isc/win32/file.c

/*
 * Copyright (C) 2000-2002, 2004, 2007, 2009, 2011-2017  Internet Systems Consortium, Inc. ("ISC")
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

/* $Id$ */

#include <config.h>

#undef rename
#include <errno.h>
#include <limits.h>
#include <stdlib.h>
#include <io.h>
#include <process.h>

#include <sys/stat.h>
#include <fcntl.h>
#include <sys/utime.h>

#include <isc/file.h>
#include <isc/mem.h>
#include <isc/print.h>
#include <isc/random.h>
#include <isc/result.h>
#include <isc/sha2.h>
#include <isc/stat.h>
#include <isc/string.h>
#include <isc/time.h>
#include <isc/util.h>

#include "errno2result.h"

static const char alphnum[] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

/*
 * Emulate UNIX mkstemp, which returns an open FD to the new file
 *
 */
static int
gettemp(char *path, isc_boolean_t binary, int *doopen) {
    char *start, *trv;
    struct stat sbuf;
    int flags = O_CREAT|O_EXCL|O_RDWR;

    if (binary)
        flags |= _O_BINARY;

    trv = strrchr(path, 'X');
    trv++;
    /* extra X's get set to 0's */
    while (*--trv == 'X') {
        isc_uint32_t which;

        isc_random_get(&which);
        *trv = alphnum[which % (sizeof(alphnum) - 1)];
    }
    /*
     * check the target directory; if you have six X's and it
     * doesn't exist this runs for a *very* long time.
     */
    for (start = trv + 1;; --trv) {
        if (trv <= path)
            break;
        if (*trv == '\\') {
            *trv = '\0';
            if (stat(path, &sbuf))
                return (0);
            if (!S_ISDIR(sbuf.st_mode)) {
                errno = ENOTDIR;
                return (0);
            }
            *trv = '\\';
            break;
        }
    }

    for (;;) {
        if (doopen) {
            if ((*doopen =
                open(path, flags, _S_IREAD | _S_IWRITE)) >= 0)
                return (1);
            if (errno != EEXIST)
                return (0);
        } else if (stat(path, &sbuf))
            return (errno == ENOENT ? 1 : 0);

        /* tricky little algorithm for backward compatibility */
        for (trv = start;;) {
            if (!*trv)
                return (0);
            if (*trv == 'z')
                *trv++ = 'a';
            else {
                if (isdigit(*trv))
                    *trv = 'a';
                else
                    ++*trv;
                break;
            }
        }
    }
    /*NOTREACHED*/
}

static int
mkstemp(char *path, isc_boolean_t binary) {
    int fd;

    return (gettemp(path, binary, &fd) ? fd : -1);
}

/*
 * XXXDCL As the API for accessing file statistics undoubtedly gets expanded,
 * it might be good to provide a mechanism that allows for the results
 * of a previous stat() to be used again without having to do another stat,
 * such as perl's mechanism of using "_" in place of a file name to indicate
 * that the results of the last stat should be used.  But then you get into
 * annoying MP issues.   BTW, Win32 has stat().
 */
static isc_result_t
file_stats(const char *file, struct stat *stats) {
    isc_result_t result = ISC_R_SUCCESS;

    REQUIRE(file != NULL);
    REQUIRE(stats != NULL);

    if (stat(file, stats) != 0)
        result = isc__errno2result(errno);

    return (result);
}

static isc_result_t
fd_stats(int fd, struct stat *stats) {
    isc_result_t result = ISC_R_SUCCESS;

    REQUIRE(stats != NULL);

    if (fstat(fd, stats) != 0)
        result = isc__errno2result(errno);

    return (result);
}

isc_result_t
isc_file_getsizefd(int fd, off_t *size) {
    isc_result_t result;
    struct stat stats;

    REQUIRE(size != NULL);

    result = fd_stats(fd, &stats);

    if (result == ISC_R_SUCCESS)
        *size = stats.st_size;
    return (result);
}

isc_result_t
isc_file_mode(const char *file, mode_t *modep) {
    isc_result_t result;
    struct stat stats;

    REQUIRE(modep != NULL);

    result = file_stats(file, &stats);
    if (result == ISC_R_SUCCESS)
        *modep = (stats.st_mode & 07777);
    return (result);
}

