git ssb

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#include <stddef.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <err.h>
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#include <sys/wait.h>
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#include <sys/inotify.h>
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#include <dlfcn.h>
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#include <pthread.h>
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#include "ccdl.h"
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static unsigned int tmp_i = 0;
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static const char *mktemp()
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{
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	const char *tmpdir = getenv("TMPDIR");
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	if (!tmpdir) tmpdir = "/tmp";
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	static char buf[256];
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	if (snprintf(buf, sizeof(buf), "%s/ccdl-%d-%i.so",
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				tmpdir, getpid(), tmp_i++) < 0) return NULL;
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	return buf;
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}
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void lib_init(struct lib *lib, const char *src_fname, const char *sym_name)
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{
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	lib->src_fname = src_fname;
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	lib->lib_fname = NULL;
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	lib->sym_name = sym_name;
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	lib->handle = NULL;
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	lib->sym = NULL;
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}
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static int compile(const char *src, const char *lib)
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{
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	if (!src || !lib) return -1;
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	int child = fork();
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	if (child < 0) return -1;
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	if (child == 0) {
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		char *const argv[] = {
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			"cc", (char *)src, "-o", (char *)lib,
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			"-fPIC", "-shared", "-lm", "-std=c99",
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			NULL};
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		return execvp(argv[0], argv);
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	} else {
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		int wstatus;
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		if (waitpid(child, &wstatus, 0) < 0) {
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			return -1;
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		} else if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) == 0) {
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			return 0;
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		} else {
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			return -1;
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		}
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	}
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}
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int lib_build(struct lib *lib)
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{
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	void *handle = lib->handle;
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	if (!handle) {
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		const char *lib_fname = lib->lib_fname;
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		if (!lib_fname) {
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			const char *src_fname = lib->src_fname;
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			if (!src_fname) return -1;
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			lib_fname = mktemp();
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			if (!lib_fname) return -1;
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			lib->lib_fname = lib_fname;
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			if (compile(src_fname, lib_fname)) return -1;
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		}
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		handle = dlopen(lib_fname, RTLD_NOW);
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		lib->handle = handle;
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	}
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	const char *sym_name = lib->sym_name;
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	if (!sym_name) return -1;
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	void *sym = dlsym(handle, sym_name);
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	if (!sym) return -1;
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	lib->sym = sym;
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	return 0;
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}
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void *lib_get(struct lib *lib)
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{
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	if (!lib->sym) lib_build(lib);
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	return lib->sym;
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}
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void lib_deinit(struct lib *lib)
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{
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	if (lib->handle) {
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		dlclose(lib->handle);
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		lib->handle = NULL;
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		lib->sym = NULL;
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	}
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	if (lib->lib_fname) {
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		unlink(lib->lib_fname);
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		lib->lib_fname = NULL;
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	}
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}
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void ccdl_init(struct ccdl *ccdl, const char *src_fname, const char *sym_name)
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{
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	lib_init(&ccdl->libs[0], src_fname, sym_name);
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	lib_init(&ccdl->libs[1], src_fname, sym_name);
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	ccdl->lib = &ccdl->libs[0];
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}
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static struct lib *ccdl_get_old_lib(struct ccdl *ccdl)
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{
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	return ccdl->lib == &ccdl->libs[1] ? &ccdl->libs[0] : &ccdl->libs[1];
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}
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void *ccdl_get(struct ccdl *ccdl)
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{
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	struct lib *old_lib = ccdl_get_old_lib(ccdl);
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	if (old_lib) {
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		lib_deinit(old_lib);
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	}
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	return lib_get(ccdl->lib);
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}
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static int ccdl_watch_run(struct ccdl *ccdl)
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{
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	int ifd = inotify_init();
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	if (ifd < 0) {
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		warn("inotify_init");
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		return -1;
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	}
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	if (!ccdl || !ccdl->lib || !ccdl->lib->src_fname) {
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		warn("missing lib filename");
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		return -1;
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	}
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	if (inotify_add_watch(ifd, ccdl->lib->src_fname, IN_MODIFY) < 0) {
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		warn("watch");
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		return -1;
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	}
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	while (1) {
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		struct inotify_event ev;
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		ssize_t len = read(ifd, &ev, sizeof ev);
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		//printf("readed %zd %u %u %u\n", len, sizeof ev, ev.len, ev.mask);
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		if (len < 0) {
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			warn("read");
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			return -1;
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		}
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		if (len < sizeof ev) {
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			warn("small read");
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			continue;
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		}
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		if (ev.len > 0) {
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			warn("unexpected name");
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			return -1;
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		}
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		if (!(ev.mask & IN_MODIFY)) {
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			printf("unknown mask: %u\n", ev.mask);
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			continue;
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		}
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		(void)ccdl_rebuild(ccdl);
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	}
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	return 0;
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}
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static void *ccdl_watch_run_thread(void *ccdl)
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{
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	return (void *)ccdl_watch_run(ccdl);
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}
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int ccdl_watch(struct ccdl *ccdl)
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{
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	pthread_t *id = &ccdl->watcher_thread;
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	if (pthread_create(id, NULL, ccdl_watch_run_thread, ccdl)) return -1;
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	return 0;
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}
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int ccdl_rebuild(struct ccdl *ccdl)
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{
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	struct lib *old_lib, *new_lib;
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	old_lib = ccdl->lib;
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	new_lib = ccdl_get_old_lib(ccdl);
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	lib_deinit(new_lib);
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	if (lib_build(new_lib) < 0) return -1;
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	ccdl->lib = new_lib;
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	return 0;
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}
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int ccdl_deinit(struct ccdl *ccdl)
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{
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	pthread_t thread = ccdl->watcher_thread;
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	if (thread) {
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		void *retval;
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		pthread_join(thread, &retval);
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		return (int)retval;
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	}
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	return 0;
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}
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