1.\" $NetBSD: openpam_readword.3,v 1.8 2023/06/30 21:46:20 christos Exp $ 2.\" 3.\" Generated from openpam_readword.c by gendoc.pl 4.Dd June 27, 2023 5.Dt OPENPAM_READWORD 3 6.Os 7.Sh NAME 8.Nm openpam_readword 9.Nd read a word from a file, respecting shell quoting rules 10.Sh SYNOPSIS 11.In sys/types.h 12.In stdio.h 13.In security/pam_appl.h 14.In security/openpam.h 15.Ft "char *" 16.Fn openpam_readword "FILE *f" "int *lineno" "size_t *lenp" 17.Sh DESCRIPTION 18The 19.Fn openpam_readword 20function reads the next word from a file, and 21returns it in a NUL-terminated buffer allocated with 22.Xr malloc 3 . 23.Pp 24A word is a sequence of non-whitespace characters. 25However, whitespace characters can be included in a word if quoted or 26escaped according to the following rules: 27.Bl -bullet 28.It 29An unescaped single or double quote introduces a quoted string, 30which ends when the same quote character is encountered a second 31time. 32The quotes themselves are stripped. 33.It 34Within a single- or double-quoted string, all whitespace characters, 35including the newline character, are preserved as-is. 36.It 37Outside a quoted string, a backslash escapes the next character, 38which is preserved as-is, unless that character is a newline, in 39which case it is discarded and reading continues at the beginning of 40the next line as if the backslash and newline had not been there. 41In all cases, the backslash itself is discarded. 42.It 43Within a single-quoted string, double quotes and backslashes are 44preserved as-is. 45.It 46Within a double-quoted string, a single quote is preserved as-is, 47and a backslash is preserved as-is unless used to escape a double 48quote. 49.El 50.Pp 51In addition, if the first non-whitespace character on the line is a 52hash character (#), the rest of the line is discarded. 53If a hash character occurs within a word, however, it is preserved 54as-is. 55A backslash at the end of a comment does cause line continuation. 56.Pp 57If 58.Fa lineno 59is not 60.Dv NULL , 61the integer variable it points to is 62incremented every time a quoted or escaped newline character is read. 63.Pp 64If 65.Fa lenp 66is not 67.Dv NULL , 68the length of the word (after quotes and 69backslashes have been removed) is stored in the variable it points to. 70.Sh RETURN VALUES 71If successful, the 72.Fn openpam_readword 73function returns a pointer to a 74dynamically allocated NUL-terminated string containing the first word 75encountered on the line. 76.Pp 77The caller is responsible for releasing the returned buffer by passing 78it to 79.Xr free 3 . 80.Pp 81If 82.Fn openpam_readword 83reaches the end of the line or file before any 84characters are copied to the word, it returns 85.Dv NULL . 86In the former 87case, the newline is pushed back to the file. 88.Pp 89If 90.Fn openpam_readword 91reaches the end of the file while a quote or 92backslash escape is in effect, it sets 93.Va errno 94to 95.Dv EINVAL 96and returns 97.Dv NULL . 98.Sh IMPLEMENTATION NOTES 99The parsing rules are intended to be equivalent to the normal POSIX 100shell quoting rules. 101Any discrepancy is a bug and should be reported to the author along 102with sample input that can be used to reproduce the error. 103.Pp 104.Sh SEE ALSO 105.Xr openpam_readline 3 , 106.Xr openpam_readlinev 3 , 107.Xr pam 3 108.Sh STANDARDS 109The 110.Fn openpam_readword 111function is an OpenPAM extension. 112.Sh AUTHORS 113The 114.Fn openpam_readword 115function and this manual page were 116developed by 117.An Dag-Erling Sm\(/orgrav Aq Mt des@des.no . 118