Allow overriding the path of various /sbin helpers at build time

ntfs-3g uses several external programs at runtime:
- /sbin/mount
- /sbin/umount
- /sbin/modprobe

Allow overriding the paths to these binaries at build time instead of
requiring their presence at these specific expected paths. The default
values keep being their (most common) /sbin location.

configure.ac

@@ -185,6 +185,30 @@ AC_ARG_ENABLE(
 	]
 )
 
+AC_ARG_WITH(
+	[mount-helper],
+	[AS_HELP_STRING([--with-mount-helper=BIN],[use the specified binary as mount helper @<:@default=/sbin/mount@:>@])],
+	[mount_helper="$withval"],
+	[mount_helper="/sbin/mount"]
+)
+AC_DEFINE_UNQUOTED([MOUNT_HELPER], ["$mount_helper"], [Binary used as mount helper.])
+
+AC_ARG_WITH(
+	[umount-helper],
+	[AS_HELP_STRING([--with-umount-helper=BIN],[use the specified binary as umount helper @<:@default=/sbin/umount@:>@])],
+	[umount_helper="$withval"],
+	[umount_helper="/sbin/umount"]
+)
+AC_DEFINE_UNQUOTED([UMOUNT_HELPER], ["$umount_helper"], [Binary used as umount helper.])
+
+AC_ARG_WITH(
+	[modprobe-helper],
+	[AS_HELP_STRING([--with-modprobe-helper=BIN],[use the specified binary as modprobe helper @<:@default=/sbin/modprobe@:>@])],
+	[modprobe_helper="$withval"],
+	[modprobe_helper="/sbin/modprobe"]
+)
+AC_DEFINE_UNQUOTED([MODPROBE_HELPER], ["$modprobe_helper"], [Binary used as modprobe helper.])
+
 # pthread_rwlock_t requires _GNU_SOURCE
 AC_GNU_SOURCE
 

libfuse-lite/mount_util.c

@@ -89,10 +89,10 @@ int fuse_mnt_add_mount(const char *progname, const char *fsname,
             exit(1);
         }
         rmdir(tmp);
-        execle("/sbin/mount", "/sbin/mount", "-F", type, "-o", opts,
+        execle(MOUNT_HELPER, MOUNT_HELPER, "-F", type, "-o", opts,
               fsname, mnt, NULL, &env);
-        fprintf(stderr, "%s: failed to execute /sbin/mount: %s\n", progname,
-                strerror(errno));
+        fprintf(stderr, "%s: failed to execute %s: %s\n", progname,
+                MOUNT_HELPER, strerror(errno));
         exit(1);
     }
     res = waitpid(res, &status, 0);
@@ -126,14 +126,14 @@ int fuse_mnt_umount(const char *progname, const char *mnt, int lazy)
 
         setuid(geteuid());
         if (lazy) {
-            execle("/sbin/umount", "/sbin/umount", mnt,
+            execle(UMOUNT_HELPER, UMOUNT_HELPER, mnt,
                    NULL, &env);
         } else {
-            execle("/sbin/umount", "/sbin/umount", "-f", mnt,
+            execle(UMOUNT_HELPER, UMOUNT_HELPER, "-f", mnt,
                    NULL, &env);
         }
-        fprintf(stderr, "%s: failed to execute /sbin/umount: %s\n", progname,
-                strerror(errno));
+        fprintf(stderr, "%s: failed to execute %s: %s\n", progname,
+                UMOUNT_HELPER, strerror(errno));
         exit(1);
     }
     res = waitpid(res, &status, 0);

src/lowntfs-3g.c

@@ -4463,7 +4463,7 @@ static fuse_fstype load_fuse_module(void)
 	int i;
 	struct stat st;
 	pid_t pid;
-	const char *cmd = "/sbin/modprobe";
+	const char *cmd = MODPROBE_HELPER;
 	char *env = (char*)NULL;
 	struct timespec req = { 0, 100000000 };   /* 100 msec */
 	fuse_fstype fstype;

src/ntfs-3g.c

@@ -4171,7 +4171,7 @@ static fuse_fstype load_fuse_module(void)
 	int i;
 	struct stat st;
 	pid_t pid;
-	const char *cmd = "/sbin/modprobe";
+	const char *cmd = MODPROBE_HELPER;
 	char *env = (char*)NULL;
 	struct timespec req = { 0, 100000000 };   /* 100 msec */
 	fuse_fstype fstype;