source/lib/xfile.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    stdio replacement
   4    Copyright (C) Andrew Tridgell 2001
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 /*
  21   stdio is very convenient, but on some systems the file descriptor
  22   in FILE* is 8 bits, so it fails when more than 255 files are open.
  23
  24   XFILE replaces stdio. It is less efficient, but at least it works
  25   when you have lots of files open
  26
  27   The main restriction on XFILE is that it doesn't support seeking,
  28   and doesn't support O_RDWR. That keeps the code simple.
  29 */
  30
  31 #include "includes.h"
  32
  33 #define XBUFSIZE BUFSIZ
  34
  35 static XFILE _x_stdin =  { 0, NULL, NULL, XBUFSIZE, 0, O_RDONLY, X_IOFBF, 0 };
  36 static XFILE _x_stdout = { 1, NULL, NULL, XBUFSIZE, 0, O_WRONLY, X_IOLBF, 0 };
  37 static XFILE _x_stderr = { 2, NULL, NULL, 0, 0, O_WRONLY, X_IONBF, 0 };
  38
  39 XFILE *x_stdin = &_x_stdin;
  40 XFILE *x_stdout = &_x_stdout;
  41 XFILE *x_stderr = &_x_stderr;
  42
  43 #define X_FLAG_EOF 1
  44 #define X_FLAG_ERROR 2
  45 #define X_FLAG_EINVAL 3
  46
  47 /* simulate setvbuf() */
  48 int x_setvbuf(XFILE *f, char *buf, int mode, size_t size)
  49 {
  50         if (x_fflush(f) != 0) return -1;
  51         if (f->bufused) return -1;
  52
  53         /* on files being read full buffering is the only option */
  54         if ((f->open_flags & O_ACCMODE) == O_RDONLY) {
  55                 mode = X_IOFBF;
  56         }
  57
  58         /* destroy any earlier buffer */
  59         SAFE_FREE(f->buf);
  60         f->buf = 0;
  61         f->bufsize = 0;
  62         f->next = NULL;
  63         f->bufused = 0;
  64         f->buftype = mode;
  65
  66         if (f->buftype == X_IONBF) return 0;
  67
  68         /* if buffering then we need some size */
  69         if (size == 0) size = XBUFSIZE;
  70
  71         f->bufsize = size;
  72         f->bufused = 0;
  73
  74         return 0;
  75 }
  76
  77 /* allocate the buffer */
  78 static int x_allocate_buffer(XFILE *f)
  79 {
  80         if (f->buf) return 1;
  81         if (f->bufsize == 0) return 0;
  82         f->buf = (char *)SMB_MALLOC(f->bufsize);
  83         if (!f->buf) return 0;
  84         f->next = f->buf;
  85         return 1;
  86 }
  87
  88
  89 /* this looks more like open() than fopen(), but that is quite deliberate.
  90    I want programmers to *think* about O_EXCL, O_CREAT etc not just
  91    get them magically added
  92 */
  93 XFILE *x_fopen(const char *fname, int flags, mode_t mode)
  94 {
  95         XFILE *ret;
  96
  97         ret = SMB_MALLOC_P(XFILE);
  98         if (!ret) {
  99                 return NULL;
 100         }
 101
 102         memset(ret, 0, sizeof(XFILE));
 103
 104         if ((flags & O_ACCMODE) == O_RDWR) {
 105                 /* we don't support RDWR in XFILE - use file
 106                    descriptors instead */
 107                 SAFE_FREE(ret);
 108                 errno = EINVAL;
 109                 return NULL;
 110         }
 111
 112         ret->open_flags = flags;
 113
 114         ret->fd = sys_open(fname, flags, mode);
 115         if (ret->fd == -1) {
 116                 SAFE_FREE(ret);
 117                 return NULL;
 118         }
 119
 120         x_setvbuf(ret, NULL, X_IOFBF, XBUFSIZE);
 121
 122         return ret;
 123 }
 124
 125 XFILE *x_fdup(const XFILE *f)
 126 {
 127         XFILE *ret;
 128         int fd;
 129
 130         fd = dup(x_fileno(f));
 131         if (fd < 0) {
