src/SDL_hints.c
author Philipp Wiesemann
Wed, 29 Oct 2014 20:29:32 +0100
changeset 9202 01bb8e3ba14f
parent 9201 21d9f9babb30
child 9204 b331795924d3
permissions -rw-r--r--
Fixed SDL_AddHintCallback() crashing if no more memory available.

The return value of SDL_malloc() was not checked and NULL therefore not handled.
Also added setting of error message for the other SDL_malloc() in this function.
     1 /*
     2   Simple DirectMedia Layer
     3   Copyright (C) 1997-2014 Sam Lantinga <slouken@libsdl.org>
     4 
     5   This software is provided 'as-is', without any express or implied
     6   warranty.  In no event will the authors be held liable for any damages
     7   arising from the use of this software.
     8 
     9   Permission is granted to anyone to use this software for any purpose,
    10   including commercial applications, and to alter it and redistribute it
    11   freely, subject to the following restrictions:
    12 
    13   1. The origin of this software must not be misrepresented; you must not
    14      claim that you wrote the original software. If you use this software
    15      in a product, an acknowledgment in the product documentation would be
    16      appreciated but is not required.
    17   2. Altered source versions must be plainly marked as such, and must not be
    18      misrepresented as being the original software.
    19   3. This notice may not be removed or altered from any source distribution.
    20 */
    21 #include "./SDL_internal.h"
    22 
    23 #include "SDL_hints.h"
    24 #include "SDL_error.h"
    25 
    26 
    27 /* Assuming there aren't many hints set and they aren't being queried in
    28    critical performance paths, we'll just use linked lists here.
    29  */
    30 typedef struct SDL_HintWatch {
    31     SDL_HintCallback callback;
    32     void *userdata;
    33     struct SDL_HintWatch *next;
    34 } SDL_HintWatch;
    35 
    36 typedef struct SDL_Hint {
    37     char *name;
    38     char *value;
    39     SDL_HintPriority priority;
    40     SDL_HintWatch *callbacks;
    41     struct SDL_Hint *next;
    42 } SDL_Hint;
    43 
    44 static SDL_Hint *SDL_hints;
    45 
    46 SDL_bool
    47 SDL_SetHintWithPriority(const char *name, const char *value,
    48                         SDL_HintPriority priority)
    49 {
    50     const char *env;
    51     SDL_Hint *hint;
    52     SDL_HintWatch *entry;
    53 
    54     if (!name || !value) {
    55         return SDL_FALSE;
    56     }
    57 
    58     env = SDL_getenv(name);
    59     if (env && priority < SDL_HINT_OVERRIDE) {
    60         return SDL_FALSE;
    61     }
    62 
    63     for (hint = SDL_hints; hint; hint = hint->next) {
    64         if (SDL_strcmp(name, hint->name) == 0) {
    65             if (priority < hint->priority) {
    66                 return SDL_FALSE;
    67             }
    68             if (!hint->value || !value || SDL_strcmp(hint->value, value) != 0) {
    69                 for (entry = hint->callbacks; entry; ) {
    70                     /* Save the next entry in case this one is deleted */
    71                     SDL_HintWatch *next = entry->next;
    72                     entry->callback(entry->userdata, name, hint->value, value);
    73                     entry = next;
    74                 }
    75                 SDL_free(hint->value);
    76                 hint->value = value ? SDL_strdup(value) : NULL;
    77             }
    78             hint->priority = priority;
    79             return SDL_TRUE;
    80         }
    81     }
    82 
    83     /* Couldn't find the hint, add a new one */
    84     hint = (SDL_Hint *)SDL_malloc(sizeof(*hint));
    85     if (!hint) {
    86         return SDL_FALSE;
    87     }
    88     hint->name = SDL_strdup(name);
    89     hint->value = value ? SDL_strdup(value) : NULL;
    90     hint->priority = priority;
    91     hint->callbacks = NULL;
    92     hint->next = SDL_hints;
    93     SDL_hints = hint;
    94     return SDL_TRUE;
    95 }
    96 
    97 SDL_bool
