From 18615acf6008813e283cd49d45a2bf719a221c1d Mon Sep 17 00:00:00 2001
From: leitner <leitner>
Date: Fri, 16 Sep 2016 16:22:00 +0000
Subject: [PATCH] instead of calling mmap with a size of 0 (which will fail),
 skip the syscall and fail directly

---
 mmap/mmap_private.c | 2 +-
 mmap/mmap_read.c    | 2 +-
 mmap/mmap_readat.c  | 2 +-
 mmap/mmap_shared.c  | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/mmap/mmap_private.c b/mmap/mmap_private.c
index 1850ce0..771ecf9 100644
--- a/mmap/mmap_private.c
+++ b/mmap/mmap_private.c
@@ -28,7 +28,7 @@ char* mmap_private(const char* filename,size_t * filesize) {
   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; }
+    if (o==0 || (sizeof(off_t)!=sizeof(size_t) && o > (off_t)(size_t)-1)) { close(fd); return 0; }
     *filesize=(size_t)o;
     map=(char*)mmap(0,*filesize,PROT_READ|PROT_WRITE,MAP_PRIVATE,fd,0);
     if (map==(char*)-1)
diff --git a/mmap/mmap_read.c b/mmap/mmap_read.c
index 7d9055f..1dfc597 100644
--- a/mmap/mmap_read.c
+++ b/mmap/mmap_read.c
@@ -28,7 +28,7 @@ extern const char* mmap_read(const char* filename,size_t * filesize) {
   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; }
+    if (o==0 || (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);
diff --git a/mmap/mmap_readat.c b/mmap/mmap_readat.c
index e7de33d..0503d6b 100644
--- a/mmap/mmap_readat.c
+++ b/mmap/mmap_readat.c
@@ -20,7 +20,7 @@ extern const char* mmap_readat(const char* filename,size_t * filesize,int dirfd)
   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; }
+    if (o==0 || (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);
diff --git a/mmap/mmap_shared.c b/mmap/mmap_shared.c
index 3064d7c..60f1cb1 100644
--- a/mmap/mmap_shared.c
+++ b/mmap/mmap_shared.c
@@ -28,7 +28,7 @@ extern char* mmap_shared(const char* filename,size_t * filesize) {
   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; }
+    if (o==0 || (sizeof(off_t)!=sizeof(size_t) && o > (off_t)(size_t)-1)) { close(fd); return 0; }
     *filesize=(size_t)o;
     if (o) {
       map=mmap(0,*filesize,PROT_READ|PROT_WRITE,MAP_SHARED,fd,0);