split_nameval.c

[詳解]

/*++
/* NAME
/*  split_nameval 3
/* SUMMARY
/*  name-value splitter
/* SYNOPSIS
/*  #include <split_nameval.h>
/*
/*  const char *split_nameval(buf, name, value)
/*  char    *buf;
/*  char    **name;
/*  char    **value;
/* DESCRIPTION
/*  split_nameval() takes a logical line from readlline() and expects
/*  text of the form "name = value" or "name =". The buffer
/*  argument is broken up into name and value substrings.
/*
/*  Arguments:
/* .IP buf
/*  Result from readlline() or equivalent. The buffer is modified.
/* .IP name
/*  Upon successful completion, this is set to the name
/*  substring.
/* .IP value
/*  Upon successful completion, this is set to the value
/*  substring.
/* FEATURES
/* SEE ALSO
/*  dict(3) mid-level dictionary routines
/* BUGS
/* DIAGNOSTICS
/*  Fatal errors: out of memory.
/*
/*  The result is a null pointer in case of success, a string
/*  describing the error otherwise: missing '=' after attribute
/*  name; missing attribute name.
/* 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 <ctype.h>
#include <string.h>

/* Utility library. */

#include <msg.h>
#include <stringops.h>

/* split_nameval - split text into name and value */

const char *split_nameval(char *buf, char **name, char **value)
{
    char   *np;             /* name substring */
    char   *vp;             /* value substring */
    char   *cp;
    char   *ep;

    /*
     * Ugly macros to make complex expressions less unreadable.
     */
#define SKIP(start, var, cond) do { \
    for (var = start; *var && (cond); var++) \
        /* void */; \
    } while (0)

#define TRIM(s) do { \
    char *p; \
    for (p = (s) + strlen(s); p > (s) && ISSPACE(p[-1]); p--) \
        /* void */; \
    *p = 0; \
    } while (0)

    SKIP(buf, np, ISSPACE(*np));        /* find name begin */
    if (*np == 0)
    return ("missing attribute name");
    SKIP(np, ep, !ISSPACE(*ep) && *ep != '=');  /* find name end */
    SKIP(ep, cp, ISSPACE(*cp));         /* skip blanks before '=' */
    if (*cp != '=')             /* need '=' */
    return ("missing '=' after attribute name");
    *ep = 0;                    /* terminate name */
    cp++;                   /* skip over '=' */
    SKIP(cp, vp, ISSPACE(*vp));         /* skip leading blanks */
    TRIM(vp);                   /* trim trailing blanks */
    *name = np;
    *value = vp;
    return (0);
}