[Tarantool-patches] [PATCH 12/12] popen: allow to close parent's end of std* fds
Alexander Turenko
alexander.turenko at tarantool.org
Tue Apr 14 14:38:21 MSK 2020
The function popen_shutdown() checks whether std{in,out,err} was piped
and closes the parent's end. A user should have ability to send EOF for
child's stdin for stream programs like `grep`. It is better when there
is a function that encapsulates proper checks, error messages and the
actual actions.
This commit in particular reverts
1ef95b99f6553b246729e7bb5bdc19038043db74 ('popen: remove redundant fd
check before perform IO'), because now the check is meaningful: an fd
may become closed before the whole popen handle will be deleted.
Part of #4031
---
src/lib/core/popen.c | 170 ++++++++++++++++++++++++++++++++-----------
src/lib/core/popen.h | 3 +
2 files changed, 130 insertions(+), 43 deletions(-)
diff --git a/src/lib/core/popen.c b/src/lib/core/popen.c
index 640dffc2b..8760429c2 100644
--- a/src/lib/core/popen.c
+++ b/src/lib/core/popen.c
@@ -34,6 +34,43 @@ static RLIST_HEAD(popen_head);
static int dev_null_fd_ro = -1;
static int dev_null_fd_wr = -1;
+static const struct {
+ unsigned int mask;
+ unsigned int mask_devnull;
+ unsigned int mask_close;
+ int fileno;
+ int *dev_null_fd;
+ int parent_idx;
+ int child_idx;
+ bool nonblock;
+} pfd_map[POPEN_FLAG_FD_STDEND_BIT] = {
+ {
+ .mask = POPEN_FLAG_FD_STDIN,
+ .mask_devnull = POPEN_FLAG_FD_STDIN_DEVNULL,
+ .mask_close = POPEN_FLAG_FD_STDIN_CLOSE,
+ .fileno = STDIN_FILENO,
+ .dev_null_fd = &dev_null_fd_ro,
+ .parent_idx = 1,
+ .child_idx = 0,
+ }, {
+ .mask = POPEN_FLAG_FD_STDOUT,
+ .mask_devnull = POPEN_FLAG_FD_STDOUT_DEVNULL,
+ .mask_close = POPEN_FLAG_FD_STDOUT_CLOSE,
+ .fileno = STDOUT_FILENO,
+ .dev_null_fd = &dev_null_fd_wr,
+ .parent_idx = 0,
+ .child_idx = 1,
+ }, {
+ .mask = POPEN_FLAG_FD_STDERR,
+ .mask_devnull = POPEN_FLAG_FD_STDERR_DEVNULL,
+ .mask_close = POPEN_FLAG_FD_STDERR_CLOSE,
+ .fileno = STDERR_FILENO,
+ .dev_null_fd = &dev_null_fd_wr,
+ .parent_idx = 0,
+ .child_idx = 1,
+ },
+};
+
/**
* Register popen handle in a pids map.
*/
@@ -213,7 +250,8 @@ handle_free(struct popen_handle *handle)
* Returns 0 if so and -1 otherwise (and set a diag).
*/
static inline int
-popen_may_io(struct popen_handle *handle, unsigned int io_flags)
+popen_may_io(struct popen_handle *handle, unsigned int idx,
+ unsigned int io_flags, bool allow_closed)
{
if (!(io_flags & handle->flags)) {
diag_set(IllegalParams, "popen: handle does not support the "
@@ -221,6 +259,12 @@ popen_may_io(struct popen_handle *handle, unsigned int io_flags)
return -1;
}
+ if (! allow_closed && handle->ios[idx].fd < 0) {
+ diag_set(IllegalParams, "popen: attempt to operate on a closed "
+ "file descriptor");
+ return -1;
+ }
+
return 0;
}
@@ -299,6 +343,7 @@ stdX_str(unsigned int index)
* - count: data is too big.
* - flags: POPEN_FLAG_FD_STDIN bit is unset.
* - handle: handle does not support the requested IO operation.
+ * - handle: attempt to operate on a closed fd.
* - SocketError: an IO error occurs at write().
* - TimedOut: @a timeout quota is exceeded.
* - FiberIsCancelled: cancelled by an outside code.
@@ -327,11 +372,11 @@ popen_write_timeout(struct popen_handle *handle, const void *buf,
return -1;
}
- if (popen_may_io(handle, flags) != 0)
- return -1;
-
int idx = STDIN_FILENO;
+ if (popen_may_io(handle, idx, flags, false) != 0)
+ return -1;
+
say_debug("popen: %d: write idx [%s:%d] buf %p count %zu "
"fds %d timeout %.9g",
handle->pid, stdX_str(idx), idx, buf, count,
@@ -362,6 +407,7 @@ popen_write_timeout(struct popen_handle *handle, const void *buf,
* - count: buffer is too big.
* - flags: stdout and stdrr are both choosen or both missed
* - handle: handle does not support the requested IO operation.
+ * - handle: attempt to operate on a closed fd.
* - SocketError: an IO error occurs at read().
* - TimedOut: @a timeout quota is exceeded.
* - FiberIsCancelled: cancelled by an outside code.
@@ -390,12 +436,12 @@ popen_read_timeout(struct popen_handle *handle, void *buf,
return -1;
}
- if (popen_may_io(handle, flags) != 0)
- return -1;
-
int idx = flags & POPEN_FLAG_FD_STDOUT ?
