trunk/src/files.c

/***************************************
 $Header: /home/amb/CVS/routino/src/files.c,v 1.1 2008-12-31 12:20:07 amb Exp $

 Functions to map a file into memory.
 ******************/ /******************
 Written by Andrew M. Bishop

 This file Copyright 2008 Andrew M. Bishop
 It may be distributed under the GNU Public License, version 2, or
 any higher version.  See section COPYING of the GNU Public license
 for conditions under which this file may be redistributed.
 ***************************************/


#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>

#include "functions.h"

/*+ A structure to contain the file mapping between file descriptor and address. +*/
struct filemapping
{
 int fd;                        /*+ The file descriptor. +*/
 void *address;                 /*+ The address the file is mapped to. +*/
 size_t length;                 /*+ The length of the mapped file. +*/
};

/*+ The current set of file mappings. +*/
static struct filemapping *mappings=NULL;

/*+ The number of file mappings +*/
static int nmappings=0;


/*++++++++++++++++++++++++++++++++++++++
  Open a file and map it into memory.

  void *MapFile Returns the address of the file.

  const char *filename The name of the file to open.
  ++++++++++++++++++++++++++++++++++++++*/

void *MapFile(const char *filename)
{
 int fd;
 struct stat buf;
 void *address;

 /* Open the file */

 fd=open(filename,O_RDONLY);

 if(fd==-1)
    return(NULL);

 /* Get the length of the file */

 if(fstat(fd,&buf))
   {
    close(fd);
    return(NULL);
   }

 /* Map the file */

 address=mmap(NULL,buf.st_size,PROT_READ,MAP_PRIVATE,fd,0);

 if(!address)
   {
    close(fd);
    return(NULL);
   }

 /* Store the file mapping */

 nmappings++;
 mappings=(struct filemapping*)realloc((void*)mappings,nmappings*sizeof(struct filemapping));

 mappings[nmappings-1].fd=fd;
 mappings[nmappings-1].address=address;
 mappings[nmappings-1].length=buf.st_size;

 return(address);
}


/*++++++++++++++++++++++++++++++++++++++
  Unmap a file and close it.

  void *address The address of the mapped file.
  ++++++++++++++++++++++++++++++++++++++*/

void UnMapFile(void *address)
{
 int i;

 /* Search for the file mapping and unmap it and close it. */

 for(i=0;i<nmappings;i++)
   {
    if(address==mappings[i].address)
      {
       munmap(mappings[i].address,mappings[i].length);

       close(mappings[i].fd);

       mappings[i].fd=-1;
       mappings[i].address=NULL;
       mappings[i].length=0;

       break;
      }
   }
}


/*++++++++++++++++++++++++++++++++++++++
  Write a new file to disk.

  int WriteFile Returns 0 if OK or something else in case of an error.

  const char *filename The name of the file to create.

  void *address The address of the data to be written.

  size_t length The length of data to write.
  ++++++++++++++++++++++++++++++++++++++*/

int WriteFile(const char *filename,void *address,size_t length)
{
 int fd;

 /* Open the file */

 fd=open(filename,O_WRONLY|O_CREAT|O_TRUNC,S_IRWXU|S_IRGRP|S_IROTH);

 if(fd==-1)
    return(-1);

 /* Write the data */

 if(write(fd,address,length)!=length)
    return(-1);

 /* Close the file */

 close(fd);

 return(0);
}
1	/***************************************
2	$Header: /home/amb/CVS/routino/src/files.c,v 1.1 2008-12-31 12:20:07 amb Exp $
3
4	Functions to map a file into memory.
5	****************/ /****************
6	Written by Andrew M. Bishop
7
8	This file Copyright 2008 Andrew M. Bishop
9	It may be distributed under the GNU Public License, version 2, or
10	any higher version. See section COPYING of the GNU Public license
11	for conditions under which this file may be redistributed.
12	***************************************/
13
14
15	#include <unistd.h>
16	#include <stdlib.h>
17	#include <fcntl.h>
18	#include <sys/types.h>
19	#include <sys/stat.h>
20	#include <sys/mman.h>
21
22	#include "functions.h"
23
24	/+ A structure to contain the file mapping between file descriptor and address. +/
25	struct filemapping
26	{
27	int fd; /+ The file descriptor. +/
28	void address; /+ The address the file is mapped to. +*/
29	size_t length; /+ The length of the mapped file. +/
30	};
31
32	/+ The current set of file mappings. +/
33	static struct filemapping *mappings=NULL;
34
35	/+ The number of file mappings +/
36	static int nmappings=0;
37
38
39	/*++++++++++++++++++++++++++++++++++++++
40	Open a file and map it into memory.
41
42	void *MapFile Returns the address of the file.
43
44	const char *filename The name of the file to open.
45	++++++++++++++++++++++++++++++++++++++*/
46
47	void MapFile(const char filename)
48	{
49	int fd;
50	struct stat buf;
51	void *address;
52
53	/* Open the file */
54
55	fd=open(filename,O_RDONLY);
56
57	if(fd==-1)
58	return(NULL);
59
60	/* Get the length of the file */
61
62	if(fstat(fd,&buf))
63	{
64	close(fd);
65	return(NULL);
66	}
67
68	/* Map the file */
69
70	address=mmap(NULL,buf.st_size,PROT_READ,MAP_PRIVATE,fd,0);
71
72	if(!address)
73	{
74	close(fd);
75	return(NULL);
76	}
77
78	/* Store the file mapping */
79
80	nmappings++;
81	mappings=(struct filemapping)realloc((void)mappings,nmappings*sizeof(struct filemapping));
82
83	mappings[nmappings-1].fd=fd;
84	mappings[nmappings-1].address=address;
85	mappings[nmappings-1].length=buf.st_size;
86
87	return(address);
88	}
89
90
91	/*++++++++++++++++++++++++++++++++++++++
92	Unmap a file and close it.
93
94	void *address The address of the mapped file.
95	++++++++++++++++++++++++++++++++++++++*/
96
97	void UnMapFile(void *address)
98	{
99	int i;
100
101	/* Search for the file mapping and unmap it and close it. */
102
103	for(i=0;i<nmappings;i++)
104	{
105	if(address==mappings[i].address)
106	{
107	munmap(mappings[i].address,mappings[i].length);
108
109	close(mappings[i].fd);
110
111	mappings[i].fd=-1;
112	mappings[i].address=NULL;
113	mappings[i].length=0;
114
115	break;
116	}
117	}
118	}
119
120
121	/*++++++++++++++++++++++++++++++++++++++
122	Write a new file to disk.
123
124	int WriteFile Returns 0 if OK or something else in case of an error.
125
126	const char *filename The name of the file to create.
127
128	void *address The address of the data to be written.
129
130	size_t length The length of data to write.
131	++++++++++++++++++++++++++++++++++++++*/
132
133	int WriteFile(const char filename,void address,size_t length)
134	{
135	int fd;
136
137	/* Open the file */
138
139	fd=open(filename,O_WRONLY\|O_CREAT\|O_TRUNC,S_IRWXU\|S_IRGRP\|S_IROTH);
140
141	if(fd==-1)
142	return(-1);
143
144	/* Write the data */
145
146	if(write(fd,address,length)!=length)
147	return(-1);
148
149	/* Close the file */
150
151	close(fd);
152
153	return(0);
154	}