diff options
| -rw-r--r-- | Makefile | 1 | ||||
| -rw-r--r-- | tmp-objdir.c | 273 | ||||
| -rw-r--r-- | tmp-objdir.h | 54 |
3 files changed, 328 insertions, 0 deletions
@@ -831,6 +831,7 @@ LIB_OBJS += submodule-config.o LIB_OBJS += symlinks.o LIB_OBJS += tag.o LIB_OBJS += tempfile.o +LIB_OBJS += tmp-objdir.o LIB_OBJS += trace.o LIB_OBJS += trailer.o LIB_OBJS += transport.o diff --git a/tmp-objdir.c b/tmp-objdir.c new file mode 100644 index 000000000..9443868be --- /dev/null +++ b/tmp-objdir.c @@ -0,0 +1,273 @@ +#include "cache.h" +#include "tmp-objdir.h" +#include "dir.h" +#include "sigchain.h" +#include "string-list.h" +#include "strbuf.h" +#include "argv-array.h" + +struct tmp_objdir { + struct strbuf path; + struct argv_array env; +}; + +/* + * Allow only one tmp_objdir at a time in a running process, which simplifies + * our signal/atexit cleanup routines. It's doubtful callers will ever need + * more than one, and we can expand later if so. You can have many such + * tmp_objdirs simultaneously in many processes, of course. + */ +static struct tmp_objdir *the_tmp_objdir; + +static void tmp_objdir_free(struct tmp_objdir *t) +{ + strbuf_release(&t->path); + argv_array_clear(&t->env); + free(t); +} + +static int tmp_objdir_destroy_1(struct tmp_objdir *t, int on_signal) +{ + int err; + + if (!t) + return 0; + + if (t == the_tmp_objdir) + the_tmp_objdir = NULL; + + /* + * This may use malloc via strbuf_grow(), but we should + * have pre-grown t->path sufficiently so that this + * doesn't happen in practice. + */ + err = remove_dir_recursively(&t->path, 0); + + /* + * When we are cleaning up due to a signal, we won't bother + * freeing memory; it may cause a deadlock if the signal + * arrived while libc's allocator lock is held. + */ + if (!on_signal) + tmp_objdir_free(t); + return err; +} + +int tmp_objdir_destroy(struct tmp_objdir *t) +{ + return tmp_objdir_destroy_1(t, 0); +} + +static void remove_tmp_objdir(void) +{ + tmp_objdir_destroy(the_tmp_objdir); +} + +static void remove_tmp_objdir_on_signal(int signo) +{ + tmp_objdir_destroy_1(the_tmp_objdir, 1); + sigchain_pop(signo); + raise(signo); +} + +/* + * These env_* functions are for setting up the child environment; the + * "replace" variant overrides the value of any existing variable with that + * "key". The "append" variant puts our new value at the end of a list, + * separated by PATH_SEP (which is what separate values in + * GIT_ALTERNATE_OBJECT_DIRECTORIES). + */ +static void env_append(struct argv_array *env, const char *key, const char *val) +{ + const char *old = getenv(key); + + if (!old) + argv_array_pushf(env, "%s=%s", key, val); + else + argv_array_pushf(env, "%s=%s%c%s", key, old, PATH_SEP, val); +} + +static void env_replace(struct argv_array *env, const char *key, const char *val) +{ + argv_array_pushf(env, "%s=%s", key, val); +} + +static int setup_tmp_objdir(const char *root) +{ + char *path; + int ret = 0; + + path = xstrfmt("%s/pack", root); + ret = mkdir(path, 0777); + free(path); + + return ret; +} + +struct tmp_objdir *tmp_objdir_create(void) +{ + static int installed_handlers; + struct tmp_objdir *t; + + if (the_tmp_objdir) + die("BUG: only one tmp_objdir can be used at a time"); + + t = xmalloc(sizeof(*t)); + strbuf_init(&t->path, 0); + argv_array_init(&t->env); + + strbuf_addf(&t->path, "%s/incoming-XXXXXX", get_object_directory()); + + /* + * Grow the strbuf beyond any filename we expect to be placed in it. + * If tmp_objdir_destroy() is called by a signal handler, then + * we should be able to use the strbuf to remove files without + * having to call malloc. + */ + strbuf_grow(&t->path, 1024); + + if (!mkdtemp(t->path.buf)) { + /* free, not destroy, as we never touched the filesystem */ + tmp_objdir_free(t); + return NULL; + } + + the_tmp_objdir = t; + if (!installed_handlers) { + atexit(remove_tmp_objdir); + sigchain_push_common(remove_tmp_objdir_on_signal); + installed_handlers++; + } + + if (setup_tmp_objdir(t->path.buf)) { + tmp_objdir_destroy(t); + return NULL; + } + + env_append(&t->env, ALTERNATE_DB_ENVIRONMENT, + absolute_path(get_object_directory())); + env_replace(&t->env, DB_ENVIRONMENT, absolute_path(t->path.buf)); + + return t; +} + +/* + * Make sure we copy packfiles and their associated metafiles in the correct + * order. All