searchinpath.c

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/* @(#)searchinpath.c   1.5 16/08/01 Copyright 1999-2016 J. Schilling */
#include <schily/mconfig.h>
#ifndef lint
static  UConst char sccsid[] =
    "@(#)searchinpath.c 1.5 16/08/01 Copyright 1999-2016 J. Schilling";
#endif
/*
 *  Search a file name in the PATH of the current exeecutable.
 *  Return the path to the file name in allocated space.
 *
 *  Copyright (c) 1999-2016 J. Schilling
 */
/*
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * See the file CDDL.Schily.txt in this distribution for details.
 * A copy of the CDDL is also available via the Internet at
 * http://www.opensource.org/licenses/cddl1.txt
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file CDDL.Schily.txt from this distribution.
 */
 
#include <schily/mconfig.h>
#include <schily/string.h>
#include <schily/unistd.h>
#include <schily/stdlib.h>      /* getexecname() */
#include <schily/stat.h>
#include <schily/standard.h>
#include <schily/schily.h>
#include <schily/errno.h>
 
 
#define NAMEMAX 4096
 
EXPORT  char    *searchfileinpath   __PR((char *name, int mode,
                            int file_mode,
                            char *path));
LOCAL   char    *searchonefile      __PR((char *name, int mode,
                            BOOL plain_file,
                            char *xn,
                            char *nbuf,
                            char *np, char *ep));
#if defined(__DJGPP__)
LOCAL   char    *strbs2s        __PR((char *s));
#endif
 
#ifdef  JOS
#define enofile(t)          ((t) == EMISSDIR || \
                    (t)  == ENOFILE || \
                    (t)  == EISADIR || \
                    (t)  == EIOERR)
#else
#define enofile(t)          ((t) == ENOENT || \
                    (t)  == ENOTDIR || \
                    (t)  == EISDIR || \
                    (t)  == EIO)
#endif
 
/*
 * Search for the "name" file in the PATH of the user.
 * Assume that the file is ... bin/../name.
 */
EXPORT char *
searchfileinpath(name, mode, file_mode, path)
    char    *name;          /* Find <execname>/../name in PATH  */
    int mode;           /* Mode for access() e.g. X_OK      */
    int file_mode;      /* How to check files           */
    char    *path;          /* PATH to use if not NULL      */
{
    char    pbuf[NAMEMAX];
    char    *nbuf = pbuf;
    char    *np;
    char    *ep;
    char    *xn;
    int nlen = strlen(name);
    int oerrno = geterrno();
    int err = 0;
#ifdef  HAVE_GETEXECNAME
    char    *pn = (char *)getexecname();    /* pn is on the stack */
#else
    char    *pn = getexecpath();        /* pn is from strdup() */
    char    ebuf[NAMEMAX];
 
    if (pn) {
        strlcpy(ebuf, pn, sizeof (ebuf));
        free(pn);
        pn = ebuf;
    }
#endif
 
    if (pn == NULL)
        xn = get_progname();
    else
        xn = pn;
    if ((np = strrchr(xn, '/')) != NULL)
        xn = ++np;
 
    /*
     * getexecname() is the best choice for our seach. getexecname()
     * returns either "foo" (if called from the current directory) or
     * an absolute path after symlinks have been resolved.
     * If getexecname() returns a path with slashes, try to search
     * first relatively to the known location of the current binary.
     */
    if ((file_mode & SIP_ONLY_PATH) == 0 &&
        pn != NULL && strchr(pn, '/') != NULL) {
        strlcpy(nbuf, pn, sizeof (pbuf));
        np = nbuf + strlen(nbuf);
 
        while (np > nbuf && np[-1] != '/')
            *--np = '\0';
        pn = &nbuf[sizeof (pbuf) - 1];
        if ((np = searchonefile(name, mode,
                file_mode & (SIP_PLAIN_FILE|SIP_NO_STRIPBIN),
                xn,
                nbuf, np, pn)) != NULL) {
            seterrno(oerrno);
            return (np);
        }
    }
 
    if (file_mode & SIP_NO_PATH)
        return (NULL);
 
    if (path == NULL)
        path = getenv("PATH");
    if (path == NULL)
        return (NULL);
 
 
#ifdef __DJGPP__
    path = strdup(path);
    if (path == NULL)
        return (NULL);
    strbs2s(path);  /* PATH under DJGPP can contain both slashes */
#endif
 
    /*
     * A PATH name search should lead us to the path under which we
     * called the binary, but not necessarily to the install path as
     * we may have been called thorugh a symlink or hardlink. In case
     * of a symlink, we can follow the link. In case of a hardlink, we
     * are lost.
     */
    ep = &nbuf[sizeof (pbuf) - 1];
    for (;;) {
        np = nbuf;
        while (*path != PATH_ENV_DELIM && *path != '\0' &&
            np < &nbuf[sizeof (pbuf) - nlen])
                *np++ = *path++;
        *np = '\0';
        if ((np = searchonefile(name, mode,
                file_mode & (SIP_PLAIN_FILE|SIP_NO_STRIPBIN),
                xn,
                nbuf, np, ep)) != NULL) {
#ifdef __DJGPP__
            free(path);
#endif
            seterrno(oerrno);
            return (np);
        }
        if (err == 0) {
            err = geterrno();
            if (enofile(err))
                err = 0;
        }
        if (*path == '\0')
            break;
        path++;
    }
#ifdef __DJGPP__
    free(path);
#endif
    if (err)
        seterrno(err);
    else
        seterrno(oerrno);
    return (NULL);
}
 
LOCAL char *
searchonefile(name, mode, plain_file, xn, nbuf, np, ep)
    register char   *name;      /* Find <execname>/../name in PATH  */
        int mode;       /* Mode for access() e.g. X_OK      */
        BOOL    plain_file; /* Whether to check only plain files    */
        char    *xn;        /* The basename of the executable   */
    register char   *nbuf;      /* Name buffer base         */
    register char   *np;        /* Where to append name to path     */
    register char   *ep;        /* Point to last valid char in nbuf */
{
    struct stat sb;
 
    while (np > nbuf && np[-1] == '/')
        *--np = '\0';
    if (xn) {
        *np++ = '/';
        strlcpy(np, xn, ep - np);
        if (stat(nbuf, &sb) < 0)
            return (NULL);
        if (!S_ISREG(sb.st_mode))
            return (NULL);
        *--np = '\0';
    }
    if ((plain_file & SIP_NO_STRIPBIN) == 0) {
        if (np >= &nbuf[4] && streql(&np[-4], "/bin"))
            np = &np[-4];
    }
    plain_file &= SIP_PLAIN_FILE;
    *np++ = '/';
    *np   = '\0';
    strlcpy(np, name, ep - np);
 
    seterrno(0);
    if (stat(nbuf, &sb) >= 0) {
        if ((!plain_file || S_ISREG(sb.st_mode)) &&
            (eaccess(nbuf, mode) >= 0)) {
            return (strdup(nbuf));
        }
        if (geterrno() == 0)
            seterrno(EACCES);
    }
    return (NULL);
}
 
#ifdef __DJGPP__
LOCAL char *
strbs2s(s)
    char    *s;
{
    char    *tmp = s;
 
    if (tmp) {
        while (*tmp) {
            if (*tmp == '\\')
                *tmp = '/';
            tmp++;
        }
    }
    return (s);
}
#endif