add mmap_readat
parent
82b17dbfe3
commit
5c999f4c62
@ -0,0 +1,23 @@
|
|||||||
|
.TH mmap_readat 3
|
||||||
|
.SH NAME
|
||||||
|
mmap_readat \- memory map a file for reading
|
||||||
|
.SH SYNTAX
|
||||||
|
.B #include <mmap.h>
|
||||||
|
|
||||||
|
char* \fBmmap_readat\fP(const char* \fIfilename\fR,size_t* \fIfilesize\fR,int \fIdirfd\fR);
|
||||||
|
.SH DESCRIPTION
|
||||||
|
mmap_readat opens \fIfilename\fR for reading, maps the whole file into
|
||||||
|
memory, closes the file, writes the length of the file to \fIfilesize\fR
|
||||||
|
and returns a pointer to the mapped file.
|
||||||
|
|
||||||
|
If \fIfilename\fR is a relative path and \fIdirfd\fR is not -1,
|
||||||
|
\fIfilename\fR is interpreted relative to \fIdirfd\fR, which must be an
|
||||||
|
open directory.
|
||||||
|
|
||||||
|
The file is unmapped by the operating system if the process terminates.
|
||||||
|
It can also be manually unmapped by calling \fBmunmap\fR from
|
||||||
|
<sys/mman.h>.
|
||||||
|
|
||||||
|
If the file could not be opened or mapped, (void*)0 is returned.
|
||||||
|
.SH "SEE ALSO"
|
||||||
|
mmap_unmap(3)
|
@ -0,0 +1,36 @@
|
|||||||
|
#define _POSIX_C_SOURCE 200809
|
||||||
|
#define _ATFILE_SOURCE
|
||||||
|
|
||||||
|
#include <sys/types.h>
|
||||||
|
#include <unistd.h>
|
||||||
|
#ifndef __MINGW32__
|
||||||
|
#include <sys/stat.h>
|
||||||
|
#include <unistd.h>
|
||||||
|
#include <fcntl.h>
|
||||||
|
#include <sys/mman.h>
|
||||||
|
#endif
|
||||||
|
#include "open.h"
|
||||||
|
#include "mmap.h"
|
||||||
|
|
||||||
|
extern const char* mmap_readat(const char* filename,size_t * filesize,int dirfd) {
|
||||||
|
#ifdef __MINGW32__
|
||||||
|
return 0;
|
||||||
|
#else
|
||||||
|
int fd=openat(dirfd,filename,O_RDONLY);
|
||||||
|
char *map;
|
||||||
|
if (fd>=0) {
|
||||||
|
register off_t o=lseek(fd,0,SEEK_END);
|
||||||
|
if (sizeof(off_t)!=sizeof(size_t) && o > (off_t)(size_t)-1) { close(fd); return 0; }
|
||||||
|
*filesize=(size_t)o;
|
||||||
|
if (o>0) {
|
||||||
|
map=mmap(0,*filesize,PROT_READ,MAP_SHARED,fd,0);
|
||||||
|
if (map==(char*)-1)
|
||||||
|
map=0;
|
||||||
|
} else
|
||||||
|
map="";
|
||||||
|
close(fd);
|
||||||
|
return map;
|
||||||
|
}
|
||||||
|
return 0;
|
||||||
|
#endif
|
||||||
|
}
|
Loading…
Reference in New Issue