util.c

   1 /* util.c -- utility functions for gzip support
   2
   3    Copyright (C) 1997-1999, 2001-2002, 2006, 2009-2024 Free Software
   4    Foundation, Inc.
   5    Copyright (C) 1992-1993 Jean-loup Gailly
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3, or (at your option)
  10    any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  19
  20 #include <config.h>
  21 #include <ctype.h>
  22 #include <errno.h>
  23 #include <limits.h>
  24 #include <unistd.h>
  25 #include <fcntl.h>
  26 #include <stdlib.h>
  27
  28 #include "crc.h"
  29 #include "tailor.h"
  30 #include "gzip.h"
  31 #include <dirname.h>
  32 #include <xalloc.h>
  33
  34 #ifndef EPIPE
  35 # define EPIPE 0
  36 #endif
  37
  38 static int write_buffer (int, voidp, unsigned int);
  39
  40 /* Shift register contents.  */
  41 static ulg crc = 0L;
  42
  43 /* ===========================================================================
  44  * Copy input to output unchanged: zcat == cat with --force.
  45  * IN assertion: insize bytes have already been read in inbuf and inptr bytes
  46  * already processed or copied.
  47  * 'in' and 'out' are the input and output file descriptors.
  48  */
  49 int
  50 copy (int in, int out)
  51 {
  52     int got;
  53
  54     errno = 0;
  55     while (insize > inptr) {
  56         write_buf(out, (char*)inbuf + inptr, insize - inptr);
  57         got = read_buffer (in, (char *) inbuf, INBUFSIZ);
  58         if (got == -1)
  59             read_error();
  60         bytes_in += got;
  61         insize = (unsigned)got;
  62         inptr = 0;
  63     }
  64     return OK;
  65 }
  66
  67 /* ===========================================================================
  68  * Run a set of bytes through the crc shift register.  If s is a NULL
  69  * pointer, then initialize the crc shift register contents instead.
  70  * Return the current crc in either case.
  71  * S points to N bytes to pump through.
  72  */
  73 ulg
  74 updcrc (uch const *s, unsigned n)
  75 {
  76     crc = (s == NULL ? 0 : crc32_update (crc, (const char *) s, n));
  77     return crc;
  78 }
  79
  80 /* Return a current CRC value.  */
  81 ulg
  82 getcrc ()
  83 {
  84   return crc;
  85 }
  86
  87 #ifdef IBM_Z_DFLTCC
  88 /* Set a new CRC value.  */
  89 void
  90 setcrc (ulg c)
  91 {
  92   crc = c;
  93 }
  94 #endif
  95
  96 /* ===========================================================================
  97  * Clear input and output buffers
  98  */
  99 void clear_bufs()
 100 {
 101     outcnt = 0;
 102     insize = inptr = 0;
 103     bytes_in = bytes_out = 0L;
 104 }
 105
 106 /* ===========================================================================
 107  * Fill the input buffer. This is called only when the buffer is empty.
 108  * EOF_OK is set if EOF acceptable as a result.