/*
 * isc_file_safemovefile is needed to be defined here to ensure that
 * any file with the new name is renamed to a backup name and then the
 * rename is done. If all goes well then the backup can be deleted,
 * otherwise it gets renamed back.
 */

int
isc_file_safemovefile(const char *oldname, const char *newname) {
    BOOL filestatus;
    char buf[512];
    struct stat sbuf;
    BOOL exists = FALSE;
    int tmpfd;

    /*
     * Make sure we have something to do
     */
    if (stat(oldname, &sbuf) != 0) {
        errno = ENOENT;
        return (-1);
    }

    /*
     * Rename to a backup the new file if it still exists
     */
    if (stat(newname, &sbuf) == 0) {
        exists = TRUE;
        strlcpy(buf, newname, sizeof(buf));
        strlcat(buf, ".XXXXX", sizeof(buf));
        tmpfd = mkstemp(buf, ISC_TRUE);
        if (tmpfd > 0)
            _close(tmpfd);
        (void)DeleteFile(buf);
        _chmod(newname, _S_IREAD | _S_IWRITE);

        filestatus = MoveFile(newname, buf);
    }
    /* Now rename the file to the new name
     */
    _chmod(oldname, _S_IREAD | _S_IWRITE);

    filestatus = MoveFile(oldname, newname);
    if (filestatus == 0) {
        /*
         * Try to rename the backup back to the original name
         * if the backup got created
         */
        if (exists == TRUE) {
            filestatus = MoveFile(buf, newname);
            if (filestatus == 0)
                errno = EACCES;
        }
        return (-1);
    }

    /*
     * Delete the backup file if it got created
     */
    if (exists == TRUE)
        (void)DeleteFile(buf);
    return (0);
}

isc_result_t
isc_file_getmodtime(const char *file, isc_time_t *time) {
    int fh;

    REQUIRE(file != NULL);
    REQUIRE(time != NULL);

    if ((fh = open(file, _O_RDONLY | _O_BINARY)) < 0)
        return (isc__errno2result(errno));

    if (!GetFileTime((HANDLE) _get_osfhandle(fh),
             NULL,
             NULL,
             &time->absolute))
    {
        close(fh);
        errno = EINVAL;
        return (isc__errno2result(errno));
    }
    close(fh);
    return (ISC_R_SUCCESS);
}

isc_result_t
isc_file_getsize(const char *file, off_t *size) {
    isc_result_t result;
    struct stat stats;

    REQUIRE(file != NULL);
    REQUIRE(size != NULL);

    result = file_stats(file, &stats);

    if (result == ISC_R_SUCCESS)
        *size = stats.st_size;

    return (result);
}

isc_result_t
isc_file_settime(const char *file, isc_time_t *time) {
    int fh;

    REQUIRE(file != NULL && time != NULL);

    if ((fh = open(file, _O_RDWR | _O_BINARY)) < 0)
        return (isc__errno2result(errno));

    /*
     * Set the date via the filedate system call and return.  Failing
     * this call implies the new file times are not supported by the
     * underlying file system.
     */
    if (!SetFileTime((HANDLE) _get_osfhandle(fh),
             NULL,
             &time->absolute,
             &time->absolute))
    {
        close(fh);
        errno = EINVAL;
        return (isc__errno2result(errno));
    }

    close(fh);
    return (ISC_R_SUCCESS);

}

#undef TEMPLATE
#define TEMPLATE "XXXXXXXXXX.tmp" /* 14 characters. */

isc_result_t
isc_file_mktemplate(const char *path, char *buf, size_t buflen) {
    return (isc_file_template(path, TEMPLATE, buf, buflen));
}

isc_result_t
isc_file_template(const char *path, const char *templet, char *buf,
          size_t buflen)
{
    char *s;

    REQUIRE(path != NULL);
    REQUIRE(templet != NULL);
    REQUIRE(buf != NULL);

    s = strrchr(templet, '\\');
    if (s != NULL)
        templet = s + 1;

    s = strrchr(path, '\\');

    if (s != NULL) {
        size_t prefixlen = s - path + 1;
        if ((prefixlen + strlen(templet) + 1) > buflen)
            return (ISC_R_NOSPACE);

