.\" (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands. .\" See the copyright notice in the ACK home directory, in the file "Copyright". .\" .\" $Header$ .TH LINT 1 "$Revision$" .SH NAME lint \- a C program checker .SH SYNOPSIS .B lint [ \-abhuvx \-KR -ansi ] [file | libname | \-l\fIxxx\fP ] ... .br .B lint \-L\fIlibname\fP [ file | libname2 | \-l\fIxxx\fP ] ... .br .SH DESCRIPTION .I Lint does an extensive consistency and plausibility check on a set of C program files. When it detects a doubtful construction (which need not be an error) it gives a warning. .PP It does a full flow-of-control check, except that .BR goto s are not followed and that the fact that a function never returns is not propagated. If, however, no .BR goto s are used, each call of a non-returning function is followed by /*NOTREACHED*/ and each switch has a default clause (possibly consisting of /*NOTREACHED*/), the initialization state of all local variables will be checked correctly. .PP .I Lint checks the types of the arguments implied by the format in a call of .IR printf() , .IR scanf() and family, if the format string is a direct argument in the call. Formats of user functions can be indicated using a FORMAT pseudo-comment; see below. .PP .I Libraries .PP The second command (using the .BR \-L -option) is used to maintain lint libraries; these are ASCII files that contain the output of the first pass. A library name ends in .BR .llb . A lint user library can be created and updated by using the .B \-L option. The .I libname end in .BR .llb , and can be passed to .I lint again as a normal argument. .PP Standard libraries are searched by default or by explicitly giving the .B \-l option; their format is identical to that of the user library files. Possibilities are .BR \-lm , .B \-ltermcap and .BR \-lcurses . .B \-lc is default; a single .B \-l tells .I lint not to use the standard C library. The standard libraries are searched for in the standard lint directory or in the directory given in the environment variable LINTLIB, if present. .PP .I Options .PP The .BR \-D , .B \-U and .B \-I options are recognized as separate arguments and conform to those of .IR cc . The .B \-KR option tells .I lint to check strictly according to Kernighan & Ritchie; since .I lint is trying to be helpful rather than obnoxious, this is not the default. The .B \-ansi option tells lint to check according to ANSI C. .PP .I Lint understands the following additional options: .TP .B a Warn about conversions that may cause a loss of precision. .TP .B b Do not report not-reachable .I break statements. This flag may be useful when .I lint is run on a generated source file. .TP .B h Apply several heuristics: signal "null effects", possible pointer alignment problems and odd constructs; report definitions of variables that have a scope wider than necessary: extern variables that are used in one file only, automatic variables that could be more local. .TP .B u Do not complain about unused and undefined functions and global variables. .TP .B v Do not warn about unused arguments of functions. .TP .B x Complain about unused external variables. .PP .I Pseudo-comments .PP The following pseudo-comments can be used to influence the behaviour of .IR lint: .TP /*\ ARGSUSED\ */ Do not warn about arguments not used in the next function (see also the \-\fBv\fR option). .TP /*\ NOTREACHED\ */ This tells .I lint that the flow of control "cannot reach" this comment. This is a way to tell .I lint that a statement never "returns". .TP /*\ LINTLIBRARY\ */ The definitions following this pseudo-comment are assumed to be part of a library. It suppresses complaints about unused functions and variables and is used in the creation of lint libraries. It implies /*\ ARGSUSED\ */. .TP /*\ VARARGS\fIn\fR\ */ The next function can be called with a variable number of arguments. Only check the types of the first \fIn\fR arguments. The \fIn\fR must follow the word VARARGS immediately. /*\ VARARGS0\ */ may be abbreviated to /*\ VARARGS\ */. .TP /*\ FORMAT\fIn\fR $ ... $\ */ The \fIn\fP-th argument (counting from 0) of the next function declaration corresponds to a .IR printf -like format string. Details about the format are given between the $$; see below. A missing $$ repeats the latest format. The \fIn\fR must follow the word FORMAT immediately. /*\ FORMAT\fIn\fR $ ... $\ */ implies /*\ VARARGS\fIn+1\fP\ */; if the format is followed by more required arguments, a separate /*\ VARARGS\fIm\fP\ */ must be given after the FORMAT pseudo-comment. .IP If the printf-like heading also has to conform to some varargs.h convention, error messages may result; these can be suppressed by appending the letter v to the word FORMAT\fIn\fR without intervening space. .PP .I Formats .PP The $$-part of the FORMAT pseudo-comment consists of a list of format specifications, each of the form .IR %T = type , where .I T is an arbitrary (short) string and .I type is the expected type in "C normal form" (like in a cast, with no superfluous parentheses and without the use of typedefs). E.g., %ld=long indicates that the format string ld corresponds to a parameter of type long. For a shorter notation see the example below. .I Lint recognizes conversion specifications of the form %[N|*|][.[N|*]]T where N is a number, the * is itself and T is a string as defined above. For the above example this would include %ld, %5.2ld, %.*ld, etc. .PP Example: the FORMAT pseudo-comment for .I printf() is: .br /*\ FORMAT0 $ .br %[dox] = int %l[dox] = long %[DOX] = long .br %u = unsigned int %lu = unsigned long %U = unsigned long .br %[feg] = double .br %c = int %s = char * .br $\ */ .PP .I Output .PP Some users feel it is a good idea to pipe the output of .I lint through the command .br sort \-t' ' +0d \-1 +2n \-3 .br where the character between the apostrophes is a space. .SH "ENVIRONMENT VARIABLES" LINTFLAGS additional flag arguments (e.g. LINTFLAGS=\-h) .br LINTLIB directory in which the standard libraries are looked up .SH FILES .IP ???/lnt 24 first pass .IP ???/lpass2/lpass2 second pass .IP ???/llib/*.llb lint libraries .SH SEE ALSO cem(1) .br Frans Kunst, .I Lint, a C Program Checker .SH BUGS Conflicting options in the command line are not detected. .br After a label, all automatic variables are assumed initialized. .SH AUTHOR Frans Kunst, Vrije Universiteit, Amsterdam. .br Dick Grune, Vrije Universiteit, Amsterdam. .br