 109  */
 110 int
 111 fill_inbuf (int eof_ok)
 112 {
 113     int len;
 114
 115     /* Read as much as possible */
 116     insize = 0;
 117     do {
 118         len = read_buffer (ifd, (char *) inbuf + insize, INBUFSIZ - insize);
 119         if (len == 0) break;
 120         if (len == -1) {
 121           read_error();
 122           break;
 123         }
 124         insize += len;
 125     } while (insize < INBUFSIZ);
 126
 127     if (insize == 0) {
 128         if (eof_ok) return EOF;
 129         flush_window();
 130         errno = 0;
 131         read_error();
 132     }
 133     bytes_in += (off_t)insize;
 134     inptr = 1;
 135     return inbuf[0];
 136 }
 137
 138 /* Like the standard read function, except do not attempt to read more
 139    than INT_MAX bytes at a time.  */
 140 int
 141 read_buffer (int fd, voidp buf, unsigned int cnt)
 142 {
 143   int len;
 144   if (INT_MAX < cnt)
 145     cnt = INT_MAX;
 146   len = read (fd, buf, cnt);
 147
 148 #if defined F_SETFL && O_NONBLOCK && defined EAGAIN
 149   /* Input files are opened O_NONBLOCK for security reasons.  On some
 150      file systems this can cause read to fail with errno == EAGAIN.  */
 151   if (len < 0 && errno == EAGAIN)
 152     {
 153       int flags = fcntl (fd, F_GETFL);
 154       if (0 <= flags)
 155         {
 156           if (! (flags & O_NONBLOCK))
 157             errno = EAGAIN;
 158           else if (fcntl (fd, F_SETFL, flags & ~O_NONBLOCK) != -1)
 159             len = read (fd, buf, cnt);
 160         }
 161     }
 162 #endif
 163
 164   return len;
 165 }
 166
 167 /* Likewise for 'write'.  */
 168 static int
 169 write_buffer (int fd, voidp buf, unsigned int cnt)
 170 {
 171   if (INT_MAX < cnt)
 172     cnt = INT_MAX;
 173   return write (fd, buf, cnt);
 174 }
 175
 176 /* ===========================================================================
 177  * Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
 178  * (used for the compressed data only)
 179  */
 180 void flush_outbuf()
 181 {
 182     if (outcnt == 0) return;
 183
 184     write_buf (ofd, outbuf, outcnt);
 185     outcnt = 0;
 186 }
 187
 188 /* ===========================================================================
 189  * Write the output window window[0..outcnt-1] and update crc and bytes_out.
 190  * (Used for the decompressed data only.)
 191  */
 192 void flush_window()
 193 {
 194     if (outcnt == 0) return;
 195     updcrc(window, outcnt);
 196
 197     write_buf (ofd, window, outcnt);
 198     outcnt = 0;
 199 }
 200
 201 /* ===========================================================================
 202  * Update the count of output bytes.  If testing, do not do any
 203  * output.  Otherwise, write the buffer, checking for errors.
 204  */
 205 void
 206 write_buf (int fd, voidp buf, unsigned  cnt)
 207 {
 208     unsigned  n;
 209
 210     bytes_out += cnt;
 211     if (test)
 212       return;
 213
 214     while ((n = write_buffer (fd, buf, cnt)) != cnt) {
 215         if (n == (unsigned)(-1)) {
 216             write_error();
 217         }
 218         cnt -= n;
 219         buf = (voidp)((char*)buf+n);
 220     }
 221 }
 222
 223 /* ========================================================================
 224  * Put string s in lower case, return s.
 225  */
 226 char *
 227 strlwr (char *s)
 228 {
 229     char *t;
 230     for (t = s; *t; t++)
 231       *t = tolow ((unsigned char) *t);
 232     return s;
 233 }
 234
 235 /* ========================================================================
 236  * Return the base name of a file (remove any directory prefix and
 237  * any version suffix). For systems with file names that are not
 238  * case sensitive, force the base name to lower case.
 239  */
 240 char *
 241 gzip_base_name (char *fname)
 242 {
 243     fname = last_component (fname);
 244     if (casemap('A') == 'a') strlwr(fname);
 245     return fname;
 246 }
 247
 248 /* ========================================================================
 249  * Unlink a file, working around the unlink readonly bug (if present).
 250  */
 251 int
 252 xunlink (char *filename)
 253 {
 254   int r = unlink (filename);
 255
 256 #ifdef UNLINK_READONLY_BUG
 257   if (r != 0)
 258     {
 259       int e = errno;
 260       if (chmod (filename, S_IWUSR) != 0)
 261         {
 262           errno = e;
 263           return -1;
 264         }
 265
 266       r = unlink (filename);
 267     }
 268 #endif
 269
 270   return r;
 271 }
 272
 273 #ifdef NO_MULTIPLE_DOTS
 274 /* ========================================================================
 275  * Make a file name legal for file systems not allowing file names with
 276  * multiple dots or starting with a dot (such as MSDOS), by changing
 277  * all dots except the last one into underlines.  A target dependent
 278  * function can be used instead of this simple function by defining the macro
 279  * MAKE_LEGAL_NAME in tailor.h and providing the function in a target
 280  * dependent module.
