From 7db2616c44481f634b3843689334db818b35cb56 Mon Sep 17 00:00:00 2001 From: Augustin Cavalier Date: Thu, 18 Nov 2021 16:34:03 -0500 Subject: [PATCH] dirent: Use an actual flexible-length array for d_name. GCC 11 treats [1] as a fixed-length array and not a flexible-length array, and so some things that used direct strcmp("..", ent->d_name), for instance, would be optimized out as being always unequal, which was the cause of #17389. Using a real FLA informs GCC that there is going to be more than one byte of data, and thus this fixes that bug. BeOS used [1] and not [0], possibly because it had to deal with compilers (MetroWerks? Early GCC2?) that did not support FLAs. GCC 2.95 does, using [0], and GCC 4 does, using [], so we can go with that here. (I did try using [0] for both, which seems to be OK with GCC 11, but GCC 8 throws errors when d_name is dereferenced directly as being-out-of-bounds. So, we have to use the #if here and give newer GCC the [] syntax and not [0] to avoid that problem.) The real question probably is whether or not we should backport some variant of these changes to R1/beta3, as software at HaikuPorts very well may run in to the same issue. (The alternative workaround is to compile with -O1 and not -O2 for any affected software.) But maybe this is an argument for keeping with the beta4 schedule of this coming January... --- headers/posix/dirent.h | 6 +++++- headers/private/fs_shell/fssh_dirent.h | 6 +++++- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/headers/posix/dirent.h b/headers/posix/dirent.h index 9622a265ac..aeac58e3d2 100644 --- a/headers/posix/dirent.h +++ b/headers/posix/dirent.h @@ -15,7 +15,11 @@ typedef struct dirent { ino_t d_ino; /* inode number */ ino_t d_pino; /* parent inode (only for queries) */ unsigned short d_reclen; /* length of this record, not the name */ - char d_name[1]; /* name of the entry (null byte terminated) */ +#if __GNUC__ == 2 + char d_name[0]; /* name of the entry (null byte terminated) */ +#else + char d_name[]; /* name of the entry (null byte terminated) */ +#endif } dirent_t; typedef struct __DIR DIR; diff --git a/headers/private/fs_shell/fssh_dirent.h b/headers/private/fs_shell/fssh_dirent.h index 73220e5499..aa33b81b68 100644 --- a/headers/private/fs_shell/fssh_dirent.h +++ b/headers/private/fs_shell/fssh_dirent.h @@ -14,7 +14,11 @@ typedef struct fssh_dirent { fssh_ino_t d_ino; /* inode number */ fssh_ino_t d_pino; /* parent inode (only for queries) */ unsigned short d_reclen; /* length of this record, not the name */ - char d_name[1]; /* name of the entry (null byte terminated) */ +#if __GNUC__ == 2 + char d_name[0]; /* name of the entry (null byte terminated) */ +#else + char d_name[]; /* name of the entry (null byte terminated) */ +#endif } fssh_dirent_t; typedef struct {