diff options
| -rw-r--r-- | libbutl/filesystem.cxx | 83 | ||||
| -rw-r--r-- | libbutl/filesystem.mxx | 21 |
2 files changed, 51 insertions, 53 deletions
diff --git a/libbutl/filesystem.cxx b/libbutl/filesystem.cxx index d453006..ea084b9 100644 --- a/libbutl/filesystem.cxx +++ b/libbutl/filesystem.cxx @@ -909,52 +909,53 @@ namespace butl { using namespace win32; - if (!dir) - { - // Try to create a regular symbolic link without elevated privileges by - // passing the new SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE flag. - // The flag is new and it may not be defined at compile-time so we pass - // its literal value. - // - // We may also be running on an earlier version of Windows (before 10 - // build 14972) that doesn't support it. The natural way to handle that - // would have been to check the build of Windows that we are running on - // but that turns out to not be that easy (requires a deprecated API, - // specific executable manifest setup, a dance on one leg, and who knows - // what else). - // - // So instead we are going to just make the call and if the result is - // the invalid argument error, assume that the flag is not recognized. - // Except that this error can also be returned if the link path or the - // target path are invalid. So if we get this error, we also stat the - // two paths to make sure we don't get the same error for them. - // - if (CreateSymbolicLinkA (link.string ().c_str (), - target.string ().c_str (), - 0x2)) - return; + // Try to create a symbolic link without elevated privileges by passing + // the new SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE flag. The flag is + // new and it may not be defined at compile-time so we pass its literal + // value. + // + // We may also be running on an earlier version of Windows (before 10 + // build 14972) that doesn't support it. The natural way to handle that + // would have been to check the build of Windows that we are running on + // but that turns out to not be that easy (requires a deprecated API, + // specific executable manifest setup, a dance on one leg, and who knows + // what else). + // + // So instead we are going to just make the call and if the result is the + // invalid argument error, assume that the flag is not recognized. Except + // that this error can also be returned if the link path or the target + // path are invalid. So if we get this error, we also stat the two paths + // to make sure we don't get the same error for them. + // + if (CreateSymbolicLinkA (link.string ().c_str (), + target.string ().c_str (), + 0x2 | (dir ? SYMBOLIC_LINK_FLAG_DIRECTORY : 0))) + return; - // Note that ERROR_INVALID_PARAMETER means that either the function - // doesn't recognize the SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE - // flag (that happens on elder systems) or the target or link paths are - // invalid. Thus, we additionally check the paths to distinguish the - // cases. - // - if (GetLastError () == ERROR_INVALID_PARAMETER) + // Note that ERROR_INVALID_PARAMETER means that either the function + // doesn't recognize the SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE + // flag (that happens on elder systems) or the target or link paths are + // invalid. Thus, we additionally check the paths to distinguish the + // cases. + // + if (GetLastError () == ERROR_INVALID_PARAMETER) + { + auto invalid = [] (const path& p) { - auto invalid = [] (const path& p) - { - return GetFileAttributesA (p.string ().c_str ()) == - INVALID_FILE_ATTRIBUTES && - GetLastError () == ERROR_INVALID_PARAMETER; - }; + return GetFileAttributesA (p.string ().c_str ()) == + INVALID_FILE_ATTRIBUTES && + GetLastError () == ERROR_INVALID_PARAMETER; + }; - if (invalid (target) || invalid (link)) - throw_generic_error (EINVAL); - } + if (invalid (target) || invalid (link)) + throw_generic_error (EINVAL); + } + // Fallback to creating a junction if we failed to create a directory + // symlink and bail out for a file symlink. + // + if (!dir) throw_generic_error (ENOSYS, "file symlinks not supported"); - } // Create as a junction. // diff --git a/libbutl/filesystem.mxx b/libbutl/filesystem.mxx index 186c9db..5bb1ac2 100644 --- a/libbutl/filesystem.mxx +++ b/libbutl/filesystem.mxx @@ -248,18 +248,15 @@ LIBBUTL_MODEXPORT namespace butl // Developer Mode enabled or if the process runs in the elevated command // prompt. // - // - Directory symlinks are implemented via the Windows junction mechanism - // that doesn't require a process to have administrative privileges and so - // a junction can be created regardless of the Windows version and mode. - // Note that junctions, in contrast to symlinks, may only store target - // absolute paths. Thus, when create a directory symlink we complete its - // target path against the current directory (unless it is already - // absolute) and normalize. - // - // (@@ TODO: At some point we may want to support creating directory - // symlinks if possible and falling back to junctions otherwise. One - // potential issue here is with relative target paths which the caller - // cannot rely on staying relative.) + // - Directory symlinks are implemented via the Windows symlink mechanism if + // possible (see above) and via the Windows junction mechanism otherwise. + // Note that creating a junction doesn't require a process to have + // administrative privileges and so succeeds regardless of the Windows + // version and mode. Also note that junctions, in contrast to symlinks, + // may only store target absolute paths. Thus, when create a junction we + // complete its target path against the current directory (unless it is + // already absolute) and normalize, which makes it impossible for a + // mksymlink() caller to rely on target path staying relative. // // - Functions other than mksymlink() fully support symlinks, considering // the Windows file symlinks (file-type reparse points referring to files) |