Workaround musl bug when mountdir has whitespace (#761)

Fixes https://github.com/libfuse/libfuse/issues/634 and https://github.com/mpartel/bindfs/issues/106

diff --git a/meson.build b/meson.build
index 0b3bd680013ae9bb3d565b21326e821e3f6b5036..6aa23c1c2bae61b5a76a292a1ba1ef600ca65a7b 100644 (file)
--- a/meson.build
+++ b/meson.build
@@ -151,6 +151,38 @@ else
      message('Disabling versioned libc symbols')
 endif
 
+# Older versions of musl libc don't unescape entries in /etc/mtab
+# Try to detect this behaviour, and work around, if necessary.
+detect_getmntent_needs_unescape = '''
+#define _GNU_SOURCE
+#include <mntent.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+#define dir_space_tab "dir\\040space\\011tab"
+
+int main()
+{
+    const char *fake_mtab = "name " dir_space_tab " type opts 0 0\n";
+    FILE *f = fmemopen((void *)fake_mtab, strlen(fake_mtab) + 1, "r");
+    struct mntent *entp = getmntent(f);
+    fclose(f);
+    if(NULL == entp)
+        exit(EXIT_FAILURE);
+    if (0 == strcmp(entp->mnt_dir, dir_space_tab))
+        printf("needs escaping\n");
+    else
+        printf("no need to escape\n");
+}
+'''
+
+result = cc.run(detect_getmntent_needs_unescape)
+if result.compiled() and result.returncode() == 0 and result.stdout().strip() == 'needs escaping'
+  message('getmntent does not unescape')
+  add_project_arguments('-DGETMNTENT_NEEDS_UNESCAPING', language: 'c')
+endif
+
 # Write private test results into fuse_config.h (stored in build directory)
 configure_file(output: 'fuse_config.h', configuration : private_cfg)
 

diff --git a/util/fusermount.c b/util/fusermount.c
index f8124cb3598dc999379be1452150b1b8d678e912..7a6bc24f8288da7543c35f0fed3bdd185db8722f 100644 (file)
--- a/util/fusermount.c
+++ b/util/fusermount.c
@@ -7,7 +7,7 @@
 */
 /* This program does the mounting and unmounting of FUSE filesystems */
 
-#define _GNU_SOURCE /* for clone */
+#define _GNU_SOURCE /* for clone and strchrnul */
 #include "fuse_config.h"
 #include "mount_util.h"
 
@@ -63,6 +63,59 @@ static int mount_max = 1000;
 
 static int auto_unmount = 0;
 
+#ifdef GETMNTENT_NEEDS_UNESCAPING
+// Older versions of musl libc don't unescape entries in /etc/mtab
+
+// unescapes octal sequences like \040 in-place
+// That's ok, because unescaping can not extend the length of the string.
+static void unescape(char *buf) {
+       char *src = buf;
+       char *dest = buf;
+       while (1) {
+               char *next_src = strchrnul(src, '\\');
+               int offset = next_src - src;
+               memmove(dest, src, offset);
+               src = next_src;
+               dest += offset;
+
+               if(*src == '\0') {
+                       *dest = *src;
+                       return;
+               }
+               src++;
+
+               if('0' <= src[0] && src[0] < '2' &&
+                  '0' <= src[1] && src[1] < '8' &&
+                  '0' <= src[2] && src[2] < '8') {
+                       *dest++ = (src[0] - '0') << 6
+                               | (src[1] - '0') << 3
+                               | (src[2] - '0') << 0;
+                       src += 3;
+               } else if (src[0] == '\\') {
+                       *dest++ = '\\';
+                       src += 1;
+               } else {
+                       *dest++ = '\\';
+               }
+       }
+}
+
+static struct mntent *GETMNTENT(FILE *stream)
+{
+       struct mntent *entp = getmntent(stream);
+       if(entp != NULL) {
+               unescape(entp->mnt_fsname);
+               unescape(entp->mnt_dir);
+               unescape(entp->mnt_type);
+               unescape(entp->mnt_opts);
+       }
+       return entp;
+}
+#else
+#define GETMNTENT getmntent
+#endif // GETMNTENT_NEEDS_UNESCAPING
+
+
 static const char *get_user_name(void)
 {
        struct passwd *pw = getpwuid(getuid());
@@ -169,7 +222,7 @@ static int may_unmount(const char *mnt, int quiet)
        uidlen = sprintf(uidstr, "%u", getuid());
 
        found = 0;
-       while ((entp = getmntent(fp)) != NULL) {
+       while ((entp = GETMNTENT(fp)) != NULL) {
                if (!found && strcmp(entp->mnt_dir, mnt) == 0 &&
                    (strcmp(entp->mnt_type, "fuse") == 0 ||
                     strcmp(entp->mnt_type, "fuseblk") == 0 ||
@@ -261,7 +314,7 @@ static int check_is_mount_child(void *p)
        }
 
        count = 0;
-       while (getmntent(fp) != NULL)
+       while (GETMNTENT(fp) != NULL)
                count++;
        endmntent(fp);
 
@@ -280,7 +333,7 @@ static int check_is_mount_child(void *p)
        }
 
        found = 0;
-       while ((entp = getmntent(fp)) != NULL) {
+       while ((entp = GETMNTENT(fp)) != NULL) {
                if (count > 0) {
                        count--;
                        continue;
@@ -464,7 +517,7 @@ static int count_fuse_fs(void)
                        strerror(errno));
                return -1;
        }
-       while ((entp = getmntent(fp)) != NULL) {
+       while ((entp = GETMNTENT(fp)) != NULL) {
                if (strcmp(entp->mnt_type, "fuse") == 0 ||
                    strncmp(entp->mnt_type, "fuse.", 5) == 0)
                        count ++;