lib/krb5/store_stdio.c

   1 /*
   2  * Copyright (c) 2017 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * 3. Neither the name of the Institute nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #include "krb5_locl.h"
  35 #include "store-int.h"
  36
  37 #ifndef HAVE_FSEEKO
  38 #define fseeko fseek
  39 #define ftello ftell
  40 #endif
  41
  42 typedef struct stdio_storage {
  43     FILE *f;
  44     off_t pos;
  45 } stdio_storage;
  46
  47 #define F(S) (((stdio_storage*)(S)->data)->f)
  48 #define POS(S) (((stdio_storage*)(S)->data)->pos)
  49
  50 static ssize_t
  51 stdio_fetch(krb5_storage * sp, void *data, size_t size)
  52 {
  53     char *cbuf = (char *)data;
  54     ssize_t count;
  55     size_t rem = size;
  56
  57     /* similar pattern to net_read() to support pipes */
  58     while (rem > 0) {
  59         count = fread(cbuf, 1, rem, F(sp));
  60         if (count < 0) {
  61             POS(sp) = -1;
  62             if (errno == EINTR)
  63                 continue;
  64             else
  65                 return count;
  66         } else if (count == 0) {
  67             if (POS(sp) >= 0)
  68                 POS(sp) += size - rem;
  69             return size - rem;
  70         }
  71         cbuf += count;
  72         rem -= count;
  73     }
  74     if (POS(sp) >= 0)
  75         POS(sp) += size;
  76     return size;
  77 }
  78
  79 static ssize_t
  80 stdio_store(krb5_storage * sp, const void *data, size_t size)
  81 {
  82     const char *cbuf = (const char *)data;
  83     ssize_t count;
  84     size_t rem = size;
  85
  86     /* similar pattern to net_write() to support pipes */
  87     while (rem > 0) {
  88         count = fwrite(cbuf, 1, rem, F(sp));
  89         if (count < 0) {
  90             if (errno == EINTR)
  91                 continue;
  92             /*
  93              * What does it mean to have a short write when using stdio?
  94              *
  95              * It can't mean much.  After all stdio is buffering, so
  96              * earlier writes that appeared complete may have failed,
  97              * and so we don't know how much we really failed to write.
  98              */
  99             POS(sp) = -1;
 100             return -1;
 101         }
 102         if (count == 0) {
 103             POS(sp) = -1;
 104             return -1;
 105         }
 106         cbuf += count;
 107         rem -= count;
 108     }
 109     if (POS(sp) >= 0)
 110         POS(sp) += size;
 111     return size;
 112 }
 113
 114 static off_t
 115 stdio_seek(krb5_storage * sp, off_t offset, int whence)
 116 {
 117     int save_errno = errno;
 118
 119     if (whence == SEEK_SET && POS(sp) == offset)
 120         return POS(sp);
 121
 122     if (whence == SEEK_CUR && POS(sp) >= 0 && offset == 0)
 123         return POS(sp);
 124
 125     if (fseeko(F(sp), offset, whence) != 0)
 126         return -1;
 127     errno = save_errno;
 128     return POS(sp) = ftello(F(sp));
 129 }
 130
 131 static int
 132 stdio_trunc(krb5_storage * sp, off_t offset)
 133 {
 134     off_t tmpoff;
 135     int save_errno = errno;
 136
 137     if (fflush(F(sp)) == EOF)
 138         return errno;
 139     tmpoff = ftello(F(sp));
 140     if (tmpoff > offset)
 141         tmpoff = offset;
 142     if (ftruncate(fileno(F(sp)), offset) == -1)
 143         return errno;
 144     if (fseeko(F(sp), 0, SEEK_END) == -1)
 145         return errno;
 146     if (fseeko(F(sp), tmpoff, SEEK_SET) == -1)
 147         return errno;
 148     errno = save_errno;
 149     POS(sp) = tmpoff;
 150     return 0;
 151 }
 152
 153 static int
 154 stdio_sync(krb5_storage * sp)
 155 {
 156     if (fflush(F(sp)) == EOF)
 157         return errno;
 158     if (fsync(fileno(F(sp))) == -1)
 159         return errno;
 160     return 0;
 161 }
 162
 163 static void
 164 stdio_free(krb5_storage * sp)
 165 {
 166     int save_errno = errno;
 167
 168     if (F(sp) != NULL && fclose(F(sp)) == 0)
 169         errno = save_errno;
 170     F(sp) = NULL;
 171 }
 172
 173 /**
 174  * Open a krb5_storage using stdio for buffering.
 175  *
 176  * @return A krb5_storage on success, or NULL on out of memory error.
 177  *
 178  * @ingroup krb5_storage
 179  *
 180  * @sa krb5_storage_emem()
 181  * @sa krb5_storage_from_fd()
 182  * @sa krb5_storage_from_mem()
 183  * @sa krb5_storage_from_readonly_mem()
 184  * @sa krb5_storage_from_data()
 185  * @sa krb5_storage_from_socket()
 186  */
 187
 188 KRB5_LIB_FUNCTION krb5_storage * KRB5_LIB_CALL
 189 krb5_storage_stdio_from_fd(int fd_in, const char *mode)
 190 {
 191     krb5_storage *sp;
 192     off_t off;
 193     FILE *f;
 194     int saved_errno = errno;
 195     int fd;
 196
 197     off = lseek(fd_in, 0, SEEK_CUR);
 198     if (off == -1)
 199         return NULL;
 200
 201 #ifdef _MSC_VER
 202     /*
 203      * This function used to try to pass the input to
 204      * _get_osfhandle() to test if the value is a HANDLE
 205      * but this doesn't work because doing so throws an
 206      * exception that will result in Watson being triggered
 207      * to file a Windows Error Report.
 208      */
 209     fd = _dup(fd_in);
 210 #else
 211     fd = dup(fd_in);
 212 #endif
 213
 214     if (fd < 0)
 215         return NULL;
 216
 217     f = fdopen(fd, mode);
 218     if (f == NULL) {
 219         (void) close(fd);
 220         return NULL;
 221     }
 222
 223     errno = saved_errno;
 224
 225     if (fseeko(f, off, SEEK_SET) == -1) {
 226         saved_errno = errno;
 227         (void) fclose(f);
 228         errno = saved_errno;
 229         return NULL;
 230     }
 231
 232     errno = ENOMEM;
 233     sp = malloc(sizeof(krb5_storage));
 234     if (sp == NULL) {
 235         saved_errno = errno;
 236         (void) fclose(f);
 237         errno = saved_errno;
 238         return NULL;
 239     }
 240
 241     errno = ENOMEM;
 242     sp->data = malloc(sizeof(stdio_storage));
 243     if (sp->data == NULL) {
 244         saved_errno = errno;
 245         (void) fclose(f);
 246         free(sp);
 247         errno = saved_errno;
 248         return NULL;
 249     }
 250     sp->flags = 0;
 251     sp->eof_code = HEIM_ERR_EOF;
 252     F(sp) = f;
 253     POS(sp) = off;
 254     sp->fetch = stdio_fetch;
 255     sp->store = stdio_store;
 256     sp->seek = stdio_seek;
 257     sp->trunc = stdio_trunc;
 258     sp->fsync = stdio_sync;
 259     sp->free = stdio_free;
 260     sp->max_alloc = UINT_MAX/8;
 261     return sp;
 262 }