diff options
| -rw-r--r-- | archival/libarchive/data_extract_all.c | 6 | ||||
| -rw-r--r-- | coreutils/link.c | 41 | ||||
| -rw-r--r-- | docs/nofork_noexec.txt | 32 |
3 files changed, 71 insertions, 8 deletions
diff --git a/archival/libarchive/data_extract_all.c b/archival/libarchive/data_extract_all.c index bd034af..1830ffb 100644 --- a/archival/libarchive/data_extract_all.c +++ b/archival/libarchive/data_extract_all.c @@ -127,8 +127,9 @@ void FAST_FUNC data_extract_all(archive_handle_t *archive_handle) if (hard_link) { res = link(hard_link, dst_name); if (res != 0 && !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET)) { + /* shared message */ bb_perror_msg("can't create %slink " - "from %s to %s", "hard", + "%s to %s", "hard", dst_name, hard_link); } @@ -181,8 +182,9 @@ void FAST_FUNC data_extract_all(archive_handle_t *archive_handle) if (res != 0 && !(archive_handle->ah_flags & ARCHIVE_EXTRACT_QUIET) ) { + /* shared message */ bb_perror_msg("can't create %slink " - "from %s to %s", "sym", + "%s to %s", "sym", dst_name, file_header->link_target); } diff --git a/coreutils/link.c b/coreutils/link.c new file mode 100644 index 0000000..ac3ef85 --- /dev/null +++ b/coreutils/link.c @@ -0,0 +1,41 @@ +/* + * link implementation for busybox + * + * Copyright (C) 2017 Denys Vlasenko <vda.linux@googlemail.com> + * + * Licensed under GPLv2, see file LICENSE in this source tree. + */ +//config:config LINK +//config: bool "link" +//config: default y +//config: help +//config: link creates hard links between files. + +//applet:IF_LINK(APPLET_NOFORK(link, link, BB_DIR_BIN, BB_SUID_DROP, link)) + +//kbuild:lib-$(CONFIG_LINK) += link.o + +//usage:#define link_trivial_usage +//usage: "FILE LINK" +//usage:#define link_full_usage "\n\n" +//usage: "Create hard LINK to FILE" + +#include "libbb.h" + +/* This is a NOFORK applet. Be very careful! */ + +int link_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; +int link_main(int argc UNUSED_PARAM, char **argv) +{ + opt_complementary = "=2"; /* exactly 2 params */ + getopt32(argv, ""); + argv += optind; + if (link(argv[0], argv[1]) != 0) { + /* shared message */ + bb_perror_msg_and_die("can't create %slink " + "%s to %s", "hard", + argv[1], argv[0] + ); + } + return EXIT_SUCCESS; +} diff --git a/docs/nofork_noexec.txt b/docs/nofork_noexec.txt index c58f5a8..2fb184a 100644 --- a/docs/nofork_noexec.txt +++ b/docs/nofork_noexec.txt @@ -33,6 +33,7 @@ roughly are: * do not expect shared global variables/buffers to be in their "initialized" state. Examples: xfunc_error_retval can be != 1, bb_common_bufsiz1 can be scribbled over, ... + (although usually xfunc_error_retval's state is not a problem). * do not expect that stdio wasn't used before. Calling set[v]buf() can be disastrous. * ... @@ -81,18 +82,37 @@ are probably not worth the effort. Any NOFORK applet is also a NOEXEC applet. + Calling NOFORK applets + +API to call NOFORK applets is two functions: + + run_nofork_applet(appno, argv) + spawn_and_wait(argv) // only if FEATURE_PREFER_APPLETS=y + +First one is directly used by shells if FEATURE_SH_NOFORK=y. +Second one is used by many applets, but main users are xargs and find. +It itself calls run_nofork_applet(), if argv[0] turned out to be a name +of a NOFORK applet. + +run_nofork_applet() saves/inits/restores option parsing, xfunc_error_retval, +applet_name. Thus, for example, caller does not need to worry about +option_mask32 getting trashed. + + Relevant CONFIG options FEATURE_PREFER_APPLETS BB_EXECVP(cmd, argv) will try to exec /proc/self/exe - if command's name matches some applet name - applet tables will contain NOFORK/NOEXEC bits + if command's name matches some applet name; spawn_and_wait(argv) will do NOFORK/NOEXEC tricks -FEATURE_SH_STANDALONE (needs FEATURE_PREFER_APPLETS=y) +//TODO: the above two things probably should have separate options? + +FEATURE_SH_STANDALONE shells will try to exec /proc/self/exe if command's name matches - some applet name - shells will do NOEXEC trick on NOEXEC applets + some applet name; shells will do NOEXEC trick on NOEXEC applets + +//TODO: split (same as for PREFER_APPLETS) -FEATURE_SH_NOFORK (needs FEATURE_PREFER_APPLETS=y) +FEATURE_SH_NOFORK shells will do NOFORK trick on NOFORK applets |