lint(1)

NAME

lint − a C program checker

SYNOPSIS

lint [ −# ] [ −### ] [ −a ] [ −b ] [ −Cfilename ] [ −c ]

[ −dirout=dir ] [ −err=warn ] [ −errchk=l ] [ −errfmt=f ]

[ −errhdr=h ] [ −erroff=t ] [ −errtags=a ]

[ −F ] [ −fd ] [ −flagsrc=file ] [ −h ]

[ −Idir ] [ −k ] [ −Ldir ] [ −lx ] [ −m ]

[ −Ncheck=c ] [ −Nlevel=n ] [ −n ] [ −ox ] [ −p ]

[ −Rfile ] [ −s ] [ −u ] [ −V ] [ −v ] [ −Wfile ]

[ −x ] [ −XCC=a ] [ −Xexplicitpar=a ]

[ −Xkeeptmp=a ] [ −Xtemp=dir ] [ −Xtime=a ]

[ −Xtransition=a ] [ −y ]

files

DESCRIPTION

lint detects features of C program files which are likely to be bugs, non-portable, or wasteful.

lint also checks type usage more strictly than the compiler. lint issues error and warning messages. Among the things it detects are:

•Unreachable statements

•Loops not entered at the top

•Automatic variables declared and not used

•Logical expressions whose value is constant.

lint checks for functions that return values in some places and not in others, functions called with varying numbers or types of arguments, and functions whose values are not used or whose values are used but none returned.

lint can operate in two modes: basic, which is the default for the lint program, and enhanced, which includes everything done by basic lint, plus provides additional, detailed analysis of code.

In enhanced mode, the analysis includes:

•Structure and flow analysis of source program

•Constant propagations and constant expression evaluations

•Analysis of control flow and data flow

•Analysis of data types usages

Thus, lint can detect the following problems in enhanced mode:

•Unused #include directives, variables, and procedures

•Memory usage after its deallocation

•Unused assignments

•Usage of a variable value before its initialization

•Deallocation of non-allocated memory

•Usage of pointers when writing in constant data segment

•Non-equivalent macro redefinitions

•Unreached code

•Nonconformity of the usages of value types in unions

•Implicit casts of actual arguments.

The enhanced mode is enabled by the −Nlevel or −Ncheck options (see descriptions below).

Arguments whose names end with .c are taken to be C source files; arguments ending in .i are taken to be preprocessor output files (produced with the −P option to the compiler).

Arguments whose names end with .ln are taken to be the result of an earlier invocation of lint with either the −C, −c, or the −o option used. The .ln files are analogous to .o (object) files that are produced by the cc(1) command when given a .c file as input. Files with other suffixes are warned about and ignored.

In enhanced mode, lint produces .ln files which store additional information than .ln files produced in basic mode. In enhanced mode, lint can read and understand all .ln files generated by either basic or enhanced lint modes. In basic mode, lint can read and understand .ln files generated only using basic lint mode.

lint takes all the .c, .i, .ln, and llib-lx.ln (specified by −lx) files and processes them in their command-line order. By default, lint appends the standard C lint library (llib-lc.ln) to the end of the list of files. When the −C or −c option is used, the .ln and the llib-lx.ln files are ignored. When the −C or −c option is not used, the second pass of lint checks the .ln and the llib-lx.ln list of files for mutual compatibility.

Any number of lint options may be used, in any order, intermixed with file-name arguments. The lint options are:

−# Show each component as it is invoked (verbose mode).

−###
Show each component as it is invoked, but, unlike the −# option, do not actually execute.

−a Suppress complaints about assignments of long values to variables that are not long.

−b Suppress complaints about break statements that cannot be reached.

−Cfilename
Produce a .ln file with the file name specified by filename . These .ln files are the product of lint’s first pass only. filename can be a complete path name.

−c Cause lint to produce a .ln file for every .c file on the command line. These .ln files are the product of lint’s first pass only, and are not checked for inter-function compatibility.

−dirout=dir
Set a directory name where all lint output files be will be placed. This option affects the −c option.

−err=warn
Treat all warnings as errors. The result is that both warnings and errors cause lint to exit with a failure status.

−errchk=l
Check structural arguments passed by value; Check portability to environment for which the size of long integers and pointers is 64 bits.

l is a comma-separated list of checks that consists of one or more of the following:

structarg Check structural arguments passed by value and report the cases when formal parameter type is not known.

longptr64
Check portability to environment for which the size of long integers and pointers is 64 bits and the size of plain integers is 32 bits. Check assignments of pointer expressions and long integer expressions to plain integers, even when explicit cast is used.