        /* Copy 'prefixlen' bytes and NUL terminate. */
        strlcpy(buf, path, ISC_MIN(prefixlen + 1, buflen));
        strlcat(buf, templet, buflen);
    } else {
        if ((strlen(templet) + 1) > buflen)
            return (ISC_R_NOSPACE);

        strlcpy(buf, templet, buflen);
    }

    return (ISC_R_SUCCESS);
}

isc_result_t
isc_file_renameunique(const char *file, char *templet) {
    int fd;
    int res = 0;
    isc_result_t result = ISC_R_SUCCESS;

    REQUIRE(file != NULL);
    REQUIRE(templet != NULL);

    fd = mkstemp(templet, ISC_TRUE);
    if (fd == -1)
        result = isc__errno2result(errno);
    else
        close(fd);

    if (result == ISC_R_SUCCESS) {
        res = isc_file_safemovefile(file, templet);
        if (res != 0) {
            result = isc__errno2result(errno);
            (void)unlink(templet);
        }
    }
    return (result);
}

static isc_result_t
openuniquemode(char *templet, int mode, isc_boolean_t binary, FILE **fp) {
    int fd;
    FILE *f;
    isc_result_t result = ISC_R_SUCCESS;

    REQUIRE(templet != NULL);
    REQUIRE(fp != NULL && *fp == NULL);

    /*
     * Win32 does not have mkstemp. Using emulation above.
     */
    fd = mkstemp(templet, binary);

    if (fd == -1)
        result = isc__errno2result(errno);
    if (result == ISC_R_SUCCESS) {
#if 1
        UNUSED(mode);
#else
        (void)fchmod(fd, mode);
#endif
        f = fdopen(fd, binary ? "wb+" : "w+");
        if (f == NULL) {
            result = isc__errno2result(errno);
            (void)remove(templet);
            (void)close(fd);
        } else
            *fp = f;
    }

    return (result);
}

isc_result_t
isc_file_openuniqueprivate(char *templet, FILE **fp) {
    int mode = _S_IREAD | _S_IWRITE;
    return (openuniquemode(templet, mode, ISC_FALSE, fp));
}

isc_result_t
isc_file_openunique(char *templet, FILE **fp) {
    int mode = _S_IREAD | _S_IWRITE;
    return (openuniquemode(templet, mode, ISC_FALSE, fp));
}

isc_result_t
isc_file_openuniquemode(char *templet, int mode, FILE **fp) {
    return (openuniquemode(templet, mode, ISC_FALSE, fp));
}

isc_result_t
isc_file_bopenuniqueprivate(char *templet, FILE **fp) {
    int mode = _S_IREAD | _S_IWRITE;
    return (openuniquemode(templet, mode, ISC_TRUE, fp));
}

isc_result_t
isc_file_bopenunique(char *templet, FILE **fp) {
    int mode = _S_IREAD | _S_IWRITE;
    return (openuniquemode(templet, mode, ISC_TRUE, fp));
}

isc_result_t
isc_file_bopenuniquemode(char *templet, int mode, FILE **fp) {
    return (openuniquemode(templet, mode, ISC_TRUE, fp));
}

isc_result_t
isc_file_remove(const char *filename) {
    int r;

    REQUIRE(filename != NULL);

    r = unlink(filename);
    if (r == 0)
        return (ISC_R_SUCCESS);
    else
        return (isc__errno2result(errno));
}

isc_result_t
isc_file_rename(const char *oldname, const char *newname) {
    int r;

    REQUIRE(oldname != NULL);
    REQUIRE(newname != NULL);

    r = isc_file_safemovefile(oldname, newname);
    if (r == 0)
        return (ISC_R_SUCCESS);
    else
        return (isc__errno2result(errno));
}

isc_boolean_t
isc_file_exists(const char *pathname) {
    struct stat stats;

