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build system: fix parallel building issue

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The files generated by the include/config/MARKER target are in the
dependency list for applets/applet_tables.
If applets/applet_tables is created first during applets_dir then it will
be created again later as part of $(busybox-dirs).
As a result include/applet_tables.h is created again. This time while other
build commands may need it.

Let applets_dir depend on include/config/MARKER to avoid this particular
race condition and create the header files atomically to ensure that the
compiler never sees incomplete files.

Signed-off-by: Michael Olbrich <m.olbrich@pengutronix.de>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Michael Olbrich 2018-04-12 10:36:54 +02:00 committed by Denys Vlasenko
parent c783cf78af
commit 43dd006222
2 changed files with 15 additions and 3 deletions
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2
Makefile
View File

@ -368,7 +368,7 @@ gen_build_files: $(wildcard $(srctree)/*/*.c) $(wildcard $(srctree)/*/*/*.c)
# we depend on scripts_basic, since scripts/basic/fixdep # we depend on scripts_basic, since scripts/basic/fixdep
# must be built before any other host prog # must be built before any other host prog
PHONY += applets_dir PHONY += applets_dir
applets_dir: scripts_basic gen_build_files applets_dir: scripts_basic gen_build_files include/config/MARKER
$(Q)$(MAKE) $(build)=applets $(Q)$(MAKE) $(build)=applets
applets/%: applets_dir ; applets/%: applets_dir ;

16
applets/applet_tables.c
View File

@ -10,6 +10,7 @@
#include <sys/types.h> #include <sys/types.h>
#include <sys/stat.h> #include <sys/stat.h>
#include <fcntl.h> #include <fcntl.h>
#include <limits.h>
#include <stdlib.h> #include <stdlib.h>
#include <string.h> #include <string.h>
#include <stdio.h> #include <stdio.h>
@ -61,6 +62,7 @@ static int str_isalnum_(const char *s)
int main(int argc, char **argv) int main(int argc, char **argv)
{ {
int i, j; int i, j;
char tmp1[PATH_MAX], tmp2[PATH_MAX];
// In find_applet_by_name(), before linear search, narrow it down // In find_applet_by_name(), before linear search, narrow it down
// by looking at N "equidistant" names. With ~350 applets: // by looking at N "equidistant" names. With ~350 applets:
@ -84,7 +86,8 @@ int main(int argc, char **argv)
if (!argv[1]) if (!argv[1])
return 1; return 1;
i = open(argv[1], O_WRONLY | O_TRUNC | O_CREAT, 0666); snprintf(tmp1, PATH_MAX, "%s.%u.new", argv[1], (int) getpid());
i = open(tmp1, O_WRONLY | O_TRUNC | O_CREAT, 0666);
if (i < 0) if (i < 0)
return 1; return 1;
dup2(i, 1); dup2(i, 1);
@ -209,12 +212,21 @@ int main(int argc, char **argv)
// fclose(fp); // fclose(fp);
// } // }
// if (strcmp(line_old, line_new) != 0) { // if (strcmp(line_old, line_new) != 0) {
fp = fopen(argv[2], "w"); snprintf(tmp2, PATH_MAX, "%s.%u.new", argv[2], (int) getpid());
fp = fopen(tmp2, "w");
if (!fp) if (!fp)
return 1; return 1;
fputs(line_new, fp); fputs(line_new, fp);
if (fclose(fp))
return 1;
// } // }
} }
if (fclose(stdout))
return 1;
if (rename(tmp1, argv[1]))
return 1;
if (rename(tmp2, argv[2]))
return 1;
return 0; return 0;
} }