git-mktag: be more careful in reading the input.

Instead of always assuming it can be read with a single
read() system call, loop around properly.

Pointed out by Pasky, but I ended up implementing it differently
from his suggested patch.

diff --git a/mktag.c b/mktag.c
index aa4a6d8..8cbbef6 100644 (file)
--- a/mktag.c
+++ b/mktag.c
@@ -106,7 +106,18 @@ int main(int argc, char **argv)
                usage("cat <signaturefile> | git-mktag");
 
        // Read the signature
-       size = read(0, buffer, MAXSIZE);
+       size = 0;
+       for (;;) {
+               int ret = read(0, buffer + size, MAXSIZE - size);
+               if (!ret)
+                       break;
+               if (ret < 0) {
+                       if (errno == EAGAIN)
+                               continue;
+                       break;
+               }
+               size += ret;
+       }
 
        // Verify it for some basic sanity: it needs to start with "object <sha1>\ntype "
        if (verify_tag(buffer, size) < 0)