From f92f1d0181853b989f9377debb56902e3e21c9a8 Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Sun, 22 Jun 2014 13:54:40 +0200 Subject: find: use sysconf(_SC_ARG_MAX) to determine the command-line size limit The find utility uses a hardcoded value of 32 * 1024 as the limit of the command-line length when calling 'find -exec ... {} +'. This results in over 4 times more execve() calls than in coreutils' find. This patch uses the limit defined in system headers. Based on the patch by Bartosz Golaszewski . Signed-off-by: Denys Vlasenko --- findutils/find.c | 4 +++- findutils/xargs.c | 26 ++++++++++---------------- 2 files changed, 13 insertions(+), 17 deletions(-) (limited to 'findutils') diff --git a/findutils/find.c b/findutils/find.c index 493f72e61..56a7ed3ab 100644 --- a/findutils/find.c +++ b/findutils/find.c @@ -419,6 +419,7 @@ struct globals { smallint need_print; smallint xdev_on; recurse_flags_t recurse_flags; + IF_FEATURE_FIND_EXEC_PLUS(unsigned max_argv_len;) } FIX_ALIASING; #define G (*(struct globals*)&bb_common_bufsiz1) #define INIT_G() do { \ @@ -428,6 +429,7 @@ struct globals { /* we have to zero it out because of NOEXEC */ \ memset(&G, 0, sizeof(G)); \ IF_FEATURE_FIND_MAXDEPTH(G.minmaxdepth[1] = INT_MAX;) \ + IF_FEATURE_FIND_EXEC_PLUS(G.max_argv_len = bb_arg_max() - 2048;) \ G.need_print = 1; \ G.recurse_flags = ACTION_RECURSE; \ } while (0) @@ -677,7 +679,7 @@ ACTF(exec) ap->file_len += strlen(fileName) + sizeof(char*) + 1; /* If we have lots of files already, exec the command */ rc = 1; - if (ap->file_len >= 32*1024) + if (ap->file_len >= G.max_argv_len) rc = do_exec(ap, NULL); return rc; } diff --git a/findutils/xargs.c b/findutils/xargs.c index 0ba5b566d..76c4747fe 100644 --- a/findutils/xargs.c +++ b/findutils/xargs.c @@ -523,12 +523,7 @@ int xargs_main(int argc, char **argv) argc++; } - /* -s NUM default. fileutils-4.4.2 uses 128k, but I heasitate - * to use such a big value - first need to change code to use - * growable buffer instead of fixed one. - */ - n_max_chars = 32 * 1024; - /* Make smaller if system does not allow our default value. + /* * The Open Group Base Specifications Issue 6: * "The xargs utility shall limit the command line length such that * when the command line is invoked, the combined argument @@ -536,16 +531,15 @@ int xargs_main(int argc, char **argv) * in the System Interfaces volume of IEEE Std 1003.1-2001) * shall not exceed {ARG_MAX}-2048 bytes". */ - { - long arg_max = 0; -#if defined _SC_ARG_MAX - arg_max = sysconf(_SC_ARG_MAX) - 2048; -#elif defined ARG_MAX - arg_max = ARG_MAX - 2048; -#endif - if (arg_max > 0 && n_max_chars > arg_max) - n_max_chars = arg_max; - } + n_max_chars = bb_arg_max(); + if (n_max_chars > 32 * 1024) + n_max_chars = 32 * 1024; + /* + * POSIX suggests substracting 2048 bytes from sysconf(_SC_ARG_MAX) + * so that the process may safely modify its environment. + */ + n_max_chars -= 2048; + if (opt & OPT_UPTO_SIZE) { n_max_chars = xatou_range(max_chars, 1, INT_MAX); } -- cgit v1.2.3