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