A minor correction. I've missed a test for an error case. Updated patch can be
found in the attachments.
Sven
--- make-4.2.1/configure.ac 2016-06-06 13:27:31.000000000 +0100
+++ make-4.2.1.1/configure.ac 2016-10-09 18:33:34.574257275 +0100
@@ -176,10 +176,30 @@
AS_IF([test "$have_guile" = yes],
[AC_DEFINE([HAVE_GUILE], [1], [Embed GNU Guile support])])
AM_CONDITIONAL([HAVE_GUILE], [test "$have_guile" = yes])
+AC_CHECK_FUNCS[open close read lseek atoi]
+AC_CACHE_CHECK([for /proc/loadavg usability], [ac_cv_proc_loadavg],
+ [ac_cv_proc_loadavg=no
+ AC_RUN_IFELSE([AC_LANG_SOURCE([[#include <fcntl.h>
+#include <unistd.h>
+#include <stdlib.h>
+int main() {
+ int fd, i, n; char str[64];
+ fd = open("/proc/loadavg", O_RDONLY);
+ if (fd < 0 || read(fd, str, 64) < 0 || lseek(fd, 0, SEEK_SET) < 0) return 1;
+ for (str[63] = i = n = 0; i < 3 && n < 64; ++n) if (str[n] == ' ') ++i;
+ return i < 3 || atoi(&str[n]) < 1 || close(fd) < 0;}]])],
+ [ac_cv_proc_loadavg=yes],
+ [ac_cv_proc_loadavg=no],
+ [ac_cv_proc_loadavg="no (cross-compiling)"])])
+AS_IF([test "$ac_cv_proc_loadavg" = yes],
+[ AC_DEFINE([HAVE_PROC_LOADAVG], [1],
+ [Define to 1 when /proc/loadavg exists and appears usable])
+])
+
AC_FUNC_GETLOADAVG
# AC_FUNC_GETLOADAVG is documented to set the NLIST_STRUCT value, but it
# doesn't. So, we will.
--- make-4.2.1/job.c 2016-05-21 21:22:32.000000000 +0100
+++ make-4.2.1.1/job.c 2016-10-09 20:02:43.047767201 +0100
@@ -1925,10 +1925,60 @@
static int
load_too_high (void)
{
#if defined(__MSDOS__) || defined(VMS) || defined(_AMIGA) ||
defined(__riscos__)
return 1;
+#elif defined(HAVE_PROC_LOADAVG)
+ /* Read from /proc/loadavg and use the number of active running
+ tasks & threads to determine if we can start another process. */
+#define PROC_LOADAVG_SIZE 64
+ static int fd = -2;
+ char proc_loadavg[PROC_LOADAVG_SIZE];
+ int i, p;
+
+ if (max_load_average < 0 || fd == -1)
+ return 0;
+
+ if (fd == -2)
+ {
+ fd = open ("/proc/loadavg", O_RDONLY);
+ if (fd < 0)
+ {
+ perror_with_name (_("cannot open /proc/loadavg: "), "open");
+ fd = -1;
+ return 0;
+ }
+ }
+ if (read (fd, proc_loadavg, PROC_LOADAVG_SIZE) < 0)
+ {
+ perror_with_name (_("cannot read /proc/loadavg: "), "read");
+ close(fd);
+ fd = -1;
+ return 0;
+ }
+ if (lseek (fd, 0, SEEK_SET) < 0)
+ {
+ perror_with_name (_("cannot seek on /proc/loadavg: "), "lseek");
+ close(fd);
+ fd = -1;
+ return 0;
+ }
+ proc_loadavg[PROC_LOADAVG_SIZE-1] = '\0';
+ for (i = p = 0; i < 3 && p < PROC_LOADAVG_SIZE; ++p)
+ {
+ if (proc_loadavg[p] == ' ')
+ ++i;
+ }
+ if (i < 3)
+ {
+ errno = ENOTSUP;
+ perror_with_name (_("unsupported format of /proc/loadavg: "),
"load_too_high");
+ close (fd);
+ fd = -1;
+ return 0;
+ }
+ return max_load_average < (double) atoi (&proc_loadavg[p]);
#else
static double last_sec;
static time_t last_now;
double load, guess;
time_t now;
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