Commit Graph

15577 Commits

Author SHA1 Message Date
Denys Vlasenko
49015a60cb hush: fix mishandling of "true | f() { echo QWE; }"
function                                             old     new   delta
run_pipe                                            1820    1826      +6

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-04-03 13:02:43 +02:00
Denys Vlasenko
5fa0505f8a hush: fix "set -e; false || x=1; echo OK"
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-04-03 11:21:13 +02:00
Denys Vlasenko
11752d46d1 hush: one-word, no-globbing handling of local/export/readonly args
function                                             old     new   delta
done_word                                            738     790     +52

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-04-03 08:20:58 +02:00
Denys Vlasenko
f50e14632f ash: parser: Fix parameter expansion inside inner double quotes
Upstream email:

    parser: Fix parameter expansion inside inner double quotes

    The parsing of parameter expansion inside inner double quotes
    breaks because we never look for ENDVAR while innerdq is true.

            echo "${x#"${x+''}"''}

    This patch fixes it by pushing the syntax stack if innerdq is
    true and we enter a new parameter expansion.

    This patch also fixes a corner case where a bad substitution error
    occurs within arithmetic expansion.

    Reported-by: Denys Vlasenko <vda.linux@googlemail.com>
    Fixes: ab1cecb40478 (" parser: Add syntax stack for recursive...")
    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

function                                             old     new   delta
readtoken1                                          2880    2898     +18

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-04-02 21:00:59 +02:00
Denys Vlasenko
abf755615e hush: fix a backslash-removal bug in case
function                                             old     new   delta
run_list                                            1270    1053    -217

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-04-02 17:25:18 +02:00
Denys Vlasenko
9a95df9046 ash: expand: Fix bugs with words connected to the right of $@
Upstream email:

    This is actually composed of two bugs.  First of all our tracking
    of quotemark is wrong so anything after "$@" becomes quoted.  Once
    we fix that then the problem is that the first space character
    after "$@" is not recognised as an IFS.

    This patch fixes both.

    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-04-02 14:27:50 +02:00
Denys Vlasenko
355ec353be ash: redir: Fix typo in noclobber code
Upstream commit "redir: Fix typo in noclobber code"

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-04-02 13:34:57 +02:00
Denys Vlasenko
c4c2012284 ash: parser: Fix single-quoted patterns in here-documents
Upstream commit:

    From: Herbert Xu <herbert@gondor.apana.org.au>
    Date: Fri, 9 Mar 2018 23:07:53 +0800
    parser: Fix single-quoted patterns in here-documents

    The script

            x=*
            cat <<- EOF
                    ${x#'*'}
            EOF

    prints * instead of nothing as it should.  The problem is that
    when we're in sqsyntax context in a here-document, we won't add
    CTLESC as we should.  This patch fixes it:

    Reported-by: Harald van Dijk <harald@gigawatt.nl>
    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-04-02 13:29:20 +02:00
Denys Vlasenko
8b536eb40d hush: remove stray debugging printout
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-04-02 13:26:16 +02:00
Denys Vlasenko
216913c290 ash: parser: Add syntax stack for recursive parsing
This closes 10821.

Upstream patch:

    From: Herbert Xu <herbert@gondor.apana.org.au>
    Date: Fri, 9 Mar 2018 00:14:02 +0800
    parser: Add syntax stack for recursive parsing

    Without a stack of syntaxes we cannot correctly these two cases
    together:

            "${a#'$$'}"
            "${a#"${b-'$$'}"}"

    A recursive parser also helps in some other corner cases such
    as nested arithmetic expansion with paratheses.

    This patch adds a syntax stack allocated from the stack using
    alloca.  As a side-effect this allows us to remove the naked
    backslashes for patterns within double-quotes, which means that
    EXP_QPAT also has to go.

    This patch also fixes removes any backslashes that precede right
    braces when they are present within a parameter expansion context,
    and backslashes that precede double quotes within inner double
    quotes inside a parameter expansion in a here-document context.

    The idea of a recursive parser is based on a patch by Harald van
    Dijk.