STDOUT_FILENO : STDERR_FILENO;
+ if (popen_may_io(handle, idx, flags, false) != 0)
+ return -1;
+
say_debug("popen: %d: read idx [%s:%d] buf %p count %zu "
"fds %d timeout %.9g",
handle->pid, stdX_str(idx), idx, buf, count,
@@ -405,6 +451,80 @@ popen_read_timeout(struct popen_handle *handle, void *buf,
timeout);
}
+/**
+ * Close parent's ends of std* fds.
+ *
+ * The following @a flags controls which fds should be closed:
+ *
+ * POPEN_FLAG_FD_STDIN close parent's end of child's stdin
+ * POPEN_FLAG_FD_STDOUT close parent's end of child's stdout
+ * POPEN_FLAG_FD_STDERR close parent's end of child's stderr
+ *
+ * The main reason to use this function is to send EOF to
+ * child's stdin. However parent's end of stdout / stderr
+ * may be closed too.
+ *
+ * The function does not fail on already closed fds (idempotence).
+ * However it fails on attempt to close the end of a pipe that was
+ * never exist. In other words, a subset of ..._FD_STD{IN,OUT,ERR}
+ * flags used at a handle creation may be used here.
+ *
+ * The function does not close any fds on a failure: either all
+ * requested fds are closed or neither of them.
+ *
+ * Returns 0 at success, otherwise -1 and set a diag.
+ *
+ * Possible errors:
+ *
+ * - IllegalParams: a parameter check fails:
+ * - flags: neither stdid, stdout nor stderr is choosen.
+ * - handle: handle does not support the requested IO operation
+ * (one of fds is not piped).
+ */
+int
+popen_shutdown(struct popen_handle *handle, unsigned int flags)
+{
+ assert(handle != NULL);
+
+ if ((flags & (POPEN_FLAG_FD_STDIN |
+ POPEN_FLAG_FD_STDOUT |
+ POPEN_FLAG_FD_STDERR)) == 0) {
+ diag_set(IllegalParams,
+ "popen: neither stdin, stdout nor stderr is choosen");
+ return -1;
+ }
+
+ /* Verify the operation. */
+ for (int idx = STDIN_FILENO; idx < POPEN_FLAG_FD_STDEND_BIT; ++idx) {
+ /* Operate only on asked fds. */
+ unsigned int op_mask = pfd_map[idx].mask;
+ if ((flags & op_mask) == 0)
+ continue;
+
+ if (popen_may_io(handle, idx, op_mask, true) != 0)
+ return -1;
+ }
+
+ /* Perform the operation. */
+ for (int idx = STDIN_FILENO; idx < POPEN_FLAG_FD_STDEND_BIT; ++idx) {
+ /* Operate only on asked fds. */
+ unsigned int op_mask = pfd_map[idx].mask;
+ if ((flags & op_mask) == 0)
+ continue;
+
+ /* Skip already closed fds. */
+ if (handle->ios[idx].fd < 0)
+ continue;
+
+ say_debug("popen: %d: shutdown idx [%s:%d] fd %s",
+ handle->pid, stdX_str(idx), idx,
+ handle->ios[idx].fd);
+ coio_close_io(loop(), &handle->ios[idx]);
+ }
+
+ return 0;
+}
+
/**
* Encode signal status into a human readable form.
*
@@ -865,42 +985,6 @@ popen_new(struct popen_opts *opts)
int saved_errno;
size_t i;
- static const struct {
- unsigned int mask;
- unsigned int mask_devnull;
- unsigned int mask_close;
- int fileno;
- int *dev_null_fd;
- int parent_idx;
- int child_idx;
- bool nonblock;
- } pfd_map[POPEN_FLAG_FD_STDEND_BIT] = {
- {
- .mask = POPEN_FLAG_FD_STDIN,
- .mask_devnull = POPEN_FLAG_FD_STDIN_DEVNULL,
- .mask_close = POPEN_FLAG_FD_STDIN_CLOSE,
- .fileno = STDIN_FILENO,
- .dev_null_fd = &dev_null_fd_ro,
- .parent_idx = 1,
- .child_idx = 0,
- }, {
- .mask = POPEN_FLAG_FD_STDOUT,
- .mask_devnull = POPEN_FLAG_FD_STDOUT_DEVNULL,
- .mask_close = POPEN_FLAG_FD_STDOUT_CLOSE,
- .fileno = STDOUT_FILENO,
- .dev_null_fd = &dev_null_fd_wr,
- .parent_idx = 0,
- .child_idx = 1,
- }, {
- .mask = POPEN_FLAG_FD_STDERR,
- .mask_devnull = POPEN_FLAG_FD_STDERR_DEVNULL,
- .mask_close = POPEN_FLAG_FD_STDERR_CLOSE,
- .fileno = STDERR_FILENO,
- .dev_null_fd = &dev_null_fd_wr,
- .parent_idx = 0,
- .child_idx = 1,
- },
- };
/*
* At max we could be skipping each pipe end
* plus dev/null variants and logfd
diff --git a/src/lib/core/popen.h b/src/lib/core/popen.h
index 4cdd95175..c068d5028 100644
--- a/src/lib/core/popen.h
+++ b/src/lib/core/popen.h
@@ -175,6 +175,9 @@ popen_read_timeout(struct popen_handle *handle, void *buf,
size_t count, unsigned int flags,
ev_tstamp timeout);
+extern int
+popen_shutdown(struct popen_handle *handle, unsigned int flags);
+
extern void
popen_state(struct popen_handle *handle, int *state, int *exit_code);
--
2.25.0
More information about the Tarantool-patches
mailing list