libc-bottom-half/cloudlibc/src/libc/fcntl/openat.c

   1 // Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
   2 //
   3 // SPDX-License-Identifier: BSD-2-Clause
   4
   5 #include <common/errno.h>
   6
   7 #include <assert.h>
   8 #include <wasi/api.h>
   9 #include <wasi/libc.h>
  10 #include <errno.h>
  11 #include <fcntl.h>
  12 #include <string.h>
  13
  14 #ifdef __wasilibc_unmodified_upstream // fstat
  15 static_assert(O_APPEND == __WASI_FDFLAG_APPEND, "Value mismatch");
  16 static_assert(O_DSYNC == __WASI_FDFLAG_DSYNC, "Value mismatch");
  17 static_assert(O_NONBLOCK == __WASI_FDFLAG_NONBLOCK, "Value mismatch");
  18 static_assert(O_RSYNC == __WASI_FDFLAG_RSYNC, "Value mismatch");
  19 static_assert(O_SYNC == __WASI_FDFLAG_SYNC, "Value mismatch");
  20 #else
  21 static_assert(O_APPEND == __WASI_FDFLAGS_APPEND, "Value mismatch");
  22 static_assert(O_DSYNC == __WASI_FDFLAGS_DSYNC, "Value mismatch");
  23 static_assert(O_NONBLOCK == __WASI_FDFLAGS_NONBLOCK, "Value mismatch");
  24 static_assert(O_RSYNC == __WASI_FDFLAGS_RSYNC, "Value mismatch");
  25 static_assert(O_SYNC == __WASI_FDFLAGS_SYNC, "Value mismatch");
  26 #endif
  27
  28 #ifdef __wasilibc_unmodified_upstream // fstat
  29 static_assert(O_CREAT >> 12 == __WASI_O_CREAT, "Value mismatch");
  30 static_assert(O_DIRECTORY >> 12 == __WASI_O_DIRECTORY, "Value mismatch");
  31 static_assert(O_EXCL >> 12 == __WASI_O_EXCL, "Value mismatch");
  32 static_assert(O_TRUNC >> 12 == __WASI_O_TRUNC, "Value mismatch");
  33 #else
  34 static_assert(O_CREAT >> 12 == __WASI_OFLAGS_CREAT, "Value mismatch");
  35 static_assert(O_DIRECTORY >> 12 == __WASI_OFLAGS_DIRECTORY, "Value mismatch");
  36 static_assert(O_EXCL >> 12 == __WASI_OFLAGS_EXCL, "Value mismatch");
  37 static_assert(O_TRUNC >> 12 == __WASI_OFLAGS_TRUNC, "Value mismatch");
  38 #endif
  39
  40 int openat(int fd, const char *path, int oflag, ...) {
  41 #ifdef __wasilibc_unmodified_upstream // fstat
  42 #else
  43     return __wasilibc_openat_nomode(fd, path, oflag);
  44 }
  45
  46 int __wasilibc_openat_nomode(int fd, const char *path, int oflag) {
  47 #endif
  48   // Compute rights corresponding with the access modes provided.
  49   // Attempt to obtain all rights, except the ones that contradict the
  50   // access mode provided to openat().
  51 #ifdef __wasilibc_unmodified_upstream // Let the WASI implementation check this instead.
  52   __wasi_rights_t min = 0;
  53 #endif
  54   __wasi_rights_t max =
  55 #ifdef __wasilibc_unmodified_upstream // fstat
  56       ~(__WASI_RIGHT_FD_DATASYNC | __WASI_RIGHT_FD_READ |
  57         __WASI_RIGHT_FD_WRITE | __WASI_RIGHT_FILE_ALLOCATE |
  58         __WASI_RIGHT_FILE_READDIR | __WASI_RIGHT_FILE_STAT_FPUT_SIZE |
  59 #else
  60       ~(__WASI_RIGHTS_FD_DATASYNC | __WASI_RIGHTS_FD_READ |
  61         __WASI_RIGHTS_FD_WRITE | __WASI_RIGHTS_FD_ALLOCATE |
  62         __WASI_RIGHTS_FD_READDIR | __WASI_RIGHTS_FD_FILESTAT_SET_SIZE |
  63 #endif
  64 #ifdef __wasilibc_unmodified_upstream // RIGHT_MEM_MAP_EXEC
  65         __WASI_RIGHT_MEM_MAP_EXEC);
  66 #else
  67         0);
  68 #endif
  69   switch (oflag & O_ACCMODE) {
  70     case O_RDONLY:
  71     case O_RDWR:
  72     case O_WRONLY:
  73       if ((oflag & O_RDONLY) != 0) {
  74 #ifdef __wasilibc_unmodified_upstream // Let the WASI implementation check this instead.
