tests: teach the test-tool to generate NUL bytes and use it

In cc95bc2025 (t5562: replace /dev/zero with a pipe from
generate_zero_bytes, 2019-02-09), we replaced usage of /dev/zero (which
is not available on NonStop, apparently) by a Perl script snippet to
generate NUL bytes.

Sadly, it does not seem to work on NonStop, as t5562 reportedly hangs.

Worse, this also hangs in the Ubuntu 16.04 agents of the CI builds on
Azure Pipelines: for some reason, the Perl script snippet that is run
via `generate_zero_bytes` in t5562's 'CONTENT_LENGTH overflow ssite_t'
test case tries to write out an infinite amount of NUL bytes unless a
broken pipe is encountered, that snippet never encounters the broken
pipe, and keeps going until the build times out.

Oddly enough, this does not reproduce on the Windows and macOS agents,
nor in a local Ubuntu 18.04.

This developer tried for a day to figure out the exact circumstances
under which this hang happens, to no avail, the details remain a
mystery.

In the end, though, what counts is that this here change incidentally
fixes that hang (maybe also on NonStop?). Even more positively, it gets
rid of yet another unnecessary Perl invocation.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Makefile b/Makefile
index f0b2299172cf631470e1935869021bebb0e5ea96..c5240942f29e788ac08daa9329de52aaa3415708 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -740,6 +740,7 @@ TEST_BUILTINS_OBJS += test-dump-split-index.o
 TEST_BUILTINS_OBJS += test-dump-untracked-cache.o
 TEST_BUILTINS_OBJS += test-example-decorate.o
 TEST_BUILTINS_OBJS += test-genrandom.o
+TEST_BUILTINS_OBJS += test-genzeros.o
 TEST_BUILTINS_OBJS += test-hash.o
 TEST_BUILTINS_OBJS += test-hashmap.o
 TEST_BUILTINS_OBJS += test-hash-speed.o

diff --git a/t/helper/test-genzeros.c b/t/helper/test-genzeros.c
new file mode 100644 (file)
index 0000000..9532f5b
--- /dev/null
+++ b/t/helper/test-genzeros.c
@@ -0,0 +1,21 @@
+#include "test-tool.h"
+#include "git-compat-util.h"
+
+int cmd__genzeros(int argc, const char **argv)
+{
+       long count;
+
+       if (argc > 2) {
+               fprintf(stderr, "usage: %s [<count>]\n", argv[0]);
+               return 1;
+       }
+
+       count = argc > 1 ? strtol(argv[1], NULL, 0) : -1L;
+
+       while (count < 0 || count--) {
+               if (putchar(0) == EOF)
+                       return -1;
+       }
+
+       return 0;
+}

diff --git a/t/helper/test-tool.c b/t/helper/test-tool.c
index 50c55f8b1a3baf2df88214824b01fb707966ebc7..99db7409b812898b461e75c8bd14e910f9e10e5c 100644 (file)
--- a/t/helper/test-tool.c
+++ b/t/helper/test-tool.c
@@ -19,6 +19,7 @@ static struct test_cmd cmds[] = {
        { "dump-untracked-cache", cmd__dump_untracked_cache },
        { "example-decorate", cmd__example_decorate },
        { "genrandom", cmd__genrandom },
+       { "genzeros", cmd__genzeros },
        { "hashmap", cmd__hashmap },
        { "hash-speed", cmd__hash_speed },
        { "index-version", cmd__index_version },

diff --git a/t/helper/test-tool.h b/t/helper/test-tool.h
index a563df49bf086b92eb24b3f90f6194eed059de81..25abed1cf2acc9e84cf1ed78eebe97c7c4d728ca 100644 (file)
--- a/t/helper/test-tool.h
+++ b/t/helper/test-tool.h
@@ -16,6 +16,7 @@ int cmd__dump_split_index(int argc, const char **argv);
 int cmd__dump_untracked_cache(int argc, const char **argv);
 int cmd__example_decorate(int argc, const char **argv);
 int cmd__genrandom(int argc, const char **argv);
+int cmd__genzeros(int argc, const char **argv);
 int cmd__hashmap(int argc, const char **argv);
 int cmd__hash_speed(int argc, const char **argv);
 int cmd__index_version(int argc, const char **argv);

diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index 094c07748aad423bff0eb8d5ff65ddceb3a4f5a6..80402a428f7735a031658a904d4f623f38e43464 100644 (file)
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -120,13 +120,7 @@ remove_cr () {
 # If $1 is 'infinity', output forever or until the receiving pipe stops reading,
 # whichever comes first.
 generate_zero_bytes () {
-       perl -e 'if ($ARGV[0] == "infinity") {
-               while (-1) {
-                       print "\0"
-               }
-       } else {
-               print "\0" x $ARGV[0]
-       }' "$@"
+       test-tool genzeros "$@"
 }
 
 # In some bourne shell implementations, the "unset" builtin returns