%all Perform all of errchk’s checks.

%none Perform none of errchk’s checks. This is the default.

no%structarg
Perform none of errchk’s structarg checks.

no%longptr64
Perform none of errchk’s longptr64 checks.

The values may be a comma separated list, for example, -errchk=longptr64,structarg.

The default is -errchk=%none. Specifying -errchk is equivalent to specifying -errchk=%all.

−errfmt=f
Specify the format of lint output. f can be one of the following: macro, simple, src, or tab.

The −errfmt values are:

macro Display the source code, the line number, and the place of the error, with macro unfolding.

simple Display the line number and the place number, in brackets, of the error, for one-line (simple) diagnostic messages. Similar to the −s option, but includes error-position information.

src Display the source code, the line number, and the place of the error (no macro unfolding).

tab Display in tabular format.

The default is −errfmt = tab . Specifying −errfmt is equivalent to specifying −errfmt = tab.

If more than one format is specified, the last format specified is used, and lint warns about the unused formats.

−errhdr=h
Enables the reporting of certain messages for header files. h is a comma-separated list that consists of one or more of the following: dir, no%dir, %all, %none, %user.

The −errhdr values are:

dir Check header files used in directory dir.

no%dir Do not check header files used in the directory dir.

%all Check all used header files.

%none Do not check header files. This is the default.

%user Check all used user header files, that is, all header files except those in /usr/include and its subdirectories, as well as those supplied by the compiler.

The default is −errhdr=%none. Specifying −errhdr is equivalent to specifying −errhdr=%user.

−erroff=t
Suppress or enable lint error messages. t is a comma-separated list that consists of one or more of the following: tag, no%tag, %all, %none.

The −erroff values are:

tag Suppress the message specified by this tag.

no%tag Enable the message specified by this tag.

%all Suppress all messages.

%none Enable all messages. This is the default.

The default is −erroff=%none. Specifying −erroff is equivalent to specifying −erroff=%all.

-errtags=a
Display the message tag for each error message. a can be either yes or no. The default is −errtags=no. Specifying −errtags is equivalent to −errtags=yes.

Works with all −errfmt options.

−F Print path names of files. lint normally prints the file name without the path.

−fd Report about old-style function definitions and declarations.

−flagsrc=file
Execute lint with options contained in the file file. Multiple options can be specified in file, one per line.

−h Do not apply heuristic tests that attempt to intuit bugs, improve style, and reduce waste.

−Idir Search for included header files in the directory dir before searching the current directory and/or the standard place.

−k Alter the behavior of /∗LINTED [message]∗/ directives or NOTE(LINTED(message)) annotations. Normally, lint suppresses warning messages for the code following these directives. Instead of suppressing the messages, lint prints an additional message containing the comment inside the directive or annotation.

−Ldir Search for lint libraries in dir before searching the standard place.

−lx Include the lint library llib-lx.ln. For example, you can include a lint version of the math library llib-lm.ln by inserting −lm on the command line. This argument does not suppress the default use of llib-lc.ln. These lint libraries must be in the assumed directory. This option can be used to reference local lint libraries and is useful in the development of multi-file projects.

−m Suppress complaints about external symbols that could be declared static.

−Ncheck=c
Check header files for corresponding declarations; check macros. c is a comma-separated list of checks that consists of one or more of the following:

macro Check for consistency of macro definitions across files.

extern Check for one-to-one correspondence of declarations between source files and their associated header files (for example, for file1.c and file1.h). Ensure that there are neither extraneous nor missing extern declarations in a header file.

%all Perform all of
Ncheck’s checks.

%none Perform none of
Ncheck’s checks. This is the default.

no%macro
Perform none of Ncheck’s macro checks.

no%extern
Perform none of Ncheck’s extern checks.

The values may be combined with a comma, for example, −Ncheck=extern,macro.

The default is −Ncheck=%none. Specifying −Ncheck is equivalent to specifying −Ncheck=%all.

−Nlevel=n
Specify the level of analysis for reporting problems. This option allows you to control the amount of detected errors. The higher the level, the longer the verification time. n is a number: 1, 2, 3, or 4.

−Nlevel=1 Analyze single procedures. Report unconditional errors that occur on some program execution paths. Does not do global data and control flow analysis.

−Nlevel=2 The default. Analyze the whole program, including global data and control flow. Report unconditional errors that occur on some program execution paths.

−Nlevel=3 Analyze the whole program, including constant propagation, cases when constants are used as actual arguments, as well as the analysis performed under −Nlevel=2.

