percentm.c

[詳解]

/*++
/* NAME
/*  percentm 3
/* SUMMARY
/*  expand %m embedded in string to system error text
/* SYNOPSIS
/*  #include <percentm.h>
/*
/*  char    *percentm(const char *src, int err)
/* DESCRIPTION
/*  The percentm() routine makes a copy of the null-terminated string
/*  given via the \fIsrc\fR argument, with %m sequences replaced by
/*  the system error text corresponding to the \fIerr\fR argument.
/*  The result is overwritten upon each successive call.
/*
/*  Arguments:
/* .IP src
/*  A null-terminated input string with zero or more %m sequences.
/* .IP err
/*  A legal \fIerrno\fR value. The text corresponding to this error
/*  value is used when expanding %m sequences.
/* SEE ALSO
/*  syslog(3) system logger library
/* HISTORY
/* .ad
/* .fi
/*  A percentm() routine appears in the TCP Wrapper software
/*  by Wietse Venema.
/* LICENSE
/* .ad
/* .fi
/*  The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*  Wietse Venema
/*  IBM T.J. Watson Research
/*  P.O. Box 704
/*  Yorktown Heights, NY 10598, USA
/*--*/

/* System libraries. */

#include <sys_defs.h>
#include <string.h>

/* Utility library. */

#include "vstring.h"
#include "percentm.h"

/* percentm - replace %m by error message corresponding to value in err */

char   *percentm(const char *str, int err)
{
    static VSTRING *vp;
    const unsigned char *ip = (const unsigned char *) str;

    if (vp == 0)
    vp = vstring_alloc(100);        /* grows on demand */
    VSTRING_RESET(vp);

    while (*ip) {
    switch (*ip) {
    default:
        VSTRING_ADDCH(vp, *ip++);
        break;
    case '%':
        switch (ip[1]) {
        default:                /* leave %<any> alone */
        VSTRING_ADDCH(vp, *ip++);
        /* FALLTHROUGH */
        case '\0':              /* don't fall off end */
        VSTRING_ADDCH(vp, *ip++);
        break;
        case 'm':               /* replace %m */
        vstring_strcat(vp, strerror(err));
        ip += 2;
        break;
        }
    }
    }
    VSTRING_TERMINATE(vp);
    return (vstring_str(vp));
}