resolve-system-dependencies: implement in C++

Makefile

@@ -13,6 +13,7 @@ makefiles = \
   src/nix-collect-garbage/local.mk \
   src/nix-prefetch-url/local.mk \
   src/buildenv/local.mk \
+  src/resolve-system-dependencies/local.mk \
   perl/local.mk \
   scripts/local.mk \
   corepkgs/local.mk \

src/resolve-system-dependencies/local.mk

@@ -0,0 +1,7 @@
+programs += resolve-system-dependencies
+
+resolve-system-dependencies_DIR := $(d)
+
+resolve-system-dependencies_LIBS := libstore libmain libutil libformat
+
+resolve-system-dependencies_SOURCES := $(d)/resolve-system-dependencies.cc

src/resolve-system-dependencies/resolve-system-dependencies.cc

@@ -0,0 +1,201 @@
+#include "derivations.hh"
+#include "globals.hh"
+#include "shared.hh"
+#include "store-api.hh"
+#include <sys/utsname.h>
+#include <algorithm>
+#include <iostream>
+#include <fstream>
+#include <mach-o/loader.h>
+#include <mach-o/swap.h>
+
+using namespace nix;
+
+typedef std::map<string, std::set<string>> SetMap;
+
+static auto cacheDir = Path{};
+
+Path resolveCacheFile(const Path & lib) {
+    Path lib2 = Path(lib);
+    std::replace(lib2.begin(), lib2.end(), '/', '%');
+    return cacheDir + "/" + lib2;
+}
+
+std::set<string> readCacheFile(const Path & file) {
+    return tokenizeString<set<string>>(readFile(file), "\n");
+}
+
+void writeCacheFile(const Path & file, std::set<string> & deps) {
+    std::ofstream fp;
+    fp.open(file);
+    for (auto & d : deps) {
+        fp << d << "\n";
+    }
+    fp.close();
+}
+
+std::string find_dylib_name(FILE *obj_file, struct load_command cmd) {
+  fpos_t pos;
+  fgetpos(obj_file, &pos);
+  struct dylib_command dylc;
+  dylc.cmd = cmd.cmd;
+  dylc.cmdsize = cmd.cmdsize;
+  fread(&dylc.dylib, sizeof(struct dylib), 1, obj_file);
+
+  char *dylib_name = (char*)calloc(cmd.cmdsize, sizeof(char));
+  fseek(obj_file,
+      // offset is calculated from the beginning of the load command, which is two
+      // uint32_t's backwards
+      dylc.dylib.name.offset - (sizeof(uint32_t) * 2) + pos,
+      SEEK_SET);
+  fread(dylib_name, sizeof(char), cmd.cmdsize, obj_file);
+  fseek(obj_file, pos, SEEK_SET);
+  return std::string(dylib_name);
+}
+
+bool seek_mach64_blob(FILE *obj_file, enum NXByteOrder end) {
+  struct fat_header head;
+  fread(&head, sizeof(struct fat_header), 1, obj_file);
+  swap_fat_header(&head, end);
+  for(uint32_t narches = 0; narches < head.nfat_arch; narches++) {
+    struct fat_arch arch;
+    fread(&arch, sizeof(struct fat_arch), 1, obj_file);
+    swap_fat_arch(&arch, 1, end);
+    if(arch.cputype == CPU_TYPE_X86_64) {
+      fseek(obj_file, arch.offset, SEEK_SET);
+      return true;
+    }
+  }
+  return false;
+}
+
+std::set<std::string> runResolver(const Path & filename) {
+  FILE *obj_file = fopen(filename.c_str(), "rb");
+  uint32_t magic;
+  fread(&magic, sizeof(uint32_t), 1, obj_file);
+  fseek(obj_file, 0, SEEK_SET);
+  enum NXByteOrder endianness;
+  if(magic == 0xBEBAFECA) {
+    endianness = NX_BigEndian;
+    if(!seek_mach64_blob(obj_file, endianness)) {
+      std::cerr << "Could not find any mach64 blobs in file " << filename << ", continuing..." << std::endl;
