* Added -o loop option for mount, and support in umount for loop
devices. Support is toggled by MOUNT_LOOP feature -- Ben Collins
<bcollins@debian.org>
-Erik
diff --git a/mount.c b/mount.c
index ee6fe15..8777a3b 100644
--- a/mount.c
+++ b/mount.c
@@ -28,7 +28,10 @@
* putting it back as a compile-time option some time),
* major adjustments to option parsing, and some serious
* dieting all around.
-*/
+ *
+ * 2000-01-12 Ben Collins <bcollins@debian.org>, Borrowed utils-linux's
+ * mount to add loop support.
+ */
#include "internal.h"
#include <stdlib.h>
@@ -41,6 +44,17 @@
#include <ctype.h>
#include <fstab.h>
+#if defined BB_FEATURE_MOUNT_LOOP
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <linux/loop.h>
+
+static int set_loop(const char *device, const char *file, int offset, int *loopro);
+static char *find_unused_loop_device (void);
+
+static int use_loop = 0;
+#endif
+
extern const char mtab_file[]; /* Defined in utility.c */
static const char mount_usage[] = "\tmount [flags]\n"
@@ -61,6 +75,9 @@
"\tasync / sync:\tWrites are asynchronous / synchronous.\n"
"\tdev / nodev:\tAllow use of special device files / disallow them.\n"
"\texec / noexec:\tAllow use of executable files / disallow them.\n"
+#if defined BB_FEATURE_MOUNT_LOOP
+ "\tloop: Mounts a file via loop device.\n"
+#endif
"\tsuid / nosuid:\tAllow set-user-id-root programs / disallow them.\n"
"\tremount: Re-mount a currently-mounted filesystem, changing its flags.\n"
"\tro / rw: Mount for read-only / read-write.\n"
@@ -91,28 +108,48 @@
{0, 0, 0}
};
-#if ! defined BB_MTAB
-#define do_mount(specialfile, dir, filesystemtype, flags, string_flags, useMtab, fakeIt, mtab_opts) \
- mount(specialfile, dir, filesystemtype, flags, string_flags)
-#else
static int
do_mount(char* specialfile, char* dir, char* filesystemtype,
long flags, void* string_flags, int useMtab, int fakeIt, char* mtab_opts)
{
int status=0;
+#if defined BB_MTAB
if (fakeIt==FALSE)
+#endif
+ {
+#if defined BB_FEATURE_MOUNT_LOOP
+ if (use_loop) {
+ int loro = flags & MS_RDONLY;
+ char *lofile = specialfile;
+ specialfile = find_unused_loop_device();
+ if (specialfile == NULL) {
+ fprintf(stderr, "Could not find a spare loop device\n");
+ exit(1);
+ }
+ if (set_loop (specialfile, lofile, 0, &loro)) {
+ fprintf(stderr, "Could not setup loop device\n");
+ exit(1);
+ }
+ if (!(flags & MS_RDONLY) && loro) { /* loop is ro, but wanted rw */
+ fprintf(stderr, "WARNING: loop device is read-only\n");
+ flags &= ~MS_RDONLY;
+ }
+ }
+#endif
status=mount(specialfile, dir, filesystemtype, flags, string_flags);
-
- if ( status == 0 ) {
- if ( useMtab==TRUE )
+ }
+#if defined BB_MTAB
+ if (status == 0) {
+ if (useMtab==TRUE)
write_mtab(specialfile, dir, filesystemtype, flags, mtab_opts);
return 0;
}
- else
- return( status);
-}
+ else
#endif
+ return(status);
+}
+
#if defined BB_MTAB
@@ -148,16 +185,20 @@
}
f++;
}
+#if defined BB_FEATURE_MOUNT_LOOP
+ if (gotone==FALSE && !strcasecmp ("loop", options)) { /* loop device support */
+ use_loop = 1;
+ gotone=TRUE;
+ }
+#endif
if (*strflags && strflags!= '\0' && gotone==FALSE) {
char *temp=strflags;
temp += strlen (strflags);
*temp++ = ',';
*temp++ = '\0';
}
- if (gotone==FALSE) {
+ if (gotone==FALSE)
strcat (strflags, options);
- gotone=FALSE;
- }
if (comma) {
*comma = ',';
options = ++comma;
@@ -356,3 +397,73 @@
goodbye:
usage( mount_usage);
}
+
+#if defined BB_FEATURE_MOUNT_LOOP
+static int set_loop(const char *device, const char *file, int offset, int *loopro)
+{
+ struct loop_info loopinfo;
+ int fd, ffd, mode;
+
+ mode = *loopro ? O_RDONLY : O_RDWR;
+ if ((ffd = open (file, mode)) < 0 && !*loopro
+ && (errno != EROFS || (ffd = open (file, mode = O_RDONLY)) < 0)) {
+ perror (file);
+ return 1;
+ }
+ if ((fd = open (device, mode)) < 0) {
+ close(ffd);
+ perror (device);
+ return 1;
+ }
+ *loopro = (mode == O_RDONLY);
+
+ memset(&loopinfo, 0, sizeof(loopinfo));
+ strncpy(loopinfo.lo_name, file, LO_NAME_SIZE);
+ loopinfo.lo_name[LO_NAME_SIZE-1] = 0;
+
+ loopinfo.lo_offset = offset;
+
+ loopinfo.lo_encrypt_key_size = 0;
+ if (ioctl(fd, LOOP_SET_FD, ffd) < 0) {
+ perror("ioctl: LOOP_SET_FD");
+ exit(1);
+ }
+ if (ioctl(fd, LOOP_SET_STATUS, &loopinfo) < 0) {
+ (void) ioctl(fd, LOOP_CLR_FD, 0);
+ perror("ioctl: LOOP_SET_STATUS");
+ exit(1);
+ }
+ close(fd);
+ close(ffd);
+ return 0;
+}
+
+static char *find_unused_loop_device (void)
+{
+ char dev[20];
+ int i, fd, somedev = 0, someloop = 0;
+ struct stat statbuf;
+ struct loop_info loopinfo;
+
+ for(i = 0; i < 256; i++) {
+ sprintf(dev, "/dev/loop%d", i);
+ if (stat (dev, &statbuf) == 0 && S_ISBLK(statbuf.st_mode)) {
+ somedev++;
+ fd = open (dev, O_RDONLY);
+ if (fd >= 0) {
+ if(ioctl (fd, LOOP_GET_STATUS, &loopinfo) == 0)
+ someloop++; /* in use */
+ else if (errno == ENXIO) {
+ close (fd);
+ return strdup(dev); /* probably free */
+ }
+ close (fd);
+ }
+ continue;
+ }
+ if (i >= 7)
+ break;
+ }
+ return NULL;
+}
+#endif /* BB_FEATURE_MOUNT_LOOP */