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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=utf-8"> 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 opens a 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.</dd> 31 <dt>path</dt> 32 <dd>Pointer to the 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>Flags</th><th>Meaning</th></tr> 37 <tr><td>FA_READ</td><td>Specifies read access to the object. Data can be read from the file.</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_CREATE_NEW</td><td>Creates a new file. The function fails with <tt>FR_EXIST</tt> if the file is existing.</td></tr> 41 <tr><td>FA_CREATE_ALWAYS</td><td>Creates a new file. If the file is existing, it will be truncated and overwritten.</td></tr> 42 <tr><td>FA_OPEN_ALWAYS</td><td>Opens the file if it is existing. If not, a new file will be created.</td></tr> 43 <tr><td>FA_OPEN_APPEND</td><td>Same as <tt>FA_OPEN_ALWAYS</tt> except the read/write pointer is set end of the file.</td></tr> 44 </table> 45 Mode flags in POSIX fopen() function corresponds to FatFs mode flags as follows:<br> 46 <table class="lst2"> 47 <tr><th>POSIX</th><th>FatFs</th></tr> 48 <tr><td>"r"</td><td>FA_READ</td></tr> 49 <tr><td>"r+"</td><td>FA_READ | FA_WRITE</td></tr> 50 <tr><td>"w"</td><td>FA_CREATE_ALWAYS | FA_WRITE</td></tr> 51 <tr><td>"w+"</td><td>FA_CREATE_ALWAYS | FA_WRITE | FA_READ</td></tr> 52 <tr><td>"a"</td><td>FA_OPEN_APPEND | FA_WRITE</td></tr> 53 <tr><td>"a+"</td><td>FA_OPEN_APPEND | FA_WRITE | FA_READ</td></tr> 54 <tr><td>"wx"</td><td>FA_CREATE_NEW | FA_WRITE</td></tr> 55 <tr><td>"w+x"</td><td>FA_CREATE_NEW | FA_WRITE | FA_READ</td></tr> 56 </table> 57 </dd> 58 </dl> 59 </div> 60 61 62 <div class="para ret"> 63 <h4>Return Values</h4> 64 <p> 65 <a href="rc.html#ok">FR_OK</a>, 66 <a href="rc.html#de">FR_DISK_ERR</a>, 67 <a href="rc.html#ie">FR_INT_ERR</a>, 68 <a href="rc.html#nr">FR_NOT_READY</a>, 69 <a href="rc.html#nf">FR_NO_FILE</a>, 70 <a href="rc.html#np">FR_NO_PATH</a>, 71 <a href="rc.html#in">FR_INVALID_NAME</a>, 72 <a href="rc.html#dn">FR_DENIED</a>, 73 <a href="rc.html#ex">FR_EXIST</a>, 74 <a href="rc.html#io">FR_INVALID_OBJECT</a>, 75 <a href="rc.html#wp">FR_WRITE_PROTECTED</a>, 76 <a href="rc.html#id">FR_INVALID_DRIVE</a>, 77 <a href="rc.html#ne">FR_NOT_ENABLED</a>, 78 <a href="rc.html#ns">FR_NO_FILESYSTEM</a>, 79 <a href="rc.html#tm">FR_TIMEOUT</a>, 80 <a href="rc.html#lo">FR_LOCKED</a>, 81 <a href="rc.html#nc">FR_NOT_ENOUGH_CORE</a>, 82 <a href="rc.html#tf">FR_TOO_MANY_OPEN_FILES</a> 83 </p> 84 </div> 85 86 87 <div class="para desc"> 88 <h4>Description</h4> 89 <p>The <tt>f_open</tt> function opens a file and creates a <em>file object</em>. The file object is used for subsequent read/write operations to the file to identify the file. Open file should be closed with <a href="close.html"><tt>f_close</tt></a> function after the session of the file access. If any change to the file is made and not closed prior to power down, media removal or re-mount, or the file can be collapsed.</p> 90 <p>If duplicated file open is needed, read <a href="appnote.html#dup">here</a> carefully. However duplicated open of a file with any write mode flag is always prohibited.</p> 91 </div> 92 93 94 <div class="para comp"> 95 <h4>QuickInfo</h4> 96 <p>Always available. Only <tt>FA_READ</tt> and <tt>FA_OPEN_EXISTING</tt> are available for the mode flags when <tt><a href="config.html#fs_readonly">FF_FS_READONLY</a> == 1</tt>.</p> 97 </div> 98 99 100 <div class="para use"> 101 <h4>Example</h4> 102 <pre> 103 <span class="c">/* Read a text file and display it */</span> 104 105 FATFS FatFs; <span class="c">/* Work area (filesystem object) for logical drive */</span> 106 107 int main (void) 108 { 109 FIL fil; <span class="c">/* File object */</span> 110 char line[100]; <span class="c">/* Line buffer */</span> 111 FRESULT fr; <span class="c">/* FatFs return code */</span> 112 113 114 <span class="c">/* Gives a work area to the default drive */</span> 115 f_mount(&FatFs, "", 0); 116 117 <span class="c">/* Open a text file */</span> 118 fr = <em>f_open</em>(&fil, "message.txt", FA_READ); 119 if (fr) return (int)fr; 120 121 <span class="c">/* Read every line and display it */</span> 122 while (f_gets(line, sizeof line, &fil)) { 123 printf(line); 124 } 125 126 <span class="c">/* Close the file */</span> 127 f_close(&fil); 128 129 return 0; 130 } 131 </pre> 132 <pre> 133 <span class="c">/* Copy a file "file.bin" on the drive 1 to drive 0 */</span> 134 135 int main (void) 136 { 137 FATFS fs0, fs1; <span class="c">/* Work area (filesystem object) for logical drives */</span> 138 FIL fsrc, fdst; <span class="c">/* File objects */</span> 139 BYTE buffer[4096]; <span class="c">/* File copy buffer */</span> 140 FRESULT fr; <span class="c">/* FatFs function common result code */</span> 141 UINT br, bw; <span class="c">/* File read/write count */</span> 142 143 144 <span class="c">/* Gives work area to each logical drive */</span> 145 f_mount(&fs0, "0:", 0); 146 f_mount(&fs1, "1:", 0); 147 148 <span class="c">/* Open source file on the drive 1 */</span> 149 fr = <em>f_open</em>(&fsrc, "1:file.bin", FA_READ); 150 if (fr) return (int)fr; 151 152 <span class="c">/* Create destination file on the drive 0 */</span> 153 fr = <em>f_open</em>(&fdst, "0:file.bin", FA_WRITE | FA_CREATE_ALWAYS); 154 if (fr) return (int)fr; 155 156 <span class="c">/* Copy source to destination */</span> 157 for (;;) { 158 f_read(&fsrc, buffer, sizeof buffer, &br); <span class="c">/* Read a chunk of data from the source file */</span> 159 if (br == 0) break; <span class="c">/* error or eof */</span> 160 f_write(&fdst, buffer, br, &bw); <span class="c">/* Write it to the destination file */</span> 161 if (bw < br) break; <span class="c">/* error or disk full */</span> 162 } 163 164 <span class="c">/* Close open files */</span> 165 f_close(&fsrc); 166 f_close(&fdst); 167 168 <span class="c">/* Unregister work area prior to discard it */</span> 169 f_mount(0, "0:", 0); 170 f_mount(0, "1:", 0); 171 172 return (int)fr; 173 } 174 </pre> 175 </div> 176 177 178 <div class="para ref"> 179 <h4>See Also</h4> 180 <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> 181 </div> 182 183 <p class="foot"><a href="../00index_e.html">Return</a></p> 184 </body> 185 </html>