hw/9pfs/9p-util-darwin.c

   1 /*
   2  * 9p utilities (Darwin Implementation)
   3  *
   4  * This work is licensed under the terms of the GNU GPL, version 2 or later.
   5  * See the COPYING file in the top-level directory.
   6  */
   7
   8 #include "qemu/osdep.h"
   9 #include "qemu/xattr.h"
  10 #include "qapi/error.h"
  11 #include "qemu/error-report.h"
  12 #include "9p-util.h"
  13
  14 ssize_t fgetxattrat_nofollow(int dirfd, const char *filename, const char *name,
  15                              void *value, size_t size)
  16 {
  17     int ret;
  18     int fd = openat_file(dirfd, filename,
  19                          O_RDONLY | O_PATH_9P_UTIL | O_NOFOLLOW, 0);
  20     if (fd == -1) {
  21         return -1;
  22     }
  23     ret = fgetxattr(fd, name, value, size, 0, 0);
  24     close_preserve_errno(fd);
  25     return ret;
  26 }
  27
  28 ssize_t flistxattrat_nofollow(int dirfd, const char *filename,
  29                               char *list, size_t size)
  30 {
  31     int ret;
  32     int fd = openat_file(dirfd, filename,
  33                          O_RDONLY | O_PATH_9P_UTIL | O_NOFOLLOW, 0);
  34     if (fd == -1) {
  35         return -1;
  36     }
  37     ret = flistxattr(fd, list, size, 0);
  38     close_preserve_errno(fd);
  39     return ret;
  40 }
  41
  42 ssize_t fremovexattrat_nofollow(int dirfd, const char *filename,
  43                                 const char *name)
  44 {
  45     int ret;
  46     int fd = openat_file(dirfd, filename, O_PATH_9P_UTIL | O_NOFOLLOW, 0);
  47     if (fd == -1) {
  48         return -1;
  49     }
  50     ret = fremovexattr(fd, name, 0);
  51     close_preserve_errno(fd);
  52     return ret;
  53 }
  54
  55 int fsetxattrat_nofollow(int dirfd, const char *filename, const char *name,
  56                          void *value, size_t size, int flags)
  57 {
  58     int ret;
  59     int fd = openat_file(dirfd, filename, O_PATH_9P_UTIL | O_NOFOLLOW, 0);
  60     if (fd == -1) {
  61         return -1;
  62     }
  63     ret = fsetxattr(fd, name, value, size, 0, flags);
  64     close_preserve_errno(fd);
  65     return ret;
  66 }
  67
  68 /*
  69  * As long as mknodat is not available on macOS, this workaround
  70  * using pthread_fchdir_np is needed.
  71  *
  72  * Radar filed with Apple for implementing mknodat:
  73  * rdar://FB9862426 (https://openradar.appspot.com/FB9862426)
  74  */
  75 #if defined CONFIG_PTHREAD_FCHDIR_NP
  76
  77 static int create_socket_file_at_cwd(const char *filename, mode_t mode) {
  78     int fd, err;
  79     struct sockaddr_un addr = {
  80         .sun_family = AF_UNIX
  81     };
  82
  83     err = snprintf(addr.sun_path, sizeof(addr.sun_path), "./%s", filename);
  84     if (err < 0 || err >= sizeof(addr.sun_path)) {
  85         errno = ENAMETOOLONG;
  86         return -1;
  87     }
  88     fd = socket(PF_UNIX, SOCK_DGRAM, 0);
  89     if (fd == -1) {
  90         return fd;
  91     }
  92     err = bind(fd, (struct sockaddr *) &addr, sizeof(addr));
  93     if (err == -1) {
  94         goto out;
  95     }
  96     /*
  97      * FIXME: Should rather be using descriptor-based fchmod() on the
  98      * socket file descriptor above (preferably before bind() call),
  99      * instead of path-based fchmodat(), to prevent concurrent transient
 100      * state issues between creating the named FIFO file at bind() and
 101      * delayed adjustment of permissions at fchmodat(). However currently
 102      * macOS (12.x) does not support such operations on socket file
 103      * descriptors yet.
 104      *
 105      * Filed report with Apple: FB9997731
 106      */
 107     err = fchmodat(AT_FDCWD, filename, mode, AT_SYMLINK_NOFOLLOW);
 108 out:
 109     close_preserve_errno(fd);
 110     return err;
 111 }
 112
 113 int qemu_mknodat(int dirfd, const char *filename, mode_t mode, dev_t dev)
 114 {
 115     int preserved_errno, err;
 116
 117     if (S_ISREG(mode) || !(mode & S_IFMT)) {
 118         int fd = openat_file(dirfd, filename, O_CREAT, mode);
 119         if (fd == -1) {
 120             return fd;
 121         }
 122         close(fd);
 123         return 0;
 124     }
 125     if (!pthread_fchdir_np) {
 126         error_report_once("pthread_fchdir_np() not available on this version of macOS");
 127         errno = ENOTSUP;
 128         return -1;
 129     }
 130     if (pthread_fchdir_np(dirfd) < 0) {
 131         return -1;
 132     }
 133     if (S_ISSOCK(mode)) {
 134         err = create_socket_file_at_cwd(filename, mode);
 135     } else {
 136         err = mknod(filename, mode, dev);
 137     }
 138     preserved_errno = errno;
 139     /* Stop using the thread-local cwd */
 140     pthread_fchdir_np(-1);
 141     if (err < 0) {
 142         errno = preserved_errno;
 143     }
 144     return err;
 145 }
 146
 147 #endif