    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

var_bash3, var_bash4 and var_bash6 tests are updated
with the output given by bash-4.3.43

With this patch, the following tests now pass for ash:

    dollar_repl_slash_bash2.tests
    squote_in_varexp2.tests
    squote_in_varexp.tests
    var_bash4.tests

function                                             old     new   delta
readtoken1                                          2615    2874    +259
synstack_push                                          -      54     +54
evalvar                                              574     571      -3
rmescapes                                            330     310     -20
subevalvar                                          1279    1258     -21
argstr                                              1146    1107     -39
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/4 up/down: 313/-83)           Total: 230 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-04-02 13:15:37 +02:00
Denys Vlasenko
e84212f834 hush: update information comment about heredoc discrepancy
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-04-01 20:11:23 +02:00
Denys Vlasenko
899ae5337a libbb: new function bb_die_memory_exhausted
function                                             old     new   delta
bb_die_memory_exhausted                                -      10     +10
xstrdup                                               28      23      -5
xsetenv                                               27      22      -5
xrealloc                                              32      27      -5
xputenv                                               22      17      -5
xmalloc                                               30      25      -5
xfdopen_helper                                        40      35      -5
xasprintf                                             44      39      -5
wget_main                                           2387    2382      -5
open_socket                                           54      49      -5
glob_brace                                           419     414      -5
bb_get_chunk_from_file                               146     141      -5
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/11 up/down: 10/-55)           Total: -45 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-04-01 19:59:37 +02:00
Quentin Rameau
e2afae6303 sed: prevent overflow of length from bb_get_chunk_from_file
This fragment did not work right:

                temp = bb_get_chunk_from_file(fp, &len);
                if (temp) {
                        /* len > 0 here, it's ok to do temp[len-1] */
                        char c = temp[len-1];

With "int len" _sign-extending_, temp[len-1] can refer to a wrong location
if len > 0x7fffffff.

Signed-off-by: Quentin Rameau <quinq@fifth.space>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-04-01 19:51:14 +02:00
Quentin Rameau
2da9724b56 libbb: remove unnecessary variable in xmalloc_fgets
Signed-off-by: Quentin Rameau <quinq@fifth.space>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-04-01 19:45:36 +02:00
Denys Vlasenko
bb6f573ad2 hush: add a comment where we differ from bash wrt heredoc EOF mark handling
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-04-01 18:55:00 +02:00
Denys Vlasenko
41fddb4372 parser: Fix backquote support in here-document EOF mark
Upstream commit:

    Author: Herbert Xu <herbert@gondor.apana.org.au>
    Date:   Thu Mar 15 18:27:30 2018 +0800
    parser: Fix backquote support in here-document EOF mark

    Currently using backquotes in a here-document EOF mark is broken
    because dash tries to do command substitution on it.  This patch
    fixes it by checking whether we're looking for an EOF mark during
    tokenisation.

    Reported-by: Harald van Dijk <harald@gigawatt.nl>
    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

With added fix for quoted-ness of the EOF mark.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-04-01 16:38:32 +02:00
Denys Vlasenko
1e5111b0f8 ash,hush: handle a few more bkslash-newline cases
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-04-01 03:04:55 +02:00
Denys Vlasenko
32e183e63e shells: fix var_LINENO1.tests false positive, add it to ash tests too
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-31 20:31:13 +02:00
Denys Vlasenko
a94eeb0b42 hush: fix heredoc_bkslash_newline1.tests failure
function                                             old     new   delta
parse_stream                                        2787    2827     +40
builtin_type                                         117     115      -2

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-31 20:16:31 +02:00
Denys Vlasenko
220be537a0 ash: use pgetc_eatbnl() in more places
Part of upstream commit:

    Date:   Thu Mar 8 08:37:11 2018 +0100
    Author: Harald van Dijk <harald@gigawatt.nl>
    parser: use pgetc_eatbnl() in more places

    dash has a pgetc_eatbnl function in parser.c which skips any
    backslash-newline combinations. It's not used everywhere it could be.
    There is also some duplicated backslash-newline handling elsewhere in
    parser.c. Replace most of the calls to pgetc() with calls to
    pgetc_eatbnl() and remove the duplicated backslash-newline handling.

