From b89af5ed5c95ebe0466830d90eedd430593a3584 Mon Sep 17 00:00:00 2001 From: Elliott Hughes Date: Wed, 20 Sep 2017 13:53:23 -0700 Subject: Fix xargs to obey POSIX's ARG_MAX restrictions. This avoids "xargs: exec echo: Argument list too long" errors in practice. find(1) needs to be fixed too, but that's a bit more complicated and a working xargs provides a workaround. Bug: http://b/65818597 Test: find /proc | strace -f -e execve ./toybox xargs echo > /dev/null --- toys/posix/xargs.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) (limited to 'toys/posix') diff --git a/toys/posix/xargs.c b/toys/posix/xargs.c index b4cb80a0..e7dd10b5 100644 --- a/toys/posix/xargs.c +++ b/toys/posix/xargs.c @@ -79,6 +79,8 @@ static char *handle_entries(char *data, char **entry) if (!*s) break; save = s; + TT.bytes += sizeof(char *); + for (;;) { if (++TT.bytes >= TT.max_bytes && TT.max_bytes) return save; if (!*s || isspace(*s)) break; @@ -95,7 +97,7 @@ static char *handle_entries(char *data, char **entry) // -0 support } else { - TT.bytes += strlen(data)+1; + TT.bytes += sizeof(char *)+strlen(data)+1; if (TT.max_bytes && TT.bytes >= TT.max_bytes) return data; if (TT.max_entries && TT.entries >= TT.max_entries) return (char *)1; @@ -112,6 +114,16 @@ void xargs_main(void) int entries, bytes, done = 0, status; char *data = NULL, **out; pid_t pid; + long posix_max_bytes; + + // POSIX requires that we never hit the ARG_MAX limit, even if we try to + // with -s. POSIX also says we have to reserve 2048 bytes "to guarantee + // that the invoked utility has room to modify its environment variables + // and command line arguments and still be able to invoke another utility", + // though obviously that's not really something you can guarantee. + posix_max_bytes = sysconf(_SC_ARG_MAX) - environ_bytes() - 2048; + if (TT.max_bytes == 0 || TT.max_bytes > posix_max_bytes) + TT.max_bytes = posix_max_bytes; if (!(toys.optflags & FLAG_0)) TT.delim = '\n'; -- cgit v1.2.3