Manual Pages  — REL2ABS

rel2abs – make an absolute path name from a relative path name

SYNOPSIS DESCRIPTION RETURN VALUES EXAMPLES ERRORS SEE ALSO AUTHORS

char *
rel2abs(const char *path, const char *base, char *result, size_t size);

The rel2abs() function makes an absolute path name from a relative path name path based on a directory base and copies the resulting path name into the memory referenced by result. The result argument must refer to a buffer capable of storing at least size character

The resulting path name may include symbolic links. abs2rel() doesn't check whether or not any path exists.

The rel2abs() function returns absolute path name on success. If an error occurs, it returns NULL.

char result[MAXPATHLEN];
char *path = rel2abs("../../src/sys", "/usr/local/lib", result, MAXPATHLEN);

yields:

path == "/usr/src/sys"

Similarly,

path1 = rel2abs("src/sys", "/usr", result, MAXPATHLEN);
path2 = rel2abs(".", "/usr/src/sys", result, MAXPATHLEN);

yields:

path1 == "/usr/src/sys"
path2 == "/usr/src/sys"

The rel2abs() function may fail and set the external variable errno to indicate the error.

[EINVAL]
	The base directory isn't an absolute path name or the size argument is zero.
[ERANGE]
	The size argument is greater than zero but smaller than the length of the pathname plus 1

Shigio Yamaguchi (shigio@tamacom.com)