    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Not adding "readtoken1(pgetc_eatbnl(), DQSYNTAX..." changes, since
readtoken1() handles the "starts with backslash + newline" case itself.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-31 19:40:56 +02:00
Martijn Dekker
ad4e961352 ash: 'nolog' and 'debug' options cause "$-" to wreak havoc
Upstream commit:

    Date:   Tue Mar 6 17:40:37 2018 +0000
    expand: 'nolog' and 'debug' options cause "$-" to wreak havoc

    Op 29-03-17 om 20:02 schreef Martijn Dekker:
    > Bug: if either the 'nolog' or the 'debug' option is set, trying to
    > expand "$-" silently aborts parsing of an entire argument.
    >
    > $ dash -o nolog -c 'set -fuC; echo "|$- are the options|"; set +o nolog; echo "|$- are the options|"'
    > |
    > |uCf are the options|
    > $ dash -o debug -c 'set -fuC; echo "|$- are the options|"; set +o debug; echo "|$- are the options|"'
    > |
    > |uCf are the options|

    This turned out to be easy to fix. The routine producing the "$-"
    expansion failed to skip options for which there is no option letter,
    but only a long-form name. In dash, 'nolog' and 'debug' are currently
    the only two such options. Patch below.

    - Martijn

    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

In bbox ash, pipefail is the option which exhibited this.

Signed-off-by: Martijn Dekker <martijn@inlv.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-31 18:30:27 +02:00
Denys Vlasenko
7bf304f371 stat: fix a typo: s/romfs/ramfs/, closes 10876
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-31 02:45:22 +02:00
Denys Vlasenko
6ffaa00338 hush: fix a signedness bug
Testcase:

set -- a ""; space=" "; printf "<%s>\n" "$@"$space

Before:
<a >
After:
<a>
<>

It usually does not bite since bbox forces -funsigned-char build.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-31 00:48:18 +02:00
Denys Vlasenko
73523079a2 ash,hush: new test dollar_repl_slash_bash2.tests
This fails for ash. hush works.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-30 23:25:24 +02:00
Denys Vlasenko
ac61f44704 ash: fix "char == CTLfoo" comparison signedness bug
It usually does not bite since bbox forces -funsigned-char build.
But for some reason void linux people disabled that.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-30 23:04:39 +02:00
Denys Vlasenko
60fb98e51d ash: use F_DUPFD_CLOEXEC and O_CLOEXEC
function                                             old     new   delta
setjobctl                                            371     367      -4
setinputfile                                         226     220      -6
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-10)             Total: -10 bytes

Based on patch by Mark Marshall <mark.marshall@omicronenergy.com>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-30 22:15:14 +02:00
Denys Vlasenko
df65dc89b4 examples/var_service: new example: dnsmasq service
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-30 20:49:16 +02:00
Natanael Copa
d9503224c8 cpio: extract "unsafe" symlinks the same way tar/unzip does
function                                             old     new   delta
cpio_main                                            588     596      +8

Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-30 20:18:12 +02:00
Denys Vlasenko
0d79d7709d svok: new applet (daemontools compat)
function                                             old     new   delta
svok_main                                              -     127    +127
packed_usage                                       32705   32757     +52
applet_names                                        2756    2761      +5
applet_main                                         1588    1592      +4
bb_banner                                             46      47      +1
sv                                                  1286    1284      -2
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 4/1 up/down: 189/-2)            Total: 187 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-30 20:02:33 +02:00
Denys Vlasenko
d892f7137f ifplugd service example: always run up/down script on startup
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-30 11:14:46 +02:00
Stefan Agner
2adaa90534 ifplugd: if SIOCSIFFLAGS fails with EADDRNOTAVAIL, don't die
When using ifplugd on a RNDIS interface with monitor mode, using
SIOCSIFFLAGS seems to fail with EADDRNOTAVAIL. Treat it the same
as if iface disappeared again.

This has been observed on a Tegra TK1 using Linux 4.14. There seem
to be a race when the kernel is creating the device:
  ifplugd(usb0): started: BusyBox v1.24.1 (2018-03-27 09:47:48 CEST)
  ifplugd(usb0): interface doesn't exist, waiting
  ifplugd(usb0): interface appeared
  ifplugd(usb0): upping interface
  ifplugd(usb0): setting interface flags failed: Cannot assign requested address
  <exit>

