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xargs: bump default -sNUM up to 32k. Use sysconf() to trim it down if necessary

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function                                             old     new   delta
xargs_main                                           819     830     +11

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2010-06-19 21:44:01 +02:00
parent e15a6c82df
commit 4a96617095
1 changed files with 27 additions and 25 deletions
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48
findutils/xargs.c
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@ -59,14 +59,6 @@
//config: are not special. //config: are not special.
#include "libbb.h" #include "libbb.h"
/* COMPAT: SYSV version defaults size (and has a max value of) to 470.
We try to make it as large as possible. */
#if !defined(ARG_MAX) && defined(_SC_ARG_MAX)
# define ARG_MAX sysconf(_SC_ARG_MAX)
#endif
#if !defined(ARG_MAX)
# define ARG_MAX 470
#endif
/* This is a NOEXEC applet. Be very careful! */ /* This is a NOEXEC applet. Be very careful! */
@ -440,42 +432,52 @@ int xargs_main(int argc, char **argv)
argc++; argc++;
} }
/* The Open Group Base Specifications Issue 6: /* -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 * "The xargs utility shall limit the command line length such that
* when the command line is invoked, the combined argument * when the command line is invoked, the combined argument
* and environment lists (see the exec family of functions * and environment lists (see the exec family of functions
* in the System Interfaces volume of IEEE Std 1003.1-2001) * in the System Interfaces volume of IEEE Std 1003.1-2001)
* shall not exceed {ARG_MAX}-2048 bytes". * shall not exceed {ARG_MAX}-2048 bytes".
*/ */
n_max_chars = ARG_MAX; /* might be calling sysconf(_SC_ARG_MAX) */ {
if (n_max_chars < 4*1024); /* paranoia */ long arg_max = 0;
n_max_chars = 4*1024; #if defined _SC_ARG_MAX
n_max_chars -= 2048; arg_max = sysconf(_SC_ARG_MAX) - 2048;
/* Sanity check for systems with huge ARG_MAX defines (e.g., Suns which #elif defined ARG_MAX
* have it at 1 meg). Things will work fine with a large ARG_MAX arg_max = ARG_MAX - 2048;
* but it will probably hurt the system more than it needs to; #endif
* an array of this size is allocated. if (arg_max > 0 && n_max_chars > arg_max)
*/ n_max_chars = arg_max;
if (n_max_chars > 20 * 1024) }
n_max_chars = 20 * 1024;
if (opt & OPT_UPTO_SIZE) { if (opt & OPT_UPTO_SIZE) {
size_t n_chars = 0;
n_max_chars = xatou_range(max_chars, 1, INT_MAX); n_max_chars = xatou_range(max_chars, 1, INT_MAX);
}
/* Account for prepended fixed arguments */
{
size_t n_chars = 0;
for (i = 0; argv[i]; i++) { for (i = 0; argv[i]; i++) {
n_chars += strlen(argv[i]) + 1; n_chars += strlen(argv[i]) + 1;
} }
n_max_chars -= n_chars; n_max_chars -= n_chars;
}
/* Sanity check */
if (n_max_chars <= 0) { if (n_max_chars <= 0) {
bb_error_msg_and_die("can't fit single argument within argument list size limit"); bb_error_msg_and_die("can't fit single argument within argument list size limit");
} }
}
buf = xzalloc(n_max_chars + 1); buf = xzalloc(n_max_chars + 1);
n_max_arg = n_max_chars; n_max_arg = n_max_chars;
if (opt & OPT_UPTO_NUMBER) { if (opt & OPT_UPTO_NUMBER) {
n_max_arg = xatou_range(max_args, 1, INT_MAX); n_max_arg = xatou_range(max_args, 1, INT_MAX);
/* Not necessary, we use growable args[]: */
/* if (n_max_arg > n_max_chars) n_max_arg = n_max_chars */
} }
/* Allocate pointers for execvp */ /* Allocate pointers for execvp */