[PATCH] If NO_MMAP is defined, fake mmap() and munmap()

@@ -27,6 +27,8 @@
 # Define NEEDS_SOCKET if linking with libc is not enough (SunOS,
 # Patrick Mauritz).
 #
+# Define NO_MMAP if you want to avoid mmap.
+#
 # Define WITH_OWN_SUBPROCESS_PY if you want to use with python 2.3.
 #
 # Define NO_IPV6 if you lack IPv6 support and getaddrinfo().

@@ -259,6 +261,10 @@ ifdef NO_STRCASESTR
 	DEFINES += -Dstrcasestr=gitstrcasestr
 	LIB_OBJS += compat/strcasestr.o
 endif
+ifdef NO_MMAP
+	DEFINES += -Dmmap=gitfakemmap -Dmunmap=gitfakemunmap -DNO_MMAP
+	LIB_OBJS += compat/mmap.o
+endif
 ifdef NO_IPV6
 	DEFINES += -DNO_IPV6 -Dsockaddr_storage=sockaddr_in
 endif

@@ -11,7 +11,9 @@
 #include <string.h>
 #include <errno.h>
 #include <limits.h>
+#ifndef NO_MMAP
 #include <sys/mman.h>
+#endif
 #include <sys/param.h>
 #include <netinet/in.h>
 #include <sys/types.h>

@@ -356,4 +358,18 @@ extern void packed_object_info_detail(st
 /* Dumb servers support */
 extern int update_server_info(int);
 
+#ifdef NO_MMAP
+
+#ifndef PROT_READ
+#define PROT_READ 1
+#define PROT_WRITE 2
+#define MAP_PRIVATE 1
+#define MAP_FAILED ((void*)-1)
+#endif
+
+extern void *gitfakemmap(void *start, size_t length, int prot , int flags, int fd, off_t offset);
+extern int gitfakemunmap(void *start, size_t length);
+
+#endif
+
 #endif /* CACHE_H */

@@ -0,0 +1,113 @@
+#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;
+}
+

@@ -9,7 +9,6 @@
 #include <fcntl.h>
 #include <sys/types.h>
 #include <sys/stat.h>
-#include <sys/mman.h>
 #include <string.h>
 #include <stdio.h>
 #include <ctype.h>