 281  */
 282 void
 283 make_simple_name (char *name)
 284 {
 285     char *p = strrchr(name, '.');
 286     if (p == NULL) return;
 287     if (p == name) p++;
 288     do {
 289         if (*--p == '.') *p = '_';
 290     } while (p != name);
 291 }
 292 #endif
 293
 294 /* Convert the value of the environment variable ENVVAR_NAME
 295    to a newly allocated argument vector, and set *ARGCP and *ARGVP
 296    to the number of arguments and to the vector, respectively.
 297    Make the new vector's zeroth element equal to the old **ARGVP.
 298    Return a pointer to the newly allocated string storage.
 299
 300    If the vector would be empty, do not allocate storage,
 301    do not set *ARGCP and *ARGVP, and return NULL.  */
 302
 303 #define SEPARATOR       " \t"   /* separators in env variable */
 304
 305 char *add_envopt(
 306     int *argcp,          /* pointer to argc */
 307     char ***argvp,       /* pointer to argv */
 308     char const *envvar_name) /* name of environment variable */
 309 {
 310     char *p;             /* running pointer through env variable */
 311     char **oargv;        /* runs through old argv array */
 312     char **nargv;        /* runs through new argv array */
 313     int  nargc = 0;      /* number of arguments in env variable */
 314     char *env_val;
 315
 316     env_val = getenv(envvar_name);
 317     if (env_val == NULL) return NULL;
 318
 319     env_val = xstrdup (env_val);
 320
 321     for (p = env_val; *p; nargc++ ) {        /* move through env_val */
 322         p += strspn(p, SEPARATOR);           /* skip leading separators */
 323         if (*p == '\0') break;
 324
 325         p += strcspn(p, SEPARATOR);          /* find end of word */
 326         if (*p) *p++ = '\0';                 /* mark it */
 327     }
 328     if (nargc == 0) {
 329         free(env_val);
 330         return NULL;
 331     }
 332     *argcp = nargc + 1;
 333     /* Allocate the new argv array, with an extra element just in case
 334      * the original arg list did not end with a NULL.
 335      */
 336     nargv = xcalloc (*argcp + 1, sizeof (char *));
 337     oargv  = *argvp;
 338     *argvp = nargv;
 339
 340     /* Copy the program name first */
 341     *nargv++ = *oargv;
 342
 343     /* Then copy the environment args */
 344     for (p = env_val; nargc > 0; nargc--) {
 345         p += strspn(p, SEPARATOR);           /* skip separators */
 346         *(nargv++) = p;                      /* store start */
 347         while (*p++) ;                       /* skip over word */
 348     }
 349
 350     *nargv = NULL;
 351     return env_val;
 352 }
 353
 354 /* ========================================================================
 355  * Error handlers.
 356  */
 357 void
 358 gzip_error (char const *m)
 359 {
 360     fprintf (stderr, "\n%s: %s: %s\n", program_name, ifname, m);
 361     abort_gzip();
 362 }
 363
 364 void
 365 xalloc_die ()
 366 {
 367   fprintf (stderr, "\n%s: memory_exhausted\n", program_name);
 368   abort_gzip ();
 369 }
 370
 371 void warning (char const *m)
 372 {
 373     WARN ((stderr, "%s: %s: warning: %s\n", program_name, ifname, m));
 374 }
 375
 376 void read_error()
 377 {
 378     fprintf (stderr, "\n%s: %s: %s\n",
 379              program_name, ifname,
 380              errno ? strerror (errno) : "unexpected end of file");
 381     abort_gzip();
 382 }
 383
 384 void write_error()
 385 {
 386   int exitcode = errno == EPIPE ? WARNING : ERROR;
 387   if (! (exitcode == WARNING && quiet))
 388     fprintf (stderr, "\n%s: %s: %s\n", program_name, ofname, strerror (errno));
 389   finish_up_gzip (exitcode);
 390 }
 391
 392 /* ========================================================================
 393  * Display compression ratio on the given stream on 6 characters.
 394  */
 395 void
 396 display_ratio (off_t num, off_t den, FILE *file)
 397 {
 398     fprintf(file, "%5.1f%%", den == 0 ? 0 : 100.0 * num / den);
 399 }