 132                 return NULL;
 133         }
 134
 135         ret = SMB_CALLOC_ARRAY(XFILE, 1);
 136         if (!ret) {
 137                 close(fd);
 138                 return NULL;
 139         }
 140
 141         ret->fd = fd;
 142         ret->open_flags = f->open_flags;
 143         x_setvbuf(ret, NULL, X_IOFBF, XBUFSIZE);
 144         return ret;
 145 }
 146
 147 /* simulate fclose() */
 148 int x_fclose(XFILE *f)
 149 {
 150         int ret;
 151
 152         /* make sure we flush any buffered data */
 153         (void)x_fflush(f);
 154
 155         ret = close(f->fd);
 156         f->fd = -1;
 157         if (f->buf) {
 158                 /* make sure data can't leak into a later malloc */
 159                 memset(f->buf, 0, f->bufsize);
 160                 SAFE_FREE(f->buf);
 161         }
 162         /* check the file descriptor given to the function is NOT one of the static
 163          * descriptor of this libreary or we will free unallocated memory
 164          * --sss */
 165         if (f != x_stdin && f != x_stdout && f != x_stderr) {
 166                 SAFE_FREE(f);
 167         }
 168         return ret;
 169 }
 170
 171 /* simulate fwrite() */
 172 size_t x_fwrite(const void *p, size_t size, size_t nmemb, XFILE *f)
 173 {
 174         ssize_t ret;
 175         size_t total=0;
 176
 177         /* we might be writing unbuffered */
 178         if (f->buftype == X_IONBF ||
 179             (!f->buf && !x_allocate_buffer(f))) {
 180                 ret = write(f->fd, p, size*nmemb);
 181                 if (ret == -1) return -1;
 182                 return ret/size;
 183         }
 184
 185
 186         while (total < size*nmemb) {
 187                 size_t n = f->bufsize - f->bufused;
 188                 n = MIN(n, (size*nmemb)-total);
 189
 190                 if (n == 0) {
 191                         /* it's full, flush it */
 192                         if (x_fflush(f) != 0) {
 193                                 return -1;
 194                         }
 195                         continue;
 196                 }
 197
 198                 memcpy(f->buf + f->bufused, total+(const char *)p, n);
 199                 f->bufused += n;
 200                 total += n;
 201         }
 202
 203         /* when line buffered we need to flush at the last linefeed. This can
 204            flush a bit more than necessary, but that is harmless */
 205         if (f->buftype == X_IOLBF && f->bufused) {
 206                 int i;
 207                 for (i=(size*nmemb)-1; i>=0; i--) {
 208                         if (*(i+(const char *)p) == '\n') {
 209                                 if (x_fflush(f) != 0) {
 210                                         return -1;
 211                                 }
 212                                 break;
 213                         }
 214                 }
 215         }
 216
 217         return total/size;
 218 }
 219
 220 /* thank goodness for asprintf() */
 221  int x_vfprintf(XFILE *f, const char *format, va_list ap)
 222 {
 223         char *p;
 224         int len, ret;
 225         va_list ap2;
 226
 227         VA_COPY(ap2, ap);
 228
 229         len = vasprintf(&p, format, ap2);
 230         if (len <= 0) {
 231                 va_end(ap2);
 232                 return len;
 233         }
 234         ret = x_fwrite(p, 1, len, f);
 235         SAFE_FREE(p);
 236
 237         va_end(ap2);
 238
 239         return ret;
 240 }
 241
 242  int x_fprintf(XFILE *f, const char *format, ...)