    REQUIRE(pathname != NULL);

    return (ISC_TF(file_stats(pathname, &stats) == ISC_R_SUCCESS));
}

isc_result_t
isc_file_isplainfile(const char *filename) {
    /*
     * This function returns success if filename is a plain file.
     */
    struct stat filestat;
    memset(&filestat,0,sizeof(struct stat));

    if ((stat(filename, &filestat)) == -1)
        return(isc__errno2result(errno));

    if(! S_ISREG(filestat.st_mode))
        return(ISC_R_INVALIDFILE);

    return(ISC_R_SUCCESS);
}

isc_result_t
isc_file_isplainfilefd(int fd) {
    /*
     * This function returns success if filename is a plain file.
     */
    struct stat filestat;
    memset(&filestat,0,sizeof(struct stat));

    if ((fstat(fd, &filestat)) == -1)
        return(isc__errno2result(errno));

    if(! S_ISREG(filestat.st_mode))
        return(ISC_R_INVALIDFILE);

    return(ISC_R_SUCCESS);
}

isc_result_t
isc_file_isdirectory(const char *filename) {
    /*
     * This function returns success if filename is a directory.
     */
    struct stat filestat;
    memset(&filestat,0,sizeof(struct stat));

    if ((stat(filename, &filestat)) == -1)
        return(isc__errno2result(errno));

    if(! S_ISDIR(filestat.st_mode))
        return(ISC_R_INVALIDFILE);

    return(ISC_R_SUCCESS);
}


isc_boolean_t
isc_file_isabsolute(const char *filename) {
    REQUIRE(filename != NULL);
    /*
     * Look for c:\path\... style, c:/path/... or \\computer\shar\path...
     * the UNC style file specs
     */
    if ((filename[0] == '\\') && (filename[1] == '\\'))
        return (ISC_TRUE);
    if (isalpha(filename[0]) && filename[1] == ':' && filename[2] == '\\')
        return (ISC_TRUE);
    if (isalpha(filename[0]) && filename[1] == ':' && filename[2] == '/')
        return (ISC_TRUE);
    return (ISC_FALSE);
}

isc_boolean_t
isc_file_iscurrentdir(const char *filename) {
    REQUIRE(filename != NULL);
    return (ISC_TF(filename[0] == '.' && filename[1] == '\0'));
}

isc_boolean_t
isc_file_ischdiridempotent(const char *filename) {
    REQUIRE(filename != NULL);

    if (isc_file_isabsolute(filename))
        return (ISC_TRUE);
    if (filename[0] == '\\')
        return (ISC_TRUE);
    if (filename[0] == '/')
        return (ISC_TRUE);
    if (isc_file_iscurrentdir(filename))
        return (ISC_TRUE);
    return (ISC_FALSE);
}

const char *
isc_file_basename(const char *filename) {
    char *s;

    REQUIRE(filename != NULL);

    s = strrchr(filename, '\\');
    if (s == NULL)
        return (filename);
    return (s + 1);
}

isc_result_t
isc_file_progname(const char *filename, char *progname, size_t namelen) {
    const char *s;
    const char *p;
    size_t len;

    REQUIRE(filename != NULL);
    REQUIRE(progname != NULL);

    /*
     * Strip the path from the name
     */
    s = isc_file_basename(filename);
    if (s == NULL) {
        return (ISC_R_NOSPACE);
    }

    /*
     * Strip any and all suffixes
     */
    p = strchr(s, '.');
    if (p == NULL) {
        if (namelen <= strlen(s))
            return (ISC_R_NOSPACE);

        strlcpy(progname, s, namelen);
        return (ISC_R_SUCCESS);
    }

    /*
     * Copy the result to the buffer
     */
    len = p - s;
    if (len >= namelen)
        return (ISC_R_NOSPACE);

    /* Copy up to 'len' bytes and NUL terminate. */
    strlcpy(progname, s, ISC_MIN(len + 1, namelen));
    return (ISC_R_SUCCESS);
}

isc_result_t
isc_file_absolutepath(const char *filename, char *path, size_t pathlen) {
    char *ptrname;
    DWORD retval;

    REQUIRE(filename != NULL);
    REQUIRE(path != NULL);

    retval = GetFullPathName(filename, (DWORD) pathlen, path, &ptrname);

    /* Something went wrong in getting the path */
    if (retval == 0)
        return (ISC_R_NOTFOUND);
    /* Caller needs to provide a larger buffer to contain the string */
    if (retval >= pathlen)
        return (ISC_R_NOSPACE);
    return (ISC_R_SUCCESS);
}

isc_result_t
isc_file_truncate(const char *filename, isc_offset_t size) {
    int fh;

