t magic_table [] = {
 	{	.name = "Windows Shell Link",
 		.magic = "\x4C\x00\x00\x00\x01\x14\x02\x00\x00\x00\x00\x00\xC0\x00\x00\x00\x00\x00\x00\x46", .len = 20, .ext = "lnk" },
 	// Raster Image Formats
-//	{ 	.name = "PNG Image",
-//		.magic = "\x89\x50\x4E\x47\x0D\x0A\x1A\xA0", .len = 8, .ext = "png" },
 	{ 	.name = "PNG Image",
 		.magic = "\x89\x50\x4E\x47", .len = 4, .ext = "png" },
 	{	.name = "JPEG Image",
@@ -101,16 +102,17 @@ filetype_t magic_table [] = {
 		.magic = "FLhd", .len = 4, .ext = "flp" },
 	{	.name = "Quake 2 Model",
 		.magic = "IDP2\x08\x00\x00\x00", .len = 8, .ext = ".md2" },
+	{	.name = "GIMP Project",
+		.magic = "gimp xcf ", .len = 9, .ext = "xcf" },
 	// Executable Formats
-		// TODO: ELF Format Printer, checks header for subtype information
 	{	.name = "MachO Binary (32-bit x86)",
 		.magic = "\xCE\xFA\xED\xFE\x07\x00\x00\x00", .len = 8, .ext = NULL },
 	{	.name = "MachO Binary (64-bit x86)",
 		.magic = "\xCF\xFA\xED\xFE\x07\x00\x00\x00", .len = 8, .ext = NULL },
 	{	.name = "MachO Binary (64-bit ARM)",
 		.magic = "\xCF\xFA\xED\xFE\x0C\x00\x00\x00", .len = 8, .ext = NULL },
 	{	.name = "ELF Binary",
-		.magic = "\x7F" "ELF", .len = 4, .ext = "bin" },
+		.magic = "\x7F" "ELF", .len = 4, .ext = "bin", .printer = elf_printer },
 	{	.name = "Portable Executable Binary",
 		.magic = "\x4D\x5A", .len = 2, .ext = "exe" },
 	{	.name = "WebAssembly Binary",

src/main.c

@@ -1,3 +1,6 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
 #include "magic.h"
 #include "magic.c"
 #include "license.h"
@@ -25,6 +28,7 @@ int main(int argc, char* argv[]) {
 		outname = (char *)(argv[1] + arglen - maxlen );
 		outname[0] = '.'; outname[1] = '.'; outname[2] = '.'; }
 	if ( type == NULL ) { printf("%s: Unknown file type\n", outname); }
+	else if ( type->info != NULL ) { printf("%s:%s\n", outname, type->info); }
 	else { printf("%s: %s\n", outname, type->name); }
 	// Scale the filesize then print
 	char prefix[] = " KMGTP";