1 files changed, 104 insertions, 7 deletions

diff --git a/run-command.h b/run-command.h
index f315868a03..50666497ae 100644
--- a/run-command.h
+++ b/run-command.h
@@ -79,17 +79,34 @@ int run_command_v_opt(const char **argv, int opt);
 int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const char *const *env);
 
 /**
- * Execute the given command, capturing its stdout in the given strbuf.
+ * Execute the given command, sending "in" to its stdin, and capturing its
+ * stdout and stderr in the "out" and "err" strbufs. Any of the three may
+ * be NULL to skip processing.
+ *
  * Returns -1 if starting the command fails or reading fails, and otherwise
- * returns the exit code of the command. The output collected in the
- * buffer is kept even if the command returns a non-zero exit. The hint field
- * gives a starting size for the strbuf allocation.
+ * returns the exit code of the command. Any output collected in the
+ * buffers is kept even if the command returns a non-zero exit. The hint fields
+ * gives starting sizes for the strbuf allocations.
  *
  * The fields of "cmd" should be set up as they would for a normal run_command
- * invocation. But note that there is no need to set cmd->out; the function
- * sets it up for the caller.
+ * invocation. But note that there is no need to set the in, out, or err
+ * fields; pipe_command handles that automatically.
+ */
+int pipe_command(struct child_process *cmd,
+		 const char *in, size_t in_len,
+		 struct strbuf *out, size_t out_hint,
+		 struct strbuf *err, size_t err_hint);
+
+/**
+ * Convenience wrapper around pipe_command for the common case
+ * of capturing only stdout.
  */
-int capture_command(struct child_process *cmd, struct strbuf *buf, size_t hint);
+static inline int capture_command(struct child_process *cmd,
+				  struct strbuf *out,
+				  size_t hint)
+{
+	return pipe_command(cmd, NULL, 0, out, hint, NULL, 0);
+}
 
 /*
  * The purpose of the following functions is to feed a pipe by running
@@ -116,9 +133,89 @@ struct async {
 	int proc_in;
 	int proc_out;
 #endif
+	int isolate_sigpipe;
 };
 
 int start_async(struct async *async);
 int finish_async(struct async *async);
+int in_async(void);
+void NORETURN async_exit(int code);
+
+/**
+ * This callback should initialize the child process and preload the
+ * error channel if desired. The preloading of is useful if you want to
+ * have a message printed directly before the output of the child process.
+ * pp_cb is the callback cookie as passed to run_processes_parallel.
+ * You can store a child process specific callback cookie in pp_task_cb.
+ *
+ * Even after returning 0 to indicate that there are no more processes,
+ * this function will be called again until there are no more running
+ * child processes.
+ *
+ * Return 1 if the next child is ready to run.
+ * Return 0 if there are currently no more tasks to be processed.
+ * To send a signal to other child processes for abortion,
+ * return the negative signal number.
+ */
+typedef int (*get_next_task_fn)(struct child_process *cp,
+				struct strbuf *out,
+				void *pp_cb,
+				void **pp_task_cb);
+
+/**
+ * This callback is called whenever there are problems starting
+ * a new process.
+ *
+ * You must not write to stdout or stderr in this function. Add your
+ * message to the strbuf out instead, which will be printed without
+ * messing up the output of the other parallel processes.
+ *
+ * pp_cb is the callback cookie as passed into run_processes_parallel,
+ * pp_task_cb is the callback cookie as passed into get_next_task_fn.
+ *
+ * Return 0 to continue the parallel processing. To abort return non zero.
+ * To send a signal to other child processes for abortion, return
+ * the negative signal number.
+ */
+typedef int (*start_failure_fn)(struct strbuf *out,
+				void *pp_cb,
+				void *pp_task_cb);
+
+/**
+ * This callback is called on every child process that finished processing.
+ *
+ * You must not write to stdout or stderr in this function. Add your
+ * message to the strbuf out instead, which will be printed without
+ * messing up the output of the other parallel processes.
+ *
+ * pp_cb is the callback cookie as passed into run_processes_parallel,
+ * pp_task_cb is the callback cookie as passed into get_next_task_fn.
+ *
+ * Return 0 to continue the parallel processing.  To abort return non zero.
+ * To send a signal to other child processes for abortion, return
+ * the negative signal number.
+ */
+typedef int (*task_finished_fn)(int result,
+				struct strbuf *out,
+				void *pp_cb,
+				void *pp_task_cb);
+
+/**
+ * Runs up to n processes at the same time. Whenever a process can be
+ * started, the callback get_next_task_fn is called to obtain the data
+ * required to start another child process.
+ *
+ * The children started via this function run in parallel. Their output
+ * (both stdout and stderr) is routed to stderr in a manner that output
+ * from different tasks does not interleave.
+ *
+ * start_failure_fn and task_finished_fn can be NULL to omit any
+ * special handling.
+ */
+int run_processes_parallel(int n,
+			   get_next_task_fn,
+			   start_failure_fn,
+			   task_finished_fn,
+			   void *pp_cb);
 
 #endif