Hi James, Thanks for documenting that! Please see some comments below. Thanks, Alex On 4/30/21 10:00 PM, Alejandro Colomar wrote: > From: "James O. D. Hunt" <jamesodhunt@xxxxxxxxx> > > Improved the `getopt(3)` man page in the following ways: > > 1) Defined the existing term "legitimate option character". > 2) Added an additional NOTE stressing that arguments are parsed in strict > order and the implications of this when numeric options are utilised. > 3) Added a new WARNINGS section that alerts the reader to the fact they > should: > - Validate all option argument. > - Take care if mixing numeric options and arguments accepting numeric > values. > > Signed-off-by: James O. D. Hunt <jamesodhunt@xxxxxxxxx> > Bugzilla: <https://bugzilla.kernel.org/show_bug.cgi?id=212887> > --- > > I'm only forwarding the patch to the list to better discuss it. > > man3/getopt.3 | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 58 insertions(+), 1 deletion(-) > > diff --git a/man3/getopt.3 b/man3/getopt.3 > index 921e747f8..ec3a5640f 100644 > --- a/man3/getopt.3 > +++ b/man3/getopt.3 > @@ -125,7 +125,13 @@ Then \fIoptind\fP is the index in \fIargv\fP of the first > \fIargv\fP-element that is not an option. > .PP > .I optstring > -is a string containing the legitimate option characters. > +is a string containing the legitimate option characters. A legitimate > +option character is any visible one byte > +.BR ascii (7) > +character (for which > +.BR isgraph (3) > +would return nonzero) that is not the null byte (\(aq\e0\(aq), Is it necessary to mention the null byte ('\0') here? It is already not in the 'visible character' set. I don't think isgraph(3) would return true for it, right? > +dash (\(aq-\(aq) or colon (\(aq:\(aq). So the only visible characters that are invalid are '-' and ':', right? BTW, you should escape the dash: (\(aq\-\(aq) See: $ man 7 man-pages | sed -n '/Generating optimal glyphs/,+19p'; Generating optimal glyphs Where a real minus character is required (e.g., for numbers such as -1, for man page cross references such as utf-8(7), or when writing options that have a leading dash, such as in ls -l), use the following form in the man page source: \- This guideline applies also to code examples. The use of real minus signs serves the following purposes: * To provide better renderings on various targets other than ASCII terminals, notably in PDF and on Uni‐ code/UTF-8‐capable terminals. * To generate glyphs that when copied from rendered pages will produce real minus signs when pasted into a termi‐ nal. > If such a > character is followed by a colon, the option requires an argument, so > .BR getopt () > @@ -402,6 +408,22 @@ routine that rechecks > .B POSIXLY_CORRECT > and checks for GNU extensions in > .IR optstring .) > + $ man 7 man-pages | sed -n '/Formatting conventions (general)/,/^$/p'; Formatting conventions (general) Paragraphs should be separated by suitable markers (usually either .PP or .IP). Do not separate paragraphs using blank lines, as this results in poor rendering in some output formats (such as PostScript and PDF). > +Command-line arguments are parsed in strict order meaning that an option requiring > +an argument will consume the next argument, regardless of whether that > +argument is the correctly specified option argument or simply the next option > +(in the scenario the user mis-specifies the command-line). For example, if $ man 7 man-pages | sed -n '/Use semantic newlines/,/^$/p'; Use semantic newlines In the source of a manual page, new sentences should be started on new lines, and long sentences should split into lines at clause breaks (commas, semicolons, colons, and so on). This convention, sometimes known as "semantic new‐ lines", makes it easier to see the effect of patches, which often operate at the level of individual sentences or sen‐ tence clauses. > +.IR optstring > +is specified as "1n:" > +and the user incorrectly specifies the command-line arguments as > +\(aqprog\ -n\ -1\(aq, the > +.IR \-n Use .I instead of .IR here. $ man 7 groff_man | sed -n '/^ *\.IR italic/,+5p'; .IR italic‐text roman‐text ... Set each argument in italics and roman, alternately. This is the first command of the .IR prologue . $ man 7 groff_man | sed -n '/^ *\.I \[text]/,+16p'; .I [text] Set text in italics. If the macro is given no argu‐ ments, the text of the next input line is set in italics. Use italics for file and path names, for environment variables, for enumeration or preprocessor constants in C, for variable (user‐determined) portions of syntax synopses, for the first occurrence only of a technical concept being introduced, for names of works of software (including commands and functions, but excluding names of operating systems or their kernels), and anywhere a parameter requiring re‐ placement by the user is encountered. An exception involves variable text in a context that is already marked up in italics, such as file or path names with variable components; in such cases, follow the > +option will be given the > +.BR optarg The same as with .I. Use .B here. See groff_man(7). > +value \(aq\-1\(aq, and the > +.IR \-1 > +option will be considered to have not been specified. > + > .SH EXAMPLES > .SS getopt() > The following trivial example program uses > @@ -542,6 +564,41 @@ main(int argc, char **argv) > exit(EXIT_SUCCESS); > } > .EE > + > +.SH WARNINGS > +Since > +.BR getopt () > +allows users to provide values to the program, every care should be taken to > +validate every option value specified by the user calling the program. > +.BR getopt () > +itself provides no validation so the programmer should perform boundary value > +checks on > +.ft I > +every > +.ft Please use: .I every > +argument to minimise the risk of bad input data being accepted by the program. > +String values should be checked to ensure they are not empty (unless > +permitted), sanitized appropriately and that internal buffers used to > +store the string values returned in \fIoptarg\fP are large enough to hold Please avoid embedding formatted text in normal text. Use a separate line: .I optarg > +pathologically long values. Numeric values should be verified to ensure they > +are within the expected permissible range of values. > + > +Further, since > +.BR getopt () > +can handle numeric options (such as \(aq-1\(aq or \(aq-2 foo\(aq), care should be > +taken when writing a program that accepts both a numeric flag option and an option > +accepting a numeric argument. Specifically, the program should sanity check the numeric > +\fIoptarg\fP value carefully to protect against the case where a user > +mis-specifies the command-line which chould result in a numeric option flag > +being specified as the \fIoptarg\fP value for the numeric option by mistake. > +For example, if > +.IR optstring > +is specified as "1n:" and the \(aqn\(aq option accepts a numeric value, if the > +command-line is specified accidentally as \(aqprog\ -n\ -1\(aq, care needs to > +be taken to ensure the program does not try to convert the \(aq-1\(aq passed > +to the \(aqn\(aq option into an unsigned numeric value since that would result > +in it being set to the largest possible integer value for the type used to > +encode it. > .SH SEE ALSO > .BR getopt (1), > .BR getsubopt (3) > -- Alejandro Colomar Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/ http://www.alejandro-colomar.es/
