job: Refactor job_write to receive WBuffer instances.

This was done to give more control over memory management to job_write callers.

src/nvim/eval.c

@@ -10540,9 +10540,10 @@ static void f_job_write(typval_T *argvars, typval_T *rettv)
     EMSG(_(e_invjob));
   }
 
-  rettv->vval.v_number = job_write(job,
-                                   xstrdup((char *)argvars[1].vval.v_string),
-                                   strlen((char *)argvars[1].vval.v_string));
+  WBuffer *buf = wstream_new_buffer(xstrdup((char *)argvars[1].vval.v_string),
+                                    strlen((char *)argvars[1].vval.v_string),
+                                    free);
+  rettv->vval.v_number = job_write(job, buf);
 }
 
 /*

src/nvim/os/job.c

@@ -260,13 +260,12 @@ void job_stop(Job *job)
 /// returns when the write request was sent.
 ///
 /// @param job The Job instance
-/// @param data Buffer containing the data to be written
-/// @param len Size of the data
+/// @param buffer The buffer which contains the data to be written
 /// @return true if the write request was successfully sent, false if writing
 ///         to the job stream failed (possibly because the OS buffer is full)
-bool job_write(Job *job, char *data, uint32_t len)
+bool job_write(Job *job, WBuffer *buffer)
 {
-  return wstream_write(job->in, wstream_new_buffer(data, len, free));
+  return wstream_write(job->in, buffer);
 }
 
 /// Sets the `defer` flag for a Job instance

src/nvim/os/job.h

@@ -12,6 +12,8 @@
 
 #include "nvim/os/rstream_defs.h"
 #include "nvim/os/event_defs.h"
+#include "nvim/os/wstream.h"
+#include "nvim/os/wstream_defs.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "os/job.h.generated.h"