[git commit] libpwdgrp: use a better estimate of max struct size

Denys Vlasenko vda.linux at googlemail.com
Sat Jan 3 16:53:49 UTC 2015


commit: http://git.busybox.net/busybox/commit/?id=5e62a3d016633d4d97906f0f73298dc8e8b6a42b
branch: http://git.busybox.net/busybox/commit/?id=refs/heads/master

Previous code's trick with bitwise OR was giving this on 32-bit x86:

sizeof(struct passwd):28
sizeof(struct group):16
sizeof(struct spwd):36
sizeof(struct_result):60

Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
 libpwdgrp/pwd_grp.c |    9 ++++-----
 1 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/libpwdgrp/pwd_grp.c b/libpwdgrp/pwd_grp.c
index 539d2b0..f3fcec8 100644
--- a/libpwdgrp/pwd_grp.c
+++ b/libpwdgrp/pwd_grp.c
@@ -45,11 +45,10 @@ struct passdb {
 	uint8_t numfields;
 	FILE *fp;
 	char *malloced;
-	char struct_result[0
-				| sizeof(struct passwd)
-				| sizeof(struct group)
-	IF_USE_BB_SHADOW(       | sizeof(struct spwd)  )
-	/* bitwise OR above is poor man's max(a,b,c) */
+	char struct_result[
+		/* Should be max(sizeof passwd,group,spwd), but this will do: */
+		IF_NOT_USE_BB_SHADOW(sizeof(struct passwd))
+		IF_USE_BB_SHADOW(sizeof(struct spwd))
 	];
 };
 


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