Add and use xmmap.

Everyone forgets that mmap returns MAP_FAILED rather than NULL on failure.
Every use of mmap in toybox was either doing the wrong check, or no check
at all (including the two I personally added).

2 files changed, 8 insertions, 0 deletions

diff --git a/lib/lib.h b/lib/lib.h
index effba9b4..0b93bde9 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -115,6 +115,7 @@ void xstrncpy(char *dest, char *src, size_t size);
 void xstrncat(char *dest, char *src, size_t size);
 void _xexit(void) noreturn;
 void xexit(void) noreturn;
+void *xmmap(void *addr, size_t length, int prot, int flags, int fd, off_t off);
 void *xmalloc(size_t size);
 void *xzalloc(size_t size);
 void *xrealloc(void *ptr, size_t size);
diff --git a/lib/xwrap.c b/lib/xwrap.c
index 0281e701..83f54a0a 100644
--- a/lib/xwrap.c
+++ b/lib/xwrap.c
@@ -58,6 +58,13 @@ void xexit(void)
   _xexit();
 }
 
+void *xmmap(void *addr, size_t length, int prot, int flags, int fd, off_t off)
+{
+  void *ret = mmap(addr, length, prot, flags, fd, off);
+  if (ret == MAP_FAILED) perror_exit("mmap");
+  return ret;
+}
+
 // Die unless we can allocate memory.
 void *xmalloc(size_t size)
 {