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<concept id="GUID-3314123F-205D-5E05-9041-DB9836B7812B" xml:lang="en"><title>File Access Example: Accessing the File System Using P.I.P.S.</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>This example application shows, using a P.I.P.S. (P.I.P.S. Is POSIX

on the Symbian platform) program, the restrictions on file access

that are imposed by the Symbian platform Security model. </p>

<p>It shows that programs can access their own directories, but cannot,

without platform security capabilities not available to ordinary programs,

access the directories of other programs, or the system binary directory <filepath>sys/bin</filepath>. </p>

<p>This example defines an executable file with no platform security

capabilities. The program first creates its own secure directory that

it can write to and read from. It then attempts to use a file in a

private directory of another program, and then in <filepath>sys/bin</filepath>, and shows that these attempts are denied. </p>

<section id="GUID-820F9B58-8877-414B-A18B-B591F6D67158"><title>Download</title> <p>Click on the following link to download the example: <xref href="guid-6013a680-57f9-415b-8851-c4fa63356636/zips/guid-2dae3cca-f112-4219-8f7c-6c48682d1f28.zip" scope="external">FileAccessExample.zip</xref></p><p>Click: <xref href="guid-6013a680-57f9-415b-8851-c4fa63356636/guid-2dae3cca-f112-4219-8f7c-6c48682d1f28.html" scope="peer">browse</xref> to view the example code. </p> </section>

<section id="GUID-3EAFEC43-CFDA-4E3D-8ACD-E3AAE48BE97D"><title>Description</title> <p>The following sections provide more information about the steps

that the example performs. </p> <p><b> Create a secure directory</b> </p> <p>The example creates an empty secure directory for the program

by using the <xref href="GUID-D034B02C-3B45-3DCC-A7DA-E51227032A87.dita"><apiname>mkdir(const char *,mode_t)</apiname></xref> function. </p> <p>This empty secure directory is created in <filepath>C:\private\E80000C9</filepath>, as 0xE80000C9 is a unique identifier for the program (as specified

by the third UID in its project file). </p></section>

<section id="GUID-D9F306FF-D14E-4BCC-BAE6-55804F31CA0D"> <p><b>Write

and read a file in the private directory </b> </p> <p>The example

writes and reads a file in the secure directory using the <xref href="GUID-935A007C-D95C-3EEB-B796-603AF3612A97.dita"><apiname>fopen(const char *, const char *)</apiname></xref> and other file stream

functions. </p> <p><b> Write and read a file in the private directory

of another program </b> </p> <p>The example attempts to write and

read a file in the secure directory of another program. </p> <p>The <xref href="GUID-64886CC6-072F-3542-855A-5D733FC761E8.dita"><apiname>fopen()</apiname></xref> function is expected to return <codeph>NULL</codeph>, indicating that access is not possible, as the program has insufficient

platform security capabilities. </p><p><b> Write and read a file in

the sys/bin directory</b> </p> <p>The example attempts to write and

read a file in the system's <filepath>sys/bin</filepath> directory,

where program binaries are stored. </p> <p>Again, the <xref href="GUID-64886CC6-072F-3542-855A-5D733FC761E8.dita"><apiname>fopen()</apiname></xref> function is expected to return <codeph>NULL</codeph>, indicating

that access is not possible, as the program has insufficient platform

security capabilities. </p> </section>

<section id="GUID-EB4F71F2-D55D-43C5-B55F-F211D170056F"><title>Related

APIs</title><p><xref href="GUID-D034B02C-3B45-3DCC-A7DA-E51227032A87.dita"><apiname>mkdir(const char *,mode_t)</apiname></xref></p><p><xref href="GUID-935A007C-D95C-3EEB-B796-603AF3612A97.dita"><apiname>fopen(const char *, const char *)</apiname></xref></p></section>

<section id="GUID-81AA0C7F-5D43-4EFB-9DD0-4A8A79922576"><title>Build</title> <p>The <xref href="GUID-3100800B-B2F7-50EF-BD4C-3C345ECCB2A5.dita">Symbian

build process</xref> describes how to build this example application. </p> <p>The example builds an executable called <filepath>fileaccessexample.exe</filepath> in the standard locations. </p> <p>To run the example, start <filepath>fileaccessexample.exe</filepath> from the file system or from your

IDE. After launching the executable, depending on the emulator you

are using, you may need to navigate away from the application launcher

or shell screen to view the console. </p> </section>