Fix a bug in gitfo_read_file()

In particular, when asked to read an empty file, this function
calls malloc() with a zero size allocation request. Standard C
says that the behaviour of malloc() in this case is implementation
defined.

[C99, 7.20.3 says "... If the size of the space requested is zero,
the behavior is implementation-defined: either a null pointer is
returned, or the behavior is as if the size were some nonzero
value, except that the returned pointer shall not be used to
access an object."]

Finesse the issue by over-allocating by one byte. Setting the extra
byte to '\0' may also provide a useful sentinel for text files.

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

src/fileops.c

@@ -53,14 +53,14 @@ int gitfo_read_file(gitfo_buf *obj, const char *path)
 {
 	git_file fd;
 	off_t len;
-	void *buff;
+	unsigned char *buff;
 
 	assert(obj && path && *path);
 
 	if ((fd = gitfo_open(path, O_RDONLY)) < 0)
 		return GIT_ERROR;  /* TODO: error handling */
 
-	if (((len = gitfo_size(fd)) < 0) || ((buff = malloc(len)) == NULL)) {
+	if (((len = gitfo_size(fd)) < 0) || ((buff = malloc(len+1)) == NULL)) {
 		gitfo_close(fd);
 		return GIT_ERROR;  /* TODO: error handling */
 	}
@@ -70,6 +70,7 @@ int gitfo_read_file(gitfo_buf *obj, const char *path)
 		free(buff);
 		return GIT_ERROR;  /* TODO: error handling */
 	}
+	buff[len] = '\0';
 
 	gitfo_close(fd);