Implement "more" and "less" commands in guestfish.

Use commands such as:
  more /etc/passwd
  less /etc/fstab

These commands are specific to guestfish.

TODO

@@ -156,7 +156,6 @@ Extra commands / functionality:
     fts(3) / ftw(3)
 
   guestfish only:
-    more/less (like cat, but pipes it through $PAGER)
     cat file | pipe-cmd should have a generic form? like
       'file | less' or 'file | sort'?
 

fish/Makefile.am

@@ -27,7 +27,8 @@ guestfish_SOURCES = \
 	fish.c \
 	fish.h \
 	glob.c \
-	lcd.c
+	lcd.c \
+	more.c
 
 guestfish_CFLAGS = \
 	-I$(top_builddir)/src -Wall \

fish/edit.c

@@ -29,24 +29,6 @@
 
 /* guestfish edit command, suggested by Ján Ondrej, implemented by RWMJ */
 
-static int
-xwrite (int fd, const void *buf, size_t len)
-{
-  int r;
-
-  while (len > 0) {
-    r = write (fd, buf, len);
-    if (r == -1) {
-      perror ("write");
-      return -1;
-    }
-    buf += r;
-    len -= r;
-  }
-
-  return 0;
-}
-
 static char *
 load_file (const char *filename, int *len_r)
 {

fish/fish.c

@@ -724,6 +724,9 @@ issue_command (const char *cmd, char *argv[], const char *pipecmd)
     r = do_lcd (cmd, argc, argv);
   else if (strcasecmp (cmd, "glob") == 0)
     r = do_glob (cmd, argc, argv);
+  else if (strcasecmp (cmd, "more") == 0 ||
+	   strcasecmp (cmd, "less") == 0)
+    r = do_more (cmd, argc, argv);
   else
     r = run_action (cmd, argc, argv);
 
@@ -818,6 +821,21 @@ display_builtin_command (const char *cmd)
 	      "    Glob runs <command> with wildcards expanded in any\n"
 	      "    command args.  Note that the command is run repeatedly\n"
 	      "    once for each expanded argument.\n"));
+  else if (strcasecmp (cmd, "more") == 0 ||
+	   strcasecmp (cmd, "less") == 0)
+    printf (_("more - view a file in the pager\n"
+	      "     more <filename>\n"
+	      "\n"
+	      "    This is used to view a file in the pager.\n"
+	      "\n"
+	      "    It is the equivalent of (and is implemented by)\n"
+	      "    running \"cat\" and using the pager.\n"
+	      "\n"
+	      "    Normally it uses $PAGER, but if you use the alias\n"
+	      "    \"less\" then it always uses \"less\".\n"
+	      "\n"
+	      "    NOTE: This will not work reliably for large files\n"
+	      "    (> 2 MB) or binary files containing \\0 bytes.\n"));
   else if (strcasecmp (cmd, "help") == 0)
     printf (_("help - display a list of commands or help on a command\n"
 	      "     help cmd\n"
@@ -959,3 +977,21 @@ add_history_line (const char *line)
   nr_history_lines++;
 #endif
 }
+
+int
+xwrite (int fd, const void *buf, size_t len)
+{
+  int r;
+
+  while (len > 0) {
+    r = write (fd, buf, len);
+    if (r == -1) {
+      perror ("write");
+      return -1;
+    }
+    buf += r;
+    len -= r;
+  }
+
+  return 0;
+}

fish/fish.h

@@ -45,6 +45,7 @@ extern void print_table (char * const * const argv);
 extern int launch (guestfs_h *);
 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);
 
 /* in cmds.c (auto-generated) */
 extern void list_commands (void);
@@ -73,6 +74,9 @@ extern int do_lcd (const char *cmd, int argc, char *argv[]);
 /* in glob.c */
 extern int do_glob (const char *cmd, int argc, char *argv[]);
 
+/* in more.c */
+extern int do_more (const char *cmd, int argc, char *argv[]);
+
 /* This should just list all the built-in commands so they can
  * be added to the generated auto-completion code.
  */
@@ -83,6 +87,7 @@ extern int do_glob (const char *cmd, int argc, char *argv[]);
   "echo", \
   "edit", "vi", "emacs", \
   "lcd", \
-  "glob"
+  "glob", \
+  "more", "less"
 
 #endif /* FISH_H */

fish/more.c

@@ -0,0 +1,93 @@
+/* guestfish - the filesystem interactive shell
+ * Copyright (C) 2009 Red Hat Inc. 
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <inttypes.h>
+
+#include "fish.h"
+
+int
+do_more (const char *cmd, int argc, char *argv[])
+{
+  char filename[] = "/tmp/guestfishXXXXXX";
+  char buf[256];
+  const char *pager;
+  char *content;
+  int r, fd;
+
+  if (argc != 1) {
+    fprintf (stderr, _("use '%s filename' to page a file\n"), cmd);
+    return -1;
+  }
+
+  /* Choose a pager. */
+  if (strcasecmp (cmd, "less") == 0)
+    pager = "less";
+  else {
+    pager = getenv ("PAGER");
+    if (pager == NULL)
+      pager = "more";
+  }
+
+  /* Download the file and write it to a temporary. */
+  fd = mkstemp (filename);
+  if (fd == -1) {
+    perror ("mkstemp");
+    return -1;
+  }
+
+  if ((content = guestfs_cat (g, argv[0])) == NULL) {
+    close (fd);
+    unlink (filename);
+    return -1;
+  }
+
+  if (xwrite (fd, content, strlen (content)) == -1) {
+    close (fd);
+    unlink (filename);
+    free (content);
+    return -1;
+  }
+
+  free (content);
+
+  if (close (fd) == -1) {
+    perror (filename);
+    unlink (filename);
+    return -1;
+  }
+
+  /* View it. */
+  /* XXX Safe? */
+  snprintf (buf, sizeof buf, "%s %s", pager, filename);
+
+  r = system (buf);
+  unlink (filename);
+  if (r != 0) {
+    perror (buf);
+    return -1;
+  }
+
+  return 0;
+}