]> cloudbase.mooo.com Git - z180-stamp.git/blob - fatfs/doc/en/open.html
Version 0.6.8.2
[z180-stamp.git] / fatfs / doc / en / open.html
1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
2 <html lang="en">
3 <head>
4 <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
5 <meta http-equiv="Content-Style-Type" content="text/css">
6 <link rel="up" title="FatFs" href="../00index_e.html">
7 <link rel="alternate" hreflang="ja" title="Japanese" href="../ja/open.html">
8 <link rel="stylesheet" href="../css_e.css" type="text/css" media="screen" title="ELM Default">
9 <title>FatFs - f_open</title>
10 </head>
11
12 <body>
13
14 <div class="para func">
15 <h2>f_open</h2>
16 <p>The f_open function creates a <em>file object</em> to be used to access the file.</p>
17 <pre>
18 FRESULT f_open (
19 FIL* <span class="arg">fp</span>, <span class="c">/* [OUT] Pointer to the file object structure */</span>
20 const TCHAR* <span class="arg">path</span>, <span class="c">/* [IN] File name */</span>
21 BYTE <span class="arg">mode</span> <span class="c">/* [IN] Mode flags */</span>
22 );
23 </pre>
24 </div>
25
26 <div class="para arg">
27 <h4>Parameters</h4>
28 <dl class="par">
29 <dt>fp</dt>
30 <dd>Pointer to the blank file object structure to be created.</dd>
31 <dt>path</dt>
32 <dd>Pointer to a null-terminated string that specifies the <a href="filename.html">file name</a> to open or create.</dd>
33 <dt>mode</dt>
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>
35 <table class="lst">
36 <tr><th>Value</th><th>Description</th></tr>
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>
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>
39 <tr><td>FA_OPEN_EXISTING</td><td>Opens the file. The function fails if the file is not existing. (Default)</td></tr>
40 <tr><td>FA_OPEN_ALWAYS</td><td>Opens the file if it is existing. If not, a new file is created.<br>
41 To append data to the file, use <a href="lseek.html"><tt>f_lseek()</tt></a> function after file open in this method.</td></tr>
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>
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>
44 </table>
45 </dd>
46 </dl>
47 </div>
48
49
50 <div class="para ret">
51 <h4>Return Values</h4>
52 <p>
53 <a href="rc.html#ok">FR_OK</a>,
54 <a href="rc.html#de">FR_DISK_ERR</a>,
55 <a href="rc.html#ie">FR_INT_ERR</a>,
56 <a href="rc.html#nr">FR_NOT_READY</a>,
57 <a href="rc.html#ok">FR_NO_FILE</a>,
58 <a href="rc.html#np">FR_NO_PATH</a>,
59 <a href="rc.html#in">FR_INVALID_NAME</a>,
60 <a href="rc.html#de">FR_DENIED</a>,
61 <a href="rc.html#ex">FR_EXIST</a>,
62 <a href="rc.html#io">FR_INVALID_OBJECT</a>,
63 <a href="rc.html#wp">FR_WRITE_PROTECTED</a>,
64 <a href="rc.html#id">FR_INVALID_DRIVE</a>,
65 <a href="rc.html#ne">FR_NOT_ENABLED</a>,
66 <a href="rc.html#ns">FR_NO_FILESYSTEM</a>,
67 <a href="rc.html#tm">FR_TIMEOUT</a>,
68 <a href="rc.html#lo">FR_LOCKED</a>,
69 <a href="rc.html#nc">FR_NOT_ENOUGH_CORE</a>,
70 <a href="rc.html#tf">FR_TOO_MANY_OPEN_FILES</a>
71 </p>
72 </div>
73
74
75 <div class="para desc">
76 <h4>Description</h4>
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>
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>
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>
80 </div>
81
82
83 <div class="para comp">
84 <h4>QuickInfo</h4>
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>
86 </div>
87
88
89 <div class="para use">
90 <h4>Example</h4>
91 <pre>
92 <span class="c">/* Read a text file and display it */</span>
93
94 FATFS FatFs; <span class="c">/* Work area (file system object) for logical drive */</span>
95
96 int main (void)
97 {
98 FIL fil; <span class="c">/* File object */</span>
99 char line[82]; <span class="c">/* Line buffer */</span>
100 FRESULT fr; <span class="c">/* FatFs return code */</span>
101
102
103 <span class="c">/* Register work area to the default drive */</span>
104 f_mount(&amp;FatFs, "", 0);
105
106 <span class="c">/* Open a text file */</span>
107 fr = f_open(&amp;fil, "message.txt", FA_READ);
108 if (fr) return (int)fr;
109
110 <span class="c">/* Read all lines and display it */</span>
111 while (f_gets(line, sizeof line, &amp;fil))
112 printf(line);
113
114 <span class="c">/* Close the file */</span>
115 f_close(&amp;fil);
116
117 return 0;
118 }
119 </pre>
120 <pre>
121 <span class="c">/* Copy a file "file.bin" on the drive 1 to drive 0 */</span>
122
123 int main (void)
124 {
125 FATFS fs[2]; <span class="c">/* Work area (file system object) for logical drives */</span>
126 FIL fsrc, fdst; <span class="c">/* File objects */</span>
127 BYTE buffer[4096]; <span class="c">/* File copy buffer */</span>
128 FRESULT fr; <span class="c">/* FatFs function common result code */</span>
129 UINT br, bw; <span class="c">/* File read/write count */</span>
130
131
132 <span class="c">/* Register work area for each logical drive */</span>
133 f_mount(&amp;fs[0], "0:", 0);
134 f_mount(&amp;fs[1], "1:", 0);
135
136 <span class="c">/* Open source file on the drive 1 */</span>
137 fr = f_open(&amp;fsrc, "1:file.bin", FA_OPEN_EXISTING | FA_READ);
138 if (fr) return (int)fr;
139
140 <span class="c">/* Create destination file on the drive 0 */</span>
141 fr = f_open(&amp;fdst, "0:file.bin", FA_CREATE_ALWAYS | FA_WRITE);
142 if (fr) return (int)fr;
143
144 <span class="c">/* Copy source to destination */</span>
145 for (;;) {
146 fr = f_read(&amp;fsrc, buffer, sizeof buffer, &amp;br); <span class="c">/* Read a chunk of source file */</span>
147 if (fr || br == 0) break; <span class="c">/* error or eof */</span>
148 fr = f_write(&amp;fdst, buffer, br, &amp;bw); <span class="c">/* Write it to the destination file */</span>
149 if (fr || bw &lt; br) break; <span class="c">/* error or disk full */</span>
150 }
151
152 <span class="c">/* Close open files */</span>
153 f_close(&amp;fsrc);
154 f_close(&amp;fdst);
155
156 <span class="c">/* Unregister work area prior to discard it */</span>
157 f_mount(NULL, "0:", 0);
158 f_mount(NULL, "1:", 0);
159
160 return (int)fr;
161 }
162 </pre>
163 </div>
164
165
166 <div class="para ref">
167 <h4>See Also</h4>
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>
169 </div>
170
171 <p class="foot"><a href="../00index_e.html">Return</a></p>
172 </body>
173 </html>