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Import fatfs R0.10b
[z180-stamp.git] / fatfs / doc / en / open.html
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L		 1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">\r
2<html lang="en">\r
3<head>\r
4<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">\r
5<meta http-equiv="Content-Style-Type" content="text/css">\r
6<link rel="up" title="FatFs" href="../00index_e.html">\r
7<link rel="alternate" hreflang="ja" title="Japanese" href="../ja/open.html">\r
8<link rel="stylesheet" href="../css_e.css" type="text/css" media="screen" title="ELM Default">\r
9<title>FatFs - f_open</title>\r
10</head>\r
11\r
12<body>\r
13\r
14<div class="para func">\r
15<h2>f_open</h2>\r
16<p>The f_open function creates a <em>file object</em> to be used to access the file.</p>\r
17<pre>\r
18FRESULT f_open (\r
19 FIL* <span class="arg">fp</span>, <span class="c">/* [OUT] Pointer to the file object structure */</span>\r
20 const TCHAR* <span class="arg">path</span>, <span class="c">/* [IN] File name */</span>\r
21 BYTE <span class="arg">mode</span> <span class="c">/* [IN] Mode flags */</span>\r
22);\r
23</pre>\r
24</div>\r
25\r
26<div class="para arg">\r
27<h4>Parameters</h4>\r
28<dl class="par">\r
29<dt>fp</dt>\r
30<dd>Pointer to the blank file object structure to be created.</dd>\r
31<dt>path</dt>\r
32<dd>Pointer to a null-terminated string that specifies the <a href="filename.html">file name</a> to open or create.</dd>\r
33<dt>mode</dt>\r
34<dd>Mode flags that specifies the type of access and open method for the file. It is specified by a combination of following flags.<br>\r
35<table class="lst">\r
36<tr><th>Value</th><th>Description</th></tr>\r
37<tr><td>FA_READ</td><td>Specifies read access to the object. Data can be read from the file. Combine with <tt>FA_WRITE</tt> for read-write access.</td></tr>\r
38<tr><td>FA_WRITE</td><td>Specifies write access to the object. Data can be written to the file. Combine with <tt>FA_READ</tt> for read-write access.</td></tr>\r
39<tr><td>FA_OPEN_EXISTING</td><td>Opens the file. The function fails if the file is not existing. (Default)</td></tr>\r
40<tr><td>FA_OPEN_ALWAYS</td><td>Opens the file if it is existing. If not, a new file is created.<br>\r
41To append data to the file, use <a href="lseek.html"><tt>f_lseek()</tt></a> function after file open in this method.</td></tr>\r
42<tr><td>FA_CREATE_NEW</td><td>Creates a new file. The function fails with <tt>FR_EXIST</tt> if the file is existing.</td></tr>\r
43<tr><td>FA_CREATE_ALWAYS</td><td>Creates a new file. If the file is existing, it will be truncated and overwritten.</td></tr>\r
44</table>\r
45</dd>\r
46</dl>\r
47</div>\r
48\r
49\r
50<div class="para ret">\r
51<h4>Return Values</h4>\r
52<p>\r
53<a href="rc.html#ok">FR_OK</a>,\r
54<a href="rc.html#de">FR_DISK_ERR</a>,\r
55<a href="rc.html#ie">FR_INT_ERR</a>,\r
56<a href="rc.html#nr">FR_NOT_READY</a>,\r
57<a href="rc.html#ok">FR_NO_FILE</a>,\r
58<a href="rc.html#np">FR_NO_PATH</a>,\r
59<a href="rc.html#in">FR_INVALID_NAME</a>,\r
60<a href="rc.html#de">FR_DENIED</a>,\r
61<a href="rc.html#ex">FR_EXIST</a>,\r
62<a href="rc.html#io">FR_INVALID_OBJECT</a>,\r
63<a href="rc.html#wp">FR_WRITE_PROTECTED</a>,\r
64<a href="rc.html#id">FR_INVALID_DRIVE</a>,\r
65<a href="rc.html#ne">FR_NOT_ENABLED</a>,\r
66<a href="rc.html#ns">FR_NO_FILESYSTEM</a>,\r
67<a href="rc.html#tm">FR_TIMEOUT</a>,\r
68<a href="rc.html#lo">FR_LOCKED</a>,\r
69<a href="rc.html#nc">FR_NOT_ENOUGH_CORE</a>,\r
70<a href="rc.html#tf">FR_TOO_MANY_OPEN_FILES</a>\r
71</p>\r
72</div>\r
73\r
74\r
75<div class="para desc">\r
76<h4>Description</h4>\r
77<p>After <tt>f_open()</tt> function succeeded, the file object is valid. The file object is used for subsequent read/write functions to identify the file. To close an open file, use <a href="close.html"><tt>f_close()</tt></a> function. If the file is modified and not closed properly, the file data will be collapsed.</p>\r
