Re: [Libguestfs] [PATCH nbdkit 3/5] vddk: Miscellaneous improvements to reexec code.

On 6/2/20 7:27 AM, Richard W.M. Jones wrote: >Use an extensible buffer (a vector<char>) when reading >/proc/self/cmdline. > >Tidy up some error messages. >--- > plugins/vddk/reexec.c | 57 ++++++++++++++++++++++++++----------------- > 1 file changed, 35 insertions(+), 22 deletions(-) > >@@ -80,42 +95,40 @@ perform_reexec (const char *env, const char *prepend) > * until we get a short read. This assumes nbdkit did not alter its > * original argv[]. > */ >- fd = open ("/proc/self/cmdline", O_RDONLY); >+ fd = open (cmdline_file, O_RDONLY|O_CLOEXEC); > if (fd == -1) { >- nbdkit_debug ("failure to parse original argv: %m"); >+ nbdkit_debug ("open: %s: %m", cmdline_file); > return; > } >- do { >- char *p = realloc (buf, buflen * 2); >+ for (;;) { > ssize_t r; >- if (!p) { >- nbdkit_debug ("failure to parse original argv: %m"); >+ if (buffer_reserve (&buf, 512) == -1) { >+ nbdkit_debug ("realloc: %m"); > return; > } Pre-existing bug, which you did not fix here. If we failed here, we are leaking fd. You slightly improved the situation by marking the leaked fd O_CLOEXEC, but that really doesn't matter if we properly fix the code to close(fd) before any early return, at which point the lifetime of fd is only during single-threaded execution and O_CLOEXEC doesn't matter.