+#define STRIDE_LENGTH 8
+/*
+ * Helper function which zeros out _num_ blocks starting at _blk_. In
+ * case of an error, the details of the error is returned via _ret_blk_
+ * and _ret_count_ if they are non-NULL pointers. Returns 0 on
+ * success, and an error code on an error.
+ *
+ * As a special case, if the first argument is NULL, then it will
+ * attempt to free the static zeroizing buffer. (This is to keep
+ * programs that check for memory leaks happy.)
+ */
+errcode_t e2fsck_zero_blocks(ext2_filsys fs, blk_t blk, int num,
+ blk_t *ret_blk, int *ret_count)
+{
+ int j, count, next_update, next_update_incr;
+ static char *buf;
+ errcode_t retval;
+
+ /* If fs is null, clean up the static buffer and return */
+ if (!fs) {
+ if (buf) {
+ free(buf);
+ buf = 0;
+ }
+ return 0;
+ }
+ /* Allocate the zeroizing buffer if necessary */
+ if (!buf) {
+ buf = malloc(fs->blocksize * STRIDE_LENGTH);
+ if (!buf) {
+ com_err("malloc", ENOMEM,
+ _("while allocating zeroizing buffer"));
+ exit(1);
+ }
+ memset(buf, 0, fs->blocksize * STRIDE_LENGTH);
+ }
+ /* OK, do the write loop */
+ next_update = 0;
+ next_update_incr = num / 100;
+ if (next_update_incr < 1)
+ next_update_incr = 1;
+ for (j = 0; j < num; j += STRIDE_LENGTH, blk += STRIDE_LENGTH) {
+ count = num - j;
+ if (count > STRIDE_LENGTH)
+ count = STRIDE_LENGTH;
+ retval = io_channel_write_blk(fs->io, blk, count, buf);
+ if (retval) {
+ if (ret_count)
+ *ret_count = count;
+ if (ret_blk)
+ *ret_blk = blk;
+ return retval;
+ }
+ }
+ return 0;
+}
+
+/*
+ * Check to see if a filesystem is in /proc/filesystems.
+ * Returns 1 if found, 0 if not
+ */
+int fs_proc_check(const char *fs_name)
+{
+ FILE *f;
+ char buf[80], *cp, *t;
+
+ f = fopen("/proc/filesystems", "r");
+ if (!f)
+ return (0);
+ while (!feof(f)) {
+ if (!fgets(buf, sizeof(buf), f))
+ break;
+ cp = buf;
+ if (!isspace(*cp)) {
+ while (*cp && !isspace(*cp))
+ cp++;
+ }
+ while (*cp && isspace(*cp))
+ cp++;
+ if ((t = strchr(cp, '\n')) != NULL)
+ *t = 0;
+ if ((t = strchr(cp, '\t')) != NULL)
+ *t = 0;
+ if ((t = strchr(cp, ' ')) != NULL)
+ *t = 0;
+ if (!strcmp(fs_name, cp)) {
+ fclose(f);
+ return (1);
+ }
+ }
+ fclose(f);
+ return (0);
+}
+
+/*
+ * Check to see if a filesystem is available as a module
+ * Returns 1 if found, 0 if not
+ */
+int check_for_modules(const char *fs_name)
+{
+#ifdef __linux__
+ struct utsname uts;
+ FILE *f;
+ char buf[1024], *cp, *t;
+ int i;
+
+ if (uname(&uts))
+ return (0);
+ snprintf(buf, sizeof(buf), "/lib/modules/%s/modules.dep", uts.release);
+
+ f = fopen(buf, "r");
+ if (!f)
+ return (0);
+ while (!feof(f)) {
+ if (!fgets(buf, sizeof(buf), f))
+ break;
+ if ((cp = strchr(buf, ':')) != NULL)
+ *cp = 0;
+ else
+ continue;
+ if ((cp = strrchr(buf, '/')) != NULL)
+ cp++;
+ i = strlen(cp);
+ if (i > 3) {
+ t = cp + i - 3;
+ if (!strcmp(t, ".ko"))
+ *t = 0;
+ }
+ if (!strcmp(cp, fs_name)) {
+ fclose(f);
+ return (1);
+ }
+ }
+ fclose(f);
+#endif /* __linux__ */
+ return (0);
+}