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| <title>Debugging with GDB: open</title> |
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| <a name="open-1"></a> |
| <h4 class="unnumberedsubsubsec">open</h4> |
| <a name="index-open_002c-file_002di_002fo-system-call"></a> |
| |
| <dl compact="compact"> |
| <dt>Synopsis:</dt> |
| <dd><div class="smallexample"> |
| <pre class="smallexample">int open(const char *pathname, int flags); |
| int open(const char *pathname, int flags, mode_t mode); |
| </pre></div> |
| |
| </dd> |
| <dt>Request:</dt> |
| <dd><p>‘<samp>Fopen,<var>pathptr</var>/<var>len</var>,<var>flags</var>,<var>mode</var></samp>’ |
| </p> |
| <p><var>flags</var> is the bitwise <code>OR</code> of the following values: |
| </p> |
| <dl compact="compact"> |
| <dt><code>O_CREAT</code></dt> |
| <dd><p>If the file does not exist it will be created. The host |
| rules apply as far as file ownership and time stamps |
| are concerned. |
| </p> |
| </dd> |
| <dt><code>O_EXCL</code></dt> |
| <dd><p>When used with <code>O_CREAT</code>, if the file already exists it is |
| an error and open() fails. |
| </p> |
| </dd> |
| <dt><code>O_TRUNC</code></dt> |
| <dd><p>If the file already exists and the open mode allows |
| writing (<code>O_RDWR</code> or <code>O_WRONLY</code> is given) it will be |
| truncated to zero length. |
| </p> |
| </dd> |
| <dt><code>O_APPEND</code></dt> |
| <dd><p>The file is opened in append mode. |
| </p> |
| </dd> |
| <dt><code>O_RDONLY</code></dt> |
| <dd><p>The file is opened for reading only. |
| </p> |
| </dd> |
| <dt><code>O_WRONLY</code></dt> |
| <dd><p>The file is opened for writing only. |
| </p> |
| </dd> |
| <dt><code>O_RDWR</code></dt> |
| <dd><p>The file is opened for reading and writing. |
| </p></dd> |
| </dl> |
| |
| <p>Other bits are silently ignored. |
| </p> |
| |
| <p><var>mode</var> is the bitwise <code>OR</code> of the following values: |
| </p> |
| <dl compact="compact"> |
| <dt><code>S_IRUSR</code></dt> |
| <dd><p>User has read permission. |
| </p> |
| </dd> |
| <dt><code>S_IWUSR</code></dt> |
| <dd><p>User has write permission. |
| </p> |
| </dd> |
| <dt><code>S_IRGRP</code></dt> |
| <dd><p>Group has read permission. |
| </p> |
| </dd> |
| <dt><code>S_IWGRP</code></dt> |
| <dd><p>Group has write permission. |
| </p> |
| </dd> |
| <dt><code>S_IROTH</code></dt> |
| <dd><p>Others have read permission. |
| </p> |
| </dd> |
| <dt><code>S_IWOTH</code></dt> |
| <dd><p>Others have write permission. |
| </p></dd> |
| </dl> |
| |
| <p>Other bits are silently ignored. |
| </p> |
| |
| </dd> |
| <dt>Return value:</dt> |
| <dd><p><code>open</code> returns the new file descriptor or -1 if an error |
| occurred. |
| </p> |
| </dd> |
| <dt>Errors:</dt> |
| <dd> |
| <dl compact="compact"> |
| <dt><code>EEXIST</code></dt> |
| <dd><p><var>pathname</var> already exists and <code>O_CREAT</code> and <code>O_EXCL</code> were used. |
| </p> |
| </dd> |
| <dt><code>EISDIR</code></dt> |
| <dd><p><var>pathname</var> refers to a directory. |
| </p> |
| </dd> |
| <dt><code>EACCES</code></dt> |
| <dd><p>The requested access is not allowed. |
| </p> |
| </dd> |
| <dt><code>ENAMETOOLONG</code></dt> |
| <dd><p><var>pathname</var> was too long. |
| </p> |
| </dd> |
| <dt><code>ENOENT</code></dt> |
| <dd><p>A directory component in <var>pathname</var> does not exist. |
| </p> |
| </dd> |
| <dt><code>ENODEV</code></dt> |
| <dd><p><var>pathname</var> refers to a device, pipe, named pipe or socket. |
| </p> |
| </dd> |
| <dt><code>EROFS</code></dt> |
| <dd><p><var>pathname</var> refers to a file on a read-only filesystem and |
| write access was requested. |
| </p> |
| </dd> |
| <dt><code>EFAULT</code></dt> |
| <dd><p><var>pathname</var> is an invalid pointer value. |
| </p> |
| </dd> |
| <dt><code>ENOSPC</code></dt> |
| <dd><p>No space on device to create the file. |
| </p> |
| </dd> |
| <dt><code>EMFILE</code></dt> |
| <dd><p>The process already has the maximum number of files open. |
| </p> |
| </dd> |
| <dt><code>ENFILE</code></dt> |
| <dd><p>The limit on the total number of files open on the system |
| has been reached. |
| </p> |
| </dd> |
| <dt><code>EINTR</code></dt> |
| <dd><p>The call was interrupted by the user. |
| </p></dd> |
| </dl> |
| |
| </dd> |
| </dl> |
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