−Nlevel=4 Analyze the whole program, and report conditional errors that could occur when certain program execution paths are used, as well as the analysis performed under −Nlevel=3.

The default is −Nlevel=2. Specifying −Nlevel is equivalent to specifying −Nlevel=2.

−n Do not check compatibility against the standard C lint library.

−ox Cause lint to create a lint library with the name llib-lx.ln. This library is created from all the .ln files that lint used in its second pass. The −c option nullifies any use of the −o option. To produce a llib-lx.ln without extraneous messages, you can use the −x option. The −v option is useful if the source file(s) for the lint library are just external interfaces. The lint library produced can be used later if lint is invoked with the −lx option.

By default, you create libraries in lint’s basic format. If you use lint’s enhanced mode, the library created will be in enhanced format, and can only be used in enhanced mode.

−p Attempt to check portability to other dialects of C. Along with stricter checking, this option causes all non-external names to be truncated to eight characters and all external names to be truncated to six characters and one case.

−Rfile Write a .ln file to file, for use by cxref(1). This option disables the enhanced mode, if it is switched on.

−s Produce one-line diagnostics only. lint occasionally buffers messages to produce a compound report.

−u Suppress complaints about functions and external variables used and not defined, or defined and not used. This option is suitable for running lint on a subset of files of a larger program.

−V Write to standard error the product name and release.

−v Suppress complaints about unused arguments in functions.

−Wfile Write a .ln file to file, for use by cflow(1). This option disables the enhanced mode, if it is switched on.

−x Do not report variables referred to by external declarations but never used.

−XCC=a
Accept C++-style comments. a can be either yes or no. In particular, // can be used to indicate the start of a comment. The default is −XCC=no; specifying −XCC is equivalent to specifying −XCC=yes.

−Xexplicitpar=a
(SPARC) Directs lint to recognize #pragma MP directives. a can be either yes or no. The default is −Xexplicitpar=no; specifying −Xexplicitpar is equivalent to specifying −Xexplicitpar=yes.

−Xkeeptmp=a
Keep temporary files created during linting instead of deleting them automatically. a can be either yes or no. The default is −Xkeeptmp=no; specifying −Xkeeptmp is equivalent to specifying −Xkeeptmp=yes.

−Xtemp=dir
Set the directory for temporary files to dir. Without this option, temporary files go into /tmp.

−Xtime=a
Report the execution time for each lint pass. a can be either yes or no. The default is −Xtime=no; specifying −Xtime is equivalent to specifying −Xtime=yes.

−Xtransition=a
Issue warnings for the differences between K&R C and Sun ANSI C. a can be either yes or no. The default is −Xtransition=no; specifying −Xtransition is equivalent to specifying −Xtransition=yes.

−y Specify that the file being linted be treated as if the /∗LINTLIBRARY∗/ directive or the NOTE(LINTLIBRARY) annotation had been used. A lint library is normally created by using the /∗LINTLIBRARY∗/ directive or the NOTE(LINTLIBRARY) annotation.

lint recognizes many cc (1) command-line options, including −A, −D, −E, −g, −H, −O, −P, −U, −Xa, −Xc, −Xs, −Xt , and −Y , although −g and −O are ignored. Unrecognized options are warned about and ignored. The predefined macro lint is defined to allow certain questionable code to be altered or removed for lint. Thus, the symbol lint should be thought of as a reserved word for all code that is planned to be checked by lint.

lint provides the following predefinition predicate by default (not valid in −Xc mode):

#assert lint (on)

Predefinitions, not valid in −Xc mode:

sun
lint
unix
sparc (SPARC only)
i386 (Intel only)

These predefinitions are valid in all modes:

__sparc (SPARC)
__i386 (Intel)
__unix
__sun
__lint
__‘uname -s‘ ‘_uname -r‘ (example: __SunOS_5_4)
__SVR4
__BUILTIN_VA_ARG_INCR
__SUNPRO_C=0x420
__RESTRICT (-Xa and -Xt modes only)
__LITTLE ENDIAN (PowerPC)
__ppc(PowerPC)

Certain conventional comments in the C source change the behavior of lint:

/∗ARGSUSEDn∗/
makes lint check only the first n arguments for usage; a missing n is taken to be 0 (this directive acts like the −v option for the next function).

/∗CONSTCOND∗/ or /∗CONSTANTCONDITION∗/
suppresses complaints about constant operands for the conditional expression.

