This helper function copies bidirectional stream of data between
stdin/stdout and specified file descriptors.
Signed-off-by: Ilari Liusvaara <ilari.liusvaara@xxxxxxxxxxx>
---
compat/mingw.h | 5 +
transport-helper.c | 311 ++++++++++++++++++++++++++++++++++++++++++++++++++++
transport.h | 1 +
3 files changed, 317 insertions(+), 0 deletions(-)
diff --git a/compat/mingw.h b/compat/mingw.h
index 3b2477b..f27a7b6 100644
--- a/compat/mingw.h
+++ b/compat/mingw.h
@@ -23,6 +23,9 @@ typedef int pid_t;
#define WEXITSTATUS(x) ((x) & 0xff)
#define WTERMSIG(x) SIGTERM
+#define EWOULDBLOCK EAGAIN
+#define SHUT_WR SD_SEND
+
#define SIGHUP 1
#define SIGQUIT 3
#define SIGKILL 9
@@ -50,6 +53,8 @@ struct pollfd {
};
#define POLLIN 1
#define POLLHUP 2
+#define POLLOUT 4
+#define POLLNVAL 8
#endif
typedef void (__cdecl *sig_handler_t)(int);
diff --git a/transport-helper.c b/transport-helper.c
index acfc88e..0c094d6 100644
--- a/transport-helper.c
+++ b/transport-helper.c
@@ -862,3 +862,314 @@ int transport_helper_init(struct transport *transport, const char *name)
transport->smart_options = &(data->transport_options);
return 0;
}
+
+/*
+ * Linux pipes can buffer 65536 bytes at once (and most platforms can
+ * buffer less), so attempt reads and writes with up to that size.
+ */
+#define BUFFERSIZE 65536
+/* This should be enough to hold debugging message. */
+#define PBUFFERSIZE 8192
+
+/* Print bidirectional transfer loop debug message. */
+static void transfer_debug(const char *fmt, ...)
+{
+ va_list args;
+ char msgbuf[PBUFFERSIZE];
+ static int debug_enabled = -1;
+
+ if (debug_enabled < 0)
+ debug_enabled = getenv("GIT_TRANSLOOP_DEBUG") ? 1 : 0;
+ if (!debug_enabled)
+ return;
+
+ va_start(args, fmt);
+ vsnprintf(msgbuf, PBUFFERSIZE, fmt, args);
+ va_end(args);
+ fprintf(stderr, "Transfer loop debugging: %s\n", msgbuf);
+}
+
+/* Stream state: More data may be coming in this direction. */
+#define SSTATE_TRANSFERING 0
+/*
+ * Stream state: No more data coming in this direction, flushing rest of
+ * data.
+ */
+#define SSTATE_FLUSHING 1
+/* Stream state: Transfer in this direction finished. */
+#define SSTATE_FINISHED 2
+
+#define STATE_NEEDS_READING(state) ((state) <= SSTATE_TRANSFERING)
+#define STATE_NEEDS_WRITING(state) ((state) <= SSTATE_FLUSHING)
+#define STATE_NEEDS_CLOSING(state) ((state) == SSTATE_FLUSHING)
+
+/* Unidirectional transfer. */
+struct unidirectional_transfer {
+ /* Source */
+ int src;
+ /* Destination */
+ int dest;
+ /* Is source socket? */
+ int src_is_sock;
+ /* Is destination socket? */
+ int dest_is_sock;
+ /* Transfer state (TRANSFERING/FLUSHING/FINISHED) */
+ int state;
+ /* Buffer. */
+ char buf[BUFFERSIZE];
+ /* Buffer used. */
+ size_t bufuse;
+ /* Name of source. */
+ const char *src_name;
+ /* Name of destination. */
+ const char *dest_name;
+};
+
+/* Closes the target (for writing) if transfer has finished. */
+static void udt_close_if_finished(struct unidirectional_transfer *t)
+{
+ if (STATE_NEEDS_CLOSING(t->state) && !t->bufuse) {
+ t->state = SSTATE_FINISHED;
+ if (t->dest_is_sock)
+ shutdown(t->dest, SHUT_WR);
+ else
+ close(t->dest);
+ transfer_debug("Closed %s.", t->dest_name);
+ }
+}
+
+/*
+ * Tries to read read data from source into buffer. If buffer is full,
+ * no data is read. Returns 0 on success, -1 on error.
