diff options
author | Denys Vlasenko <vda.linux@googlemail.com> | 2014-06-22 15:54:40 +0400 |
---|---|---|
committer | Denys Vlasenko <vda.linux@googlemail.com> | 2014-06-22 15:54:40 +0400 |
commit | f92f1d0181853b989f9377debb56902e3e21c9a8 (patch) | |
tree | 14c0bb888dea4b92e0f8dcaec2aa9c2a40eb3966 | |
parent | 6be3a5242ce4855734a4cdd5770b6ea7adaf2b3d (diff) |
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 <bartekgola@gmail.com>.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r-- | findutils/find.c | 4 | ||||
-rw-r--r-- | findutils/xargs.c | 26 | ||||
-rw-r--r-- | include/libbb.h | 8 | ||||
-rw-r--r-- | libbb/Kbuild.src | 1 | ||||
-rw-r--r-- | libbb/sysconf.c | 16 |
5 files changed, 38 insertions, 17 deletions
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); } diff --git a/include/libbb.h b/include/libbb.h index a1a0dc18c..fa69a7fe6 100644 --- a/include/libbb.h +++ b/include/libbb.h @@ -731,6 +731,14 @@ extern void *xmalloc_open_read_close(const char *filename, size_t *maxsz_p) FAST /* Never returns NULL */ extern void *xmalloc_xopen_read_close(const char *filename, size_t *maxsz_p) FAST_FUNC RETURNS_MALLOC; +#if defined ARG_MAX +# define bb_arg_max() ((unsigned)ARG_MAX) +#elif defined _SC_ARG_MAX +unsigned bb_arg_max(void) FAST_FUNC; +#else +# define bb_arg_max() ((unsigned)(32 * 1024)) +#endif + #define SEAMLESS_COMPRESSION (0 \ || ENABLE_FEATURE_SEAMLESS_XZ \ || ENABLE_FEATURE_SEAMLESS_LZMA \ diff --git a/libbb/Kbuild.src b/libbb/Kbuild.src index 6578d1171..62680bd52 100644 --- a/libbb/Kbuild.src +++ b/libbb/Kbuild.src @@ -92,6 +92,7 @@ lib-y += skip_whitespace.o lib-y += speed_table.o lib-y += str_tolower.o lib-y += strrstr.o +lib-y += sysconf.o lib-y += time.o lib-y += trim.o lib-y += u_signal_names.o diff --git a/libbb/sysconf.c b/libbb/sysconf.c new file mode 100644 index 000000000..c5fa5e001 --- /dev/null +++ b/libbb/sysconf.c @@ -0,0 +1,16 @@ +/* vi: set sw=4 ts=4: */ +/* + * Various system configuration helpers. + * + * Copyright (C) 2014 Bartosz Golaszewski <bartekgola@gmail.com> + * + * Licensed under GPLv2 or later, see file LICENSE in this source tree. + */ +#include "libbb.h" + +#if defined _SC_ARG_MAX +unsigned FAST_FUNC bb_arg_max(void) +{ + return sysconf(_SC_ARG_MAX); +} +#endif |