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readlink
Reads the value of a symbolic link.
Syntax
#include <unistd.h>
init readlink(const char *path, char *buf, size_t bufsiz);
Parameters
path The pathname of a file.
buf Points to the region of memory where confstr() stores the
string value of the variable indicated by name.
len Is the maximum number of characters that can be placed in buf.
If this is not enough to hold the complete string value of
name, confstr() truncates the string value to len-1 characters
and appends a null terminator (the \0 character).
Return Values
Upon successful completion, the readlink() function will return the
number of bytes placed in the buffer when bufsiz is greater than zero, or
the number of bytes contained in the symbolic link when bufsiz is equal
to zero. If the return value is equal to bufsiz, the buffer need not
contain the entire contents of the symbolic link; for bufsiz can be used
to determine the size of the contents of the symbolic link. If the
readlink() function is unsuccessful, a value of -1 will be returned and
errno will be set to indicate the error.
Description
The readlink function will place the contents of the symbolic link, path,
in the buffer buf, which has size bufsiz. The contents of the returned
symbolic link will not include a null terminator. As a special case, if
the value of bufsiz is 0, no change will occur to the buffer buf and
readlink() will return the number of bytes contained in the symbolic
link.
Implementation Considerations
None.
Errors
If an error occurs, errno is set to one of the following values:
EACCES CAUSE One of the following:
* The calling process does not have search
permission to a component of the pathname.
* The calling process does not have execute
permission to the file.
ACTION One of the following:
* Make sure that the calling process has search
permission to all components of the pathname.
* Make sure that the calling process has execute
permission to the file.
ENAMETOOLONG CAUSE One of the following:
* The length of the pathname exceeds the
{PATH_MAX} limit (defined in the file
<limits.h>).
* A component of the pathname is longer than
{NAME_MAX} (defined in <limits.h>), and
{_POSIX_NO_TRUNC} is in effect for that
directory.
ACTION Make sure that both the component's length and the
full pathname length do not exceed the {NAME_MAX} or
{PATH_MAX} limits.
ENOTDIR CAUSE A component of the pathname is not a directory.
ACTION Specify a valid pathname.
Table 4-0. (cont.)
ELOOP CAUSE A loop exists in symbolic links encountered during
resolution of the path argument. This error may be
returned if more than {POSIX_SYMLOOP} symbolic links
are encountered during resolution of the path
argument.
ACTION Make sure that there is not a loop in the symbolic
links that loops more than POSIX_SYMLOOP.
ENOENT CAUSE a component of the pathname for the executable file
does not exist, ot pathname points to an empty
string.
ACTION Specify a valid pathname.
See Also
stat(), lstat(), symlink()