With this patch ifplugd is successful in upping the device the second
time around:

  ifplugd(usb0): upping interface
  ifplugd(usb0): using SIOCETHTOOL detection mode
  ifplugd(usb0): interface appeared
  ifplugd(usb0): upping interface
  ifplugd(usb0): setting interface flags failed: Cannot assign requested address
  ifplugd(usb0): interface appeared
  ifplugd(usb0): upping interface
  ifplugd(usb0): using SIOCETHTOOL detection mode
  ifplugd(usb0): link is up
  ifplugd(usb0): executing '/etc/ifplugd/ifplugd.usb.action usb0 up'
  ifplugd up
  ifplugd(usb0): exit code: 0

function                                             old     new   delta
up_iface                                             120     127      +7

Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-29 18:45:11 +02:00
Peter Korsgaard
a82fe671f5 fbsplash: support configurable image position
For some setups (E.G. for supporting different screen resolutions),
positioning the image somewhere else than the top left corner may be
interesting.

Add support for IMG_LEFT/IMG_TOP settings to specify the image location,
similar to how it is done for the progress bar.

function                                             old     new   delta
fbsplash_main                                        994    1038     +44
static.param_names                                    57      74     +17
packed_usage                                       32631   32647     +16
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/0 up/down: 77/0)               Total: 77 bytes

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-29 18:42:11 +02:00
Denys Vlasenko
03fd7e06f8 grep: fix echo "aa" | busybox grep -F -w "a" (should not match)
function                                             old     new   delta
grep_file                                           1461    1470      +9

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-29 18:03:50 +02:00
Denys Vlasenko
3be4b9b0de fstrim: do not check that specified file is on a block device
Kernel will surely inform us in FITRIM does not make sense on a given file.

function                                             old     new   delta
fstrim_main                                          241     221     -20

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-29 16:05:10 +02:00
Denys Vlasenko
d1b845706d hush: add a FIXME comment
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-28 18:42:54 +02:00
Denys Vlasenko
9acd63c92c ash,hush: fix "saved" redirected fds still visible in children
Based on a patch by Mark Marshall <mark.marshall@omicronenergy.com>

function                                             old     new   delta
dup_CLOEXEC                                            -      49     +49
fcntl_F_DUPFD                                         46       -     -46

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-28 18:35:07 +02:00
Denys Vlasenko
e4defe826b libbb: use BUILD_BUG_ON in utoa_to_buf()
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-28 17:12:56 +02:00
Kaarle Ritvanen
123fdda0a4 ifupdown: do not fail if interface disappears during ifdown
Interface may not exist because it got deleted by an ifdown hook script
earlier. This may happen when a virtual interface, such as VLAN, has multiple
iface blocks defined.

function                                             old     new   delta
static_down6                                          14      40     +26
static_down                                           54      70     +16
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 42/0)               Total: 42 bytes

Signed-off-by: Kaarle Ritvanen <kaarle.ritvanen@datakunkku.fi>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-28 00:02:52 +02:00
Denys Vlasenko
46ba2468a3 ioctl(SIOCGIFINDEX) does not require clearing of entire ifr
function                                             old     new   delta
INET6_setroute                                       492     472     -20
do_iplink                                           1357    1330     -27
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-47)             Total: -47 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-27 23:55:43 +02:00
Mark Marshall
98592db323 netstat: produce numeric-ip output for non-resolved names
If we don't ask for numerical output, and the symbolic look-up failed
we used to get "(null)", but the numeric output would be better.

function                                             old     new   delta
ip_port_str                                          109     121     +12

Signed-off-by: Mark Marshall <mark.marshall@omicronenergy.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-27 23:28:53 +02:00
Ron Yorston
b5820d9fd8 ssl_client: fix option parsing
The wrong character was used to indicate options taking an integer
parameter.

Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-20 11:41:51 +01:00
Denys Vlasenko
b3e98b1ccc top: fix "warning: unused variable new_mask"
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-19 20:00:10 +01:00
Denys Vlasenko
3c08437db7 tar: add -o and -k to short --help too
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-16 04:02:23 +01:00
Denys Vlasenko
1ee222e1bf tar: add -k and -o to --help
-o	Don't restore user:group
    -k	Don't replace existing files

