diff options
Diffstat (limited to 'libarchive/archive_write_disk_posix.c')
| -rw-r--r-- | libarchive/archive_write_disk_posix.c | 78 |
1 files changed, 70 insertions, 8 deletions
diff --git a/libarchive/archive_write_disk_posix.c b/libarchive/archive_write_disk_posix.c index df4b02f5efa1..cc53a3d318e0 100644 --- a/libarchive/archive_write_disk_posix.c +++ b/libarchive/archive_write_disk_posix.c @@ -253,6 +253,8 @@ struct archive_write_disk { struct archive_entry *entry; /* Entry being extracted. */ char *name; /* Name of entry, possibly edited. */ struct archive_string _name_data; /* backing store for 'name' */ + char *tmpname; /* Temporary name * */ + struct archive_string _tmpname_data; /* backing store for 'tmpname' */ /* Tasks remaining for this object. */ int todo; /* Tasks deferred until end-of-archive. */ @@ -354,6 +356,7 @@ struct archive_write_disk { static int la_opendirat(int, const char *); +static int la_mktemp(struct archive_write_disk *); static void fsobj_error(int *, struct archive_string *, int, const char *, const char *); static int check_symlinks_fsobj(char *, int *, struct archive_string *, @@ -407,6 +410,30 @@ static ssize_t _archive_write_disk_data_block(struct archive *, const void *, size_t, int64_t); static int +la_mktemp(struct archive_write_disk *a) +{ + int oerrno, fd; + mode_t mode; + + archive_string_empty(&a->_tmpname_data); + archive_string_sprintf(&a->_tmpname_data, "%s.XXXXXX", a->name); + a->tmpname = a->_tmpname_data.s; + + fd = __archive_mkstemp(a->tmpname); + if (fd == -1) + return -1; + + mode = a->mode & 0777 & ~a->user_umask; + if (fchmod(fd, mode) == -1) { + oerrno = errno; + close(fd); + errno = oerrno; + return -1; + } + return fd; +} + +static int la_opendirat(int fd, const char *path) { const int flags = O_CLOEXEC #if defined(O_BINARY) @@ -1826,6 +1853,14 @@ finish_metadata: if (a->fd >= 0) { close(a->fd); a->fd = -1; + if (a->tmpname) { + if (rename(a->tmpname, a->name) == -1) { + archive_set_error(&a->archive, errno, + "rename failed"); + ret = ARCHIVE_FATAL; + } + a->tmpname = NULL; + } } /* If there's an entry, we can release it now. */ archive_entry_free(a->entry); @@ -2103,17 +2138,28 @@ restore_entry(struct archive_write_disk *a) } if (!S_ISDIR(a->st.st_mode)) { - /* A non-dir is in the way, unlink it. */ if (a->flags & ARCHIVE_EXTRACT_CLEAR_NOCHANGE_FFLAGS) (void)clear_nochange_fflags(a); - if (unlink(a->name) != 0) { - archive_set_error(&a->archive, errno, - "Can't unlink already-existing object"); - return (ARCHIVE_FAILED); + + if ((a->flags & ARCHIVE_EXTRACT_SAFE_WRITES) && + S_ISREG(a->st.st_mode)) { + /* Use a temporary file to extract */ + if ((a->fd = la_mktemp(a)) == -1) + return ARCHIVE_FAILED; + a->pst = NULL; + en = 0; + } else { + /* A non-dir is in the way, unlink it. */ + if (unlink(a->name) != 0) { + archive_set_error(&a->archive, errno, + "Can't unlink already-existing " + "object"); + return (ARCHIVE_FAILED); + } + a->pst = NULL; + /* Try again. */ + en = create_filesystem_object(a); } - a->pst = NULL; - /* Try again. */ - en = create_filesystem_object(a); } else if (!S_ISDIR(a->mode)) { /* A dir is in the way of a non-dir, rmdir it. */ if (a->flags & ARCHIVE_EXTRACT_CLEAR_NOCHANGE_FFLAGS) @@ -2215,6 +2261,13 @@ create_filesystem_object(struct archive_write_disk *a) } free(linkname_copy); archive_string_free(&error_string); + /* + * Unlinking and linking here is really not atomic, + * but doing it right, would require us to construct + * an mktemplink() function, and then use rename(2). + */ + if (a->flags & ARCHIVE_EXTRACT_SAFE_WRITES) + unlink(a->name); r = link(linkname, a->name) ? errno : 0; /* * New cpio and pax formats allow hardlink entries @@ -2253,6 +2306,13 @@ create_filesystem_object(struct archive_write_disk *a) linkname = archive_entry_symlink(a->entry); if (linkname != NULL) { #if HAVE_SYMLINK + /* + * Unlinking and linking here is really not atomic, + * but doing it right, would require us to construct + * an mktempsymlink() function, and then use rename(2). + */ + if (a->flags & ARCHIVE_EXTRACT_SAFE_WRITES) + unlink(a->name); return symlink(linkname, a->name) ? errno : 0; #else return (EPERM); @@ -2288,6 +2348,7 @@ create_filesystem_object(struct archive_write_disk *a) /* POSIX requires that we fall through here. */ /* FALLTHROUGH */ case AE_IFREG: + a->tmpname = NULL; a->fd = open(a->name, O_WRONLY | O_CREAT | O_EXCL | O_BINARY | O_CLOEXEC, mode); __archive_ensure_cloexec_flag(a->fd); @@ -2449,6 +2510,7 @@ _archive_write_disk_free(struct archive *_a) archive_write_disk_set_user_lookup(&a->archive, NULL, NULL, NULL); archive_entry_free(a->entry); archive_string_free(&a->_name_data); + archive_string_free(&a->_tmpname_data); archive_string_free(&a->archive.error_string); archive_string_free(&a->path_safe); a->archive.magic = 0; |