    REQUIRE(filename != NULL && size >= 0);

    if ((fh = open(filename, _O_RDWR | _O_BINARY)) < 0)
        return (isc__errno2result(errno));

    if(_chsize(fh, size) != 0) {
        close(fh);
        return (isc__errno2result(errno));
    }
    close(fh);

    return (ISC_R_SUCCESS);
}

isc_result_t
isc_file_safecreate(const char *filename, FILE **fp) {
    isc_result_t result;
    int flags;
    struct stat sb;
    FILE *f;
    int fd;

    REQUIRE(filename != NULL);
    REQUIRE(fp != NULL && *fp == NULL);

    result = file_stats(filename, &sb);
    if (result == ISC_R_SUCCESS) {
        if ((sb.st_mode & S_IFREG) == 0)
            return (ISC_R_INVALIDFILE);
        flags = O_WRONLY | O_TRUNC;
    } else if (result == ISC_R_FILENOTFOUND) {
        flags = O_WRONLY | O_CREAT | O_EXCL;
    } else
        return (result);

    fd = open(filename, flags, S_IRUSR | S_IWUSR);
    if (fd == -1)
        return (isc__errno2result(errno));

    f = fdopen(fd, "w");
    if (f == NULL) {
        result = isc__errno2result(errno);
        close(fd);
        return (result);
    }

    *fp = f;
    return (ISC_R_SUCCESS);
}

isc_result_t
isc_file_splitpath(isc_mem_t *mctx, const char *path, char **dirname,
           char const ** basename)
{
    char *dir;
    const char *file, *slash;
    char *backslash;

    slash = strrchr(path, '/');

    backslash = strrchr(path, '\\');
    if ((slash != NULL && backslash != NULL && backslash > slash) ||
        (slash == NULL && backslash != NULL))
        slash = backslash;

    if (slash == path) {
        file = ++slash;
        dir = isc_mem_strdup(mctx, "/");
    } else if (slash != NULL) {
        file = ++slash;
        dir = isc_mem_allocate(mctx, slash - path);
        if (dir != NULL)
            strlcpy(dir, path, slash - path);
    } else {
        file = path;
        dir = isc_mem_strdup(mctx, ".");
    }

    if (dir == NULL)
        return (ISC_R_NOMEMORY);

    if (*file == '\0') {
        isc_mem_free(mctx, dir);
        return (ISC_R_INVALIDFILE);
    }

    *dirname = dir;
    *basename = file;

    return (ISC_R_SUCCESS);
}

void *
isc_file_mmap(void *addr, size_t len, int prot,
          int flags, int fd, off_t offset)
{
    void *buf;
    ssize_t ret;
    off_t end;

    UNUSED(addr);
    UNUSED(prot);
    UNUSED(flags);

    end = lseek(fd, 0, SEEK_END);
    lseek(fd, offset, SEEK_SET);
    if (end - offset < (off_t) len)
        len = end - offset;

    buf = malloc(len);
    if (buf == NULL)
        return (NULL);

    ret = read(fd, buf, (unsigned int) len);
    if (ret != (ssize_t) len) {
        free(buf);
        buf = NULL;
    }

    return (buf);
}

int
isc_file_munmap(void *addr, size_t len) {
    UNUSED(len);
    free(addr);
    return (0);
}

#define DISALLOW "\\/:ABCDEFGHIJKLMNOPQRSTUVWXYZ"
#ifndef PATH_MAX
#define PATH_MAX 1024
#endif

isc_result_t
isc_file_sanitize(const char *dir, const char *base, const char *ext,
          char *path, size_t length)
{
    char buf[PATH_MAX], hash[PATH_MAX];
    size_t l = 0;

    REQUIRE(base != NULL);
    REQUIRE(path != NULL);

    l = strlen(base) + 1;

    /*
     * allow room for a full sha256 hash (64 chars
     * plus null terminator)
     */
    if (l < 65)
        l = 65;

    if (dir != NULL)
        l += strlen(dir) + 1;
    if (ext != NULL)
        l += strlen(ext) + 1;

    if (l > length || l > PATH_MAX)
        return (ISC_R_NOSPACE);

