NAME

mkstr − extract error messages from C source into a file

SYNOPSIS

mkstr [ − ] messagefile prefix file ... 

DESCRIPTION

Mkstr examines a C program and creates a file containing error message strings used by the program.  Programs with many error diagnostics can be made much smaller by referring to places in the file, and reduce system overhead in running the program. 

Mkstr processes each of the specified files, placing a revised version of each in a file whose name consists of the specified prefix concatenated in front of the original name.  A typical usage of mkstr would be

mkstr mystrings xx *.c

This command would cause all the error messages from the C source files in the current directory to be placed in the file mystrings and revised copies of the source for these files to be placed in files whose names are prefixed with xx. 

When processing the error messages in the source for transfer to the message file, mkstr searches for the string error(" in the input file.  Each time it is encountered, the C string starting after the leading quote is placed in the message file, followed by a null character and a new-line character.  The null character terminates the message so that it can be easily used when retrieved, and the new-line character makes it possible to conveniently cat the error message file to review its contents. 

The modified copy of the input file is identical to the original, except that each occurrence of any string that was moved to the error message file is replaced by an offset pointer usable by lseek to retrieve the message. 

If the command line includes the optional −, extracted error messages are placed at the end of the specified message file instead of overwriting it.  This enables you to process individual files that are part of larger programs that have been previously processed by mkstr without reprocessing all the files. 

All functions used by the original program whose names end in "error" that also can take a constant string as their first argument should be rewritten so that they search for the string in the error message file. 

For example, a program based on the previous example usage would resemble the following:

 #include <stdio.h>
#include <sys/types.h>
#include <fcntl.h>
 char errfile[] = "mystrings";
 error(offset, a2, a3, a4)
int offset, a1, a2, a3;
{
    char msg[256];
    static int fd = -1;
 if (fd < 0) {
    fd = open(errfile, O_RDONLY);
    if (fd < 0) {
perror(errfile);
exit(1);
    }
}
 if (lseek(fd, (off_t) offset, 0) || read(fd, msg, 256) <= 0) {
    printf("? Can’t find error message in %s:\n", errfile);
    perror(errfile);
    exit(1);
}
 printf(msg, a1, a2, a3);
}

SEE ALSO

lseek(2), perror(3C), xstr(1). 

BUGS

Strings in calls to functions whose names end in ’error’, notably perror(3C), may be replaced with offsets by mkstr.

Calls to error functions whose first argument is not a string constant are left unmodified without warning. 

Hewlett-Packard Company  —  Version B.1,  May 11, 2021