From 3c2643a7dbac370b7232f4e5ac15fd77b9ff396d Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Dag-Erling=20Sm=C3=B8rgrav?= Date: Wed, 19 Nov 2025 11:43:13 +0100 Subject: [PATCH] sh: Don't assume EINTR means SIGALRM While waiting for input in the read builtin, if select() is interrupted but there is no pending signal, we act like we timed out, and return the same status as if we had been interrupted by SIGALRM, instead of looping until we actually do time out. * Replace the single select() call with a ppoll() loop. * Improve validation of the timeout value. We now accept things like "1h30m15s", which we used to silently truncate to "1h". The flip side is that we no longer accept things like "1hour" or "5sec". * Modify the existing `read -t 0` test case to verify that read returns immediately when there is input and fails immediately when there isn't. * Add a second test case which performs the same tests with a non-zero timeout value. PR: 290844 MFC after: 1 week Fixes: c4539460e3a4 ("sh: Improve error handling in read builtin:") Reviewed by: jilles, bdrewery Differential Revision: https://reviews.freebsd.org/D53761 --- bin/sh/miscbltin.c | 83 +++++++++++++++++++++++----------- bin/sh/sh.1 | 6 ++- bin/sh/tests/builtins/Makefile | 1 + bin/sh/tests/builtins/read11.0 | 19 +++++++- bin/sh/tests/builtins/read12.0 | 32 +++++++++++++ 5 files changed, 112 insertions(+), 29 deletions(-) create mode 100644 bin/sh/tests/builtins/read12.0 diff --git a/bin/sh/miscbltin.c b/bin/sh/miscbltin.c index 9d0280bb548..bbf0aa5b8bd 100644 --- a/bin/sh/miscbltin.c +++ b/bin/sh/miscbltin.c @@ -40,11 +40,14 @@ #include #include #include -#include + #include +#include +#include #include #include #include +#include #include "shell.h" #include "options.h" @@ -162,17 +165,18 @@ readcmd(int argc __unused, char **argv __unused) int is_ifs; int saveall = 0; ptrdiff_t lastnonifs, lastnonifsws; - struct timeval tv; - char *tvptr; - fd_set ifds; + sigset_t set, oset; + intmax_t number, timeout; + struct timespec tnow, tend, tresid; + struct pollfd pfd; + char *endptr; ssize_t nread; int sig; struct fdctx fdctx; rflag = 0; prompt = NULL; - tv.tv_sec = -1; - tv.tv_usec = 0; + timeout = -1; while ((i = nextopt("erp:t:")) != '\0') { switch(i) { case 'p': @@ -184,22 +188,29 @@ readcmd(int argc __unused, char **argv __unused) rflag = 1; break; case 't': - tv.tv_sec = strtol(shoptarg, &tvptr, 0); - if (tvptr == shoptarg) - error("timeout value"); - switch(*tvptr) { - case 0: - case 's': - break; - case 'h': - tv.tv_sec *= 60; - /* FALLTHROUGH */ - case 'm': - tv.tv_sec *= 60; - break; - default: - error("timeout unit"); - } + timeout = 0; + do { + number = strtol(shoptarg, &endptr, 0); + if (number < 0 || endptr == shoptarg) + error("timeout value"); + switch (*endptr) { + case 's': + endptr++; + break; + case 'h': + number *= 60; + /* FALLTHROUGH */ + case 'm': + number *= 60; + endptr++; + break; + } + if (*endptr != '\0' && + !(*endptr >= '0' && *endptr <= '9')) + error("timeout unit"); + timeout += number; + shoptarg = endptr; + } while (*shoptarg != '\0'); break; } } @@ -212,13 +223,33 @@ readcmd(int argc __unused, char **argv __unused) if ((ifs = bltinlookup("IFS", 1)) == NULL) ifs = " \t\n"; - if (tv.tv_sec >= 0) { + if (timeout >= 0) { /* * Wait for something to become available. */ - FD_ZERO(&ifds); - FD_SET(0, &ifds); - status = select(1, &ifds, NULL, NULL, &tv); + pfd.fd = STDIN_FILENO; + pfd.events = POLLIN; + status = sig = 0; + sigfillset(&set); + sigprocmask(SIG_SETMASK, &set, &oset); + if (pendingsig) { + /* caught a signal already */ + status = -1; + } else if (timeout == 0) { + status = poll(&pfd, 1, 0); + } else { + clock_gettime(CLOCK_UPTIME, &tnow); + tend = tnow; + tend.tv_sec += timeout; + do { + timespecsub(&tend, &tnow, &tresid); + status = ppoll(&pfd, 1, &tresid, &oset); + if (status >= 0 || pendingsig != 0) + break; + clock_gettime(CLOCK_UPTIME, &tnow); + } while (timespeccmp(&tnow, &tend, <)); + } + sigprocmask(SIG_SETMASK, &oset, NULL); /* * If there's nothing ready, return an error. */ diff --git a/bin/sh/sh.1 b/bin/sh/sh.1 index 7ef22fa352b..affb653cd3a 100644 --- a/bin/sh/sh.1 +++ b/bin/sh/sh.1 @@ -31,7 +31,7 @@ .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" -.Dd May 1, 2025 +.Dd November 17, 2025 .Dt SH 1 .Os .Sh NAME @@ -2544,6 +2544,10 @@ to explicitly specify seconds, minutes or hours. If none is supplied, .Ql s is assumed. +Multiple value-unit groups may be stringed together, in which case +they are added up, e.g.\& +.Ql 1h30m15s +which adds up to 5,415 seconds. .Pp The .Fl e diff --git a/bin/sh/tests/builtins/Makefile b/bin/sh/tests/builtins/Makefile index 407d2aeaa06..0246009cce8 100644 --- a/bin/sh/tests/builtins/Makefile +++ b/bin/sh/tests/builtins/Makefile @@ -143,6 +143,7 @@ ${PACKAGE}FILES+= read8.0 ${PACKAGE}FILES+= read9.0 ${PACKAGE}FILES+= read10.0 ${PACKAGE}FILES+= read11.0 +${PACKAGE}FILES+= read12.0 ${PACKAGE}FILES+= return1.0 ${PACKAGE}FILES+= return2.1 ${PACKAGE}FILES+= return3.1 diff --git a/bin/sh/tests/builtins/read11.0 b/bin/sh/tests/builtins/read11.0 index 5bae80318b1..07bd3e70644 100644 --- a/bin/sh/tests/builtins/read11.0 +++ b/bin/sh/tests/builtins/read11.0 @@ -1,3 +1,5 @@ +# Verify that `read -t 0 v` succeeds immediately if input is available +# and fails immediately if not set -e @@ -6,12 +8,25 @@ trap 'rm -rf "$T"' 0 cd $T mkfifo fifo1 # Open fifo1 for writing -{ sleep 10; } >fifo1 & +{ echo new_value; sleep 10; } >fifo1 & # Wait for the child to open fifo1 for writing exec 3fifo1 & +# Wait for the child to open fifo1 for writing +exec 3