Open System Services System Calls Reference Manual (G06.25+, H06.03+)

System Functions (a - d) access(2)

NAME

access - Determines the accessibility of a ﬁle

LIBRARY

G-series native OSS processes: system library

H-series OSS processes: implicit libraries

SYNOPSIS

#include <unistd.h>

int access(

const char *path,

int access_mode);

PARAMETERS

path Points to the ﬁle pathname. When the path parameter refers to a symbolic link,

the access() function returns information about the ﬁle pointed to by the sym-

bolic link.

Permission to access all components of the path parameter is determined by

using a real user ID instead of an effective user ID, and by using a real group ID

instead of an effective group ID.

access_mode Speciﬁes the type of access. The bit pattern contained in the access_mode

parameter is constructed by a logical OR of values from the following list:

F_OK Checks to see whether the ﬁle exists.

R_OK Checks read permission.

W_OK Checks write permission.

X_OK Checks execute (search) permission.

DESCRIPTION

The access() function checks the accessibility of a ﬁle speciﬁed by a pathname.

Only access bits are checked. A directory can be indicated as writable by access(), but an

attempt to open it for writing could fail (although ﬁles can be created there).

To override the ﬁle access control mechanism, a process must have a user ID of the super ID.

Files in the Guardian File System

If the speciﬁed pathname resolves to the /G directory itself, the calling process has read and exe-

cute access but not write access. The permissions are "r-xr-xr-x".

If the speciﬁed pathname resolves to a Guardian process name, the calling process has execute

access but not read or write access. The permissions are "--x--x--x".

If the speciﬁed pathname resolves to a Guardian disk volume or subvolume, then the calling pro-

cess has read, write, and execute access. The permissions are "rwxrwxrwx".

If the speciﬁed pathname resolves to a regular Guardian disk ﬁle, then Guardian standard secu-

rity and Safeguard ﬁle-level protection govern access. Refer to the stat(2) reference page for

more information.

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