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Yank writing-back support from gitfakemmap. 

We do not write through our use of mmap(), so make sure callers pass
MAP_PRIVATE and remove support for writing changes back.

Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Junio C Hamano 2005-10-08 15:54:36 -07:00
parent 730d48a2ef
commit f48000fcbe
1 changed files with 6 additions and 69 deletions
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75
compat/mmap.c
View File

@ -4,43 +4,33 @@
#include <errno.h>
#include "../cache.h"
typedef struct fakemmapwritable {
void *start;
size_t length;
int fd;
off_t offset;
struct fakemmapwritable *next;
} fakemmapwritable;
static fakemmapwritable *writablelist = NULL;
void *gitfakemmap(void *start, size_t length, int prot , int flags, int fd, off_t offset)
{
int n = 0;
if(start != NULL)
if (start != NULL || !(flags & MAP_PRIVATE))
die("Invalid usage of gitfakemmap.");
if(lseek(fd, offset, SEEK_SET)<0) {
if (lseek(fd, offset, SEEK_SET) < 0) {
errno = EINVAL;
return MAP_FAILED;
}
start = xmalloc(length);
if(start == NULL) {
if (start == NULL) {
errno = ENOMEM;
return MAP_FAILED;
}
while(n < length) {
while (n < length) {
int count = read(fd, start+n, length-n);
if(count == 0) {
if (count == 0) {
memset(start+n, 0, length-n);
break;
}
if(count < 0) {
if (count < 0) {
free(start);
errno = EACCES;
return MAP_FAILED;
@ -49,65 +39,12 @@ void *gitfakemmap(void *start, size_t length, int prot , int flags, int fd, off_
n += count;
}
if(prot & PROT_WRITE) {
fakemmapwritable *next = xmalloc(sizeof(fakemmapwritable));
next->start = start;
next->length = length;
next->fd = dup(fd);
next->offset = offset;
next->next = writablelist;
writablelist = next;
}
return start;
}
int gitfakemunmap(void *start, size_t length)
{
fakemmapwritable *writable = writablelist, *before = NULL;
while(writable && (writable->start > start + length
|| writable->start + writable->length < start)) {
before = writable;
writable = writable->next;
}
if(writable) {
/* need to write back the contents */
int n = 0;
if(writable->start != start || writable->length != length)
die("fakemmap does not support partial write back.");
if(lseek(writable->fd, writable->offset, SEEK_SET) < 0) {
free(start);
errno = EBADF;
return -1;
}
while(n < length) {
int count = write(writable->fd, start + n, length - n);
if(count < 0) {
errno = EINVAL;
return -1;
}
n += count;
}
close(writable->fd);
if(before)
before->next = writable->next;
else
writablelist = writable->next;
free(writable);
}
free(start);
return 0;
}