78<p>If duplicated file open is needed, read <a href="appnote.html#dup">here</a> carefully. However duplicated open of a file with write mode flag is always prohibited.</p>\r
79<p>Before using any file function, a work area (file system object) must be registered to the logical drive with <a href="mount.html"><tt>f_mount()</tt></a> function. All API functions except for <a href="fdisk.html"><tt>f_fdisk()</tt></a> function can work after this procedure.</p>\r
80</div>\r
81\r
82\r
83<div class="para comp">\r
84<h4>QuickInfo</h4>\r
85<p>Always available. The mode flags, <tt>FA_WRITE, FA_CREATE_ALWAYS, FA_CREATE_NEW and FA_OPEN_ALWAYS</tt>, are not available when <tt>_FS_READONLY == 1</tt>.</p>\r
86</div>\r
87\r
88\r
89<div class="para use">\r
90<h4>Example</h4>\r
91<pre>\r
92<span class="c">/* Read a text file and display it */</span>\r
93\r
94FATFS FatFs; <span class="c">/* Work area (file system object) for logical drive */</span>\r
95\r
96int main (void)\r
97{\r
98 FIL fil; <span class="c">/* File object */</span>\r
99 char line[82]; <span class="c">/* Line buffer */</span>\r
100 FRESULT fr; <span class="c">/* FatFs return code */</span>\r
101\r
102\r
103 <span class="c">/* Register work area to the default drive */</span>\r
104 f_mount(&amp;FatFs, "", 0);\r
105\r
106 <span class="c">/* Open a text file */</span>\r
107 fr = f_open(&amp;fil, "message.txt", FA_READ);\r
108 if (fr) return (int)fr;\r
109\r
110 <span class="c">/* Read all lines and display it */</span>\r
111 while (f_gets(line, sizeof line, &amp;fil))\r
112 printf(line);\r
113\r
114 <span class="c">/* Close the file */</span>\r
115 f_close(&amp;fil);\r
116\r
117 return 0;\r
118}\r
119</pre>\r
120<pre>\r
121<span class="c">/* Copy a file "file.bin" on the drive 1 to drive 0 */</span>\r
122\r
123int main (void)\r
124{\r
125 FATFS fs[2]; <span class="c">/* Work area (file system object) for logical drives */</span>\r
126 FIL fsrc, fdst; <span class="c">/* File objects */</span>\r
127 BYTE buffer[4096]; <span class="c">/* File copy buffer */</span>\r
128 FRESULT fr; <span class="c">/* FatFs function common result code */</span>\r
129 UINT br, bw; <span class="c">/* File read/write count */</span>\r
130\r
131\r
132 <span class="c">/* Register work area for each logical drive */</span>\r
133 f_mount(&amp;fs[0], "0:", 0);\r
134 f_mount(&amp;fs[1], "1:", 0);\r
135\r
136 <span class="c">/* Open source file on the drive 1 */</span>\r
137 fr = f_open(&amp;fsrc, "1:file.bin", FA_OPEN_EXISTING | FA_READ);\r
138 if (fr) return (int)fr;\r
139\r
140 <span class="c">/* Create destination file on the drive 0 */</span>\r
141 fr = f_open(&amp;fdst, "0:file.bin", FA_CREATE_ALWAYS | FA_WRITE);\r
142 if (fr) return (int)fr;\r
143\r
144 <span class="c">/* Copy source to destination */</span>\r
145 for (;;) {\r
146 fr = f_read(&amp;fsrc, buffer, sizeof buffer, &amp;br); <span class="c">/* Read a chunk of source file */</span>\r
147 if (fr || br == 0) break; <span class="c">/* error or eof */</span>\r
148 fr = f_write(&amp;fdst, buffer, br, &amp;bw); <span class="c">/* Write it to the destination file */</span>\r
149 if (fr || bw &lt; br) break; <span class="c">/* error or disk full */</span>\r
150 }\r
151\r
152 <span class="c">/* Close open files */</span>\r
153 f_close(&amp;fsrc);\r
154 f_close(&amp;fdst);\r
155\r
156 <span class="c">/* Unregister work area prior to discard it */</span>\r
157 f_mount(NULL, "0:", 0);\r
158 f_mount(NULL, "1:", 0);\r
159\r
160 return (int)fr;\r
161}\r
162</pre>\r
163</div>\r
164\r
165\r
166<div class="para ref">\r
167<h4>See Also</h4>\r
168<p><tt><a href="read.html">f_read</a>, <a href="write.html">f_write</a>, <a href="close.html">f_close</a>, <a href="sfile.html">FIL</a>, <a href="sfatfs.html">FATFS</a></tt></p>\r
169</div>\r
170\r
171<p class="foot"><a href="../00index_e.html">Return</a></p>\r
172</body>\r
173</html>\r
Z180 Stamp Monitor