+ */
+static int udt_do_read(struct unidirectional_transfer *t)
+{
+ ssize_t bytes;
+
+ if (t->bufuse == BUFFERSIZE)
+ return 0; /* No space for more. */
+
+ transfer_debug("%s is readable", t->src_name);
+ bytes = read(t->src, t->buf + t->bufuse, BUFFERSIZE - t->bufuse);
+ if (bytes < 0 && errno != EWOULDBLOCK && errno != EAGAIN &&
+ errno != EINTR) {
+ error("read(%s) failed: %s", t->src_name, strerror(errno));
+ return -1;
+ } else if (bytes == 0) {
+ transfer_debug("%s EOF (with %i bytes in buffer)",
+ t->src_name, t->bufuse);
+ t->state = SSTATE_FLUSHING;
+ } else if (bytes > 0) {
+ t->bufuse += bytes;
+ transfer_debug("Read %i bytes from %s (buffer now at %i)",
+ (int)bytes, t->src_name, (int)t->bufuse);
+ }
+ return 0;
+}
+
+/* Tries to write data from buffer into destination. If buffer is empty,
+ * no data is written. Returns 0 on success, -1 on error.
+ */
+static int udt_do_write(struct unidirectional_transfer *t)
+{
+ size_t bytes;
+
+ if (t->bufuse == 0)
+ return 0; /* Nothing to write. */
+
+ transfer_debug("%s is writable", t->dest_name);
+ bytes = write(t->dest, t->buf, t->bufuse);
+ if (bytes < 0 && errno != EWOULDBLOCK && errno != EAGAIN &&
+ errno != EINTR) {
+ error("write(%s) failed: %s", t->dest_name, strerror(errno));
+ return -1;
+ } else if (bytes > 0) {
+ t->bufuse -= bytes;
+ if (t->bufuse)
+ memmove(t->buf, t->buf + bytes, t->bufuse);
+ transfer_debug("Wrote %i bytes to %s (buffer now at %i)",
+ (int)bytes, t->dest_name, (int)t->bufuse);
+ }
+ return 0;
+}
+
+
+/* State of bidirectional transfer loop. */
+struct bidirectional_transfer_state {
+ /* Direction from program to git. */
+ struct unidirectional_transfer ptg;
+ /* Direction from git to program. */
+ struct unidirectional_transfer gtp;
+};
+
+static void *udt_copy_task_routine(void *udt)
+{
+ struct unidirectional_transfer *t = (struct unidirectional_transfer *)udt;
+ while (t->state != SSTATE_FINISHED) {
+ if (STATE_NEEDS_READING(t->state))
+ if (udt_do_read(t))
+ return NULL;
+ if (STATE_NEEDS_WRITING(t->state))
+ if (udt_do_write(t))
+ return NULL;
+ if (STATE_NEEDS_CLOSING(t->state))
+ udt_close_if_finished(t);
+ }
+ return udt; /* Just some non-NULL value. */
+}
+
+#ifndef NO_PTHREADS
+
+/*
+ * Join thread, with apporiate errors on failure. Name is name for the
+ * thread (for error messages). Returns 0 on success, 1 on failure.
+ */
+static int tloop_join(pthread_t thread, const char *name)
+{
+ int err;
+ void *tret;
+ err = pthread_join(thread, &tret);
+ if (!tret) {
+ error("%s thread failed", name);
+ return 1;
+ }
+ if (err) {
+ error("%s thread failed to join: %s", name, strerror(err));
+ return 1;
+ }
+ return 0;
+}
+
+/*
+ * Spawn the transfer tasks and then wait for them. Returns 0 on success,
+ * -1 on failure.
+ */
+static int tloop_spawnwait_tasks(struct bidirectional_transfer_state *s)
+{
+ pthread_t gtp_thread;
+ pthread_t ptg_thread;
+ int err;
+ int ret = 0;
+ err = pthread_create(>p_thread, NULL, udt_copy_task_routine,
+ &s->gtp);
+ if (err)
+ die("Can't start thread for copying data: %s", strerror(err));
+ err = pthread_create(&ptg_thread, NULL, udt_copy_task_routine,
+ &s->ptg);
+ if (err)
+ die("Can't start thread for copying data: %s", strerror(err));
+
+ ret |= tloop_join(gtp_thread, "Git to program copy");
+ ret |= tloop_join(ptg_thread, "Program to git copy");
+ return ret;
+}
+#else
+
+/* Close the source and target (for writing) for transfer. */
+static void udt_kill_transfer(struct unidirectional_transfer *t)
+{
+ t->state = SSTATE_FINISHED;
+ /*
+ * Socket read end left open isn't a disaster if nobody
+ * attempts to read from it (mingw compat headers do not
+ * have SHUT_RD)...