    98 SDL_SetHint(const char *name, const char *value)
    99 {
   100     return SDL_SetHintWithPriority(name, value, SDL_HINT_NORMAL);
   101 }
   102 
   103 const char *
   104 SDL_GetHint(const char *name)
   105 {
   106     const char *env;
   107     SDL_Hint *hint;
   108 
   109     env = SDL_getenv(name);
   110     for (hint = SDL_hints; hint; hint = hint->next) {
   111         if (SDL_strcmp(name, hint->name) == 0) {
   112             if (!env || hint->priority == SDL_HINT_OVERRIDE) {
   113                 return hint->value;
   114             }
   115             break;
   116         }
   117     }
   118     return env;
   119 }
   120 
   121 void
   122 SDL_AddHintCallback(const char *name, SDL_HintCallback callback, void *userdata)
   123 {
   124     SDL_Hint *hint;
   125     SDL_HintWatch *entry;
   126     const char *value;
   127 
   128     if (!name || !*name) {
   129         SDL_InvalidParamError("name");
   130         return;
   131     }
   132     if (!callback) {
   133         SDL_InvalidParamError("callback");
   134         return;
   135     }
   136 
   137     SDL_DelHintCallback(name, callback, userdata);
   138 
   139     entry = (SDL_HintWatch *)SDL_malloc(sizeof(*entry));
   140     if (!entry) {
   141         SDL_OutOfMemory();
   142         return;
   143     }
   144     entry->callback = callback;
   145     entry->userdata = userdata;
   146 
   147     for (hint = SDL_hints; hint; hint = hint->next) {
   148         if (SDL_strcmp(name, hint->name) == 0) {
   149             break;
   150         }
   151     }
   152     if (!hint) {
   153         /* Need to add a hint entry for this watcher */
   154         hint = (SDL_Hint *)SDL_malloc(sizeof(*hint));
   155         if (!hint) {
   156             SDL_OutOfMemory();
   157             if(entry)
   158             {
   159               SDL_free(entry);
   160               entry = NULL;
   161             }
   162             return;
   163         }
   164         hint->name = SDL_strdup(name);
   165         hint->value = NULL;
   166         hint->priority = SDL_HINT_DEFAULT;
   167         hint->callbacks = NULL;
   168         hint->next = SDL_hints;
   169         SDL_hints = hint;
   170     }
   171 
   172     /* Add it to the callbacks for this hint */
   173     entry->next = hint->callbacks;
   174     hint->callbacks = entry;
   175 
   176     /* Now call it with the current value */
   177     value = SDL_GetHint(name);
   178     callback(userdata, name, value, value);
   179 }
   180 
   181 void
   182 SDL_DelHintCallback(const char *name, SDL_HintCallback callback, void *userdata)
   183 {
   184     SDL_Hint *hint;
   185     SDL_HintWatch *entry, *prev;
   186 
   187     for (hint = SDL_hints; hint; hint = hint->next) {
   188         if (SDL_strcmp(name, hint->name) == 0) {
   189             prev = NULL;
   190             for (entry = hint->callbacks; entry; entry = entry->next) {
   191                 if (callback == entry->callback && userdata == entry->userdata) {
   192                     if (prev) {
   193                         prev->next = entry->next;
   194                     } else {
   195                         hint->callbacks = entry->next;
   196                     }
   197                     SDL_free(entry);
   198                     break;
   199                 }
   200                 prev = entry;
   201             }
   202             return;
   203         }
   204     }
   205 }
   206 
   207 void SDL_ClearHints(void)
   208 {
   209     SDL_Hint *hint;
   210     SDL_HintWatch *entry;
   211 
   212     while (SDL_hints) {
   213         hint = SDL_hints;
   214         SDL_hints = hint->next;
   215 
   216         SDL_free(hint->name);
   217         SDL_free(hint->value);
   218         for (entry = hint->callbacks; entry; ) {
   219             SDL_HintWatch *freeable = entry;
   220             entry = entry->next;
   221             SDL_free(freeable);
   222         }
   223         SDL_free(hint);
   224     }
   225 }
   226 
   227 /* vi: set ts=4 sw=4 expandtab: */