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-16 03:55:14 +01:00
Denys Vlasenko
bbe47d9b9a tcpsvd: fix fallout from opt_complementary removal
text	   data	    bss	    dec	    hex	filename
 933035	    473	   6836	 940344	  e5938	busybox_old
 933051	    473	   6836	 940360	  e5948	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-11 23:02:50 +01:00
Denys Vlasenko
0e09ded2f1 readprofile: code shrink
function                                             old     new   delta
defaultpro                                            14       -     -14
defaultmap                                            17       -     -17
readprofile_main                                    1762    1719     -43
------------------------------------------------------------------------------
(add/remove: 0/2 grow/shrink: 0/1 up/down: 0/-74)             Total: -74 bytes
   text	   data	    bss	    dec	    hex	filename
 933081	    473	   6836	 940390	  e5966	busybox_old
 933035	    473	   6836	 940344	  e5938	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-11 19:35:58 +01:00
Denys Vlasenko
448fdcc17d ntpd: choose initial FREQHOLD_cnt dynamically
function                                             old     new   delta
update_local_clock                                   834     858     +24

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-11 17:08:02 +01:00
Denys Vlasenko
3d306bffc5 udhcpd: clamp down huge auto_times to ~2M seconds, better EINTR poll handling
EINTR _should_ only happen on two signals we trap, and safe_poll
_should_ work here just fine, but there were kernel bugs where spurious EINTRs
happen (e.g. on ptrace attach). Be safe.

function                                             old     new   delta
udhcpd_main                                         1437    1468     +31

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-11 11:39:05 +01:00
Denys Vlasenko
39dfb4de38 ntpd: suppress in-kernel frequency correction in first 8 adjtimex calls
In other words: try to correct initially existing clock offset first,
before assuming that our clock drifts.

function                                             old     new   delta
update_local_clock                                   826     834      +8
ntp_init                                             550     557      +7
filter_datapoints                                    179     173      -6
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/1 up/down: 15/-6)               Total: 9 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-10 21:25:53 +01:00
Denys Vlasenko
3293bc1469 udhcpd: fix "not dying on SIGTERM"
Fixes:
	commit 52a515d187
	"udhcp: use poll() instead of select()"
	Feb 16 2017

udhcp_sp_read() is meant to check whether signal pipe indeed has some data to read.
In the above commit, it was changed as follows:

-	if (!FD_ISSET(signal_pipe.rd, rfds))
+	if (!pfds[0].revents)
		return 0;

The problem is, the check was working for select() purely by accident.
Caught signal interrupts select()/poll() syscalls, they return with EINTR
(regardless of SA_RESTART flag in sigaction). _Then_ signal handler is invoked.
IOW: they can't see any changes to fd state caused by signal haldler
(in our case, signal handler makes signal pipe ready to be read).

For select(), it means that rfds[] bit array is unmodified, bit of signal
pipe's read fd is still set, and the above check "works": it thinks select()
says there is data to read.

This accident does not work for poll(): .revents stays clear, and we do not
try reading signal pipe as we should. In udhcpd, we fall through and block
in socket read. Further SIGTERM signals simply cause socket read to be
interrupted and then restarted (since SIGTERM handler has SA_RESTART=1).

Fixing this as follows: remove the check altogether. Set signal pipe read fd
to nonblocking mode. Always read it in udhcp_sp_read().
If read fails, assume it's EAGAIN and return 0 ("no signal seen").

udhcpd avoids reading signal pipe on every recvd packet by looping if EINTR
(using safe_poll()) - thus ensuring we have correct .revents for all fds -
and calling udhcp_sp_read() only if pfds[0].revents!=0.

udhcpc performs much fewer reads (typically it sleeps >99.999% of the time),
there is no need to optimize it: can call udhcp_sp_read() after each poll
unconditionally.

To robustify socket reads, unconditionally set pfds[1].revents=0
in udhcp_sp_fd_set() (which is before poll), and check it before reading
network socket in udhcpd.

TODO:
This might still fail: if pfds[1].revents=POLLIN, socket read may still block.
There are rare cases when select/poll indicates that data can be read,
but then actual read still blocks (one such case is UDP packets with
wrong checksum). General advise is, if you use a poll/select loop,
keep all your fds nonblocking.
Maybe we should also do that to our network sockets?

function                                             old     new   delta
udhcp_sp_setup                                        55      65     +10
udhcp_sp_fd_set                                       54      60      +6
udhcp_sp_read                                         46      36     -10
udhcpd_main                                         1451    1437     -14
udhcpc_main                                         2723    2708     -15
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/3 up/down: 16/-39)            Total: -23 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2018-03-10 19:34:39 +01:00