Add 'elfdep' tool for printing the ELF dependencies of Mach-O files

src/buildtools/CMakeLists.txt

@@ -3,4 +3,6 @@ project(buildtools)
 include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)
 
 add_executable(getuuid getuuid.c)
+add_executable(elfdep elfdep.c)
 
+#add_subdirectory(Rez)

src/buildtools/elfdep.c

@@ -0,0 +1,182 @@
+/*
+This file is part of Darling.
+
+Copyright (C) 2018-2020 Lubos Dolezel
+
+Darling is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+Darling is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with Darling.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <mach-o/loader.h>
+#include <mach-o/fat.h>
+#include <string.h>
+#include <errno.h>
+
+bool printElfdepAny(const void* mem);
+bool printElfdepMH(const struct mach_header* mhdr);
+bool printElfdepMH64(const struct mach_header_64* mhdr);
+bool printFat(const struct fat_header* fhdr);
+bool printTaf(const struct fat_header* fhdr);
+
+int main(int argc, const char** argv)
+{
+	if (argc != 2)
+	{
+		fprintf(stderr, "elfdep: Prints the ELF dependency (SONAME) of a Mach-O file, if any\n");
+		fprintf(stderr, "Usage: elfdep <macho-file>\n");
+		return EXIT_FAILURE;
+	}
+
+	int fd = open(argv[1], O_RDONLY);
+	if (fd == -1)
+	{
+		fprintf(stderr, "Cannot open %s: %s", argv[1], strerror(errno));
+		return EXIT_FAILURE;
+	}
+
+	size_t length = lseek(fd, 0, SEEK_END);
+
+	void* mem = mmap(NULL, length, PROT_READ, MAP_SHARED, fd, 0);
+	if (mem == MAP_FAILED)
+	{
+		perror("mmap");
+		return EXIT_FAILURE;
+	}
+
+	close(fd);
+
+	printElfdepAny(mem);
+
+	munmap(mem, length);
+
+	return EXIT_SUCCESS;
+}
+
+bool printElfdepAny(const void* mem)
+{
+	const struct mach_header* mhdr = (struct mach_header*) mem;
+
+	if (mhdr->magic == MH_MAGIC)
+		return printElfdepMH(mhdr);
+	else if (mhdr->magic == MH_MAGIC_64)
+		return printElfdepMH64((struct mach_header_64*) mhdr);
+	else if (mhdr->magic == FAT_MAGIC)
+		return printFat((struct fat_header*) mhdr);
+	else if (mhdr->magic == FAT_CIGAM)
+		return printTaf((struct fat_header*) mhdr);
+	else
+	{
+		fprintf(stderr, "File format not recognized\n");
+		exit(1);
+	}
+}
+
+bool printElfdep(const struct load_command* lc, const void* base)
+{
+	if (lc->cmd == LC_SEGMENT)
+	{
+		const struct segment_command* sc = (const struct segment_command*) lc;
+
+		if (strcmp(sc->segname, "__TEXT") == 0)
+		{
+			const struct section* sect = (const struct section*)(sc+1);
+			for (int i = 0; i < sc->nsects; i++)
+			{
+				if (strcmp(sect->sectname, "__elfname") == 0)
+				{
+					printf("%s\n", ((const char*)base) + sect->offset);
+					return true;
+				}
+				sect++;
+			}
+		}
+	}
+	else if (lc->cmd == LC_SEGMENT_64)
+	{
+		const struct segment_command_64* sc = (const struct segment_command_64*) lc;
+
+		if (strcmp(sc->segname, "__TEXT") == 0)
+		{
+			const struct section_64* sect = (const struct section_64*)(sc+1);
+			for (int i = 0; i < sc->nsects; i++)
+			{
+				if (strcmp(sect->sectname, "__elfname") == 0)
+				{
+					printf("%s\n", ((const char*)base) + sect->offset);
+					return true;
+				}
+				sect++;
+			}
+		}
+	}
+	return false;
+}
+
+bool printElfdepMH(const struct mach_header* mhdr)
+{
+	const uint8_t* command = (const uint8_t*)(mhdr + 1);
+	for (uint32_t i = 0; i < mhdr->ncmds; i++)
+	{
+		if (printElfdep((const struct load_command*) command, mhdr))
+			return true;
+		else
+			command += ((const struct load_command*)command)->cmdsize;
+	}
+	return false;
+}
+
+bool printElfdepMH64(const struct mach_header_64* mhdr)
+{
+	const uint8_t* command = (const uint8_t*)(mhdr + 1);
+	for (uint32_t i = 0; i < mhdr->ncmds; i++)
+	{
+		if (printElfdep((const struct load_command*) command, mhdr))
+			return true;
+		else
+			command += ((const struct load_command*)command)->cmdsize;
+	}
+	return false;
+}
+
+bool printFat(const struct fat_header* fhdr)
+{
+	const struct fat_arch* fa = ((const struct fat_arch*) (fhdr+1));
+
+	for (uint32_t i = 0; i < fhdr->nfat_arch; i++)
+	{
+		if (printElfdepAny(((char*) fhdr) + fa[i].offset))
+			return true;
+	}
+
+	return false;
+}
+
+bool printTaf(const struct fat_header* fhdr)
+{
+	const struct fat_arch* fa = ((const struct fat_arch*) (fhdr+1));
+
+	for (uint32_t i = 0; i < __builtin_bswap32(fhdr->nfat_arch); i++)
+	{
+		if (printElfdepAny(((char*) fhdr) + __builtin_bswap32(fa[i].offset)))
+			return true;
+	}
+
+	return false;
+}
+