+ *
+ * We can't fully close the socket since otherwise gtp
+ * task would first close the socket it sends data to
+ * while closing the ptg file descriptors.
+ */
+ if (!t->src_is_sock)
+ close(t->src);
+ if (t->dest_is_sock)
+ shutdown(t->dest, SHUT_WR);
+ else
+ close(t->dest);
+}
+
+/*
+ * Join process, with apporiate errors on failure. Name is name for the
+ * process (for error messages). Returns 0 on success, 1 on failure.
+ */
+static int tloop_join(pid_t pid, const char *name)
+{
+ int tret;
+ if (waitpid(pid, &tret, 0) < 0) {
+ error("%s process failed to wait: %s", name, strerror(errno));
+ return 1;
+ }
+ if (!WIFEXITED(tret) || WEXITSTATUS(tret)) {
+ error("%s process failed", name);
+ return 1;
+ }
+ return 0;
+}
+
+/*
+ * Spawn the transfer tasks and then wait for them. Returns 0 on success,
+ * -1 on failure.
+ */
+static int tloop_spawnwait_tasks(struct bidirectional_transfer_state *s)
+{
+ pid_t pid1, pid2;
+ int ret = 0;
+
+ /* Fork thread #1: git to program. */
+ pid1 = fork();
+ if (pid1 < 0)
+ die_errno("Can't start thread for copying data");
+ else if (pid1 == 0) {
+ udt_kill_transfer(&s->ptg);
+ exit(udt_copy_task_routine(&s->gtp) ? 0 : 1);
+ }
+
+ /* Fork thread #2: program to git. */
+ pid2 = fork();
+ if (pid2 < 0)
+ die_errno("Can't start thread for copying data");
+ else if (pid2 == 0) {
+ udt_kill_transfer(&s->gtp);
+ exit(udt_copy_task_routine(&s->ptg) ? 0 : 1);
+ }
+
+ /*
+ * Close both streams in parent as to not interfere with
+ * end of file detection and wait for both tasks to finish.
+ */
+ udt_kill_transfer(&s->gtp);
+ udt_kill_transfer(&s->ptg);
+ ret |= tloop_join(pid1, "Git to program copy");
+ ret |= tloop_join(pid2, "Program to git copy");
+ return ret;
+}
+#endif
+
+/*
+ * Copies data from stdin to output and from input to stdout simultaneously.
+ * Additionally filtering through given filter. If filter is NULL, uses
+ * identity filter.
+ */
+int bidirectional_transfer_loop(int input, int output)
+{
+ struct bidirectional_transfer_state state;
+
+ /* Fill the state fields. */
+ state.ptg.src = input;
+ state.ptg.dest = 1;
+ state.ptg.src_is_sock = (input == output);
+ state.ptg.dest_is_sock = 0;
+ state.ptg.state = SSTATE_TRANSFERING;
+ state.ptg.bufuse = 0;
+ state.ptg.src_name = "remote input";
+ state.ptg.dest_name = "stdout";
+
+ state.gtp.src = 0;
+ state.gtp.dest = output;
+ state.gtp.src_is_sock = 0;
+ state.gtp.dest_is_sock = (input == output);
+ state.gtp.state = SSTATE_TRANSFERING;
+ state.gtp.bufuse = 0;
+ state.gtp.src_name = "stdin";
+ state.gtp.dest_name = "remote output";
+
+ return tloop_spawnwait_tasks(&state);
+}
diff --git a/transport.h b/transport.h
index c59d973..e803c0e 100644
--- a/transport.h
+++ b/transport.h
@@ -154,6 +154,7 @@ int transport_connect(struct transport *transport, const char *name,
/* Transport methods defined outside transport.c */
int transport_helper_init(struct transport *transport, const char *name);
+int bidirectional_transfer_loop(int input, int output);
/* common methods used by transport.c and builtin-send-pack.c */
void transport_verify_remote_names(int nr_heads, const char **heads);
--
1.7.3.1.53.g597b29.dirty
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