    /* Check whether the full-length SHA256 hash filename exists */
    isc_sha256_data((const void *) base, strlen(base), hash);
    snprintf(buf, sizeof(buf), "%s%s%s%s%s",
        dir != NULL ? dir : "", dir != NULL ? "/" : "",
        hash, ext != NULL ? "." : "", ext != NULL ? ext : "");
    if (isc_file_exists(buf)) {
        strlcpy(path, buf, length);
        return (ISC_R_SUCCESS);
    }

    /* Check for a truncated SHA256 hash filename */
    hash[16] = '\0';
    snprintf(buf, sizeof(buf), "%s%s%s%s%s",
        dir != NULL ? dir : "", dir != NULL ? "/" : "",
        hash, ext != NULL ? "." : "", ext != NULL ? ext : "");
    if (isc_file_exists(buf)) {
        strlcpy(path, buf, length);
        return (ISC_R_SUCCESS);
    }

    /*
     * If neither hash filename already exists, then we'll use
     * the original base name if it has no disallowed characters,
     * or the truncated hash name if it does.
     */
    if (strpbrk(base, DISALLOW) != NULL) {
        strlcpy(path, buf, length);
        return (ISC_R_SUCCESS);
    }

    snprintf(buf, sizeof(buf), "%s%s%s%s%s",
        dir != NULL ? dir : "", dir != NULL ? "/" : "",
        base, ext != NULL ? "." : "", ext != NULL ? ext : "");
    strlcpy(path, buf, length);
    return (ISC_R_SUCCESS);
}

/*
 * Based on http://blog.aaronballman.com/2011/08/how-to-check-access-rights/
 */
isc_boolean_t
isc_file_isdirwritable(const char *path) {
    DWORD length = 0;
    HANDLE hToken = NULL;
    PSECURITY_DESCRIPTOR security = NULL;
    isc_boolean_t answer = ISC_FALSE;

    if (isc_file_isdirectory(path) != ISC_R_SUCCESS) {
        return (answer);
    }

    /*
     * Figure out buffer size. GetFileSecurity() should not succeed.
     */
    if (GetFileSecurity(path, OWNER_SECURITY_INFORMATION |
                  GROUP_SECURITY_INFORMATION |
                  DACL_SECURITY_INFORMATION,
                NULL, 0, &length))
    {
        return (answer);
    }

    if (GetLastError() != ERROR_INSUFFICIENT_BUFFER) {
        return (answer);
    }

    security = malloc(length);
    if (security == NULL) {
        return (answer);
    }

    /*
     * GetFileSecurity() should succeed.
     */
    if (!GetFileSecurity(path, OWNER_SECURITY_INFORMATION |
                   GROUP_SECURITY_INFORMATION |
                   DACL_SECURITY_INFORMATION,
                 security, length, &length))
    {
        return (answer);
    }

    if (OpenProcessToken(GetCurrentProcess(), TOKEN_IMPERSONATE |
                 TOKEN_QUERY | TOKEN_DUPLICATE |
                 STANDARD_RIGHTS_READ, &hToken))
    {
        HANDLE hImpersonatedToken = NULL;

        if (DuplicateToken(hToken, SecurityImpersonation,
                   &hImpersonatedToken))
        {
            GENERIC_MAPPING mapping;
            PRIVILEGE_SET privileges = { 0 };
            DWORD grantedAccess = 0;
            DWORD privilegesLength = sizeof(privileges);
            BOOL result = FALSE;
            DWORD genericAccessRights = GENERIC_WRITE;

            mapping.GenericRead = FILE_GENERIC_READ;
            mapping.GenericWrite = FILE_GENERIC_WRITE;
            mapping.GenericExecute = FILE_GENERIC_EXECUTE;
            mapping.GenericAll = FILE_ALL_ACCESS;

            MapGenericMask(&genericAccessRights, &mapping);
            if (AccessCheck(security, hImpersonatedToken,
                    genericAccessRights, &mapping,
                    &privileges, &privilegesLength,
                    &grantedAccess, &result))
            {
                answer = ISC_TF(result);
            }
            CloseHandle(hImpersonatedToken);
        }
        CloseHandle(hToken);
    }
    free(security);
    return (answer);
}