From f48000fcbe1009c18f1cc46e56cde2cb632071fa Mon Sep 17 00:00:00 2001
From: Junio C Hamano <junkio@cox.net>
Date: Sat, 8 Oct 2005 15:54:36 -0700
Subject: [PATCH] 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>
---
 compat/mmap.c | 163 ++++++++++++++++++----------------------------------------
 1 file changed, 50 insertions(+), 113 deletions(-)
 rewrite compat/mmap.c (68%)

diff --git a/compat/mmap.c b/compat/mmap.c
dissimilarity index 68%
index fca6321ce0..a051c4767d 100644
--- a/compat/mmap.c
+++ b/compat/mmap.c
@@ -1,113 +1,50 @@
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-#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)
-		die("Invalid usage of gitfakemmap.");
-
-	if(lseek(fd, offset, SEEK_SET)<0) {
-		errno = EINVAL;
-		return MAP_FAILED;
-	}
-
-	start = xmalloc(length);
-	if(start == NULL) {
-		errno = ENOMEM;
-		return MAP_FAILED;
-	}
-
-	while(n < length) {
-		int count = read(fd, start+n, length-n);
-
-		if(count == 0) {
-			memset(start+n, 0, length-n);
-			break;
-		}
-
-		if(count < 0) {
-			free(start);
-			errno = EACCES;
-			return MAP_FAILED;
-		}
-
-		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;
-}
-
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include "../cache.h"
+
+void *gitfakemmap(void *start, size_t length, int prot , int flags, int fd, off_t offset)
+{
+	int n = 0;
+
+	if (start != NULL || !(flags & MAP_PRIVATE))
+		die("Invalid usage of gitfakemmap.");
+
+	if (lseek(fd, offset, SEEK_SET) < 0) {
+		errno = EINVAL;
+		return MAP_FAILED;
+	}
+
+	start = xmalloc(length);
+	if (start == NULL) {
+		errno = ENOMEM;
+		return MAP_FAILED;
+	}
+
+	while (n < length) {
+		int count = read(fd, start+n, length-n);
+
+		if (count == 0) {
+			memset(start+n, 0, length-n);
+			break;
+		}
+
+		if (count < 0) {
+			free(start);
+			errno = EACCES;
+			return MAP_FAILED;
+		}
+
+		n += count;
+	}
+
+	return start;
+}
+
+int gitfakemunmap(void *start, size_t length)
+{
+	free(start);
+	return 0;
+}
+
-- 
2.11.4.GIT