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xargs: bump default -sNUM up to 32k. Use sysconf() to trim it down if necessary
function old new delta xargs_main 819 830 +11 Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
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@ -59,14 +59,6 @@
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//config: are not special.
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#include "libbb.h"
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/* COMPAT: SYSV version defaults size (and has a max value of) to 470.
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We try to make it as large as possible. */
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#if !defined(ARG_MAX) && defined(_SC_ARG_MAX)
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# define ARG_MAX sysconf(_SC_ARG_MAX)
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#endif
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#if !defined(ARG_MAX)
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# define ARG_MAX 470
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#endif
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/* This is a NOEXEC applet. Be very careful! */
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@ -440,35 +432,43 @@ int xargs_main(int argc, char **argv)
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argc++;
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}
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/* The Open Group Base Specifications Issue 6:
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/* -s NUM default. fileutils-4.4.2 uses 128k, but I heasitate
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* to use such a big value - first need to change code to use
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* growable buffer instead of fixed one.
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*/
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n_max_chars = 32 * 1024;
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/* Make smaller if system does not allow our default value.
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* The Open Group Base Specifications Issue 6:
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* "The xargs utility shall limit the command line length such that
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* when the command line is invoked, the combined argument
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* and environment lists (see the exec family of functions
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* in the System Interfaces volume of IEEE Std 1003.1-2001)
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* shall not exceed {ARG_MAX}-2048 bytes".
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*/
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n_max_chars = ARG_MAX; /* might be calling sysconf(_SC_ARG_MAX) */
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if (n_max_chars < 4*1024); /* paranoia */
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n_max_chars = 4*1024;
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n_max_chars -= 2048;
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/* Sanity check for systems with huge ARG_MAX defines (e.g., Suns which
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* have it at 1 meg). Things will work fine with a large ARG_MAX
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* but it will probably hurt the system more than it needs to;
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* an array of this size is allocated.
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*/
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if (n_max_chars > 20 * 1024)
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n_max_chars = 20 * 1024;
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{
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long arg_max = 0;
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#if defined _SC_ARG_MAX
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arg_max = sysconf(_SC_ARG_MAX) - 2048;
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#elif defined ARG_MAX
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arg_max = ARG_MAX - 2048;
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#endif
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if (arg_max > 0 && n_max_chars > arg_max)
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n_max_chars = arg_max;
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}
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if (opt & OPT_UPTO_SIZE) {
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size_t n_chars = 0;
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n_max_chars = xatou_range(max_chars, 1, INT_MAX);
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}
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/* Account for prepended fixed arguments */
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{
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size_t n_chars = 0;
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for (i = 0; argv[i]; i++) {
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n_chars += strlen(argv[i]) + 1;
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}
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n_max_chars -= n_chars;
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if (n_max_chars <= 0) {
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bb_error_msg_and_die("can't fit single argument within argument list size limit");
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}
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}
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/* Sanity check */
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if (n_max_chars <= 0) {
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bb_error_msg_and_die("can't fit single argument within argument list size limit");
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}
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buf = xzalloc(n_max_chars + 1);
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@ -476,6 +476,8 @@ int xargs_main(int argc, char **argv)
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n_max_arg = n_max_chars;
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if (opt & OPT_UPTO_NUMBER) {
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n_max_arg = xatou_range(max_args, 1, INT_MAX);
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/* Not necessary, we use growable args[]: */
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/* if (n_max_arg > n_max_chars) n_max_arg = n_max_chars */
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}
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/* Allocate pointers for execvp */
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