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OPENPAM_READWORD(3)    FreeBSD Library Functions Manual	   OPENPAM_READWORD(3)

NAME
     openpam_readword -- read a	word from a file, respecting shell quoting
     rules

LIBRARY
     Pluggable Authentication Module Library (libpam, -lpam)

SYNOPSIS
     #include <sys/types.h>
     #include <stdio.h>
     #include <security/pam_appl.h>
     #include <security/openpam.h>

     char *
     openpam_readword(FILE *f, int *lineno, size_t *lenp);

DESCRIPTION
     The openpam_readword() function reads the next word from a	file, and
     returns it	in a NUL-terminated buffer allocated with malloc(3).

     A word is a sequence of non-whitespace characters.	 However, whitespace
     characters	can be included	in a word if quoted or escaped according to
     the following rules:

     +o	 An unescaped single or	double quote introduces	a quoted string, which
	 ends when the same quote character is encountered a second time.  The
	 quotes	themselves are stripped.

     +o	 Within	a single- or double-quoted string, all whitespace characters,
	 including the newline character, are preserved	as-is.

     +o	 Outside a quoted string, a backslash escapes the next character,
	 which is preserved as-is, unless that character is a newline, in
	 which case it is discarded and	reading	continues at the beginning of
	 the next line as if the backslash and newline had not been there.  In
	 all cases, the	backslash itself is discarded.

     +o	 Within	a single-quoted	string,	double quotes and backslashes are pre-
	 served	as-is.

     +o	 Within	a double-quoted	string,	a single quote is preserved as-is, and
	 a backslash is	preserved as-is	unless used to escape a	double quote.

     In	addition, if the first non-whitespace character	on the line is a hash
     character (#), the	rest of	the line is discarded.	If a hash character
     occurs within a word, however, it is preserved as-is.  A backslash	at the
     end of a comment does cause line continuation.

     If	lineno is not NULL, the	integer	variable it points to is incremented
     every time	a quoted or escaped newline character is read.

     If	lenp is	not NULL, the length of	the word (after	quotes and backslashes
     have been removed)	is stored in the variable it points to.

RETURN VALUES
     If	successful, the	openpam_readword() function returns a pointer to a
     dynamically allocated NUL-terminated string containing the	first word
     encountered on the	line.

     The caller	is responsible for releasing the returned buffer by passing it
     to	free(3).

     If	openpam_readword() reaches the end of the line or file before any
     characters	are copied to the word,	it returns NULL.  In the former	case,
     the newline is pushed back	to the file.

     If	openpam_readword() reaches the end of the file while a quote or	back-
     slash escape is in	effect,	it sets	errno to EINVAL	and returns NULL.

IMPLEMENTATION NOTES
     The parsing rules are intended to be equivalent to	the normal POSIX shell
     quoting rules.  Any discrepancy is	a bug and should be reported to	the
     author along with sample input that can be	used to	reproduce the error.

SEE ALSO
     openpam_readline(3), openpam_readlinev(3),	pam(3)

STANDARDS
     The openpam_readword() function is	an OpenPAM extension.

AUTHORS
     The openpam_readword() function and this manual page were developed by
     Dag-Erling	Smorgrav <des@des.no>.

FreeBSD	9.3		       September 7, 2013		   FreeBSD 9.3

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | IMPLEMENTATION NOTES | SEE ALSO | STANDARDS | AUTHORS

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