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OPENPAM_READWORD(3) NetBSD Library Functions Manual OPENPAM_READWORD(3)
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openpam_readword -- read a word from a file, respecting shell quoting
openpam_readword(FILE *f, int *lineno, size_t *lenp);
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:
· 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.
· Within a single- or double-quoted string, all whitespace characters,
including the newline character, are preserved as-is.
· 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.
· Within a single-quoted string, double quotes and backslashes are pre-
· 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.
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
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.
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.
openpam_readline(3), openpam_readlinev(3), pam(3)
The openpam_readword() function is an OpenPAM extension.
The openpam_readword() function and this manual page were developed by
Dag-Erling Smørgrav <email@example.com>.
NetBSD 10.99 June 27, 2023 NetBSD 10.99