eval: allow setting cwd in {jobstart,termopen}()

Processes in vim are always started in the current directory, which
causes issues when the process is a daemon and the current directory is
a mountpoint. Fix this by adding an option to set the cwd of the new
process with jobstart(). In addition, fix termopen() so that it actually
uses the cwd option from the dict (it couldn't previously set the cwd
value due to dead code).

Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>

src/nvim/eval.c

@@ -11731,8 +11731,21 @@ static void f_jobstart(typval_T *argvars, typval_T *rettv)
 
   dict_T *job_opts = NULL;
   ufunc_T *on_stdout = NULL, *on_stderr = NULL, *on_exit = NULL;
+  char *cwd = NULL;
   if (argvars[1].v_type == VAR_DICT) {
     job_opts = argvars[1].vval.v_dict;
+
+    char *new_cwd = (char *)get_dict_string(job_opts, (char_u *)"cwd", false);
+    if (new_cwd && strlen(new_cwd) > 0) {
+      cwd = new_cwd;
+      // The new cwd must be a directory.
+      if (!os_isdir((char_u *)cwd)) {
+        EMSG2(_(e_invarg2), "expected valid directory");
+        shell_free_argv(argv);
+        return;
+      }
+    }
+
     if (!common_job_callbacks(job_opts, &on_stdout, &on_stderr, &on_exit)) {
       shell_free_argv(argv);
       return;
@@ -11742,7 +11755,7 @@ static void f_jobstart(typval_T *argvars, typval_T *rettv)
   bool pty = job_opts && get_dict_number(job_opts, (uint8_t *)"pty") != 0;
   bool detach = job_opts && get_dict_number(job_opts, (uint8_t *)"detach") != 0;
   TerminalJobData *data = common_job_init(argv, on_stdout, on_stderr, on_exit,
-                                          job_opts, pty, detach);
+                                          job_opts, pty, detach, cwd);
   Process *proc = (Process *)&data->proc;
 
   if (pty) {
@@ -16424,8 +16437,21 @@ static void f_termopen(typval_T *argvars, typval_T *rettv)
 
   ufunc_T *on_stdout = NULL, *on_stderr = NULL, *on_exit = NULL;
   dict_T *job_opts = NULL;
+  char *cwd = ".";
   if (argvars[1].v_type == VAR_DICT) {
     job_opts = argvars[1].vval.v_dict;
+
+    char *new_cwd = (char *)get_dict_string(job_opts, (char_u *)"cwd", false);
+    if (new_cwd && strlen(new_cwd) > 0) {
+      cwd = new_cwd;
+      // The new cwd must be a directory.
+      if (!os_isdir((char_u *)cwd)) {
+        EMSG2(_(e_invarg2), "expected valid directory");
+        shell_free_argv(argv);
+        return;
+      }
+    }
+
     if (!common_job_callbacks(job_opts, &on_stdout, &on_stderr, &on_exit)) {
       shell_free_argv(argv);
       return;
@@ -16433,7 +16459,7 @@ static void f_termopen(typval_T *argvars, typval_T *rettv)
   }
 
   TerminalJobData *data = common_job_init(argv, on_stdout, on_stderr, on_exit,
-                                          job_opts, true, false);
+                                          job_opts, true, false, cwd);
   data->proc.pty.width = curwin->w_width;
   data->proc.pty.height = curwin->w_height;
   data->proc.pty.term_name = xstrdup("xterm-256color");
@@ -16448,11 +16474,6 @@ static void f_termopen(typval_T *argvars, typval_T *rettv)
   topts.resize_cb = term_resize;
   topts.close_cb = term_close;
 
-  char *cwd = ".";
-  if (argvars[1].v_type == VAR_STRING
-      && os_isdir(argvars[1].vval.v_string)) {
-    cwd = (char *)argvars[1].vval.v_string;
-  }
   int pid = data->proc.pty.process.pid;
 
   char buf[1024];
@@ -21717,7 +21738,8 @@ static inline TerminalJobData *common_job_init(char **argv,
                                                ufunc_T *on_exit,
                                                dict_T *self,
                                                bool pty,
-                                               bool detach)
+                                               bool detach,
+                                               char *cwd)
 {
   TerminalJobData *data = xcalloc(1, sizeof(TerminalJobData));
   data->stopped = false;
@@ -21741,6 +21763,7 @@ static inline TerminalJobData *common_job_init(char **argv,
   proc->cb = on_process_exit;
   proc->events = data->events;
   proc->detach = detach;
+  proc->cwd = cwd;
   return data;
 }
 

src/nvim/event/libuv_process.c

@@ -25,7 +25,7 @@ bool libuv_process_spawn(LibuvProcess *uvproc)
       uvproc->uvopts.flags |= UV_PROCESS_DETACHED;
   }
   uvproc->uvopts.exit_cb = exit_cb;
-  uvproc->uvopts.cwd = NULL;
+  uvproc->uvopts.cwd = proc->cwd;
   uvproc->uvopts.env = NULL;
   uvproc->uvopts.stdio = uvproc->uvstdio;
   uvproc->uvopts.stdio_count = 3;

src/nvim/event/process.h

@@ -21,6 +21,7 @@ struct process {
   int pid, status, refcount;
   // set to the hrtime of when process_stop was called for the process.
   uint64_t stopped_time;
+  char *cwd;
   char **argv;
   Stream *in, *out, *err;
   process_exit_cb cb;
@@ -40,6 +41,7 @@ static inline Process process_init(Loop *loop, ProcessType type, void *data)
     .status = 0,
     .refcount = 0,
     .stopped_time = 0,
+    .cwd = NULL,
     .argv = NULL,
     .in = NULL,
     .out = NULL,

src/nvim/os/pty_process_unix.c

@@ -28,6 +28,7 @@
 #include "nvim/event/process.h"
 #include "nvim/os/pty_process_unix.h"
 #include "nvim/log.h"
+#include "nvim/os/os.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "os/pty_process_unix.c.generated.h"
@@ -131,6 +132,12 @@ static void init_child(PtyProcess *ptyproc) FUNC_ATTR_NONNULL_ALL
   signal(SIGTERM, SIG_DFL);
   signal(SIGALRM, SIG_DFL);
 
+  Process *proc = (Process *)ptyproc;
+  if (proc->cwd && os_chdir(proc->cwd) != 0) {
+    fprintf(stderr, "chdir failed: %s\n", strerror(errno));
+    return;
+  }
+
   setenv("TERM", ptyproc->term_name ? ptyproc->term_name : "ansi", 1);
   execvp(ptyproc->process.argv[0], ptyproc->process.argv);
   fprintf(stderr, "execvp failed: %s\n", strerror(errno));