openpam_readword.3 revision 1.4
1<<<<<<< openpam_readword.3 2.\" $NetBSD: openpam_readword.3,v 1.4 2014/10/24 18:17:56 christos Exp $ 3.\" 4======= 5>>>>>>> 1.1.1.3 6.\" Generated from openpam_readword.c by gendoc.pl 7.\" Id: openpam_readword.c 648 2013-03-05 17:54:27Z des 8.Dd September 12, 2014 9.Dt OPENPAM_READWORD 3 10.Os 11.Sh NAME 12.Nm openpam_readword 13.Nd read a word from a file, respecting shell quoting rules 14.Sh LIBRARY 15.Lb libpam 16.Sh SYNOPSIS 17.In sys/types.h 18.In stdio.h 19.In security/pam_appl.h 20.In security/openpam.h 21.Ft "char *" 22.Fn openpam_readword "FILE *f" "int *lineno" "size_t *lenp" 23.Sh DESCRIPTION 24The 25.Fn openpam_readword 26function reads the next word from a file, and 27returns it in a NUL-terminated buffer allocated with 28.Xr malloc 3 . 29.Pp 30A word is a sequence of non-whitespace characters. 31However, whitespace characters can be included in a word if quoted or 32escaped according to the following rules: 33.Bl -bullet 34.It 35An unescaped single or double quote introduces a quoted string, 36which ends when the same quote character is encountered a second 37time. 38The quotes themselves are stripped. 39.It 40Within a single- or double-quoted string, all whitespace characters, 41including the newline character, are preserved as-is. 42.It 43Outside a quoted string, a backslash escapes the next character, 44which is preserved as-is, unless that character is a newline, in 45which case it is discarded and reading continues at the beginning of 46the next line as if the backslash and newline had not been there. 47In all cases, the backslash itself is discarded. 48.It 49Within a single-quoted string, double quotes and backslashes are 50preserved as-is. 51.It 52Within a double-quoted string, a single quote is preserved as-is, 53and a backslash is preserved as-is unless used to escape a double 54quote. 55.El 56.Pp 57In addition, if the first non-whitespace character on the line is a 58hash character (#), the rest of the line is discarded. 59If a hash character occurs within a word, however, it is preserved 60as-is. 61A backslash at the end of a comment does cause line continuation. 62.Pp 63If 64.Fa lineno 65is not 66.Dv NULL , 67the integer variable it points to is 68incremented every time a quoted or escaped newline character is read. 69.Pp 70If 71.Fa lenp 72is not 73.Dv NULL , 74the length of the word (after quotes and 75backslashes have been removed) is stored in the variable it points to. 76.Sh RETURN VALUES 77If successful, the 78.Fn openpam_readword 79function returns a pointer to a 80dynamically allocated NUL-terminated string containing the first word 81encountered on the line. 82.Pp 83The caller is responsible for releasing the returned buffer by passing 84it to 85.Xr free 3 . 86.Pp 87If 88.Fn openpam_readword 89reaches the end of the line or file before any 90characters are copied to the word, it returns 91.Dv NULL . 92In the former 93case, the newline is pushed back to the file. 94.Pp 95If 96.Fn openpam_readword 97reaches the end of the file while a quote or 98backslash escape is in effect, it sets 99.Va errno 100to 101.Dv EINVAL 102and returns 103.Dv NULL . 104.Sh IMPLEMENTATION NOTES 105The parsing rules are intended to be equivalent to the normal POSIX 106shell quoting rules. 107Any discrepancy is a bug and should be reported to the author along 108with sample input that can be used to reproduce the error. 109.Pp 110.Sh SEE ALSO 111.Xr openpam_readline 3 , 112.Xr openpam_readlinev 3 , 113.Xr pam 3 114.Sh STANDARDS 115The 116.Fn openpam_readword 117function is an OpenPAM extension. 118.Sh AUTHORS 119The 120.Fn openpam_readword 121function and this manual page were 122developed by 123.An Dag-Erling Sm\(/orgrav Aq Mt des@des.no . 124