a5ec53f157
Make it easier to wrap one's head around the code and make the license explicit. It was implicit already by the LICENSE file of this repository.
132 lines
4.3 KiB
C
132 lines
4.3 KiB
C
/* Copyright 2020 Zhuowei Zhang, Oliver Smith
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* SPDX-License-Identifier: GPL-3.0-or-later
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*
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* This program gets built to a set of wrapper executables, which launch native
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* cross compilers inside foreign arch chroots. Speeds up cross compilation a
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* lot, compared to using just qemu user mode emulation or using the previous
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* distcc-based methods.
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*
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* How this program gets called:
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* - pmbootstrap creates one native arch chroot and one foreign arch chroot.
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* - The native chroot gets mounted as /native in the foreign chroot.
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* - When calling "abuild", pmbootstrap sets PATH to:
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* /native/usr/lib/crossdirect/<ARCH>:$PATH
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* - That crossdirect directory contains a crossdirect-<ARCH> binary built with
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* the matching HOSTSPEC (e.g. crossdirect-aarch64 binary with HOSTSPEC
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* aarch64-alpine-linux-musl). This binary is symlinked to:
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* - <HOSTSPEC>-c++
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* - <HOSTSPEC>-cc
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* - <HOSTSPEC>-clang
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* - <HOSTSPEC>-clang++
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* - <HOSTSPEC>-cpp
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* - <HOSTSPEC>-g++
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* - <HOSTSPEC>-gcc
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* - c++
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* - cc
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* - clang
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* - clang++
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* - cpp
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* - g++
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* - gcc
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*/
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#include <errno.h>
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#include <libgen.h>
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#include <limits.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#define NATIVE_BIN_DIR "/native/usr/lib/ccache/bin"
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void exit_userfriendly()
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{
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fprintf(stderr, "Please report this at: https://gitlab.com/postmarketOS/pmaports/issues\n");
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fprintf(stderr, "As a workaround, you can compile without crossdirect.\n");
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fprintf(stderr, "See 'pmbootstrap -h' for related options.\n");
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exit(1);
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}
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bool argv_has_arg(int argc, char **argv, const char *arg)
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{
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size_t arg_len = strlen(arg);
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for (int i = 1; i < argc; i++) {
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if (strlen(argv[i]) < arg_len)
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continue;
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if (!memcmp(argv[i], arg, arg_len))
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return true;
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}
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return false;
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}
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int main(int argc, char **argv)
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{
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// we have a max of four extra args ("-target", "HOSTSPEC", "--sysroot=/", "-Wl,-rpath-link=/lib:/usr/lib"), plus one ending null
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char *newargv[argc + 5];
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char *executableName = basename(argv[0]);
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char newExecutable[PATH_MAX];
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bool isClang = (strcmp(executableName, "clang") == 0 || strcmp(executableName, "clang++") == 0);
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bool startsWithHostSpec = (strncmp(HOSTSPEC, executableName, sizeof(HOSTSPEC) - 1) == 0);
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// linker is involved: just use qemu binary (to avoid broken cross-ld, pmaports#227)
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if (!argv_has_arg(argc, argv, "-c")) {
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snprintf(newExecutable, sizeof(newExecutable), "/usr/bin/%s", executableName);
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if (execv(newExecutable, argv) == -1) {
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fprintf(stderr, "ERROR: crossdirect: failed to execute %s: %s\n", newExecutable, strerror(errno));
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fprintf(stderr, "NOTE: this is a foreign arch binary that would run with qemu (linker is involved).\n");
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exit_userfriendly();
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}
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}
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// prepend the HOSTSPEC to GCC binaries
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if (isClang || startsWithHostSpec) {
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snprintf(newExecutable, sizeof(newExecutable), NATIVE_BIN_DIR "/%s", executableName);
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} else {
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snprintf(newExecutable, sizeof(newExecutable), NATIVE_BIN_DIR "/" HOSTSPEC "-%s", executableName);
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}
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// prepare new arguments for GCC / clang
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char **newArgsPtr = newargv;
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*newArgsPtr++ = newExecutable;
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if (isClang) {
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// clang does not use a HOSTSPEC prefix for the cross compiler
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// binary, but instead have a -target argument
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*newArgsPtr++ = "-target";
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*newArgsPtr++ = HOSTSPEC;
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}
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*newArgsPtr++ = "--sysroot=/";
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// add all arguments passed to this executable to GCC / clang and set
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// the last arg in newargv to NULL to mark its end
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memcpy(newArgsPtr, argv + 1, sizeof(char *) * (argc - 1));
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newArgsPtr += (argc - 1);
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*newArgsPtr = NULL;
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// new arguments prepared; now setup environmental vars
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char *env[] = { "LD_PRELOAD=",
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"LD_LIBRARY_PATH=/native/lib:/native/usr/lib",
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"CCACHE_PATH=/native/usr/bin",
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NULL };
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char *ldPreload = getenv("LD_PRELOAD");
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if (ldPreload) {
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if (strcmp(ldPreload, "/usr/lib/libfakeroot.so") == 0) {
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env[0] = "LD_PRELOAD=/native/usr/lib/libfakeroot.so";
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} else {
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fprintf(stderr, "ERROR: crossdirect: can't handle LD_PRELOAD: %s\n", ldPreload);
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exit_userfriendly();
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}
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}
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// finally exec GCC / clang
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if (execve(newExecutable, newargv, env) == -1) {
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fprintf(stderr, "ERROR: crossdirect: failed to execute %s: %s\n", newExecutable, strerror(errno));
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fprintf(stderr, "Maybe the target arch is missing in the ccache-cross-symlinks package?\n");
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exit_userfriendly();
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}
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return 1;
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}
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