wsutil/tempfile.c

   1 /* tempfile.c
   2  * Routines to create temporary files
   3  *
   4  * Wireshark - Network traffic analyzer
   5  * By Gerald Combs <gerald@wireshark.org>
   6  * Copyright 1998 Gerald Combs
   7  *
   8  * SPDX-License-Identifier: GPL-2.0-or-later
   9  */
  10
  11 #include "config.h"
  12 #include "tempfile.h"
  13
  14 #include <errno.h>
  15
  16 #include "file_util.h"
  17
  18 static char *
  19 sanitize_prefix(const char *prefix)
  20 {
  21   if (!prefix) {
  22       return NULL;
  23   }
  24
  25   /* The characters in "delimiters" come from:
  26    * https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file#naming-conventions.
  27    * Add to the list as necessary for other OS's.
  28    */
  29   const char *delimiters = "<>:\"/\\|?*"
  30     "\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a"
  31     "\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14"
  32     "\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f";
  33
  34   /* Sanitize the prefix to resolve bug 7877 */
  35   char *safe_prefx = g_strdup(prefix);
  36   safe_prefx = g_strdelimit(safe_prefx, delimiters, '-');
  37   return safe_prefx;
  38 }
  39
  40  /**
  41  * Create a tempfile with the given prefix (e.g. "wireshark"). The path
  42  * is created using g_file_open_tmp.
  43  *
  44  * @param tempdir [in] If not NULL, the directory in which to create the file.
  45  * @param namebuf [in,out] If not NULL, receives the full path of the temp file.
  46  *                Must be freed.
  47  * @param pfx [in] A prefix for the temporary file.
  48  * @param sfx [in] A file extension for the temporary file. NULL can be passed
  49  *                 if no file extension is needed
  50  * @param err [out] Any error returned by g_file_open_tmp. May be NULL
  51  * @return The file descriptor of the new tempfile, from mkstemps().
  52  */
  53 int
  54 create_tempfile(const char *tempdir, char **namebuf, const char *pfx, const char *sfx, GError **err)
  55 {
  56   int fd;
  57   char *safe_pfx = sanitize_prefix(pfx);
  58
  59   if (tempdir == NULL || tempdir[0] == '\0') {
  60     /* Use OS default tempdir behaviour */
  61     char* filetmpl = ws_strdup_printf("%sXXXXXX%s", safe_pfx ? safe_pfx : "", sfx ? sfx : "");
  62     g_free(safe_pfx);
  63
  64     fd = g_file_open_tmp(filetmpl, namebuf, err);
  65     g_free(filetmpl);
  66   }
  67   else {
  68     /* User-specified tempdir.
  69      * We don't get libc's help generating a random name here.
  70      */
  71     const char alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_-";
  72     const int32_t a_len = 64;
  73     char* filetmpl = NULL;
  74
  75     while(1) {
  76       g_free(filetmpl);
  77       filetmpl = ws_strdup_printf("%s%c%s%c%c%c%c%c%c%s",
  78           tempdir,
  79           G_DIR_SEPARATOR,
  80           safe_pfx ? safe_pfx : "",
  81           alphabet[g_random_int_range(0, a_len)],
  82           alphabet[g_random_int_range(0, a_len)],
  83           alphabet[g_random_int_range(0, a_len)],
  84           alphabet[g_random_int_range(0, a_len)],
  85           alphabet[g_random_int_range(0, a_len)],
  86           alphabet[g_random_int_range(0, a_len)],
  87           sfx ? sfx : "");
  88
  89       fd = ws_open(filetmpl, O_CREAT|O_EXCL|O_BINARY|O_WRONLY, 0600);
  90       if (fd >= 0) {
  91         break;
  92       }
  93       if (errno != EEXIST) {
  94         g_set_error_literal(err, G_FILE_ERROR,
  95             g_file_error_from_errno(errno), g_strerror(errno));
  96         g_free(filetmpl);
  97         filetmpl = NULL;
  98         break;
  99       }
 100       /* Loop continues if error was EEXIST, meaning the file we tried
 101        * to make already existed at the destination
 102        */
 103     }
 104
 105     if (namebuf == NULL) {
 106       g_free(filetmpl);
 107     }
 108     else {
 109       *namebuf = filetmpl;
 110     }
 111     g_free(safe_pfx);
 112   }
 113
 114   return fd;
 115 }
 116
 117 char *
 118 create_tempdir(const char *parent_dir, const char *tmpl, GError **err)
 119 {
 120   if (parent_dir == NULL || parent_dir[0] == '\0') {
 121       parent_dir = g_get_tmp_dir();
 122   }
 123
 124   char *safe_pfx = sanitize_prefix(tmpl);
 125   if (safe_pfx == NULL) {
 126     safe_pfx = g_strdup("wireshark_XXXXXX");
 127   }
 128
 129   char *temp_subdir = g_build_path(G_DIR_SEPARATOR_S, parent_dir, safe_pfx, NULL);
 130   g_free(safe_pfx);
 131   if (g_mkdtemp(temp_subdir) == NULL)
 132   {
 133       g_free(temp_subdir);
 134       g_set_error_literal(err, G_FILE_ERROR,
 135           g_file_error_from_errno(errno), g_strerror(errno));
 136       return NULL;
 137   }
 138
 139   return temp_subdir;
 140 }
 141
 142 /*
 143  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 144  *
 145  * Local Variables:
 146  * c-basic-offset: 2
 147  * tab-width: 8
 148  * indent-tabs-mode: nil
 149  * End:
 150  *
 151  * ex: set shiftwidth=2 tabstop=8 expandtab:
 152  * :indentSize=2:tabSize=8:noTabs=true:
 153  */