Fix a bug on FreeBSD caused by assuming that short reads are errors

[xonotic/darkplaces.git] / fs.c

diff --git a/fs.c b/fs.c
index e7a001bff6ae84072dc98771493869537966b58f..af62b898a3b2a330be6797f80ec34c2033bd91d3 100644 (file)
--- a/fs.c
+++ b/fs.c
@@ -109,6 +109,66 @@ static filedesc_t FILEDESC_DUP(const char *filename, filedesc_t fd) {
 }
 #endif
 
+
+/* This code seems to have originally been written with the assumption that
+ * read(..., n) returns n on success. This is not the case (refer to
+ * <https://pubs.opengroup.org/onlinepubs/9699919799/functions/read.html>).
+ * Ditto for write.
+ */
+
+/*
+====================
+ReadAll
+
+Read exactly length bytes from fd into buf. If end of file is reached,
+the number of bytes read is returned. If an error occurred, that error
+is returned. Note that if an error is returned, any previously read
+data is lost.
+====================
+*/
+static fs_offset_t ReadAll(const filedesc_t fd, void *const buf, const size_t length)
+{
+       char *const p = (char *)buf;
+       size_t cursor = 0;
+       do
+       {
+               const fs_offset_t result = FILEDESC_READ(fd, p + cursor, length - cursor);
+               if (result < 0) // Error
+                       return result;
+               if (result == 0) // EOF
+                       break;
+               cursor += result;
+       } while (cursor < length);
+       return cursor;
+}
+
+/*
+====================
+WriteAll
+
+Write exactly length bytes to fd from buf.
+If an error occurred, that error is returned.
+====================
+*/
+static fs_offset_t WriteAll(const filedesc_t fd, const void *const buf, const size_t length)
+{
+       const char *const p = (const char *)buf;
+       size_t cursor = 0;
+       do
+       {
+               const fs_offset_t result = FILEDESC_WRITE(fd, p + cursor, length - cursor);
+               if (result < 0) // Error
+                       return result;
+               cursor += result;
+       } while (cursor < length);
+       return cursor;
+}
+
+#undef FILEDESC_READ
+#define FILEDESC_READ ReadAll
+#undef FILEDESC_WRITE
+#define FILEDESC_WRITE WriteAll
+
 /** \page fs File System
 
 All of Quake's data access is through a hierchal file system, but the contents
@@ -455,7 +515,7 @@ static const char* shfolderdllnames [] =
 };
 static dllhandle_t shfolder_dll = NULL;
 
-const GUID qFOLDERID_SavedGames = {0x4C5C32FF, 0xBB9D, 0x43b0, {0xB5, 0xB4, 0x2D, 0x72, 0xE5, 0x4E, 0xAA, 0xA4}}; 
+const GUID qFOLDERID_SavedGames = {0x4C5C32FF, 0xBB9D, 0x43b0, {0xB5, 0xB4, 0x2D, 0x72, 0xE5, 0x4E, 0xAA, 0xA4}};
 #define qREFKNOWNFOLDERID const GUID *
 #define qKF_FLAG_CREATE 0x8000
 #define qKF_FLAG_NO_ALIAS 0x1000
@@ -1762,7 +1822,7 @@ const char *FS_CheckGameDir(const char *gamedir)
        ret = FS_SysCheckGameDir(va(vabuf, sizeof(vabuf), "%s%s/", fs_basedir, gamedir), buf, sizeof(buf));
        if(ret)
                return ret;
-       
+
        return fs_checkgamedir_missing;
 }
 
@@ -1795,7 +1855,7 @@ static void FS_ListGameDirs(void)
                        continue;
                if(!*info)
                        continue;
-               stringlistappend(&list2, list.strings[i]); 
+               stringlistappend(&list2, list.strings[i]);
        }
        stringlistfreecontents(&list);
 
@@ -2583,7 +2643,7 @@ int FS_CheckNastyPath (const char *path, qbool isgamedir)
 ====================
 FS_SanitizePath
 
-Sanitize path (replace non-portable characters 
+Sanitize path (replace non-portable characters
 with portable ones in-place, etc)
 ====================
 */
@@ -2740,7 +2800,7 @@ static qfile_t *FS_OpenReadFile (const char *filename, qbool quiet, qbool nonblo
                        if(count < 0)
                                return NULL;
                        linkbuf[count] = 0;
-                       
+
                        // Now combine the paths...
                        mergeslash = strrchr(filename, '/');
                        mergestart = linkbuf;
@@ -3974,7 +4034,7 @@ void FS_Which_f(cmd_state_t *cmd)
        {
                Con_Printf("usage:\n%s <file>\n", Cmd_Argv(cmd, 0));
                return;
-       }  
+       }
        filename = Cmd_Argv(cmd, 1);
        sp = FS_FindFile(filename, &index, true);
        if (!sp) {
@@ -4127,7 +4187,7 @@ unsigned char *FS_Deflate(const unsigned char *data, size_t size, size_t *deflat
                Mem_Free(tmp);
                return NULL;
        }
-       
+
        if(qz_deflateEnd(&strm) != Z_OK)
        {
                Con_Printf("FS_Deflate: deflateEnd failed\n");
@@ -4154,7 +4214,7 @@ unsigned char *FS_Deflate(const unsigned char *data, size_t size, size_t *deflat
 
        memcpy(out, tmp, strm.total_out);
        Mem_Free(tmp);
-       
+
        return out;
 }
 
@@ -4221,7 +4281,7 @@ unsigned char *FS_Inflate(const unsigned char *data, size_t size, size_t *inflat
                        case Z_STREAM_END:
                        case Z_OK:
                                break;
-                               
+
                        case Z_STREAM_ERROR:
                                Con_Print("FS_Inflate: stream error!\n");
                                break;
@@ -4237,7 +4297,7 @@ unsigned char *FS_Inflate(const unsigned char *data, size_t size, size_t *inflat
                        default:
                                Con_Print("FS_Inflate: unknown error!\n");
                                break;
-                               
+
                }
                if(ret != Z_OK && ret != Z_STREAM_END)
                {
@@ -4265,6 +4325,6 @@ unsigned char *FS_Inflate(const unsigned char *data, size_t size, size_t *inflat
        Mem_Free(outbuf.data);
 
        *inflated_size = (size_t)outbuf.cursize;
-       
+
        return out;
 }