extpar.c

[詳解]

/*++
/* NAME
/*  extpar 3
/* SUMMARY
/*  extract text from parentheses
/* SYNOPSIS
/*  #include <stringops.h>
/*
/*  char    *extpar(bp, parens, flags)
/*  char    **bp;
/*  const char *parens;
/*  int flags;
/* DESCRIPTION
/*  extpar() extracts text from an input string that is enclosed
/*  in the specified parentheses, and updates the buffer pointer
/*  to point to that text.
/*
/*  Arguments:
/* .IP bp
/*  Pointer to buffer pointer. Both the buffer and the buffer
/*  pointer are modified.
/* .IP parens
/*  One matching pair of parentheses, opening parenthesis first.
/* .IP flags
/*  EXTPAR_FLAG_NONE, or the bitwise OR of one or more flags:
/* .RS
/* .IP EXTPAR_FLAG_EXTRACT
/*  This flag is intended to instruct expar() callers that
/*  expar() should be invoked. It has no effect on expar()
/*  itself.
/* .IP EXTPAR_FLAG_STRIP
/*  Skip whitespace after the opening parenthesis, and trim
/*  whitespace before the closing parenthesis.
/* .RE
/* DIAGNOSTICS
/*  panic: the input string does not start with the opening
/*  parenthesis.
/*
/*  In case of error the result value is a dynamically-allocated
/*  string with a description of the problem that includes a
/*  copy of the offending input.  A non-null result value should
/*  be destroyed with myfree(). The following describes the errors
/*  and the state of the buffer and buffer pointer.
/* .IP "missing closing parenthesis"
/*  The buffer pointer points to text as if a closing parenthesis
/*  were present at the end of the input.
/* .IP "text after closing parenthesis"
/*  The buffer pointer points to text as if the offending text
/*  were not present.
/* SEE ALSO
/*  balpar(3) determine length of string in parentheses
/* 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 library.
  */
#include <sys_defs.h>
#include <ctype.h>

 /*
  * Utility library.
  */
#include <msg.h>
#include <stringops.h>

/* extpar - extract text from parentheses */

char   *extpar(char **bp, const char *parens, int flags)
{
    char   *cp = *bp;
    char   *err = 0;
    size_t  len;

    if (cp[0] != parens[0])
    msg_panic("extpar: no '%c' at start of text: \"%s\"", parens[0], cp);
    if ((len = balpar(cp, parens)) == 0) {
    err = concatenate("missing '", parens + 1, "' in \"",
              cp, "\"", (char *) 0);
    cp += 1;
    } else {
    if (cp[len] != 0)
        err = concatenate("syntax error after '", parens + 1, "' in \"",
                  cp, "\"", (char *) 0);
    cp += 1;
    cp[len -= 2] = 0;
    }
    if (flags & EXTPAR_FLAG_STRIP) {
    trimblanks(cp, len)[0] = 0;
    while (ISSPACE(*cp))
        cp++;
    }
    *bp = cp;
    return (err);
}