fish: Implement 'hexedit' command.

[libguestfs.git] / fish / hexedit.c

diff --git a/fish/hexedit.c b/fish/hexedit.c
new file mode 100644 (file)
index 0000000..dfa1889
--- /dev/null
+++ b/fish/hexedit.c
@@ -0,0 +1,190 @@
+/* guestfish - the filesystem interactive shell
+ * Copyright (C) 2010 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 <sys/types.h>
+#include <sys/stat.h>
+
+#include "fish.h"
+
+#define MAX_DOWNLOAD_SIZE (16 * 1024 * 1024)
+#define MAX_DOWNLOAD_SIZE_TEXT "16MB"
+
+static off_t get_size (const char *filename);
+
+int
+run_hexedit (const char *cmd, int argc, char *argv[])
+{
+  if (argc < 1 || argc > 3) {
+    fprintf (stderr, _("hexedit (device|filename) [max | start max]\n"));
+    return -1;
+  }
+
+  const char *filename = argv[0];
+  off_t size = get_size (filename);
+  if (size == -1)
+    return -1;
+
+  if (size == 0) {
+    fprintf (stderr,
+             _("hexedit: %s is a zero length file or device\n"), filename);
+    return -1;
+  }
+
+  off_t start;
+  off_t max;
+
+  if (argc == 1) {              /* hexedit device */
+    /* Check we're not going to download a huge file. */
+    if (size > MAX_DOWNLOAD_SIZE) {
+      fprintf (stderr,
+         _("hexedit: %s is larger than %s. You must supply a limit using\n"
+           "  'hexedit %s <max>' (eg. 'hexedit %s 1M') or a range using\n"
+           "  'hexedit %s <start> <max>'.\n"),
+               filename, MAX_DOWNLOAD_SIZE_TEXT,
+               filename, filename,
+               filename);
+      return -1;
+    }
+
+    start = 0;
+    max = size;
+  }
+  else {
+    if (argc == 3) {            /* hexedit device start max */
+      if (parse_size (argv[1], &start) == -1)
+        return -1;
+      if (parse_size (argv[2], &max) == -1)
+        return -1;
+    } else {                    /* hexedit device max */
+      start = 0;
+      if (parse_size (argv[1], &max) == -1)
+        return -1;
+    }
+
+    if (start + max > size)
+      max = size - start;
+  }
+
+  if (max <= 0) {
+    fprintf (stderr, _("hexedit: invalid range\n"));
+    return -1;
+  }
+
+  /* Download the requested range from the remote file|device into a
+   * local temporary file.
+   */
+  const char *editor;
+  int r;
+  struct stat oldstat, newstat;
+  char buf[BUFSIZ];
+  char tmp[] = "/tmp/guestfishXXXXXX";
+  int fd = mkstemp (tmp);
+  if (fd == -1) {
+    perror ("mkstemp");
+    return -1;
+  }
+
+  /* Choose an editor. */
+  editor = getenv ("HEXEDITOR");
+  if (editor == NULL)
+    editor = "hexedit";
+
+  snprintf (buf, sizeof buf, "/dev/fd/%d", fd);
+
+  if (guestfs_download_offset (g, filename, buf, start, max) == -1) {
+    unlink (tmp);
+    close (fd);
+    return -1;
+  }
+
+  if (close (fd) == -1) {
+    unlink (tmp);
+    return -1;
+  }
+
+  /* Get the old stat. */
+  if (stat (tmp, &oldstat) == -1) {
+    perror (tmp);
+    unlink (tmp);
+    return -1;
+  }
+
+  /* Edit it. */
+  snprintf (buf, sizeof buf, "%s %s", editor, tmp);
+
+  r = system (buf);
+  if (r != 0) {
+    perror (buf);
+    unlink (tmp);
+    return -1;
+  }
+
+  /* Get the new stat. */
+  if (stat (tmp, &newstat) == -1) {
+    perror (tmp);
+    unlink (tmp);
+    return -1;
+  }
+
+  /* Changed? */
+  if (oldstat.st_ctime == newstat.st_ctime &&
+      oldstat.st_size == newstat.st_size) {
+    unlink (tmp);
+    return 0;
+  }
+
+  /* Write new content. */
+  if (guestfs_upload_offset (g, tmp, filename, start) == -1) {
+    unlink (tmp);
+    return -1;
+  }
+
+  unlink (tmp);
+  return 0;
+}
+
+/* Get the size of the file or block device. */
+static off_t
+get_size (const char *filename)
+{
+  int64_t size;
+
+  if (STRPREFIX (filename, "/dev/")) {
+    size = guestfs_blockdev_getsize64 (g, filename);
+    if (size == -1)
+      return -1;
+  }
+  else {
+    size = guestfs_filesize (g, filename);
+    if (size == -1)
+      return -1;
+  }
+
+  /* This case should be safe because we always compile with
+   * 64 bit file offsets.
+   */
+  return (off_t) size;
+}