/∗EMPTY∗/
suppresses complaints about a null statement consequent on an if statement. This directive should be placed after the test expression, and before the semicolon. This directive is supplied to support empty if statements when a valid else statement follows. It suppresses messages on an empty else consequent.

/∗FALLTHRU∗/ or /∗FALLTHROUGH∗/
suppresses complaints about fall through to a case or default labelled statement. This directive should be placed immediately preceding the label.

/∗LINTED [message]\(∗∗/
suppresses any intra-file warning except those dealing with unused variables or functions. This directive should be placed on the line immediately preceding where the lint warning occurred. The −k option alters the way in which lint handles this directive. Instead of suppressing messages, lint prints an additional message, if any, contained in the comment. This directive is useful in conjunction with the −s option for post-lint filtering.

/∗LINTLIBRARY∗/
when −o is invoked, writes to a library .ln file only definitions in the .c file it heads. This directive suppresses complaints about unused functions and function arguments in this file.

/∗NOTREACHED∗/
at appropriate points stops comments about unreachable code. [This comment is typically placed just after calls to functions like exit(2)].

/∗PRINTFLIKEn∗/
makes lint check the first (n-1) arguments as usual. The nth argument is interpreted as a printf format string that is used to check the remaining arguments.

/∗PROTOLIBn∗/
causes lint to treat function declaration prototypes as function definitions if n is non-zero. This directive can only be used in conjunction with the /∗ LINTLIBRARY ∗/ directive. If n is zero, function prototypes are treated normally.

/∗SCANFLIKEn∗/
makes lint check the first (n-1) arguments as usual. The nth argument is interpreted as a scanf format string that is used to check the remaining arguments.

/∗VARARGSn∗/
suppresses the usual checking for variable numbers of arguments in the following function declaration. The data types of the first n arguments are checked; a missing n is taken to be 0. The use of the ellipsis terminator (...) in the definition is suggested in new or updated code.

lint directives can also be specified in the form of source code annotations, by including the file note.h, for example:

#include <note.h>.

NOTE(ARGSUSED(n))
NOTE(CONSTANTCONDITION)
NOTE(EMPTY)
NOTE(FALLTHROUGH)
NOTE(LINTLIBRARY)
NOTE(LINTED(message))
NOTE(NOTREACHED)
NOTE(PRINTFLIKE(n))
NOTE(PRINTFLIKE(func_name,n))
NOTE(PROTOLIB(n))
NOTE(SCANFLIKE(n))
NOTE(SCANFLIKE(func_name,n))
NOTE(VARARGS(n))
NOTE(VARARGS(func_name,n))

The following two directives can be used only as annotations:

NOTE(ALIGNMENT(func_name,n))
where n=1,2,4,8,16,32,64,128;
makes lint set following function result alignment in n bytes. For example, malloc() is defined as returning a char∗ or void∗ when in fact it really returns pointers that are word (or even doubleword) aligned.

NOTE(ARGUNUSED(par_name[,par_name...]))
makes lint not check the mentioned arguments for usage (this option acts only for the next function).

lint can, with certain options, show precise source file lines with pointers to the line position where the error occurred. The option enabling this feature is
−errfmt=[macro|simple|src|tab]. Under this option, lint provides the following information:

•Source line(s) and position(s)

•Macro unfolding

•Error-prone stack(s)

lint produces its first output on a per-source-file basis. Complaints regarding included files are collected and printed after all source files have been processed, if −s is not specified. Finally, if the −C or −c option is not used, information gathered from all input files is collected and checked for consistency. At this point, if it is not clear whether a complaint stems from a given source file or from one of its included files, the source filename is printed followed by a question mark.

The behavior of the −C, −c, and the −o options allows for incremental use of lint on a set of C source files. Generally, one invokes lint once for each source file with the −C or −c option. Each of these invocations produces a .ln file that corresponds to the .c file, and prints all messages that are about just that source file. After all the source files have been separately run through lint, it is invoked once more (without the −C or −c option), listing all the .ln files with the needed −lx options. This prints all the inter-file inconsistencies. This scheme works well with make; it allows make to be used to lint only the source files that have been modified since the last time the set of source files were linted.

ENVIRONMENT

TMPDIR usually /tmp but can be redefined by setting the environment variable TMPDIR [see tempnam in tmpnam(3S)].

NOTEPATH Colon separated paths of directories containing note definition files (see C User’s Guide)

FILES

lint[12] first and second passes

lint2n enhanced second pass

llib-lc.ln declarations for C Library functions (binary format)

TMPDIR/∗lint∗ temporaries

Museum