+      return std::set<string>();
+    }
+  }
+  struct mach_header_64 header;
+  fread(&header, sizeof(struct mach_header_64), 1, obj_file);
+  if(!(header.magic == MH_MAGIC_64 || header.magic == MH_CIGAM_64)) {
+    std::cerr << "Not a mach-o object file: " << filename << std::endl;
+    return std::set<string>();
+  }
+  std::set<string> libs;
+  for(uint32_t i = 0; i < header.ncmds; i++) {
+    struct load_command cmd;
+    fread(&cmd.cmd, sizeof(uint32_t), 1, obj_file);
+    fread(&cmd.cmdsize, sizeof(uint32_t), 1, obj_file);
+    switch(cmd.cmd) {
+      case LC_LOAD_DYLIB:
+      case LC_REEXPORT_DYLIB:
+        libs.insert(find_dylib_name(obj_file, cmd));
+        break;
+    }
+    fseek(obj_file, cmd.cmdsize - (sizeof(uint32_t) * 2), SEEK_CUR);
+  }
+  fclose(obj_file);
+  libs.erase(filename);
+  return libs;
+}
+
+bool isSymlink(const Path & path) {
+  struct stat st;
+  if(lstat(path.c_str(), &st))
+      throw SysError(format("getting attributes of path ‘%1%’") % path);
+
+  return S_ISLNK(st.st_mode);
+}
+
+Path resolveSymlink(const Path & path) {
+    char buf[PATH_MAX];
+    ssize_t len = readlink(path.c_str(), buf, sizeof(buf) - 1);
+    if(len != -1) {
+      buf[len] = 0;
+      return Path(buf);
+    } else {
+      throw SysError(format("readlink('%1%')") % path);
+    }
+}
+
+std::set<string> resolve_tree(const Path & path, PathSet & deps) {
+  std::set<string> results;
+  if(deps.find(path) != deps.end()) {
+    return std::set<string>();
+  }
+  deps.insert(path);
+  for (auto & lib : runResolver(path)) {
+    results.insert(lib);
+    for (auto & p : resolve_tree(lib, deps)) {
+      results.insert(p);
+    }
+  }
+  return results;
+}
+
+std::set<string> get_path(const Path & path) {
+  Path cacheFile = resolveCacheFile(path);
+  if(pathExists(cacheFile)) {
+    return readCacheFile(cacheFile);
+  }
+
+  std::set<string> deps;
+  std::set<string> paths;
+  paths.insert(path);
+
+  Path next_path = Path(path);
+  while(isSymlink(next_path)) {
+    next_path = resolveSymlink(next_path);
+    paths.insert(next_path);
+  }
+
+  for(auto & t : resolve_tree(next_path, deps)) {
+    paths.insert(t);
+  }
+
+  writeCacheFile(cacheFile, paths);
+
+  return paths;
+}
+
+int main(int argc, char ** argv) {
+    return handleExceptions(argv[0], [&]() {
+        initNix();
+
+        struct utsname _uname;
+
+        uname(&_uname);
+
+        cacheDir = (format("%1%/dependency-maps/%2%-%3%-%4%")
+            % settings.nixStateDir
+            % _uname.machine
+            % _uname.sysname
+            % _uname.release).str();
+
+        auto store = openStore();
+
+        auto drv = store->derivationFromPath(Path(argv[1]));
+        Strings impurePaths = tokenizeString<Strings>(get(drv.env, "__impureHostDeps"));
+
+        std::set<string> all_paths;
+
+        for (auto & path : impurePaths) {
+            for(auto & p : get_path(path)) {
+              all_paths.insert(p);
+            }
+        }
+
+        std::cout << "extra-chroot-dirs" << std::endl;
+        for(auto & path : all_paths) {
+          std::cout << path << std::endl;
+        }
+        std::cout << std::endl;
+    });
+}