  75         min |= (oflag & O_DIRECTORY) == 0 ? __WASI_RIGHT_FD_READ
  76                                           : __WASI_RIGHT_FILE_READDIR;
  77 #endif
  78 #ifdef __wasilibc_unmodified_upstream // RIGHT_MEM_MAP_EXEC
  79         max |= __WASI_RIGHT_FD_READ | __WASI_RIGHT_FILE_READDIR |
  80                __WASI_RIGHT_MEM_MAP_EXEC;
  81 #else
  82         max |= __WASI_RIGHTS_FD_READ | __WASI_RIGHTS_FD_READDIR;
  83 #endif
  84       }
  85       if ((oflag & O_WRONLY) != 0) {
  86 #ifdef __wasilibc_unmodified_upstream // Let the WASI implementation check this instead.
  87         min |= __WASI_RIGHT_FD_WRITE;
  88         if ((oflag & O_APPEND) == 0)
  89           min |= __WASI_RIGHT_FD_SEEK;
  90 #endif
  91 #ifdef __wasilibc_unmodified_upstream // fstat
  92         max |= __WASI_RIGHT_FD_DATASYNC | __WASI_RIGHT_FD_WRITE |
  93                __WASI_RIGHT_FILE_ALLOCATE |
  94                __WASI_RIGHT_FILE_STAT_FPUT_SIZE;
  95 #else
  96         max |= __WASI_RIGHTS_FD_DATASYNC | __WASI_RIGHTS_FD_WRITE |
  97                __WASI_RIGHTS_FD_ALLOCATE |
  98                __WASI_RIGHTS_FD_FILESTAT_SET_SIZE;
  99 #endif
 100       }
 101       break;
 102     case O_EXEC:
 103 #ifdef __wasilibc_unmodified_upstream // RIGHT_PROC_EXEC
 104       min |= __WASI_RIGHT_PROC_EXEC;
 105 #endif
 106       break;
 107     case O_SEARCH:
 108       break;
 109     default:
 110       errno = EINVAL;
 111       return -1;
 112   }
 113 #ifdef __wasilibc_unmodified_upstream // Let the WASI implementation check this instead.
 114   assert((min & max) == min &&
 115          "Minimal rights should be a subset of the maximum");
 116 #endif
 117
 118   // Ensure that we can actually obtain the minimal rights needed.
 119   __wasi_fdstat_t fsb_cur;
 120 #ifdef __wasilibc_unmodified_upstream
 121   __wasi_errno_t error = __wasi_fd_stat_get(fd, &fsb_cur);
 122 #else
 123   __wasi_errno_t error = __wasi_fd_fdstat_get(fd, &fsb_cur);
 124 #endif
 125   if (error != 0) {
 126     errno = error;
 127     return -1;
 128   }
 129 #ifdef __wasilibc_unmodified_upstream // Let the WASI implementation check this instead.
 130   if (fsb_cur.fs_filetype != __WASI_FILETYPE_DIRECTORY) {
 131     errno = ENOTDIR;
 132     return -1;
 133   }
 134   if ((min & fsb_cur.fs_rights_inheriting) != min) {
 135     errno = ENOTCAPABLE;
 136     return -1;
 137   }
 138 #endif
 139
 140   // Path lookup properties.
 141 #ifdef __wasilibc_unmodified_upstream // split out __wasi_lookup_t
 142   __wasi_lookup_t lookup = {.fd = fd, .flags = 0};
 143 #else
 144   __wasi_lookupflags_t lookup_flags = 0;
 145 #endif
 146   if ((oflag & O_NOFOLLOW) == 0)
 147 #ifdef __wasilibc_unmodified_upstream // split out __wasi_lookup_t
 148     lookup.flags |= __WASI_LOOKUP_SYMLINK_FOLLOW;
 149 #else
 150     lookup_flags |= __WASI_LOOKUPFLAGS_SYMLINK_FOLLOW;
 151 #endif
 152
 153   // Open file with appropriate rights.
 154 #ifdef __wasilibc_unmodified_upstream // split out __wasi_lookup_t and __wasi_fdstat_t
 155   __wasi_fdstat_t fsb_new = {
 156       .fs_flags = oflag & 0xfff,
 157       .fs_rights_base = max & fsb_cur.fs_rights_inheriting,
 158       .fs_rights_inheriting = fsb_cur.fs_rights_inheriting,
 159   };
 160   __wasi_fd_t newfd;
 161   error = __wasi_file_open(lookup, path, strlen(path),
 162                                  (oflag >> 12) & 0xfff, &fsb_new, &newfd);
 163 #else
 164   __wasi_fdflags_t fs_flags = oflag & 0xfff;
 165   __wasi_rights_t fs_rights_base = max & fsb_cur.fs_rights_inheriting;
 166   __wasi_rights_t fs_rights_inheriting = fsb_cur.fs_rights_inheriting;
 167   __wasi_fd_t newfd;
 168   error = __wasi_path_open(fd, lookup_flags, path, strlen(path),
 169                                  (oflag >> 12) & 0xfff,
 170                                  fs_rights_base, fs_rights_inheriting, fs_flags,
 171                                  &newfd);
 172 #endif
 173   if (error != 0) {
 174 #ifdef __wasilibc_unmodified_upstream // split out __wasi_lookup_t
 175     errno = errno_fixup_directory(lookup.fd, error);
 176 #else
 177     errno = errno_fixup_directory(fd, error);
 178 #endif
 179     return -1;
 180   }
 181   return newfd;
 182 }