of these ends_with checks are slightly expensive to do in + * the midst of a sorting routine, but in practice it shouldn't matter. + * We will have a relatively small number of packfiles to order, and loose + * objects exit early in the first line. + */ +static int pack_copy_priority(const char *name) +{ + if (!starts_with(name, "pack")) + return 0; + if (ends_with(name, ".keep")) + return 1; + if (ends_with(name, ".pack")) + return 2; + if (ends_with(name, ".idx")) + return 3; + return 4; +} + +static int pack_copy_cmp(const char *a, const char *b) +{ + return pack_copy_priority(a) - pack_copy_priority(b); +} + +static int read_dir_paths(struct string_list *out, const char *path) +{ + DIR *dh; + struct dirent *de; + + dh = opendir(path); + if (!dh) + return -1; + + while ((de = readdir(dh))) + if (!is_dot_or_dotdot(de->d_name)) + string_list_append(out, de->d_name); + + closedir(dh); + return 0; +} + +static int migrate_paths(struct strbuf *src, struct strbuf *dst); + +static int migrate_one(struct strbuf *src, struct strbuf *dst) +{ + struct stat st; + + if (stat(src->buf, &st) < 0) + return -1; + if (S_ISDIR(st.st_mode)) { + if (!mkdir(dst->buf, 0777)) { + if (adjust_shared_perm(dst->buf)) + return -1; + } else if (errno != EEXIST) + return -1; + return migrate_paths(src, dst); + } + return finalize_object_file(src->buf, dst->buf); +} + +static int migrate_paths(struct strbuf *src, struct strbuf *dst) +{ + size_t src_len = src->len, dst_len = dst->len; + struct string_list paths = STRING_LIST_INIT_DUP; + int i; + int ret = 0; + + if (read_dir_paths(&paths, src->buf) < 0) + return -1; + paths.cmp = pack_copy_cmp; + string_list_sort(&paths); + + for (i = 0; i < paths.nr; i++) { + const char *name = paths.items[i].string; + + strbuf_addf(src, "/%s", name); + strbuf_addf(dst, "/%s", name); + + ret |= migrate_one(src, dst); + + strbuf_setlen(src, src_len); + strbuf_setlen(dst, dst_len); + } + + string_list_clear(&paths, 0); + return ret; +} + +int tmp_objdir_migrate(struct tmp_objdir *t) +{ + struct strbuf src = STRBUF_INIT, dst = STRBUF_INIT; + int ret; + + if (!t) + return 0; + + strbuf_addbuf(&src, &t->path); + strbuf_addstr(&dst, get_object_directory()); + + ret = migrate_paths(&src, &dst); + + strbuf_release(&src); + strbuf_release(&dst); + + tmp_objdir_destroy(t); + return ret; +} + +const char **tmp_objdir_env(const struct tmp_objdir *t) +{ + if (!t) + return NULL; + return t->env.argv; +} + +void tmp_objdir_add_as_alternate(const struct tmp_objdir *t) +{ + add_to_alternates_memory(t->path.buf); +} diff --git a/tmp-objdir.h b/tmp-objdir.h new file mode 100644 index 000000000..b1e45b4c7 --- /dev/null +++ b/tmp-objdir.h @@ -0,0 +1,54 @@ +#ifndef TMP_OBJDIR_H +#define TMP_OBJDIR_H + +/* + * This API allows you to create a temporary object directory, advertise it to + * sub-processes via GIT_OBJECT_DIRECTORY and GIT_ALTERNATE_OBJECT_DIRECTORIES, + * and then either migrate its object into the main object directory, or remove + * it. The library handles unexpected signal/exit death by cleaning up the + * temporary directory. + * + * Example: + * + * struct tmp_objdir *t = tmp_objdir_create(); + * if (!run_command_v_opt_cd_env(cmd, 0, NULL, tmp_objdir_env(t)) && + * !tmp_objdir_migrate(t)) + * printf("success!\n"); + * else + * die("failed...tmp_objdir will clean up for us"); + * + */ + +struct tmp_objdir; + +/* + * Create a new temporary object directory; returns NULL on failure. + */ +struct tmp_objdir *tmp_objdir_create(void); + +/* + * Return a list of environment strings, suitable for use with + * child_process.env, that can be passed to child programs to make use of the + * temporary object directory. + */ +const char **tmp_objdir_env(const struct tmp_objdir *); + +/* + * Finalize a temporary object directory by migrating its objects into the main + * object database, removing the temporary directory, and freeing any + * associated resources. + */ +int tmp_objdir_migrate(struct tmp_objdir *); + +/* + * Destroy a temporary object directory, discarding any objects it contains. + */ +int tmp_objdir_destroy(struct tmp_objdir *); + +/* + * Add the temporary object directory as an alternate object store in the + * current process. + */ +void tmp_objdir_add_as_alternate(const struct tmp_objdir *); + +#endif /* TMP_OBJDIR_H */ |