Re: [PATCH] fetch--tool: fix uninitialized buffer when reading from stdin
Linus Torvalds <torvalds@linux-foundation.org> writes:
Show 9 quoted lines
> Well, that CHUNK_SIZE is just silly. I don't see why you'd have a
> chunk-size of a megabyte to begin with, IO doesn't really get any more
> efficient that way. And yeah, in this case it would easily hide the bug,
> because in practice nobody would ever test with that much input data.
>
> It might make sense to make the chunk-size smaller just from a testability
> standpoint (not to mention that it's probably currently just wasting
> memory for most users - although at least under Linux, if you never use a
> page, none will be allocated for you, so the OS may hide the wastage).
How about doing this instead?
-- >8 -- [PATCH] fetch--tool: fix uninitialized buffer when reading from stdin
The original code allocates too much space and forgets to NUL terminate the string.
Signed-off-by: Junio C Hamano <junkio@cox.net>
---
builtin-fetch--tool.c | 19 +++++++++++++------
1 files changed, 13 insertions(+), 6 deletions(-)
Show changes to builtin-fetch--tool.c +13 −6
diff --git a/builtin-fetch--tool.c b/builtin-fetch--tool.c
index 48de08d..a068f8d 100644
--- a/builtin-fetch--tool.c
+++ b/builtin-fetch--tool.c
@@ -2,17 +2,24 @@
#include "refs.h"
#include "commit.h"
-#define CHUNK_SIZE (1048576)
+#define CHUNK_SIZE 1024
static char *get_stdin(void)
{
+ int offset = 0;
char *data = xmalloc(CHUNK_SIZE);
- int offset = 0, read = 0;
- read = xread(0, data, CHUNK_SIZE);
- while (read == CHUNK_SIZE) {
- offset += CHUNK_SIZE;
+
+ while (1) {
+ int cnt = xread(0, data + offset, CHUNK_SIZE);
+ if (cnt < 0)
+ die("error reading standard input: %s",
+ strerror(errno));
+ if (cnt == 0) {
+ data[offset] = 0;
+ break;
+ }
+ offset += cnt;
data = xrealloc(data, offset + CHUNK_SIZE);
- read = xread(0, data + offset, CHUNK_SIZE);
}
return data;
}
Johannes Schindelin
