nsILocalFile:openNSPRFileDesc

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Contents 1 Summary 2 Parameters 3 Return Values 4 Example Code 5 See Also

[edit] Summary

This method is used for opening the file corresponding to this nsILocalFile.

 [noscript] PRFileDescStar openNSPRFileDesc(
   in long aFlags,
   in long aMode
 );

[edit] Parameters

aFlags

[in] Bitwise combination of the following open flags:

PR_RDONLY

Open for reading only.

PR_WRONLY

Open for writing only.

PR_RDWR

Open for reading and writing.

PR_CREATE_FILE

If the file does not exist, the file is created. If the file exists, this flag has no effect.

PR_APPEND

The file pointer is set to the end of the file prior to each write.

PR_TRUNCATE

If the file exists, its length is truncated to 0.

PR_SYNC

If set, each write will wait for both the file data and file status to be physically updated.

PR_EXCL

With PR_CREATE_FILE, if the file does not exist, the file is created. If the file already exists, no action and null is returned.

aMode

[in] A UNIX-style file permissions value. For example, the octal value 0600 may be used to limit read and write access to the current user of the system. This parameter may be ignored on systems that do not support file permissions.

[edit] Return Values

PRFileDescStar is a typedef for a pointer to PRFileDesc.

[edit] Example Code

 #include "prio.h"
 #include "nsError.h"
 #include "nsILocalFile.h"

 // Read the contents of a nsILocalFile...

 nsresult ReadLocalFile(nsILocalFile *aLocalFile)
 {
   PRFileDesc *fd;
   nsresult rv = aLocalFile->OpenNSPRFileDesc(PR_RDONLY, 0, &fd);
   if (NS_FAILED(rv))
     return rv;

   char buf[512];
   PRInt32 n;
   
   while ((n = PR_Read(fd, buf, sizeof(buf))) > 0)
   {
     // Do something with n-byte block of data from file...
   }

   if (n < 0)
     rv = NS_ERROR_UNEXPECTED;

   PR_Close(fd);
   return rv;
 }

[edit] See Also

nsILocalFile