 243 {
 244         va_list ap;
 245         int ret;
 246
 247         va_start(ap, format);
 248         ret = x_vfprintf(f, format, ap);
 249         va_end(ap);
 250         return ret;
 251 }
 252
 253 /* at least fileno() is simple! */
 254 int x_fileno(const XFILE *f)
 255 {
 256         return f->fd;
 257 }
 258
 259 /* simulate fflush() */
 260 int x_fflush(XFILE *f)
 261 {
 262         int ret;
 263
 264         if (f->flags & X_FLAG_ERROR) return -1;
 265
 266         if (f->bufused == 0 || !f->buf) return 0;
 267
 268         if ((f->open_flags & O_ACCMODE) != O_WRONLY) {
 269                 errno = EINVAL;
 270                 return -1;
 271         }
 272
 273         ret = write(f->fd, f->buf, f->bufused);
 274         if (ret == -1) return -1;
 275
 276         f->bufused -= ret;
 277         if (f->bufused > 0) {
 278                 f->flags |= X_FLAG_ERROR;
 279                 memmove(f->buf, ret + (char *)f->buf, f->bufused);
 280                 return -1;
 281         }
 282
 283         return 0;
 284 }
 285
 286 /* simulate setbuffer() */
 287 void x_setbuffer(XFILE *f, char *buf, size_t size)
 288 {
 289         x_setvbuf(f, buf, buf?X_IOFBF:X_IONBF, size);
 290 }
 291
 292 /* simulate setbuf() */
 293 void x_setbuf(XFILE *f, char *buf)
 294 {
 295         x_setvbuf(f, buf, buf?X_IOFBF:X_IONBF, XBUFSIZE);
 296 }
 297
 298 /* simulate setlinebuf() */
 299 void x_setlinebuf(XFILE *f)
 300 {
 301         x_setvbuf(f, NULL, X_IOLBF, 0);
 302 }
 303
 304
 305 /* simulate feof() */
 306 int x_feof(XFILE *f)
 307 {
 308         if (f->flags & X_FLAG_EOF) return 1;
 309         return 0;
 310 }
 311
 312 /* simulate ferror() */
 313 int x_ferror(XFILE *f)
 314 {
 315         if (f->flags & X_FLAG_ERROR) return 1;
 316         return 0;
 317 }
 318
 319 /* fill the read buffer */
 320 static void x_fillbuf(XFILE *f)
 321 {
 322         int n;
 323
 324         if (f->bufused) return;
 325
 326         if (!f->buf && !x_allocate_buffer(f)) return;
 327
 328         n = read(f->fd, f->buf, f->bufsize);
 329         if (n <= 0) return;
 330         f->bufused = n;
 331         f->next = f->buf;
 332 }
 333
 334 /* simulate fgetc() */
 335 int x_fgetc(XFILE *f)
 336 {
 337         int ret;
 338
 339         if (f->flags & (X_FLAG_EOF | X_FLAG_ERROR)) return EOF;
 340
 341         if (f->bufused == 0) x_fillbuf(f);
 342
 343         if (f->bufused == 0) {
 344                 f->flags |= X_FLAG_EOF;
 345                 return EOF;
 346         }
 347
 348         ret = *(unsigned char *)(f->next);
 349         f->next++;
 350         f->bufused--;
 351         return ret;
 352 }
 353
 354 /* simulate fread */
 355 size_t x_fread(void *p, size_t size, size_t nmemb, XFILE *f)
 356 {
 357         size_t total = 0;
 358         while (total < size*nmemb) {
 359                 int c = x_fgetc(f);
 360                 if (c == EOF) break;
 361                 (total+(char *)p)[0] = (char)c;
 362                 total++;
 363         }
 364         return total/size;
 365 }
 366
 367 /* simulate fgets() */
 368 char *x_fgets(char *s, int size, XFILE *stream)
 369 {
 370         char *s0 = s;
 371         int l = size;
 372         while (l>1) {
 373                 int c = x_fgetc(stream);
 374                 if (c == EOF) break;
 375                 *s++ = (char)c;
 376                 l--;
 377                 if (c == '\n') break;
 378         }
 379         if (l==size || x_ferror(stream)) {
 380                 return 0;
 381         }
 382         *s = 0;
 383         return s0;
 384 }
 385
 386 /* trivial seek, works only for SEEK_SET and SEEK_END if SEEK_CUR is
 387  * set then an error is returned */
 388 off_t x_tseek(XFILE *f, off_t offset, int whence)
 389 {
 390         if (f->flags & X_FLAG_ERROR)
 391                 return -1;
 392
 393         /* only SEEK_SET and SEEK_END are supported */
 394         /* SEEK_CUR needs internal offset counter */
 395         if (whence != SEEK_SET && whence != SEEK_END) {
 396                 f->flags |= X_FLAG_EINVAL;
 397                 errno = EINVAL;
 398                 return -1;
 399         }
 400
 401         /* empty the buffer */
 402         switch (f->open_flags & O_ACCMODE) {
 403         case O_RDONLY:
 404                 f->bufused = 0;
 405                 break;
 406         case O_WRONLY:
 407                 if (x_fflush(f) != 0)
 408                         return -1;
 409                 break;
 410         default:
 411                 errno = EINVAL;
 412                 return -1;
 413         }
 414
 415         f->flags &= ~X_FLAG_EOF;
 416         return (off_t)sys_lseek(f->fd, offset, whence);
 417 }