sousa-gecko/docs/nspr/reference/pr_createfilemap.md

PR_CreateFileMap

Creates a file mapping object.

Syntax

#include <prio.h>

PRFileMap* PR_CreateFileMap(
  PRFileDesc *fd,
  PRInt64 size,
  PRFileMapProtect prot);

Parameters

The function has the following parameters:

fd

A pointer to a {ref}PRFileDesc object representing the file that is to be mapped to memory.

size

Size of the file specified by fd.

prot

Protection option for read and write accesses of a file mapping. This parameter consists of one of the following options:

• PR_PROT_READONLY. Read-only access.
• PR_PROT_READWRITE. Readable, and write is shared.
• PR_PROT_WRITECOPY. Readable, and write is private (copy-on-write).

Returns

• If successful, a file mapping of type {ref}PRFileMap.
• If unsuccessful, NULL.

Description

The PRFileMapProtect enumeration used in the prot parameter is defined as follows:

typedef enum PRFileMapProtect {
  PR_PROT_READONLY,
  PR_PROT_READWRITE,
  PR_PROT_WRITECOPY
} PRFileMapProtect;

{ref}PR_CreateFileMap only prepares for the mapping a file to memory. The returned file-mapping object must be passed to {ref}PR_MemMap to actually map a section of the file to memory.

The file-mapping object should be closed with a {ref}PR_CloseFileMap call when it is no longer needed.