common/utils/quote.c

   1 /* nbdkit
   2  * Copyright Red Hat
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are
   6  * met:
   7  *
   8  * * Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *
  11  * * Redistributions in binary form must reproduce the above copyright
  12  * notice, this list of conditions and the following disclaimer in the
  13  * documentation and/or other materials provided with the distribution.
  14  *
  15  * * Neither the name of Red Hat nor the names of its contributors may be
  16  * used to endorse or promote products derived from this software without
  17  * specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  21  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  22  * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
  23  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  26  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  27  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  28  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  29  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 #include <config.h>
  34
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <string.h>
  38 #include <unistd.h>
  39
  40 /* Print str to fp, shell quoting if necessary.  This comes from
  41  * libguestfs, but was written by me so I'm relicensing it to a BSD
  42  * license for nbdkit.
  43  */
  44 void
  45 shell_quote (const char *str, FILE *fp)
  46 {
  47   /* Note possible bug in this list (XXX):
  48    * https://www.redhat.com/archives/libguestfs/2019-February/msg00036.html
  49    */
  50   const char *safe_chars =
  51     "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789.-_=,:/";
  52   size_t i, len;
  53
  54   /* If the string consists only of safe characters, output it as-is. */
  55   len = strlen (str);
  56   if (len > 0 && len == strspn (str, safe_chars)) {
  57     fputs (str, fp);
  58     return;
  59   }
  60
  61   /* Double-quote the string. */
  62   fputc ('"', fp);
  63   for (i = 0; i < len; ++i) {
  64     switch (str[i]) {
  65     case '$': case '`': case '\\': case '"':
  66       fputc ('\\', fp);
  67       /*FALLTHROUGH*/
  68     default:
  69       fputc (str[i], fp);
  70     }
  71   }
  72   fputc ('"', fp);
  73 }
  74
  75 /* Print str to fp, URI quoting if necessary.
  76  * The resulting string is safe for use in a URI path or query component,
  77  * and can be passed through the shell without further quoting.
  78  */
  79 void
  80 uri_quote (const char *str, FILE *fp)
  81 {
  82   /* safe_chars contains the RFC 3986 unreserved characters plus '/'. */
  83   const char *safe_chars =
  84     "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789.-_~/";
  85   size_t i, len;
  86
  87   /* If the string consists only of safe characters, output it as-is. */
  88   len = strlen (str);
  89   if (len == strspn (str, safe_chars)) {
  90     fputs (str, fp);
  91     return;
  92   }
  93
  94   for (i = 0; i < len; ++i) {
  95     if (strchr (safe_chars, str[i]))
  96       fputc (str[i], fp);
  97     else
  98       fprintf (fp, "%%%02X", str[i] & 0xff);
  99   }
 100 }