sane_basename.c

[詳解]

/*++
/* NAME
/*  sane_basename 3
/* SUMMARY
/*  split pathname into last component and parent directory
/* SYNOPSIS
/*  #include <stringops.h>
/*
/*  char    *sane_basename(buf, path)
/*  VSTRING *buf;
/*  const char *path;
/*
/*  char    *sane_dirname(buf, path)
/*  VSTRING *buf;
/*  const char *path;
/* DESCRIPTION
/*  These functions split a pathname into its last component
/*  and its parent directory, excluding any trailing "/"
/*  characters from the input. The result is a pointer to "/"
/*  when the input is all "/" characters, or a pointer to "."
/*  when the input is a null pointer or zero-length string.
/*
/*  sane_basename() and sane_dirname() differ as follows
/*  from standard basename() and dirname() implementations:
/* .IP \(bu
/*  They can use caller-provided storage or private storage.
/* .IP \(bu
/*  They never modify their input.
/* .PP
/*  sane_basename() returns a pointer to string with the last
/*  pathname component.
/*
/*  sane_dirname() returns a pointer to string with the parent
/*  directory. The result is a pointer to "." when the input
/*  contains no '/' character.
/*
/*  Arguments:
/* .IP buf
/*  Result storage. If a null pointer is specified, each function
/*  uses its own private memory that is overwritten upon each call.
/* .IP path
/*  The input pathname.
/* 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 <string.h>

/* Utility library. */

#include <vstring.h>
#include <stringops.h>

#define STR(x)  vstring_str(x)

/* sane_basename - skip directory prefix */

char   *sane_basename(VSTRING *bp, const char *path)
{
    static VSTRING *buf;
    const char *first;
    const char *last;

    /*
     * Your buffer or mine?
     */
    if (bp == 0) {
    bp = buf;
    if (bp == 0)
        bp = buf = vstring_alloc(10);
    }

    /*
     * Special case: return "." for null or zero-length input.
     */
    if (path == 0 || *path == 0)
    return (STR(vstring_strcpy(bp, ".")));

    /*
     * Remove trailing '/' characters from input. Return "/" if input is all
     * '/' characters.
     */
    last = path + strlen(path) - 1;
    while (*last == '/') {
    if (last == path)
        return (STR(vstring_strcpy(bp, "/")));
    last--;
    }

    /*
     * The pathname does not end in '/'. Skip to last '/' character if any.
     */
    first = last - 1;
    while (first >= path && *first != '/')
    first--;

    return (STR(vstring_strncpy(bp, first + 1, last - first)));
}

/* sane_dirname - keep directory prefix */

char   *sane_dirname(VSTRING *bp, const char *path)
{
    static VSTRING *buf;
    const char *last;

    /*
     * Your buffer or mine?
     */
    if (bp == 0) {
    bp = buf;
    if (bp == 0)
        bp = buf = vstring_alloc(10);
    }

    /*
     * Special case: return "." for null or zero-length input.
     */
    if (path == 0 || *path == 0)
    return (STR(vstring_strcpy(bp, ".")));

    /*
     * Remove trailing '/' characters from input. Return "/" if input is all
     * '/' characters.
     */
    last = path + strlen(path) - 1;
    while (*last == '/') {
    if (last == path)
        return (STR(vstring_strcpy(bp, "/")));
    last--;
    }

    /*
     * This pathname does not end in '/'. Skip to last '/' character if any.
     */
    while (last >= path && *last != '/')
    last--;
    if (last < path)                /* no '/' */
    return (STR(vstring_strcpy(bp, ".")));

    /*
     * Strip trailing '/' characters from dirname (not strictly needed).
     */
    while (last > path && *last == '/')
    last--;

    return (STR(vstring_strncpy(bp, path, last - path + 1)));
}

#ifdef TEST
#include <vstring_vstream.h>

int     main(int argc, char **argv)
{
    VSTRING *buf = vstring_alloc(10);
    char   *dir;
    char   *base;

    while (vstring_get_nonl(buf, VSTREAM_IN) > 0) {
    dir = sane_dirname((VSTRING *) 0, STR(buf));
    base = sane_basename((VSTRING *) 0, STR(buf));
    vstream_printf("input=\"%s\" dir=\"%s\" base=\"%s\"\n",
               STR(buf), dir, base);
    }
    vstream_fflush(VSTREAM_OUT);
    vstring_free(buf);
    return (0);
}

#endif