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The
function checks the accessibility of the file named by for the access
permissions indicated by The value of is the bitwise inclusive OR of
the access permissions to be checked for read permission, for write permission
and for execute/search permission) or the existence test, All components
of the pathname are checked for access permissions (including The real
user ID is used in place of the effective user ID and the real group access
list (including the real group ID) are used in place of the effective ID
for verifying permission. Even if a process has appropriate privileges
and indicates success for the file may not actually have execute permission
bits set. Likewise for and
If cannot be found or if any
of the desired access modes would not be granted, then a -1 value is returned;
otherwise a 0 value is returned.
Access to the file is denied if:
A component of the path prefix is not a directory. A component of a pathname
exceeded characters, or an entire path name exceeded characters. The
named file does not exist. Too many symbolic links were encountered in
translating the pathname. Write access is requested for a file on a read-only
file system. Write access is requested for a pure procedure (shared text)
file presently being executed. Permission bits of the file mode do not
permit the requested access, or search permission is denied on a component
of the path prefix. The owner of a file has permission checked with respect
to the ‘‘owner’’ read, write, and execute mode bits, members of the file’s group
other than the owner have permission checked with respect to the ‘‘group’’
mode bits, and all others have permissions checked with respect to the
‘‘other’’ mode bits. points outside the process’s allocated address space.
An I/O error occurred while reading from or writing to the file system.
The function conforms to
is a potential security
hole and should never be used.
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