fish: Allow -<<END as a syntax for uploading "heredocs".

For example:

    ><fs> upload -<<END /foo
    some data
    some more data
    END
    ><fs> cat /foo
    some data
    some more data

3 files changed, 177 insertions, 0 deletions

diff --git a/fish/fish.c b/fish/fish.c
index 61a84050..db3149e1 100644
--- a/fish/fish.c
+++ b/fish/fish.c
@@ -1419,3 +1419,144 @@ resolve_win_path (const char *path)
 
   return ret;
 }
+
+/* Resolve the special FileIn paths ("-" or "-<<END" or filename).
+ * The caller (cmds.c) will call free_file_in after the command has
+ * run which should clean up resources.
+ */
+static char *file_in_heredoc (const char *endmarker);
+static char *file_in_tmpfile = NULL;
+
+char *
+file_in (const char *arg)
+{
+  char *ret;
+
+  if (STREQ (arg, "-")) {
+    ret = strdup ("/dev/stdin");
+    if (!ret) {
+      perror ("strdup");
+      return NULL;
+    }
+  }
+  else if (STRPREFIX (arg, "-<<")) {
+    const char *endmarker = &arg[3];
+    if (*endmarker == '\0') {
+      fprintf (stderr, "%s: missing end marker in -<< expression\n",
+               program_name);
+      return NULL;
+    }
+    ret = file_in_heredoc (endmarker);
+    if (ret == NULL)
+      return NULL;
+  }
+  else {
+    ret = strdup (arg);
+    if (!ret) {
+      perror ("strdup");
+      return NULL;
+    }
+  }
+
+  return ret;
+}
+
+static char *
+file_in_heredoc (const char *endmarker)
+{
+  static const char template[] = "/tmp/heredocXXXXXX";
+  file_in_tmpfile = strdup (template);
+  if (file_in_tmpfile == NULL) {
+    perror ("strdup");
+    return NULL;
+  }
+
+  int fd = mkstemp (file_in_tmpfile);
+  if (fd == -1) {
+    perror ("mkstemp");
+    goto error1;
+  }
+
+  size_t markerlen = strlen (endmarker);
+
+  char buffer[BUFSIZ];
+  int write_error = 0;
+  while (fgets (buffer, sizeof buffer, stdin) != NULL) {
+    /* Look for "END"<EOF> or "END\n" in input. */
+    size_t blen = strlen (buffer);
+    if (STREQLEN (buffer, endmarker, markerlen) &&
+        (blen == markerlen ||
+         (blen == markerlen+1 && buffer[markerlen] == '\n')))
+      goto found_end;
+
+    if (xwrite (fd, buffer, blen) == -1) {
+      if (!write_error) perror ("write");
+      write_error = 1;
+      /* continue reading up to the end marker */
+    }
+  }
+
+  /* Reached EOF of stdin without finding the end marker, which
+   * is likely to be an error.
+   */
+  fprintf (stderr, "%s: end of input reached without finding '%s'\n",
+           program_name, endmarker);
+  goto error2;
+
+ found_end:
+  if (write_error) {
+    close (fd);
+    goto error2;
+  }
+
+  if (close (fd) == -1) {
+    perror ("close");
+    goto error2;
+  }
+
+  return file_in_tmpfile;
+
+ error2:
+  unlink (file_in_tmpfile);
+
+ error1:
+  free (file_in_tmpfile);
+  file_in_tmpfile = NULL;
+  return NULL;
+}
+
+void
+free_file_in (char *s)
+{
+  if (file_in_tmpfile) {
+    if (unlink (file_in_tmpfile) == -1)
+      perror (file_in_tmpfile);
+    file_in_tmpfile = NULL;
+  }
+
+  /* Free the device or file name which was strdup'd in file_in().
+   * Note it's not immediately clear, but for -<< heredocs,
+   * s == file_in_tmpfile, so this frees up that buffer.
+   */
+  free (s);
+}
+
+/* Resolve the special FileOut paths ("-" or filename).
+ * The caller (cmds.c) will call free (str) after the command has run.
+ */
+char *
+file_out (const char *arg)
+{
+  char *ret;
+
+  if (STREQ (arg, "-"))
+    ret = strdup ("/dev/stdout");
+  else
+    ret = strdup (arg);
+
+  if (!ret) {
+    perror ("strdup");
+    return NULL;
+  }
+  return ret;
+}
diff --git a/fish/fish.h b/fish/fish.h
index 5856b8ef..05135fba 100644
--- a/fish/fish.h
+++ b/fish/fish.h
@@ -65,6 +65,9 @@ extern int is_true (const char *str);
 extern char **parse_string_list (const char *str);
 extern int xwrite (int fd, const void *buf, size_t len);
 extern char *resolve_win_path (const char *path);
+extern char *file_in (const char *arg);
+extern void free_file_in (char *s);
+extern char *file_out (const char *arg);
 extern void extended_help_message (void);
 
 /* in cmds.c (auto-generated) */
diff --git a/fish/guestfish.pod b/fish/guestfish.pod
index e61d4e5b..836c4f7f 100644
--- a/fish/guestfish.pod
+++ b/fish/guestfish.pod
@@ -486,6 +486,39 @@ user ID of the process, and C<$PID> is the process ID of the server.
 
 Guestfish client and server versions must match exactly.
 
+=head1 UPLOADING AND DOWNLOADING FILES
+
+For commands such as C<upload>, C<download>, C<tar-in>, C<tar-out> and
+others which upload from or download to a local file, you can use the
+special filename C<-> to mean "from stdin" or "to stdout".  For example:
+
+ upload - /foo
+
+reads stdin and creates from that a file C</foo> in the disk image,
+and:
+
+ tar-out /etc - | tar tf -
+
+writes the tarball to stdout and then pipes that into the external
+"tar" command (see L</PIPES>).
+
+When using C<-> to read from stdin, the input is read up to the end of
+stdin.  You can also use a special "heredoc"-like syntax to read up to
+some arbitrary end marker:
+
+ upload -<<END /foo
+ input line 1
+ input line 2
+ input line 3
+ END
+
+Any string of characters can be used instead of C<END>.  The end
+marker must appear on a line of its own, without any preceeding or
+following characters (not even spaces).
+
+Note that the C<-E<lt>E<lt>> syntax only applies to parameters used to
+upload local files (so-called "FileIn" parameters in the generator).
+
 =head1 GUESTFISH COMMANDS
 
 The commands in this section are guestfish convenience commands, in