[PATCH] handle EINTR while polling scripts/hooks

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[PATCH] handle EINTR while polling scripts/hooks

Andrew Gregory
If poll() is interrupted by a signal, alpm was closing the socket it
uses for listening to script/hook output.  This would drop script output
at the least and kill the script at the worst.

Fixes FS#60396

Signed-off-by: Andrew Gregory <[hidden email]>
---
 lib/libalpm/util.c                             | 10 +++++++++-
 test/pacman/tests/TESTS                        |  1 +
 test/pacman/tests/scriptlet-signal-handling.py | 15 +++++++++++++++
 3 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 test/pacman/tests/scriptlet-signal-handling.py

diff --git a/lib/libalpm/util.c b/lib/libalpm/util.c
index eaf85e93..d33eef2a 100644
--- a/lib/libalpm/util.c
+++ b/lib/libalpm/util.c
@@ -665,6 +665,7 @@ int _alpm_run_chroot(alpm_handle_t *handle, const char *cmd, char *const argv[],
  ssize_t olen = 0, ilen = 0;
  nfds_t nfds = 2;
  struct pollfd fds[2], *child2parent = &(fds[0]), *parent2child = &(fds[1]);
+ int poll_ret;
 
  child2parent->fd = child2parent_pipefd[TAIL];
  child2parent->events = POLLIN;
@@ -685,7 +686,14 @@ int _alpm_run_chroot(alpm_handle_t *handle, const char *cmd, char *const argv[],
 #define STOP_POLLING(p) do { close(p->fd); p->fd = -1; } while(0)
 
  while((child2parent->fd != -1 || parent2child->fd != -1)
- && poll(fds, nfds, -1) > 0) {
+ && (poll_ret = poll(fds, nfds, -1)) != 0) {
+ if(poll_ret == -1) {
+ if(errno == EINTR) {
+ continue;
+ } else {
+ break;
+ }
+ }
  if(child2parent->revents & POLLIN) {
  if(_alpm_chroot_read_from_child(handle, child2parent->fd,
  ibuf, &ilen, sizeof(ibuf)) != 0) {
diff --git a/test/pacman/tests/TESTS b/test/pacman/tests/TESTS
index 5deb93c4..dc0b4ec3 100644
--- a/test/pacman/tests/TESTS
+++ b/test/pacman/tests/TESTS
@@ -150,6 +150,7 @@ TESTS += test/pacman/tests/replace102.py
 TESTS += test/pacman/tests/replace103.py
 TESTS += test/pacman/tests/replace104.py
 TESTS += test/pacman/tests/replace110.py
+TESTS += test/pacman/tests/scriptlet-signal-handling.py
 TESTS += test/pacman/tests/scriptlet-signal-reset.py
 TESTS += test/pacman/tests/scriptlet001.py
 TESTS += test/pacman/tests/scriptlet002.py
diff --git a/test/pacman/tests/scriptlet-signal-handling.py b/test/pacman/tests/scriptlet-signal-handling.py
new file mode 100644
index 00000000..e65df55b
--- /dev/null
+++ b/test/pacman/tests/scriptlet-signal-handling.py
@@ -0,0 +1,15 @@
+self.description = "Handle signal interrupts while running scriptlets/hooks"
+
+p1 = pmpkg("dummy")
+p1.install['post_install'] = """
+ kill -INT $PPID  # send an arbitrary signal that pacman catches
+ sleep 1          # give alpm time to close the socket if EINTR was not handled
+ echo to-parent   # if the interrupt is not handled this will die with SIGPIPE
+ echo success > interrupt_was_handled
+ """
+self.addpkg(p1)
+
+self.args = "-U %s" % p1.filename()
+
+self.addrule("PACMAN_RETCODE=0")
+self.addrule("FILE_EXIST=interrupt_was_handled")
--
2.19.0
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Re: [PATCH] handle EINTR while polling scripts/hooks

Allan McRae
On 13/10/18 12:16 pm, Andrew Gregory wrote:
> If poll() is interrupted by a signal, alpm was closing the socket it
> uses for listening to script/hook output.  This would drop script output
> at the least and kill the script at the worst.
>
> Fixes FS#60396
>
> Signed-off-by: Andrew Gregory <[hidden email]>

Patch is good.

A