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authorGravatar Denys Vlasenko <vda.linux@googlemail.com>2014-06-22 13:54:40 +0200
committerGravatar Denys Vlasenko <vda.linux@googlemail.com>2014-06-22 13:54:40 +0200
commitf92f1d0181853b989f9377debb56902e3e21c9a8 (patch)
tree14c0bb888dea4b92e0f8dcaec2aa9c2a40eb3966 /findutils
parent6be3a5242ce4855734a4cdd5770b6ea7adaf2b3d (diff)
downloadbusybox-f92f1d0181853b989f9377debb56902e3e21c9a8.tar.gz
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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>
Diffstat (limited to 'findutils')
-rw-r--r--findutils/find.c4
-rw-r--r--findutils/xargs.c26
2 files changed, 13 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);
}