Linux Cubed Series 7: Sunsite/Linux Cubed Series 7 - Sunsite Vol 1.iso/system/install/chlib-1.000/chlib-1/chlib/chlib.c

C/C++ Source or Header | 1993-08-16 | 4.9 KB | 204 lines

/*
 * Copyright 1993  David Engel
 *
 * This program may be used for any purpose as long as this
 * copyright notice is kept.
 */

#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include <getopt.h>
#include <unistd.h>
#include <errno.h>
#include <a.out.h>
#include <sys/stat.h>

#define VERSION "1.0 (8/16/93)"

char *prog = "chlib";

volatile void error(char *fmt, ...)
{
    va_list ap;

    fprintf(stderr, "%s: ", prog);

    va_start(ap, fmt);
    vfprintf(stderr, fmt, ap);
    va_end(ap);

    fprintf(stderr, "\n");

    exit(1);
}

/* read relevant info about a shared library. */

int libinfo(int must, char *name, unsigned *addr, unsigned *vers,
        struct stat *stbuf)
{
    FILE *file;
    struct exec exec;

    /* see if we can stat it */
    if (stat(name, stbuf))
    {
    /* if must exist flag is set, it's an error */
    if (must)
        error("can't stat %s (%s)", name, strerror(errno));
    else
        return 0;
    }

    /* try to open it */
    if ((file = fopen(name, "rb")) == NULL)
    error("can't open %s (%s)", name, strerror(errno));

    /* and read the exec header */
    if (fread(&exec, sizeof exec, 1, file) != 1)
    error("can't read exec header from %s", name);

    /* shared libs must be ZMAGIC */
    if (N_MAGIC(exec) != ZMAGIC || !exec.a_entry)
    error("%s is not a shared library", name);

    *addr = exec.a_entry;

    /* now seek to where the version number */
    if (fseek(file, N_TXTOFF(exec), SEEK_SET))
    error("can't seek to version in %s", name);

    /* and try to read the version number */
    if (fread(vers, sizeof *vers, 1, file) != 1)
    error("can't read version number from %s", name);

    /* we're done with the file */
    fclose(file);

    return 1;
}

int main(int argc, char **argv)
{
    int c;
    int force = 0;
    char *newlib;
    char *linkdir;
    char *cp, *cp2;
    char linkname[1024];
    unsigned newaddr, oldaddr;
    unsigned newvers, oldvers;
    struct stat newstat, oldstat;
    struct stat linkstat;

    prog = argv[0];
    opterr = 0;

    /* parse command-line options */
    while ((c = getopt(argc, argv, "vf")) != EOF)
    switch (c)
    {
    case 'v':
        printf("%s: version %s\n", argv[0], VERSION);
        exit(0);
    case 'f':
        force = 1;
        break;
    default:
        error("invalid option -%c", optopt);
    }

    /* must be either one or two args left */
    if (argc - optind < 1 || argc - optind > 2)
    {
    fprintf(stderr, "usage: %s [-vf] newlib [linkdir]\n", argv[0]);
    exit(1);
    }

    /* pick off newlib argument */
    newlib = argv[optind];

    /* pick off linkdir argumnet or use default */
    if (argc - optind > 1)
    {
    linkdir = argv[optind+1];

    /* strip trailing slashes from linkdir */
    for (cp = linkdir+strlen(linkdir)-1;
         cp > linkdir && *cp == '/'; cp--)
        ;
    cp[1] = '\0';
    }
    else
    linkdir = "/lib";

    /* make sure linkdir is a directory */
    if (stat(linkdir, &linkstat) || !S_ISDIR(linkstat.st_mode))
    error("%s is not a directory", linkdir);

    /* check if newlib is a valid shared library name */
    cp = strrchr(newlib, '/');
    if (cp)
    cp++;
    else
    cp = newlib;
    cp2 = strstr(cp, ".so.");
    if (cp2)
    cp2 = strchr(cp2 + 4, '.');
    if (!cp2)
    error("%s is not a shared library name", newlib);

    /* build the shared library link name */
    sprintf(linkname, "%s/", linkdir);
    strncat(linkname, cp, cp2 - cp);

    /* check for for relative newlib and absolute linkdir */
    if (*newlib != '/' && *linkdir == '/')
    {
    if (strcmp(linkdir, getcwd(NULL, 0)) != 0)
        error("current directory is not %s", linkdir);
    }

    /* read info about the new shared library */
    libinfo(1, newlib, &newaddr, &newvers, &newstat);

    /* try to read info about any existing library */
    if (libinfo(0, linkname, &oldaddr, &oldvers, &oldstat))
    {
    /* see if the link is already set to newlib */
    if (newstat.st_dev == oldstat.st_dev &&
        newstat.st_ino == oldstat.st_ino)
        error("%s already points to %s", linkname, newlib);

    /* make sure the load addresses match */
    if (newaddr != oldaddr)
        error("load address for %s (0x%x) does not match\n"
          "\tthat of current %s (0x%x)", newlib, newaddr,
          linkname, oldaddr);

    /* make sure the major version numbers match */
    if ((0xffff0000 & newvers) != (0xffff0000 & oldvers))
        error("major version for %s (%d) does not match\n"
          "\tthat of current %s (%d)", newlib, newvers >> 16,
          linkname, oldvers >> 16);

    /* make sure the new minor version number is greater */
    if (!force && (0x0000ffff & newvers) <= (0x0000ffff & oldvers))
        error("minor version of %s (%d) is not greater than\n"
          "\tthat of current %s (%d)", newlib, newvers & 0xffff,
          linkname, oldvers & 0xffff);
    }

    /* remove any existing link */
    if (!lstat(linkname, &oldstat) && remove(linkname))
    error("can't unlink %s (%s)", linkname, strerror(errno));

    /* (re)create the new link to newlib */
    if (symlink(newlib, linkname))
    error("can't create link to %s (%s)", newlib, strerror(errno));

    /* that's all folks */
    exit(0);
}