command: extend subprocess command stdin, change behavior

Make it possible to feed a string to stdin of a subprocess. Out of
laziness, it can't be an arbitrary byte string. (Would require adding an
option type that takes in a Lua byte string.)

Do not set stdin of a subprocess to fd 0 (i.e. mpv's stdin) anymore,
because it makes things more consistent. Enabling stdin didn't make too
much sense in the first place, so this behavior change seems
justifiable.

win32 support missing.

Fixes: #8003

1 files changed, 12 insertions, 0 deletions

diff --git a/osdep/subprocess.h b/osdep/subprocess.h
index 14d4896c58..4bf2dc32dd 100644
--- a/osdep/subprocess.h
+++ b/osdep/subprocess.h
@@ -22,9 +22,18 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include "misc/bstr.h"
+
 struct mp_cancel;
 
+// Incrementally called with data that was read. Buffer valid only during call.
+// size==0 means EOF.
 typedef void (*subprocess_read_cb)(void *ctx, char *data, size_t size);
+// Incrementally called to refill *mp_subprocess_fd.write_buf, whenever write_buf
+// has length 0 and the pipe is writable. While writing, *write_buf is adjusted
+// to contain only the not yet written data.
+// Not filling the buffer means EOF.
+typedef void (*subprocess_write_cb)(void *ctx);
 
 void mp_devnull(void *ctx, char *data, size_t size);
 
@@ -37,6 +46,9 @@ struct mp_subprocess_fd {
     // Note: "neutral" initialization requires setting src_fd=-1.
     subprocess_read_cb on_read;     // if not NULL, serve reads
     void *on_read_ctx;              // for on_read(on_read_ctx, ...)
+    subprocess_write_cb on_write;   // if not NULL, serve writes
+    void *on_write_ctx;             // for on_write(on_write_ctx, ...)
+    bstr *write_buf;                // must be !=NULL if on_write is set
     int src_fd;                     // if >=0, dup this FD to target FD
 };